PALAEO-ENVIRONMENTAL STUDY AREA P1 NORTH-WEST COAST (YARMOUTH

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK

PALAEO-ENVIRONMENTAL STUDY AREA P1

NORTH-WEST COAST (YARMOUTH - BOULDNOR - NEWTOWN), ISLE OF WIGHT, UK

A STUDY OF THE ARCHAEOLOGICAL AND PALAEO-ENVIRONMENTAL EVIDENCE FOR COASTAL CHANGE ON THE YARMOUTH-BOULDNOR-NEWTOWN SHORELINE OF THE WESTERN SOLENT

Plate P1 Sea-level rise, salination and coastal vegetation changes in action. On the fringe of Newtown Saltmarshes these mature oak trees have been poisoned by salt-water invasion of their root systems. The root plates of healthy oaks stands just 0.4m higher. These changes repeat the processes of prehistoric times as seen in the pollen and dendrochronological studies of this coast. West Solent, Isle of Wight.


1. INTRODUCTION

The Solent sea between the Isle of Wight and the south coast mainland of the UK has been the subject of detailed study for the LIFE project. 13 palaeo-environmental study areas have been defined on the north and south shores of the Solent, described below. Figure P1 shows the distribution of these 13 sites.

2. LOCATION

The Western Solent is drowned lowland which has become an open seaway which now separates the Isle of Wight from the Hampshire mainland. The length of the Western Solent, from Hurst Narrows to Cowes is some 20km. Discounting the narrowing effect of a large shingle spit at Hurst Castle, its width is generally 4-5km. The depth of the drowned valley lies, mostly, around -20m OD but there is a marked and active deepening at Hurst Narrows where post-inundation scouring has incised the seabed to almost -60m OD. The mainland coast of the Western Solent is low-lying and it northern shore is characterised by extensive salt marshes which can extend as much a 1km from the Hampshire shore. Passing east towards Beaulieu River, the marsh gives way to an eroding beachhead composed of residual silts. There are also low cliffs cut by wave action on old gravel deposits. On the southern shore of the Western Solent the character of the coastline is notably different for here there is a total absence of salt marsh where coastal processes are actively eroding the coastline of the Isle of Wight. There are ria inlets at Yarmouth and Newtown (Plate P1) yet between these low-lying valleys there is a relatively high cliff-line where the Hamstead Clay is subject to active erosion. East of Newtown the geology changes to the soft sands and clays of the Bagshot Beds and here the cliff-line falls to a general height of some 5-10m. At Gurnard, the coastline rises again as it approaches Cowes and here there are hard ledges of Bembridge Limestone offering a natural sea-defence at the foot of a weak coastal slope. The Western Solent ends at Cowes where the submerged lowland is joined by the drowned river valley of Southampton Water. Passing eastwards the coalesced seaways become the Eastern Solent. This is a large ria inlet and natural harbour which is sometimes synonymously known as Spithead. Yarmouth is the only Isle of Wight port in the Western Solent. It lies opposite its mainland counterpart Lymington. The two medieval ports are separated by a ferry journey of 6km. Yarmouth is built upon a low-lying isthmus of Bagshot Sand and its height makes it vulnerable to sea-level rise. The boundaries of the town have been constrained by an estuarine feeder of the Yar river. It seems that this inlet may once provided a shallow anchorage south of the town but it has since diminished to become the drained valley of the Thorley Brook. The shoreline and feeder estuaries of the Western Solent comprises woodland and agricultural land which provide a rich and extensive ecological resource. There are many designations which protect this coastline. The Isle of Wight shoreline in the Yarmouth- Bouldnor-Newtown study area is protected under the planning designation of Heritage Coast.

3. MODERN GEOGRAPHY

Yarmouth is an historic port and town of modest proportions with a population of set around 1000 persons. Its economy is essentially based on fishing, yachting and tourism. The harbour of the town is formed a stone breakwater which shelters the mouth of the Western Yar river. An important feature of the harbour is the terminal point for the Lymington- Yarmouth car ferry. This is one of three ferry routes between the Isle of Wight and the mainland. The harbour is managed by independent Harbour Commissioners who are responsible for regulating all maritime activities within the harbour, the Yar river and also the anchorage or ‘roads’ lying offshore from the town. The town contains a very fine range of

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK historic buildings which are mostly of post 17th century date. For this reason all of the historic street plan has been designated a conservation area. The historic quality of the town is an important aspect of the town’s economy and for this reason the conservation of existing buildings and the prevention of flooding is very important. The ria inlets of the Western Yar and Newtown are natural wild-life habitats statutorily protected by the Solent and Southampton Water Ramsar designation. Other statutory designations include ecological Sites of Special Scientific Interest in the two valleys and the Heritage Coast definition for the exception scenic qualities of the coastline.

4. THE CONTEMPORARY COASTAL PROBLEM 4.1 The problem of coastal erosion

The Western Solent is a relatively young tidal seaway. Its floor and coastline are scoured by an asymmetrical cycle of currents in which the ebb tide runs at greater velocity yet short duration than the flood tide (Halcrow 1997, 2, 8.1). There is a net seaward flushing of coarse bedload currents and net input of suspended sediments into the inlets and estuaries. The tidal inlets form important sediment boundaries and they are scoured by ebb currents with stable configurations unless they are subject to major changes in coarse sediment availability. This trend for infilling is a legacy of the Holocene transgression of the Solent and it is represented by thick sequences of sediments which have accumulated in the mouths of the Yar and Newtown rivers. Onshore, these ria inlets are fed by very small feeder streams and it is evidence that most of the sediment which has accrued in the mouths of these rivers is of marine origin. Much of the supply of this sediment seems to be derived from the local eroding cliffs. The extent of cliff erosion is best seen at Bouldnor where land as high as 50m gives way to a slumping and retreating cliff-line where toes of new and soft landslides are removed by the sea. Here the Shoreline Management Plan predicts cliff recession as much as 130m during the next 70 years. East of Newtown, the cliff-line extending to Cowes is also retreating and here the recession is mostly calculated to be some 50-70m during a similar time period. Between 1909 and 1975 it has been observed that cliff-top retreat has generally exceeded that of mean high water and this has causes the cliff profiles to flatten at many of the fastest receding sites (Halcrow 1997,2, 8.2). LIFE palaeo-environmental investigations and observations in the Yar and Newtown inlets show that since the river valleys of this coastline have been drowned by the sea, their saltmarsh environments have mostly developed in a state of dynamic equilibrium as the level of the sea has risen. This development has taken place over several thousand years. During this time the capture and bonding of the sediment particles has been facilitated by the root systems of intertidal plant communities which have flourished in these sheltered environments. Change and diminution of these plant communities must now be seen as a direct threat to the stability of the coastline.

4.2 The problem of coastal protection

The Shoreline Management Plan for this study area recognises five shoreline management units between the mouths of the Yar and Newtown rivers (NEW3-NEW5). At the mouth of the Yar the harbour is defended by a steel training arm with an artificial rock toe and some toe piling. To the west, the valley floor is weakly protected by a shingle spit which is volatile in nature and is variably reinforced by lengths of timber breastwork, timber groynes and a length of armour breakwater. East of the harbour the medieval town is vulnerable to flooding and its frontage is protected by a stone walls which have been built to protect the numerous individual properties which face on to the Solent (NEW 4). The character and quality of this wall varies from property to property while each acts as a revetment to the low lying alluvium on which the old town stands. While coastal erosion and sea-level rise pose problems for this old seaward frontage to the town, the Shoreline Management Plan recognises that the principal risk of flooding occurs on the river frontage where no hard defences have been built. The southern sector of the town is similarly vulnerable to flooding where 19th and 20th Century development has carried properties to the edge of the old Thorley valley inlet.

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK East of the medieval town of Yarmouth, a narrow isthmus of land between the Solent and the old Thorley inlet is defended by concrete-capped steel piling and wooden groynes (NEW 5). These defences extend as far as a new coastal residential development at ‘Port la Salle’ after which the terrain rises to unstable and undefended cliffs at Bouldnor and Hamstead (NEW 4). At Newtown a drowned river basin is defended from the sea by two ancient shingle spits which confine a narrow approach into a dendritic array of creeks. These old natural barriers defend the floor the valley from wave attack (NEW7) but their natural sustainability is now threatened by overtopping and coastal erosion. Palaeo-environmental investigations included in the LIFE study show that the old flood plain and saltmarshes of the Newtown River can be traced offshore from the present spits and that this inundated land surface was occupied in Neolithic times an event confirmed by an absolute date of 2920-2500 cal. BC (GU-5341). Since that date the present spits have been superimposed on this surface and it is seems that they have migrated and reconfigured over time. Erosion of the spits occurs when the underlying saltmarsh sediments are subjected to high water wave attack. This is currently proceeding on the Eastern Spit which is now being overtopped and eroded at optimum high water. The loss of shingle supply to this spit may be humanly induced by an interruption in the sediment supply. Offshore, licensed mineral dredging operations were carried out on Solent Bank during the 1960's and 1970's and it has since become evident that a sediment path linked this area of seabed to the Newtown shore (Bray, et a.l. 1991). Loss of natural spit defences at Newtown pose unknown implications for the intra-harbour tidal regime and the extensive and highly sensitive marine wetland environments of the Newtown creek system. A coastal protection strategy of retreating the line is now contemplated for this coastline. This could be implemented by the recharge of beach shingle, a process which seems to restore that which had been severed by imprudent offshore extraction.

4.3 The problem of mineral dredging

Dredging for commercial and navigational purposes can be damaging to in-situ archaeological remains in the intertidal zone as well as those which lie in the direct path of the dredger as it moves across the seabed. Currently there are notable flaws in the consultation procedures which permit the national heritage to be threatened in this contexts. The Department of Environment and Transport for the Regions (DETR) does not have in-house archaeological expertise to participate in the consultation procedure for offshore mineral extraction licenses neither is the archaeological expertise of English Heritage included in the procedure. The most detailed and up-to-date coastal archaeological information is more often in the hands of the planning archaeologist who is responsible for the coastal Sites and Monuments Record. This archaeologist is best placed to accrue a steadily evolving picture of the archaeology of the seabed as it is revealed each year by the array of fishermen, divers and engineering interests active in local waters. There is, however, no automatic or statutory procedure to ensure that an informed curatorial view is obtained from this source. This means that no effective curatorial constraints are placed upon the dredging operator. In the Western Solent, at the mouth of Newtown Creek, Neolithic trackways and other prehistoric structures became exposed and eroded in the 1980s after off-shore sediment paths had failed to deliver the annual flow of sand and shingle to the western spit (Bray et al 1991). The source of the path lies in the vicinity of Solent Bank, an area formerly licensed and exploited for commercial mineral extraction.

4.4 Problems posed by All-Terrain-Vehicles (ATVs)

Opportune sorties, at low tide, with ATVs can be highly damaging to in-situ archaeological remains and these seem to be a new type of threat. Their impact has been observed in the intertidal zone at Newtown, Isle of Wight, where enormous tyre tracks have rolled over areas containing the Neolithic wooden structures. Damage of this kind seems come from two sources. Some damage is the work of `night ops' conducted for military training purposes. Others are more covert activities in which similar vehicles are used to rake up shell fish. Given that the most of the national coast offers uncontrolled access these activities should be considered a direct threat to preservation in situ.

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK 5. KNOWN HISTORY AND PALAEO-ENVIRONMENTAL SETTING

During the early Middle Ages Yarmouth, Lymington Newtown all began as successful ports and trading towns but since that time all have diminished in maritime importance. Within the study area Yarmouth has become a significant coastal tourism asset while Newtown has become a highly unusual deserted medieval port, virtually transfixed in time after a devastating French raid in the year AD1377. The inlets at Yarmouth and Newtown are both occupied by extensive saltmarshes and reed beds which blanket important sediment archives. Coring, analysis and dating of these sediments has traced the evolution of these inlets to the early/middle Holocene.

6. A GEOLOGICAL AND GEOPHYSICAL INVESTIGATION OF THE SUBMERGED CLIFF AT BOULDNOR

6.1 Organising the geophysical investigations

The submerged cliff at Bouldnor represents a rare geological feature in that an apparently major vertical to near vertical cliff system has survived a major Holocene transgression. Further, the discovery in the eighties, of extensive in situ peats and substantial tree boles and root systems, dated to c. 6300 cal. yrs BC, and located at the base of the cliff suggested that the area represented a submerged prehistoric landscape with a high archaeological potential. An integrated geological and geophysical investigation of the submerged cliff was undertaken by the School of Ocean and Earth Science at the University of Southampton, as part of this EU LIFE programme. The key objectives were: a) to morphologically characterise the submerged cliff at Bouldnor, by conducting

geophysical surveys; b) to identify the composition and structure of the cliff and to investigate the relationship, if

any, to the major terrestrial cliffs on the adjacent shoreline; c) to aid the reconstruction of the prehistoric landscape in conjunction with the

archaeology investigations of the Hampshire and Wight Trust for Maritime archaeology and the palaeo-environmental work of Dr Rob Scaife.

6.2 The geology of the Bouldnor study area

The Solent and surrounding estuaries and inlets are the latest of a series of shallow-water bodies that have existed since a relatively deep Cretaceous ocean was uplifted c. 65 million years ago. A marine influence on the depositional environment continued within the Hampshire Basin and the Isle of Wight area throughout the Tertiary, however, significant fluctuations in sea-level during the Palaeogene resulted in freshwater, lacustrine and brackish conditions being present in the sedimentary record. This cyclicity has produced many environments including: shallow marine shelf to beaches, tidal flats, coastal marshes, lagoons, estuaries, rivers and lakes. Muds and sandy muds dominate much of the sedimentary succession although locally sands can be important. Within this area no Tertiary deposits younger than the lower Oligocene have been recorded either as a result on non- deposition or significant erosion post the Alpine (Miocene) orogeny, the next deposits to be recorded being of Quaternary age. The main Hampshire Basin is divided into a number of concealed subsidiary grabens separated by stable horsts. These features probably developed during the Mesozoic, tectonically fracturing an earlier pre-Mesozoic stratigraphy that had already been deformed by the late-Paleozoic Variscan orogeny. The geology of the areas can be defined by two distinct structural trends: one east to west and one north-west to south-east. The east-west trend is represented at depth by the fault bounded horst and graben structures. However, on the surface these faults are represented by a series of asymmetric anticlines and monoclines (e.g. the dominant Isle of Wight Monocline). Until recently these folds were assumed to be due to northward compression during the Alpine orogeny but it is currently thought that they represent the draping of plastic Mesozoic and Tertiary strata over active basement faults. The north-west to south-east structural trend truncates and laterally displaces the east-west features and are again believed to have their origins with the early

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK Variscan and Mesozoic tectonic events. During the Tertiary (and particularly during the Alpine Orogeny) the majority of these ancient features were re-activated. This activity resulted in the general bowl shaped warp of the Hampshire Basin, other more gentle east-west warps and the draped style of sedimentation indicative of the Tertiary sediments in this area. The Pleistocene geology of the Hampshire Basin is dominated by the sequential development of a major, eastward flowing, ‘Solent River’ system. The hypothesis of the ‘Solent River’ system dates back to Darwin-Fox in the mid-nineteenth century. In the late nineteenth century further pioneering work on this feature was advanced by Reid who recognised that a series of widespread gravel deposits found throughout Hampshire, represented fluvial deposition, in successive stages, over a long period of geological time. The Geological Memoirs produced in the early twentieth century divided these deposits into ‘Plateau Gravels’ and ‘Valley Gravels’ on the basis of their height and position relative to the modern rivers. These included riverine deposits, which related to the Solent River system. These show a broad west to east aggradation from c. +123m OD down to sea-level. Plateau and Valley Gravels, are composed almost exclusively of flint with occasional pebbles of sarsen (silicified sandstone). They rarely exceed 5-6m in thickness and are undisturbed by faulting or folding. These deposits lie on a series of terraces around the Hampshire Basin and descend from levels of c. +123 m OD in the northern part of the area down to -20 m OD at the mouth of Southampton Water. At this same locality, the floor of the ‘Solent River’ is identified at a depth of -24.4 m OD. Further, seismic surveys within the East Solent have been able to trace the submerged base of this river to a maximum incised depth of -46mOD east of the Nab Tower.

By the beginning of the Pleistocene the local rivers had already been established in approximately their present positions on a coastal plain. During periods of glacial advance and lower sea-levels the ‘Solent River’ complex developed, depositing sheets of Plateau and Valley Gravels in the East and West Solent. During the inter-glacials sea-level rise flooded the lower parts of the river system to form broad estuaries in the Solent region. After the Hoxnian Interglacial sea-level fell, the estuary disappeared and some of the gravels, below +30m OD, were deposited. During the following Ipswichian interglacial a broad estuary again developed as sea-level attained at least +7.6m OD. Again the sea retreated during the Devensian, with the Solent River excavating a channel to even greater depths and connecting with the westward flowing extension of the River Seine. Borehole data suggests the old river channel of Southampton Water passed beneath Calshot Spit, continuing south- easterly under the Brambles bank before joining the main channel which descends eastwards through the Solent. Although the morphology of the submerged sections of the ‘Solent River’ have been clearly identified in the East Solent and in Poole and Christchurch Bay, little evidence has been found on the nature of the fluvial system in the West Solent region. The seismic investigations that have been undertaken identify the area as being covered by a thin veneer of gravel (< 2m) lying directly on bedrock. This is possibly the result of the very strong currents active in the west Solent (> 2ms-1 surface currents) which have resulted in both extensive post-transgression erosion. This isparticularly evident at the Hurst Narrows where the seabed has been excavated to a depth of c. –60 m OD) and the development of extensive gravel bedforms throughout the area. The final stage in the geological history of this region is one of a marine transgression post- dating the last glacial maximum approximately 18000 yrs BP. Little is known of the immediate post-glacial period but significant work by Long and Scaife over the last five years has started to provide a reliable sea-level record for the Solent system during the Holocene. In brief, sea-level in the Solent has risen rapidly since c. 6500 cal yr BC, from c. –12 m OD to c. –2 m OD at c. 3500 cal yr BC. Between c.3500 cal. yr. BP and c. 600 cal. yr. BC sea- level rose to c. –0.6 m OD and thence to its present level (c. +2m OD).

6.3 Geophysical and geological techniques The submerged cliffs were investigated by a combination of three different geophysical techniques: swath bathymetry, Chirp sub-bottom profiler and high-frequency side scan sonar. In addition, a review of the available geological literature for the Bouldnor region was

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK collated and a composite lithostratigraphic column was produced. Reference was made to the core material obtained for the palaeoenvironmental analysis, but as a maximum penetration of only 2 m was achievable this data could only be used to calibrate the surficial stratigraphy. Finally, geomorphological mapping of the terrestrial cliff was undertaken, the data being based prinicipally on aerial photographic work from 1983 and 1997.

6.4 Swath bathymetry The swath bathymetry system, ISIS 100, designed by Submetrix Limited, was used for the Bouldnor survey. This hull-mounted system comprises two sonar transducers, an integrated motion reference unit (MRU), Differential GPS and a UNIX based acquisition system enabling a real-time display and storage of the seabed bathymetric data. The ISIS 100 system is a swath-sounding interferometric sonar system. An interferometer measures the range and angle of the incoming sound wave fronts in a time sequence of samples - a difference in the phases between sound waves, gives the angle. Slant range is obtained from the time of the sample and speed of sound. The cross-track vertical resolution of the system is 7.5 cm, whilst the angular resolution is 0.04°. Parallel survey lines were run between Yarmouth and Hamstead Ledges in a north-east to south-west direction i.e. parallel to the shoreline. One survey line was also made following the contour of the submerged cliff. The range obtained during the survey was 40 m on each side (80 m swath), therefore, the parallel tracks were run at 35 m intervals to ensure total ensonification of the area. The approximate speed of the vessel throughout the survey was 4 knots. The stored data were corrected for tidal height throughout the time of the survey and filtered to remove any data spikes using the Submetrix post-processing software. The final data was gridded at a 3m bin size.

6.5 Chirp sub-bottom profiler

Chirp is a high-resolution, digital, frequency-modulated (FM) sub-bottom profiling system that is capable of obtaining cross-sectional profiles of the sea-bed with a vertical resolution of decimetres and a maximum penetration depth of 30 to 40 m in unconsolidated sediments. These systems can operate in shallow water depths (> 2.5m) and can acquire data in an industry standard format (SEG-Y) which enables its straightforward transfer to off- line processing packages. The Chirp source differs from conventional, single frequency, sub- bottom profilers by having a repeatable, swept-frequency, pulse. This results in the data having a significantly improved signal-to-noise ratio (i.e. greater clarity), whilst the wide range of frequencies within the single pulse limits the classic trade-off between penetration and resolution. The Chirp data collected at Bouldnor was acquired using a GeoAcoustics 2 to 8 kHz swept pulse, with a 32 ms pulse length and a transmit rate of four pulses per second. This pulse provides an optimum vertical resolution of ± 0.125 m and an optimum horizontal resolution of 1.2 m in an average water depth of c. 10 m.

For the Bouldnor surveys the Chirp system was mounted onto a surface-towed catamaran allowing the survey to be carried out in water depths as little as 2.5 m. The data were processed by the GeoAcoustics Sonar Enhancement System (SES) SE880 (version 3.1). Navigation was provided by a Trimble 4000SE GPS with Focus FM differential signal (±3 m) together with Hypack, logging software and Helmsmans display. Both shore-parallel and shore perpendicular survey lines were acquired (Figure P1.2).

6.6 Side scan sonar The sidescan sonar survey was carried out at the same time as the sub-bottom profile survey described above. The GeoAcoustics dual frequency sidescan system was used using the industry standard 500 kHz (actual frequency 410 kHz) pulse. The system was mounted on the surface-towed catamaran along with the Chirp system. The same Sonar Enhancement System, GPS and Hypack software package were used for the positioning, recording and viewing of the sidescan images as for the Chirp images. Side scan sonar

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK data, from the 500 kHz (410 kHz) GeoAcoustic source provided data over a maximum range of 72 m per channel, with an along track and across track resolution of 1.26 m (at maximum range) and 0.25 m.

6.7 The result of the geophysical survey; submerged cliff morphology ; along - slope variability

From the computer generated contour plots, a greatly enhanced view and understanding of the submarine landscape can be attained. Figures P1.3 and P1.4 show a Digital Elevation Model and a two-dimensional colour plot superimposed with the Ordnance Survey Map for the area respectively. Using the data gathered for the survey area GR435500, 90500 to GR440000, 92300, and breaking this into a series of elements, individual features can be recognised, the principal ones of which include:

1 From the south west corner of the survey a distinct topographic change in the break-in- slope can be seen around GR437150, 90500. Here the seabed descends in a north- westerly direction from a regional high plateau extending back to the shoreline. The descent is about 10m over a horizontal distance of 40m, but there is also evidence of two terraces at the foot of the slope. These terraces possess a shallower angle of descent, and width of approximately 8m. Beyond these the seabed remains fairly uniform with a few undulations in height. The break-in-slope feature however is not uniform, but rather consists of a series of about 60m embayments lying adjacent to one another. This therefore suggests localised failures of the submerged coastal slope. This profile continues to run parallel to the coastline to approximately GR437680, 90680. The lower level terrace meanwhile gradually builds out from the shore to give a maximum width of some 100m at GR437550, 90760. This feature possesses a very shallow slope of 1:100 (0.6°).

At GR437680, 90680 there is a sudden seaward extension of the shelf-break of some 70m, terminating in one of the steepest profiles of the survey. Here there is an approximate descent of 12m at a slope angle of 25°. With this sudden change in slope shape, the terracing at its foot ceases to exist. Continuing in a north-easterly direction, the relief of the outcrop begins to diminish in height. This produces a gentler break-in- slope transition from the shore to the centre of the channel, and results in there being no terraces present.

At GR438050, 90900 there is again evidence of terracing at the foot of the slopes descent, but not as pronounced as before at only 2-3 metres. Although the slopes profile is not as steep as earlier sections, there still exists a prominent shelf edge running from GR438200, 91100 to GR438500, 91400. This break-in-slope continues to run parallel to the shoreline, descending in a north-westerly direction for about 40 metres. Around the base of the slope there are small zones of bulging terraces, which could also be evidence of localised failures of the submerged slope.

2 Between GR438500, 91200 and GR438800, 91450 there is a distinct ‘build-out’ from the shoreline of some 100m from where the line of the main submerged break-in- slope would have continued. This area gently descends in a north-westerly direction into the Solent, but then terminates with two additional protrusions, each approximately 50m in width. The first of these continues in the same direction as the build-out, before gently petering into the profile of the main seabed. The other however extends an additional 100m northwards, before linking into a narrow ridge that runs for 250m parallel to the shoreline, and 400m offshore from the Mean High Water mark. This feature then terminates in two topographic high points.

3 Immediately after the build-out, the shelf-break once more becomes evident, running from GR48700, 91800 to 439500, 91900. Here the horizontal descent typically


stretches for 40m, but at the foot of the slope small terraces can be seen of about 10m in width. The break-in-slope continues in the same direction as the earlier slope profile, and is about 70m shoreward of the offshore ridge.

4 At GR439350, 91800 to GR439750, 92000 the topography possesses a smoother slope that descends gently into the main channel. Two gradually sloping build-outs exist at GR439450, 91850 and GR439650, 92000, but are separated by a very prominent topographic high-point at GR439530, 91940. This feature is elongated to the north-east being elliptical in shape and approximately 100m by 75m along its main axes. This raised bedform is shown on the 1973 Ordnance Survey map as a mud-bank, although the shape is considerably different to that of this 1998 survey. This would suggest that the submerged coastal morphology in this location is strongly related to the tidal/current regime, and therefore will be subject to on-going change.

5 The Hamstead Ledges can clearly be seen between GR439800, 92050 and GR440050, 91150 as two distinct bands extending westerly from the shoreline at 278°-285° from Grid North. The southern ledge is surrounded by gently sloping terrain, possibly in terraced form, and this continues into the sheltered section between the ledges. To the north of the northern ledge there is a sudden change in depth with closely spaced contours visible. This would suggest a change in the geological structure of the region, with the weaker stratum being eroded by marine processes. However the ledges additionally mark the point where the morphology of the coast changes with the presence of the Newtown Estuary. This could therefore be a change-point in the current/tidal regime and consequently lead to different actions being experienced to that of the main Bouldnor and Hamstead shoreline.

6.8 The submerged cliff; across -slope variability Selected profiles from along the entire cliff show the marked variability in slope angle from near vertical to <5°. To date a full investigation of this slope variability has yet to be undertaken (although a basic assessment is presented by Stokes, 1999). It is hoped that work extending beyond this LIFE programme will quantitatively assess lateral slope angle variability.

It is worth noting that the terracing of the cliff sections identified from the swath bathymetry data was even more marked on the side scan sonar traces with in places up to seven individual ‘terraces’ being identified. The cause of this terracing has yet to be determined albeit Stokes (1999) speculates on potential causes. This again will represent an area of further investigation after the conclusion of the LIFE programme.

6.9 The composition of the submerged cliff at Bouldnor In order to investigate the internal structure of the submerged Bouldnor cliff a series of shore parallel and cross parallel high-resolution Chirp seismic lines were acquired. Figure P1.5 shows the Chirp line from Hamstead Ledges in the north-east to Yarmouth in the south-west. Seismo-stratigraphic analysis of these Chirp traces identify two distinct sequences within the area surveyed. The principal sequence (Sequence 1) represents a package of continuous parallel reflectors which conformably overly each other from the lowest limits of penetration (c. 22 m) up to the unconformable boundary with the second sequence (Sequence 2). A within- sequence unconformity is identified between reflectors D and D1 to F3. This is a layer approximately 1.75 - 3.5 m thick at the seabed. The parallel reflectors describe an asymmetrical syncline, plunging with an apparent dip of between 0.4° and 2.6° to the southeast. The north-easterly limb has an apparent dip of c. 6° to the south-west whilst the south- westerly limb has an apparent dip of c. 1° to the north-east, with the synclinal axis occurring at c. GR438800 91400.

Sequence 2 comprises three distinct facies, Facies 2.1, 2.2 and 2.3.. Facies 2.1 is found at the base of the submerged cliff, from Hamstead Ledges in the north-east to the south-

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK western end of Bouldnor Cliff. It presents a very strong reflector at the seabed with another strong reflector below and high backscatter in between. The surface is very uneven, often forming a line of troughs and crests with amplitudes of between 0.5-1.2 m and at wavelengths of between 6-15 m, with a reduction in overall dimensions from the north-east to the south-west. These same features are identified in both the swath bathymetry data and the side scan sonar data in the region directly seaward of the cliff. Here the axes of what can be confidently interpreted as gravel bedforms1 have a north-west to south-east orientation. These bedforms also display asymmetry with gentle north-easterly facing slopes and steeper south-westerly slopes.

Facies 2.2 is situated on top of the cliff in the north-east set of profiles, is about 1.75 m thick and is represented by a very strong double reflector at the seabed. Facies 2.3 is located on top of the cliff in the south-westerly set of profiles and has a maximum thickness of 3.5 m. It comprises a weaker double reflector at the surface with low backscatter in between and one internal reflector, over a strong double reflector with high backscatter in between. The complete seismo-stratigraphic column compiled from all of the traces is presented in Figure P1.6(a) and (b).

Finally, at several localities along the top of the cliff the sonar imagery identifies extensive areas of slumping (particularly in the south-west of the area) which through correlation with the terrestrial record (see below) can be shown to represent the toe deposits of sub-aerial cliff failures.

In the absence of deep cores calibration of Seismic Sequence 1 proved to be the most difficult part of this work. However, the overall structure of Sequence 1 (a south-easterly plunging synclinal structure) suggested that comparison with the Late Eocene and Early Oligocene sediments of the area was worthwhile. Firstly, the location of the synclinal axis of the Sequence 1 reflectors correlates exactly with the axis of the Bouldnor syncline identified from the terrestrial deposits. The continuity of reflectors and their overall conformable nature would correspond well with the generally uniform deposition of marls and clays which are typical of these Palaeogene sequences (See Figure P1.6(b)). Further, the strong individual reflectors clear identified on Figure P1.5 could be easily produced by the occasional horizons of freshwater limestones, sand horizons and occasional indurated deposits present within these sediments. In order, however, to confirm this interpretation and to locate the exact part of the stratigraphic column in which the cliff had been formed a combination of all the data sets was required.

Overlying the swath bathymetry with an aerial photograph (courtesy of the Environment Agency 1983 survey) of the Hamstead Ledges at the north-eastern tip of the cliff section enabled the identification of the prominent limestone bands of the Late Eocene Bembridge Limestone Formation. Figure P1.7 clearly shows that these limestone horizons extend offshore to form distinct north-west to south-east trending topographic highs, these feature also being identifiable in both the side scan sonar and Chirp data.

Superposition of the Chirp survey line on the swath bathymetry data showed that horizon A (Figure 4 and 5A) coincided with the a major limestone unit within the Bembridge Limestone Formation thus enabling the base of Seismic Sequence 1 to be correlated with this part of the lithological stratigraphy. Having provided strong evidence that Sequence 1 represented Late Eocene material, the thickness of the Sequence could be converted from the two-way travel time values in which the Chirp data is recorded to actual thicknesses in metres using a velocity conversion of 1660 ms-1. This value was derived from a refraction line experiment undertaken across the West Solent by Keith Dyer in 1969. This calculation gave a thickness 11 Interpretation based on comparison with the work of Langhorne et al, 1986 who investigated gravel bedforms in the West Solent.

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK of c. 22 m above the Bembridge Limestone Reflector (A) which would place the top of the submerged Sequence towards the top of the Bembridge Marls Member and into the Hamstead Member of the Upper Bouldnor Formation. Although still lacking direct core calibration this work suggests that the submerged cliff between Hamstead and Yarmouth is founded in Late Eocene sediments.

Consequently it is proposed that during its pre-transgressive phase the southern margin of ‘Solent River’ system in the West Solent was bounded to the south by a major cliff system. It is further proposed that the submerged and terrestrial cliffs along this section of the Isle of Wight coastline are intrinsically linked, with the current 100 – 350 m gap between the base of the terrestrial cliff and the start of the submerged cliff (at c. –4 m OD) having formed in response to the period of relative slow sea-level rise between c. 3500 cal. yr. BP and c. 600 cal. yr. BP.

6.10 The terrestrial cliff at Bouldnor On examination of the terrestrial cliffs at Bouldnor and the adjacent Hamstead Cliffs, several notable features can be identified. One of the most striking features is the array of fallen trees lying across the shore and the foot of the coastal bluffs. These are illustrated here. These result from the actions of the sea eroding the toe of the coastal slope, leading to the undermining of the cliff and vegetation above. This feature can be seen on slopes of all gradients, and is a visual marker to the presence of landward retreat. The greatest accumulation of these tree trunks can be seen on the western sides of the Bouldnor Cliff region, where the vegetation is dense near the edge of the shore.

At the foot of the cliff there can be seen several other features. Along the less steep sections of the cliff, there exist a number of toe bluffs, elevating the vegetation cover from the marine environment. Here, the in situ soil is eroded through small-scale failures or through the removal of material through wave and tidal action. This environment could be considered a potential analogy with to the peat and tree strewn platforms identified at the base of the submerged cliff. The presence of in situ tree boles at this submerged locality the pollen record both suggest an environment dominated by fluvial activity in the pro-cliff region prior to the transitional phase of Solent inundation.

Movements of the cliff can be identified at several sites despite the main hinterland of the cliff being covered by dense vegetation. Coastal slumping is present, and illustrates that failure can create benches as well as channeled slides. Mudslides, renowned in this region, for can be identified by their snouts which protrude on to the shoreline (Plates P1a and P1b). These create an undulating coastline morphology which often makes passage of the shore impossible at high water.

From the examination of the two sets of geomorphological maps a number of trends can be identified in an area which is continually undergoing changes from mass movement processes. The overall trend appears to suggest that the western side of Bouldnor Cliff and the entire Hamstead Cliff is undergoing degradation from compound sliding. Between these points, the cliff is subjected to a combination of this form of sliding and mudslides, producing strong evidence in the form of a highly visible scarred landscape.

The one constant which was identified during the study period was that the lower lying relief between the main Bouldnor and Hamstead Cliffs had remained stable. This can probably be attributed to the presence of low gradients which were not steep enough to cause large failures. However, recent housing development within this area has excluded part of the slope from examination and analysis. This development has caused the vegetation cover to be removed from the gentler slopes where the soil has been disturbed by construction activity.


6.11 Discussion on the submerged cliff at Bouldnor This phase of the project has presented hypotheses for the:

a) composition and structure of the submerged cliff

b) the relationship of the submerged cliff with the terrestrial Bouldnor and Hamstead cliffs

c) the dominant controls on terrestrial cliff failure and thus providing a potential analogue for movement on the steeper parts of the submerged cliff

However, to date, a major problem has arisen in the integration of the Holocene data identified from the in situ short cores and the from the archaeological survey of the submerged Mesolithic site. The sediments exposed in the submerged cliff record a sequence of intercalated freshwater, brackish and marine deposits which are typical of the sedimentary sequence found at other sites around the Solent. This sequence of deposition provides a coherent story of changing coastline morphology in response to a sea-level rising at a variable rate throughout the Holocene. Of particular note is the burial of the in situ oak boles and collapsed material beneath part of this sedimentary sequence, at the toe of the cliff in the locality of the Mesolithic site. Sedimentological analysis precludes the possibility that these overlying sediments are part of toe deposits produced by cliff failure yet the presence of Late Eocene horizons with a few decametres of the cliff edge precludes extensive shoreward deposition of Holocene material. Consequently, the actual relationship between these two intricately linked environments has yet to be deduced. Despite the lack of closure between these two models, this work has demonstrated the importance of slightly larger scale geological studies when interpreting attempting to interpret palaeo-landscapes.

6.12 Biblography for the the geophysical study The terrestrial geological background to this work was collated from the following key references:

Allen, L.G. and Gibbard, P. L. (1993) Pleistocene evolution of the Solent River of Southern England. Quaternary Science Reviews, 12, pp 503-528.

Allen, M. .J. and Gardiner, J., 2000. Our Changing Coast: A survey of the intertidal archaeology Langstone Harbour, Hampshire. CBA Research Report 124.

Bird, E. (1997) The Shaping of the Isle Of Wight. Ex Libris Press, Bradford-on-Avon. 175 pp.

Daley, B. and Edwards, N. (1971) Palaeogene warping in the Isle of Wight. Geological Magazine, 108, pp 399-405.

Dyer, K. .R. (1969) A seismic refraction line across the Solent. Geological Magazine, 106, pp 92-95.

Dyer, K. R. (1971) The distribution and movement of sediment in the Solent, Southern

Dyer, K. R. (1975) The buried channels of the ‘Solent River’, Southern England. Proceedings of the Geologists’ Association, 86, pp 239-245.

Dyer, K. R. (1980) Sedimentation and Sediment Transport. In: The Solent Estuarine System; An Assessment of Present Knowledge. Estuarine Report no. 22. pp 20-24.

Insole A., Daley B. and Carbe A., 1998. The Isle of Wight Geological Association Guide, Number 60, pp.23, 114-119

Melville, R.V. and Freshney E. C. (1982) British Regional Geology - The Hampshire Basin and adjoining areas, 4th Edition. Esturiane Publication, HMSO. 146 pp.

Nicholls, R. J. (1987) Evolution of the upper reaches of the Solent River and the formation of Poole and Christchurch Bays’,. in K. E. Barber (ed.), Field Guide to Wessex and the Isle of Wight, Quaternary Research Association, Cambridge University Press. pp 99-114.


Velegrakis, A. F. (1994) Aspects of Morphology and Sedimentology of a Transgressional Embayment System: Poole and Christchurch Bay, Southern England. Unpublished PhD thesis, Department of Oceanography, University of Southampton.

Velegrakis, A.F., Dix, J. K. and Collins, M. B., 1999. Late Pleistocene/Holocene evolution of the upper reaches of the Solent River, Southern England, based upon marine geophysical evidence. Journal of Geological Society of London. 156: 73-87.

West, I. M. (1980) Geology of the Solent Estuarine System. In: The Solent Estuarine System: An assessment of present knowledge. Esruarine Publication, Series C, No.22. pp 6-17.

White, H. J. O. (1921) Short Account of the geology of the Isle of Wight. Memoirs of the Geological Survey, G.B. HMSO.

7. PALAEO-ENVIRONMENTAL INVESTIGATIONS OF SUBMERGED SEDIMENT ARCHIVES IN THE WEST SOLENT STUDY AREA AT BOULDNOR AND YARMOUTH

7.1 Introduction to the palaeoenvironmental study and sea-level change

Whilst the peats of the Eastern Solent coastline and Southampton Water have now been studied in some detail, similar deposits in the west Solent region have only been examined in a piecemeal fashion. Previous palaeo-environmental data are few with information coming only from Hurst Castle Spit (Nicholls and Clarke 1986) and some earlier examinations of the Western Yar at Yarmouth Bridge (Devoy 1973, 1987). Peat sequences submerged in deep water along the coast between Yarmouth and Newtown Creek were originally identified as Holocene by David Tomalin and the writer in 1976. This sediment material comprised peat and grey silt/clay which was dredged from the sea bed by inshore fishing vessels. Preliminary pollen analysis demonstrated the potential of these peats to produce well preserved pollen. One sample was also identified as coming from an earlier interglacial period (possibly Ipswichian; Oxygen Isoptope Stage 5e.). This might be related to the offshore palaeochannel at Newtown.

These peat and mineral sediments at Bouldnor were first observed underwater by the the diving team of the Isle of Wight Maritime Heritage Project in 1987. This survey found a three-fold peat sequence which was exposed in a submerged cliff. (for location see Figure P1.4). Only small and inadequate core samples were initially obtained. The presence of sand also made pollen analysis difficult. These early analyses suggested a date range from the early middle Holocene (Flandrian Chronozone II; the Atlantic period to late Holocene (Flandrian chronozone III). This was sufficient to indicate that this sediment archive had accrued during eustatic changes which had led to submergence by rising sea-level. A single radiocarbon date of 7230 +/- 110 BP or 6380-5840 cal. BC (GU-5397) was obtained from wood contained within the base of the lower peat. Along with the pollen, this similarly confirmed a late-Boreal/early Atlantic age for the start of the sequence.

Although the submerged peat and sediment sequence was recognised as being important, the logistical problems of obtaining samples (cores) suitable for pollen analysis were great. This was due largely to the tidal range and flow of the Solent which allowed diving only at slack water. Until liaison with the Hampshire and Isle of Wight Trust for Maritime Archaeology, sampling was not possible. Techniques have been developed whereby divers could readily obtain continuous cores and monoliths providing suitable, continuous profiles from which sequential pollen samples could be obtained and the stratigraphy described (in the laboratory).


Litho- and bio-stratigraphical examination of these cores (see Figure P1.8) have been compared with an estuarine core obtained from the Western Yar River underneath Yarmouth (west) Spit and the earlier Wootton-Quarr Project (Tomalin et al. forthcoming).

These investigations have been undertaken for the LIFE project providing pollen and diatom data from the submerged stratigraphical sequences. Radiocarbon dating of these sites has allowed reconstruction of the vegetation and environment from c.8000 Ka. BP and along with the lithostratigraphical analysis and sub-surface profiling (Dix et al.) has enabled a model to be created of the development of the North West Wight coastline. This development is closely linked to relative sea-level change (RSL) and radiocarbon dates from these sites have been fitted within the Solent sea-level/altitude graph (Long and Tooley 1995; Long and Scaife forthcoming) and to establish an independent time-altitude graph for Relative Sea-level (RSL) in the Western Solent. Ultimately this will be compared with more regional data from southern England (Long 1992; Long and Innes 1993, Long et al. 2000).

This section presents the results of environmental analyses including pollen, spores, diatom analyses and the stratigraphy of the sites examined at Bouldnor Cliff, Yarmouth and additional comparative sites in the Eastern Solent at Ranelagh (North) Spit. The Bouldnor sequence is considered to be a valuable archive of the position and development of sea-level during the last 8000 years of the Holocene. The sediments here appear to have formed in a larger estuary complex of which the present Yar estuary remains whilst much has been submerged and/or eroded by the Solent during the later Holocene (the last 2 Ka.). Comparisons and correlation’s of the Bouldnor sequence and the Western Yar are made. In addition to studies based in the Western Solent, sequences at Ranelagh North Spit on Wootton Haven and in Sandown Bay have also been examined in this study. Both provide data for periods which are not available in the Yarmouth and Bouldnor archive. At Ranelagh North, minerogenic silts overly peats dated to 2680+/-60BP (2920-2610 cal. BC) (Oxa- 7163) to 3800+/-60BP (2470-2040 cal. BC) (Oxa-7164) thus providing clear evidence for the late prehistoric, final phase of Solent inundation and coastline development.

At Bouldnor, the upper peat is typically eroded by the transgression. Sandown bay at the site of the new waste treatment plants and at the proposed sewage outflow pipe has also yielded peat relating to Holocene changes in sea-level and in the latter particularly, an early Holocene (Chronozone Ia) submerged peat which fills an early Holocene palaeochannel. These deposits accumulated at a time prior to the first clear evidence of post-glacial marine transgression and will provide evidence for early Holocene tree and shrub migration into southern England after the close of the Devensian cold stage at c. 10,000Ka. BP. Data from these sites add substantially to the more geographically focused studies undertaken along the coastline of the North East coast (at Wootton-Quarr; Tomalin et al. forthcoming).

7.2 Methods of analysis

To obtain evidence of Holocene sea-level change and past vegetation and environment, a number of techniques have been integrated. These can be divided into three broad methodological aspects: sampling; sediment description and microfossil extraction techniques and data handling.

7.3 The calculation of Relative Sea-level Rise (RSL) To address the question of changes in relative sea-level (RSL), it is now accepted that time/altitude graphs of sea-level is the most acceptable way of demonstrating Holocene changes. Such a graph is made up of sea-level index points each of which represents a dated and accurately measured height (Ordnance Datum) of peat and sediment contacts representing stages of coastal sedimentological change. This basic information should be backed up by litho- and biostratigraphical studies including pollen and diatoms which establish whether the peat or mineral sediments in question are truly related to eustatic changes i.e. they are not earlier, non-sea-level geomorphological features such as the palaeochannels of earlier drainage systems. This methodology has been established and

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK described by Tooley (1978, 1979) and Shennan (1982, 1986, 1989, 1994) and used along the south coast at Romney Marsh especially Long 1993; Long and Innes 1993). It is this

basic approach which has been utilised in both the earlier Wootton Quarr studies (Long and Scaife in Tomalin et al. forthcoming) and the LIFE sampling programme.

In all of these studies samples were taken from the upper and lower peat/silt contacts in a range of intertidal, and submerged contexts. All of these stratigraphic units were fixed with reference to the U.K. national Ordnance Datum (OD) at Newlyn These contacts represent marine transgressional/regressional contacts. Shennan established that these contexts formed within +/- 0.20 metres of MHWST (Shennan 1982). The Solent requires further calibration with the index point being lowered to mean sea-level by subtracting the MHWST value from the observed altitude of the index point. This is due to the variation in the height of modern tide levels in the Solent area. The final result provides changes in mean sea-level (MSL). Obtaining these data has been intricately linked with radiocarbon dating and biostratigraphical (largely pollen analysis) of the sediments providing local and regional environmental data. From this a suggested general model of the processes of intertidal peat formation has been produced (Long et al. 2000).

7.4 Radiocarbon measurements

Samples for radiocarbon dating have been taken in close association with litho- and biostratigraphical studies. Material has been obtained from monolith columns and cores obtained from the underwater site at Bouldnor Cliff (see Momber this volume) and Sandown Bay and from bore-holes at a number of estuarine sites containing deep sediment fills (Wootton Haven, Newtown, Western Yar at Yarmouth Spit). Absolute radiocarbon measurements have been obtained from the Beta Analytic, Oxford and East Kilbride dating laboratories. Measurements have been calibrated into calender years using the programme of Stuiver and Reimer (1993). These dates are plotted on the time/altitude graph of Relative Sea-level (RSL) at the two sigma error. Because of the vertical compaction of sediments and inherent error, the vertical extent of the data is fixed on the RSL curve at +/- 0.5 metres. These results have been given in Volume 1.

7.5 The analysis of pollen and diatom microfossils

Samples for pollen analysis have been obtained using hand corers (Russian/Jowsey) and gouges (Eijelkamp) and mechanical/powered corers (Cobra) with 1 metre long chamber of 10cm to 4 cm diameter. In the special case of the submerged peat and mineral sediments at Bouldnor, both core and monolith samples were obtained underwater by divers of the Hampshire and Isle of Wight Trust for Maritime Archaeology.

All samples cores and monoliths were stored in the laboratory of the University of Southampton (Geography and SOC) where they were described and sub-sampled for pollen, and diatom analyses and for radiocarbon dating.

7.6 Pollen extraction procedures

Standard techniques were used for the extraction of the sub-fossil pollen and spores (Moore and Webb 1978; Moore et al. 1992) with the addition of micromesh sieving (10u) to aid with removal of the substantial clay fraction in these alluvial sediments. Extraction comprised:

-Samples of 2-4 ml size.

-Deflocculation with 10% NaOh

-Sieving at 150u for removal of the coarse fraction

-Sieving at 10u (residue kept) for removal of clay

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK -Hydrofluoric acid (boiling) digestion of silica

-Erdtman's acetolysis (Sulphuric acid/Acetic Anhydride 1:9)

-Washing/centrifuging

-Staining with aqueous safranin and mounting in glycerol jelly.

Absolute pollen frequencies were calculated using added exotics to known volumes of sample (Stockmarr 1971). Pollen was examined, identified and counted using an Olympus biological research microscope fitted with Leitz optics at magnifications of x400 and x1000 with normal transmitted and phase contrast lighting. An extensive pollen reference/comparative collection is available for identification of difficult/critical taxa (Palaeopol). Pollen sums of 300 or more grains of dry land taxa were counted for each level where possible, plus all extant spores and pollen of marsh taxa (largely Cyperaceae) and fern spores miscellaneous pre-Quaternary palynomorphs. Where Alnus (alder) was abundant this was excluded from the pollen sum (Janssen, 1969) and was calcualted within the fen/aquatic catagory. Pollen diagrams have been plotted using the progammes 'Tilia' and 'Tilia Graph'. Percentage calculations used for the construction of these pollen diagrams were as follows:

Sum = % total dry land pollen (tdlp)

Fen/aquatic = % tdlp+sum of marsh/aquatics

Spores= % tdlp+sum of spores

Misc.= % tdlp+sum of misc. taxa.

Taxonomy used follows that of Moore and Webb (1978) modified according to Bennett et al. (1994) for pollen types and Stace (1992) for plant descriptions. These procedures were carried out in the Palaeoecology Laboratory of the Department of Geography, University of Southampton

7.7 Diatom extraction procedures

Diatom extraction and preparation followed standard procedures outlined by Battarbee (1986). Samples were processed using hydrogen peroxide for removal of organic content and centrifuged at 1000 rpm. The cleaned mineral solution were dehydrated on microscope coverslips and then mounted in Naphrax on microscope slides. Diatoms were examined at x400 and x100 in plain and phase contrast using and Olympus BH1 microscope fitted with Leitz optics. Where necessary, diatom identifications were confirmed using the publications (Denys 1992; Hartley 1996; Hendy 1964; Hustdedt 1957). As with pollen analysis, these procedures were carried out in the Palaeoecology Laboratory of the Department of Geography, University of Southampton.

7.8 Existing/comparative data

Results of the analyses undertaken for the LIFE programme have been compared with the existing database for the Isle of Wight and near Solent region Godwin and Godwin 1940; Godwin 1945 Haskins 1978; Scaife 1980,1987, 1994,1998 and in Tomalin et al. forthcoming; Barber and Clarke. 1987; Long and Tooley 1995; Long and Scaife 1996 Long et al. 1996; 2000). A radiocarbon dated Holocene vegetation and environmental history of change has been established for the Isle of Wight (Scaife 1980, 1982, 1987; Scaife and Burrin 1992) providing the basis for understanding of the complex habitats of the coastal zone as found in North-East Wight at Wootton-Quarr (Scaife in Tomalin et al. forthcoming/in press) and North-West Wight at Yarmouth-Bouldnor presented here.


8. POLLEN ANALYSIS AND ENVIRONMENTAL HISTORY OF THE WEST SOLENT: THE SUBMERGED PROFILE LYING OFF-SHORE FROM BOULDNOR CLIFF

8.1 Introduction

The sequence of mineral and organogenic sediments at Bouldnor Cliff provide a valuable sediment archive of middle and late Holocene environmental and sea-level change. Three distinct peat sequences have been recognised which are intercalated with mineral sediments. These sediment units are named Bouldnor 1 to 3 and have been radiocarbon dated. Samples of these were obtained by the Hampshire and Isle of Wight Trust for Maritime Archaeology. Altitudinal measurements were also made for the peat/sediment interfaces and especially at the point where radiocarbon dates measurements have been made (usually the lower sediment/peat interfaces of the three peat levels).

8.2 Upper Peat Bed C (Bouldnor 1) The upper peat bed is the highest recognised peat at Bouldnor with its surface exposed at the top of the peat cliff. The peat sequences lies at a depth of -3.72 m OD to -4.10m OD and radiocarbon dated at its base to 5580+/-60 BP ( 4525-4330 cal. BC) (Beta-140102) and has provide a valuable datum point to the sea-level change/altitude graph for the Western Solent. Radiocarbon dating of the upper surface has not yet been carried out but it is likely that erosion will have taken place by the most recent marine inundation. This is widely evidence at other sites in the Solent and Southampton Water Long et al. 1996).

Depth in cm. within stratified unit: 0 –22 Detrital monocot. peat. Brown. 22-24 Peat with some silt content. 24-32 Black humified detrital peat 32-39 Fine organic mud with Phragmites (5580+/-60BP). 39-42 Organic mud/grey silt transition. 42-89 Grey silt/clay with a few organic ?roots. Homogeneous 7.5YR 5/0 61-70 Void in core. 77-83 Void in core.

Table 1 Stratigraphy of the Upper Peat horizon at Bouldnor, Isle of Wight, UK.

8.3 The Pollen zonation of the upper peat at Bouldnor

See Figure P1.9(d). Three principal pollen zones can be recognised in this peat profile. These are characterised from the base of the profile upwards as follows:

l.p.a.z. BLD1:A (44-38cm). This zone corresponds with the transition from the underlying alluvial silt into the peat. It is distinguished by the quantity of re-worked pre-Quaternary palynomorphs which are derived from the local Tertiary bedrock lithologies. The vegetation contemporary with this transition was dominated by Quercus (oak) with Corylus avellana (hazel). This was likely to be growing close to, or on the site of deposition. The small values of Tilia (cf. T. cordata) (small leaved lime/lindens) may be indicative of its growth on the better drained soils of higher ground to the east. The small quantities of its pollen in this and subsequent zones are important since this taxon is usually poorly represented in pollen spectra. That is, because it is entomophilous (insect pollinated) producing smaller numbers

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK of pollen for example than taxa such as oak, pine and hazel which are anemophilous (wind pollinated). Furthermore, it flowers during mid-summer when other trees are in full leaf which also inhibits its wide spread dispersion.

l.p.a.z. BLD1:B (38-6cm.) This principal zone spans the main part of the uppermost Bouldnor peat. Quercus (oak) and Corylus avellana hazel) remain the dominant woodland/tree types with Tilia (lindens), Fraxinus (ash) and Ulmus (elm) in areas further afield. However, in this zone there is a marked expansion of some herbs including Poaceae (grasses), Chenopodium type (goosefoots, oraches and glass worts) and Cyperaceae (sedges). These show that the autochthonous vegetation had become progressively dominated by grass-sedge fen after its earlier phase of salt marsh and alluvial sedimentation. This is comparable with the peat macrostratigraphy which comprises largely monocotyledonous and detrital organic material. The greater importance of Chenopodiaceae is most likely to represent salt tolerant/demanding plants (halophytes) which are typical of middle and upper salt marsh habitats (e.g. sea-blite, sea aster, oraches and sea lavender). Chenopodiaceae in the more minerogenic sediments are largely attributable to Salicornia spp. (glassworts) growing on the lower mud-flats.

The general environmental picture gained for this period of peat formation is one of grass sedge fen developing out of salt marsh after a relative fall in (negative eustatic) sea-level. The presence of substantial quantities of oak and hazel also suggests that these trees became established on the drier areas of this mire habitat. This has been similarly evidenced in the latter stages of peat formation at Wootton-Quarr during the later stages of a hydroseral succession. Taxus (yew) is a notable record since although not now associated with such mire habitats, remains of this tree are relatively common in fen peats in East Anglia (Godwin 1975) and the peats of the Thames floodplain in London (Sidell et al. 1995; Scaife in Sidell et al. 2000) along with oak, ash and more typical fen carr elements (alder, willow, Rhamnus) (Godwin 1975). The high values of Chenopodiaceae and the sporadic Plantago maritima (sea plantain) demonstrate that marine/salt marsh conditions were also local to this fen community and pollen of these halophytes may have been transported and deposited via airborne or fluvial vectors.

l.p.a.z. BLD1:C (6-0cm). This uppermost zone is delimited by a significant change in the mire ecology from grass-sedge fen to one of more acid conditions with growth of Sphagnum (bog moss) and associated taxa including Osmunda regalis (Royal fern) and spores of Tiletia, a rust associated with Sphagnum. Apart from the changes in the autochthonous components, the flora of the drier and terrestrial zone remained similar to that of the preceding zone. Thus, Quercus and Corylus avellana remained dominant with subordinate levels of other taxa such as Alnus (alder).

It is not clear why an ecological transition to a more acidic habitat/ecology occurred in the uppermost zone of this peat. Such levels of Sphagnum but with Osmunda regalis suggests that the community was on the mesotrophic side of typical bog pH values. For such development, changing nutrient supply (i.e. reduction in bases) occurred. This could have been due to continued peat growth to a point above the local groundwater table where aeolian/rain water was the main supply. This would have been nutrient deficient giving rise to less nutrient demanding plants such as typically happens in the ombrotrophic bogs of the North and West of the country, but which have occurred in the past in southern England at rare sites such as Cranes Moor, Hampshire and Amberly, Sussex.

Alternatively, it is possible that changes in the fluvial system resulted in drainage from more acid bedrock areas (e.g. Tertiary sands and gravels) similarly causing local acidification. Whichever cause, this past habitat is of some interest since Sphagnum communities are especially rare in the Isle of Wight with the only areas of remaining bog being at Bohemia and Munsley in the central part of the Isle of Wight. After zone BLD1:C, a marine transgression clearly took place which resulted in the submergence of this peat sequence.

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK The top of the peat shows no evidence of marine sediment deposition and it is possible that some erosion and truncation may have occurred. Whilst a radiocarbon date from the top of this peat would be of value, it should be considered that this will only provide an earliest date for submergence.

8.4 Diatoms in the fluvio-marine sediments underlying the upper peat at Bouldnor Examination of the diatom content within the grey minerogenic sediments immediately underlying the peat has been undertaken. Preservation and abundance of diatoms are not great in the samples so far examined. However, they were present in sufficient quantity and of diagnostic types to ascertain that the sediment was subject to marine/saline influences prior to the drying out and peat formation. The main diatom taxa included; Actinoptychus senarius; Cocconeis scutellum; cf. Synedra; Diploneis didyma; Nitzschia sp., Paralia sulcata.

8.5 Middle Peat Bed B (Bouldnor 2)See Figure P1.9c. The ‘middle’ of the three peat sequences found offshore at Bouldnor Cliff is here termed Bouldnor 2 and lies at a depth -3.72 mOD and -4.10mOD. The peat layer is intercalated within grey marine or brackish water salt marsh sediments and appears to represents a minor relative still stand in the progressively rising later Holocene sea-level.

8.6 The stratigraphy of the middle peat B at Bouldnor This profile is the lower half (1100B) of an auger profile (1100) taken through the ‘upper peats’ (Bouldnor 1), upper silts into the ‘middle peats’ of Bouldnor 2 and underlying silt/clay.

Depth in cm. within stratigraphic unit: 0-14 Grey silty clay (7.5YR 4/0) with some organic rootlets. 14-16 Disturbed silt/clay mixed with underlying peat. 16-33 Brown detrital peat with little structure. 33-34 Distinct transition/boundary. 5870+/-80BP. (Oxa-***) 34-100 Homogeneous grey silty clay (7.5Y 4/0) with monocot. rootlets

penetrating vertically. Some black streaking (Mn?).

Table 2 Stratigraphy of the Middle Peat horizon at Bouldnor, Isle of Wight, UK.

8.7 Pollen zonation of middle peat bed B at Bouldnor

Three local pollen assemblage zones (l.p.a.z.) have been recognised in this pollen profile (Figure P1.9c). These are characterised as follows from the base of the profile upwards.

l.p.a.z. BLD2:a (60cm to 34cm). Quercus-Corylus avellana-Chenopodium type-Pre- Quaternary. Generally homogeneous pollen assemblages. Arboreal pollen is dominated by Quercus (to 40%) with Corylus avellana type (to 25%), Tilia (to 9%) and Alnus (to 10%) with sporadic occurrences of Betula, Pinus, Ulmus, Fraxinus and Ilex. Herbs are dominated by Chenopodium type (to 25%), Poaceae (20%) expanding into zone 2. Marsh and aquatic taxa comprise Cyperaceae to 13%) with sporadic Potamogeton, Typha/Sparganium and halophytes-Ruppia maritima, Armeria 'B' line, Plantago maritima and Hystrichospheres/dinoflagellates. There are very substantial numbers of pre-Quaternary palynomorphs.

l.p.a.z. BLD2:b. (34cm to 20cm) Poaceae. Poaceae are dominant peaking sharply to 70% with Aster type (to 6%). There is a reduction in herb diversity. Tree pollen remains

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK dominated by Quercus and Corylus plus other types noted in zone 1. However, small numbers of Pinus previously present, decline. Percentages are, however, reduced due to the within sum expansion of Poaceae (i.e. statistical effect). There are sharp declines in pre-Quaternary spores and Cyperaceae to low values or absence.

l.p.a.z. BLD2:c (20cm to 8cm). Quercus-Corylus avellana type-Chenopodiaceae- Cyperaceae. This zone is characterised by a re-expansion of Chenopodiaceae (to 22%) and Cyperacieare (to 10%). There is also an increase in Fraxinus and pre-Quaternary palynomorphs. Alnus peaks at 14% and corylus avellana type also becomes important at 28%. There is also an increase in pollen diversity with increased marsh and aquatic types including Ruppia maritima, Potamogeton type and Typha/Sparganium.

8.8 The inferred vegetation of middle peat bed B

The principal zones recorded reflect the stratigraphical changes/lithostratigraphic units. Thus, there are three major taphonomic changes reflecting the differences between the peat and sediment and also in the depositional context of the lower and upper silts. Zone BLD2:a contains very substantial numbers of pre-Quaternary pollen and spores derived from bedrock Cretaceous and Tertiary lithologies (e.g. Cycadopollenites, Milfordia). Although these are present in the upper sediments overlying the peat (in zone BLD2:c), numbers are far fewer. This clearly suggests a different sediment source, transport mechanism or direction of transport/sediment source. Although it is not possible to confirm this at present, it seems plausible that lower sediments contain a greater alluvial component with sediment river transported from inland sources. Alternatively, it is possible that near-shore reworking of the coastal cliff line was more active during zone BLD2:a. It is, however, clear that the depositional environment was at least brackish tidal water since there are halophytic taxa present. These include Chenopodium type (oraches and glassworts), Armeria ‘B’ line (sea lavender and thrift) and Ruppia maritima (beaked tasselweed). The latter is especially unusual since this is now a rare and local plant of backwater salt marshes. It has previously been recorded at Firestone Copse (Scaife in Tomalin et al. forthcoming). It is concluded, therefore, that the inorganic sediments were deposited under salt marsh or estuarine conditions rather than open marine conditions.

Outside of the depositional zone, the terrestrial vegetation was dominated by Quercus (oak), Corylus avellana (hazel) and possibly Tilia (lime/lindens). The latter is a poor pollen producer compared with oak and hazel and as such was likely more important than illustrated from the pollen spectra. This is due to its entomophily and production of small numbers of grains during mid summer when trees in full leaf inhibit polen dispersion. It is also known to have been dominant during the middle Holocene to late-Prehistoric period. Pinus (pine) values are relatively high. Here this is attributed to marine/fluvial transport which commonly causes over-representation of such saccate pollen grains.

Zone BLD2:b corresponds with the ’middle peat’ of Bouldnor at a depth of (-3.72 to -4.10m OD). There is a clear cessation of fluvial/marine conditions allowing organic peat accumulation consisting of monocotyledonous (grass but may include sedges and rushes). The decline in Chenopodiaceae noted in zone BLD2:a shows the absence of saline conditions on-site. Proximity to the sea during the period of peat accumulation is difficult to ascertain but absence of those typical halophytes noted in zone 1 suggests that it was at some distance. Some reduction in Corylus (hazel) and Quercus suggests that pollen in the previous zone was fluvially derived whereas in zone 2, airborne pollen transport/dispersion seems more likely. This again demonstrates the importance of oak and hazel woodland but possibly with other which are trees which are less well represented in the pollen spectra (cf. Tilia, Fraxinus and Fagus for example).

Re-expansion of Chenopodiaceae in zone BLD2:c with other, but sporadic, halophytes, marks a return to saline conditions. It is, however, significant that higher values of Alnus and

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK Cyperaceae than in the underlying peat suggests that pollen/sediment was being derived from rivers exiting into the Solent.

8.9 Lower Peat Bed A (Bouldnor 3) See Figures P1.9(a) and P1.9(b). Two separate cores were used to obtain pollen profiles from the deepest of the three peat horizons submerged in the Solent at Bouldnor cliff. This basal deposit occurs at c.10m to12m blow Ordnance Datum and appears to be an extensive spread of peat skiting an earlier coastline. These basal peats possibly represent the transitional phase of Solent inundation; that is, a peat forming marsh/fen caused by regionally rising sea-levels creating higher groundwater tables and anaerobic conditions. A second profile was obtained by the Hampshire and Isle of Wight Trust. Given the importance of this basal peat this was also pollen analysed. Two radiocarbon dates of 7640 +/-70BP (6615-6395 cal. BC) and (Beta-140104) 7440+/-60BP (6430-6120 cal. BC) (GU- 5420) demonstrate that the peat formed at or just prior to the Boreal/Atlantic transition (Flandrian I/II), that is, at the end of rapid Holocene sea-level change which resulted in separation of England from the European mainland and very possibly the Isle of Wight from the mainland. Apart from the major physiographic changes which occurred, the period was also critical in terms of vegetation migration into the region and climatic change resulting from increased oceanicity of climate.

8.10 The stratigraphy of Lower Peat bed A at Bouldnor (Bouldnor 3a-3b) The stratigraphy of the analysed profile comprises largely black, humic detrital peat with silt bands and wood and twig fragments. There is a very substantial trunk between 27-21cm which negated pollen sampling at this level. Hence the one level gap at 24cm in the pollen diagram (P1.9(a) and (b)).

Depth cm. within stratigraphic unit: 0-17 Predominantly black detrital peat with wood/twig fragments throughout with

monocot. root fragments 15 Wood 17-21 Wood and organic detritus in grey silt. Mottled 7.5Y 5/0 to 7.5Y

4/0 21-27 Large Wood-trunk fragments 27-34 Grey clay/silt 7.5Y 5/0 to 7.5Y 4/0 31-32 Wood (7640+/-70 BP and 7440+/-60BP).

Table 3 Stratigraphy of Lower Peat horizon at Bouldnor, Isle of Wight, UK.

8.11 The pollen sequence in peat bed A (Bouldnor 3-a & 3-b) Two pollen assemblage zones have been recognised in this profile. These are delimited and characterised as follows.

l.p.a.z. BLD3:a (32-24cm) Pinus-Quercus-Corylus avellana type. Pinus attains highest values (to 33%) with Quercus (23%), Corylus avellana type (58%), Ulmus (to 10%). There are few herbs with only sporadic occurrences of Poaceae, Filipendula, and marsh taxa - Cyperaceae and Typha/Sparganium. There are substantial numbers of spores in the basal level comprising largely monolete Dryopteris type with derived pre-Quaternary palynomorphs and lesser numbers of Polypodium vulgare and Pteridium aquilinum.

l.p.a.z. BLD3:b (24-0 cm) Quercus-Corylus avellana type-Alnus. This zone is delimited by expansion of Alnus to 57% with Quercus (20%) and Corylus avellana type (53%). Herbs remain sparse with sporadic Poaceae, Apiaceae and Viola type. Cyperaceae decrease from

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK 16cm. High values of spores and pre-Quaternary palynomorphs in zone 1 decrease substantially.

8.12 Discussion on Lower Peat A at Bouldnor (Bouldnor 3a-3b) The lower zone of this peat bed (zone 3-a) was somewhat humified and produced only modest pollen frequencies.This contrasted with zone 3-b (which occurred at slightly higher level (c. 1 metre) and had an abundance of well preserved pollen. As a consequence, a smaller pollen sum was counted in zone 3-a but sufficient was obtained to delimit the characteristics of the local vegetation at the time of peat accumulation.

Overall, the profile of zone 3-a exhibits similar vegetation characteristics to the slightly higher profile offered by zone 3-b. It shows a local vegetation dominated by Quercus (oak) and Corylus avellana (hazel) with lesser elements of Ulmus (elm) and fen carr trees and shrubs. The latter habitat is clearly dominated by on-site growth of Alnus (alder) with occasional Salix (willows) and possibly Viburnum (cf. lantana) with a herb layer of sedges and in wetter areas, of Typha/Sparganium (reed-mace and bur reeds).

The change between pollen zones 3-a and 3-b essentially marks the transition from a sedimentary environment (?freshwater) to one of peat forming anaerobic conditions. This change also importantly occurred in response to regionally rising sea-levels at the end of the Boreal period (Flandrian Chronozone Ic) at c.7000BP which resulted in the separation of Britain from continental Europe and possibly separation of the Isle of Wight from the mainland. This is in accord with a radiocarbon date of 7230 +/-110 BP from wood obtained from the base of the peat (such as found here) in 1984 (Wootton-Quarr; Tomalin et al. in press). The substantial pine values in the lowest level (zone 1) are expected from this (late- Boreal) period although it is also recognised that these saccate pollen grains may also be over-represented in the fluvial environment responsible for the inorganic/minerogenic content of the lower peat and underlying lithostratigraphy. The expansion of Alnus is also commensurate with this broad date marking the Holocene migration of alder into this region aided by expansion of wetland habitats suited to its growth.

The variation in absolute pollen frequencies noted between this profile and Bouldnor 3-a is pronounced and may be due to a number of factors. These suggestions are as follows,

-The lower peat of this platform was exposed on the Solent sea floor for a substantial period of time causing more degradation of the pollen than peat (zone3-a) occurring nearer to the submerged, underwater cliff.

-The peat accumulated in a slightly different environment and drier carr habitat. Certainly the stratigraphy of profile 3-a is more complex than profile 3-b.

8.13 The pollen sequence in lower peat bed A (Bouldnor 3-b) This profile occurs at a slightly higher level (c. 1 metre) than 3-a above. In this profile there are no significant fluctuations in the pollen spectra recovered and thus, no pollen zonation has been carried out. Alnus which was important and was possibly growing on site was excluded from the pollen sum (tdlp) and included in the fen category (Janssen, 1969). This prevented the statistical effects of on-site high pollen producers on the record of dry land taxa. The principal vegetation components are characterised as follows:

c.i.) Tree and Shrub: Quercus (to 70% at 24cm) and Corylus avellana type (to 55%) are the dominant taxa. Other trees include Betula (to 5%), Pinus (<5%) Ulmus (6%) and sporadic Tilia (uppermost level), Taxus, Rhamnus, Viburnum and Prunus type.

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK c.ii.) Herbs: There are notably few herbs with only sporadic occurrences of Caltha type, Chenopodiaceae Apiaceae, Rumex, Artemisia and Poaceae. Some of these may also be referable to the marsh category (below) but have pollen morphologies which do not allow separation to a lower taxonomic level thus allowing ecological categorisation.

c.iii.) Marsh: Alnus (80%) attains markedly high values and as such was excluded from the pollen sum (Janssen 1969) since this was clearly the dominant autochthonous/mire vegetation element. Other marsh shrubs include possibly Rhamnus catharticus and Salix. Sporadic occurrences of Lythrum salicaria, Typha/Sparganium type and Cyperaceae are also reed swamp elements. Aquatic taxa include Potamogeton type (but which may include Triglochin) and possibly Lemna.

c.iv.) Ferns: There are few spores of ferns. Polypodium vulgare is most continuous (<5%) with sporadic Dryopteris (monolete) type and Pteridium aquilinum.

This lowest of three peat profiles at Bouldnor lies at a depth (-12 mOD) which suggests that it accumulated at c.7,500 BP, that is, by comparison with regional sea-level/time/altitude graphs. This is also be confirmed by the radiocarbon dates of 7440+/-60BP (GU-5420) and 7640+/-70BP (Beta-140104) obtained from wood taken from the base of the peat. As such, this sequence spans a critical time when post-glacial sea-levels had risen sharply during the early Holocene to the point which saw separation of Britain from mainland Europe and possibly the Isle of Wight from the mainland. Subsequently, the rate of relative sea-level change slowed down but by this time the essential coastal outline of the Hampshire Basin had been achieved. Separation of Britain from Europe may also have had implications for climate with increased oceanicity (the start of the middle Holocene Atlantic period; Flandrian II) and for patterns of vegetation migration. With regard to the latter, it is clear that trees which had not arrived by the time of inundation of the English Channel would not be able expand their range (without human influence).

This peat sequence demonstrates the transitional character of the vegetation between the late-Boreal (Flandrian Chronozone Ic) and the more stable Mid-Holocene, Atlantic period (Mangerud et al. 1974). It is known that the former period was dominated by pine with hazel and is evidenced from sites at Gatcombe and Godshill, Isle of Wight (Scaife 1980,1981,1987) and on the mainland at Testwood, Southampton (Scaife forthcoming), Cranes Moor, Hampshire (Barber et al. 1987) and Southampton, Mountbatten Centre (Scaife 1998) and Testwood Lakes (Scaife 1997 and forthcoming). This woodland was competitively ousted by oak and elm which became co-dominant or dominant towards the later part of the period. The start of the middle Holocene, Atlantic period (Flandrian chronozone II) is characterised by sharply increasing percentages and thus presence of alder and thermophiles including notably lime/lindens (Tilia). This environmental change was brought about by increased humidity possibly due to expansion of the coastline and a temperature amelioration. The Bouldnor 3 (3-a and 3-b) sequences span this environmental transition represents a short time span at c. 6500-7500 years BP. The start of peat accumulation was most likely associated with the relative sea-level rise which caused ponding back of freshwater river systems flowing into the Solent. This would have caused localised waterlogging through higher groundwater table resulting in anaerobic conditions and peat accumulation.

Such an environment was also favourable for colonisation by alder which was at this time expanding its range throughout the country (Birks 1989). This was also in response to this increase of available growth habitats and to the increased humidity at the start of the Atlantic period. This event was in fact the original marker for the onset of the Atlantic period, Godwin’s pollen zone VIIa (Godwin 1940,1956,1975). It is, however, now recognised as being an asynchronous phenomenon broadly spanning the period c.7,000Bp. but with some evidence of earlier Holocene expansion (e.g. the Thames; Devoy 1979,1980 and Hampshire Basin Scaife 1980,1981,1998). Bouldnor 3 has very substantial quantities of alder pollen which clearly illustrates the on-site growth of invasive alder carr woodland. The minor records of buckthorn (Rhamnus cathartica), willow (Salix) and yew (Taxus) are noted


as typical lower tree and shrub elements of the carr woodland with a ground flora of sedges and other reed-swamp elements. The latter are not, however, well represented.

Apart from the alder discussed above, oak and hazel are the dominant tree components of this profile and along with elm probably formed the woodland of nearby drier land. However, two points must be noted.. First, these trees are wind pollinated and will have traveled farther afield than insect pollinated taxa and will be represented in higher proportions (Andersen 1970,1973). Second, it is possible therefore, that these trees and shrubs will grow in the drier areas of wetland carr communities. Identification of timbers obtained from the lower peats may provide some indication of this. Of the other tree elements also present, birch and pine were probably not significant locally at this time because the percentage values are small and these taxa are wind pollinated thus suggesting a long distance/regional source of origin. A single record of Tilia (lime) at the top of the profile, may be significant as indicating the start of lime expansion (ultimately to dominance) during the early Atlantic period.

The age range and character of the peat and mineral sediment present at Bouldnor provides a very substantial record of changes in relative sea-levels for the Solent and is certainly the best sequence so far analysed in this region and beacuse of the sensitivity of this site/enviroment to eustatic change, may form a regional type sequence similar to that offered by Devoy’s work in the Lower Thames (Devoy 1979,1980). The following is a summary of the datum heights and radiocarbon dates for the Bouldnor profile.

Code Name of peat) Bed C/Bouldnor 1 Upper Peat Bed Upper silt Bed B/Bouldnor 2 Middle Peat Bed Middle Silt Bed A/Bouldnor 3-a Lower Peat Bed Bed A/Bouldnor 3-b Lower Peat Bed Basal Freshwater Silt BedrockTertiary Base ??�

O.D. Height (base -3.72 to -4.10mOD -4.10 to -4.76mOD -4.76 to -5.36mOD -5.36 to -11.68mOD -11.68 to-12.0mOD

-12.00m OD

C14 Date (BP) 5580+/60BP(Beta-140102)

5870+/-80BP (Beta-140103)

7640+/-70BP Beta-140104)

7440+/-60BP (GU-5420) < c.7500 BP

Table 4 Summary of Bouldnor stages, Isle of Wight, UK

9. YARMOUTH SPIT: POLLEN ANALYSIS OF THE MIDDLE HOLOCENE SEDIMENT SEQUENCE

9.1 Introduction to the Yarmouth core

Yarmouth Spit was selected during the Wootton-Quarr project as a site which offered a potential opportunity to reconstruct the palaeo-environmental history and past Relative Sea- levels (RSL) of the Western Solent. Earlier work by Devoy (1987) and Sutherland (1984) had also viewed this site as one of importance. A number of boreholes were sunk in at the mouth of the Western Yar and a core/borehole of 12.30m depth was sunk at Yarmouth Spit to a level of -11.30m OD (Figure P1.10). Pollen data from 18 pollen samples were obtained from the deep peats contained within the palaeochannel of the river. Stratigraphical analysis and radiocarbon dating previously carried out on this profile make this core the only other fully examined Holocene sequence for the Western Solent region; the other being Bouldnor. The two cores have a particular value in allowing comparison between locations set 1km appart.


General comments on the stratigraphy of the pollen anlysed core from the West Spit at Noton, Yarmouth.

This core was sunk with a Cobra mechanical auger with the assistance of Matthew Canti of the Ancient Monuments Laboratory and Nick Blake. A stitz auger head was employed to recover 1m contuous samples.The core was driven to a depth of Notyon spitEst Spit atouit

9.2 Pollen zonation at Yarmouth

Three pollen zones have so far been recognised in the Yar Spit pollen diagram (Figure P11a). These are delimited and characterised from the base upwards and have been extracted from stratigraphic units 17- 10. The genreral stratigraphy of the core has been simmarised in volume 1 this report.

YAR:1 10.60 - 9.60 m. Quercus-Corylus avellana type-Alnus. Trees (to 50%) are characterised by Quercus (to 35%), Corylus avellana type (to 60%) and Alnus (38%) with Ulmus (9%). There are few herbs (18%) with Poaceae the only taxon of significance (to 15%). Wetland/marsh taxa are dominated by Alnus (60%) with some Salix, Typha/Sparganium and Cyperaceae. There are substantial numbers of derived/pre-Quaternary palynomorphs.

YAR: 2 9.60 - 7.60m Quercus-Tilia-Corylus avellana type-Chenopodiaceae-Poaceae. Alnus declines to <20% while Quercus and Corylus avellana type remain important at previous (zone 1) numbers. Tilia (to 10%), Fraxinus (sporadically) are incoming. Herbs become more important with expansion of Chenopodiaceae (to 19%) and Poaceae (av. 20- 30%). Marsh herb taxa become more important in relation to declining Alnus. Typha/Sparganium and Cyperaceae are dominant (12% and 20% resp). Spores of ferns similarly expand with Pteridium aquilinum and monolete Dryopteris type (20%) being important. There are sporadic Polypodium vulgare. Pre-Quaternary palynomorphs remain important.

YAR:3 7.60 - 6.60m Quercus-Corylus-type-Poaceae. There are reductions in Ulmus and Tilia. Quercus and Corylus type remain dominant. Herb assemblages become more diverse and include Rumex spp., large Poaceae/cereal type (>45u). There are reductions in Typha/Sparganium and Cyperaceae noted in zone 2. There is a sharp reduction/absence of pre-Quaternary palynomorphs.

9.3 The past coastal vegetation and environment at Yarmouth

Radiocarbon dating shows that this peat and inorganic sediment sequence started to accumulate sometime shortly before 7320+/-110BP (6380-5840 cal. BC) (GU-5397), that is, during the late-Boreal (Flandrian Chronozone I). There are indications that the earliest sediments (gyttja) accumulated in still water conditions, perhaps lacustrine with fringing alder carr woodland (units 8 and 19) and on-site in units 17a and 17b. This is the base don stratigraphy and pollen evidence (high Alnus values). The terrestrial vegetation during this basal zone (YAR:1 was dominated locally by Quercus (oak) and Corylus avellana (hazel) with Ulmus (elm). This woodland community represents the late Boreal (Flandrian Chronozone Ic) vegetation after Pinus had been out-competed by deciduous woodland and immediately prior to colonisation by the typical middle Holocene thermophiles (Tilia-lime and Fraxinus- ash).

Pollen zone YAR:2 is stratigraphically complex comprising banded organic lenses with Phragmites and intercalated inorganic horizons. This complexity is mirrored in the pollen assemblages. These show that marine influences were present as indicated by Chenopodiaceae (glassworts, oraches and goosefoots). However, freshwater marsh

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK conditions became more extensive locally with the destruction (through water-logging) of alder carr woodland. During this period, Tilia and Fraxinus became important elements of the local woodland on drier soils (both are poorly represented palynologically) while Quercus and Ulmus remained important. This zone clearly marks the onset of the middle Holocene, Atlantic period (Flandrian II; Godwins pollen zone VIIa). The substantial peat deposits between 7.6m and 6.6m formed in a freshwater marsh (sedge-reed-swamp with apparently less marine influences. A radiocarbon date of 5,680+/-100 BP (4780-4350 cal. BC) (GU-5382) for the base of this peat unit (10) demonstrates that this change occurred towards the end of the Atlantic period and lasted until 4730+/-50BP (3650-3360 cal. BC) (GU-5419) in what is traditionally regarded as the Sub-Boreal (early part of Flandrian Chronozone III), the late prehistoric period.

The reduction in Ulmus to low values at 7.20m and the presence of large Poaceae/Cereal type with Plantago lanceolata is possibly the Neolithic ‘Primary Elm Decline’ phenomena variously dated to between 5,500-5000 BP (Smith and Pilcher 1973) and at 4850 +/-80 BP at Gatcombe Withy Bed (Scaife 1980, 1988). This diagnostic event is broadly synchronous across Britain and although many causal factors have been suggested (Smith 1970; Scaife 1988), it is now largely felt that insect borne disease was promoted by early Neolithic opening of the woodland for habitation and agriculture (landnam) allowing its spread more readily (Girling 1988). Certainly, the decline in elm pollen at this time is very often closely associated with the first occurrence of cereal pollen and weeds of habitation and cultivation (Scaife 1988) and to some extent this is the case here.

Above this late-prehistoric (late Mesolithic-Neolithic) peat, there is a substantial thickness of grey sediments which are of marine/salt marsh origin. These mark the principal late- Holocene transgression of the coastline and coastal valleys. It is possible that some truncation of the upper peat surface has occurred. Subsequently development of and/or migration of the spit onto this site effectively sealed this sediment sequence.

9.4 The depositional history at Yarmouth

The sedimentary archive present in the Western Yar valley developed in response to RSL in the early-middle Holocene which affected the existing hydrological system by (a). ponding back river systems, (b) reducing the erosive potential of the river systems, (c.) increasing sedimentary responses (d.) locally raising groundwater table. These effects resulted in the development of a freshwater lagoon/lake between c. 8,000 and 7,000 BP in the low lying channels. Alder migrating into Southern England was provided with habitats suited to its colonisation. With the final stages of the sharply rising sea-level at c.7,000BP, the more deeply incised (Devensian erosion) valleys were inundated by marine waters and became tidal channels during the first half of Atlantic period (i.e. 7000-6,000 BP). Fresh and brackish water reed swamp developed with Phragmites, Reed-mace, burr-reed, sedges and salt marsh elements (Chenopodiaceae, Poaceae Aster etc. With slowing down of RSL in the latter part of the Atlantic (c. 6,000-5,000 BP) the balance of sedimentation to RSL became stabilised possibly causing development of peat (fen) into the sub-Boreal (Neolithic) It is this peat which may be correlated with the sub-boreal peats seen around the Solent margins and especially at Wootton-Quarr. However, here, it appears that the peat development at Yarmouth was some centuries earlier in the west Solent than seen at Wootton-Quarr (East Solent). This may in some way relate to the overall pattern of Solent marine inundation and breaching of the island from the mainland. The pattern of events is summarised later in this text.

9.5 Summary and conclusions on the cored sequence at Yarmouth

The peats and minerogenic sediments of the Western Yar have been examined from underneath Yarmouth Spit. Radiocarbon dating places the initiation at c.7,500 BP and is comparable with the dates for peat initiation at Bouldnor Cliff. Pollen analysis has demonstrated a vegetation dominated by oak, elm and hazel woodland on drier soils and


development of alder carr in wetter habitats. The start of the middle Holocene Atlantic period is manifested by incoming of lime and ash woodland and marine inundation of the deeper river channels. This also gave rise to extension of sedge fen/reed swamp and possibly halophytic/salt marsh communities from c.7,000 to 6,000 BP. Environmental stablisation occurred in the later Atlantic period from 6,000-5,000BP with peat accumulating in a freshwater sedge-fen. Further RSL during the sub-Boreal caused widespread marine inundation and sedimentation of the freshwater marshes to be replaced by salt marsh and intertidal mud-flats along the tidal reaches of the river. Development of the spit at its present location sealed this sedimentary sequence.

The biostratigraphy, radiocarbon dating and lithostratigraphy act as a vital near shore comparison/control to the deep submerged Bouldnor Cliff profile. Both have produced valuable information allowing construction of a sea-level graph for the western Solent region. Furthermore, there are indications of differences of sea-level change between the west and west Solent which may have implications to the date of separation of the Isle of Wight from the mainland.

10 THE WESTERN SOLENT: A SUMMARY DISCUSSION ON CHANGES IN THE HOLOCENE COASTAL ENVIRONMENT

The two radiocarbon dated profile of Yarmouth west Spit and submerged peats at Bouldnor Cliff illustrate the changing vegetation and environment and effects of Solent sea-level history for the last 8. Ka.. These data come from the studies of pollen, diatoms, litho- and biostratigraphy, underwater sampling and survey. To understand the coastal development which resulted in today’s morphology, it is necessary to consider the history of the Solent prior to the sediment accumulation which occurred consequent upon rising Holocene sea- level.

Minimum sea-level during the height of the last cold stage (Devensian glacial period Oi stages 2-3) were at c.-130m OD, thus placing the coastline at the edge of the continental shelf. Polar and montane ice sheets contained this water. For whatever reasons, warming and the start of polar ice sheet melting instigated rising sea-levels from c. 15 Ka. with melting of the ice sheet, ‘unloading’ of the crust caused the start of isostatic recovery of the downwarped northern latitudes and corresponding start of submergence of land in the middle latitudes (i.e. here, relevent to southern England). Thus, the balance between these two factors gave rise to a relative sea-level (RSL) which progressively rose at varying rates from this date onwards. These global changes were influenced at a local level by local tectonics (neotectonics), earlier (polycyclic) geomorphological development and other factors especially human activity specific to the present, Holocene interglacial.

The three organic sequences at Bouldnor and the intercalated mineral sediments clearly relate to such changes in relative sea-level and may be considered as the principal (type site) for the Western Solent (see Figure P1.8). The top of the uppermost peat (Bouldnor 3) lies at a depth of c.-3.78 mOD. The biostratigraphy (pollen and diatoms) demonstrates saline conditions prior to formation of the middle peat and subsequently in the period after formation of the middle peat and prior to the upper peat 1. For this formation to have taken place at least stable salt marsh conditions must have existed with still stands or retrogressive phases when peat acummulated.

Given our present state of knowledge of the Bouldnor peats, the upper peat, Bouldnor 1 seems likely to correlate with YAR:3 and the extensive foreshore peats occurring at similar OD heights at Wootton-Quarr, Newton Creek and in Southampron Water. This unit dates to the late-Neolithic and early-middle Bronze Age. Deeper peats within the Fishbourne channel, Newton and Yarmouth creeks (YAR:1) may relate to the first major marine inundation (the Flandrian) at c. 7000-6600 BP. Earlier work on spot samples obtained from

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK the lowest peats at Bouldnor (Bouldnor 3) indicates that all of these ‘lower’ peat deposits accumulated in response to rising base levels caused by rising post-glacial sea-levels. This would have caused locally wetter conditions favourable for peat growth (i.e. anaerobic conditions).

The peat of Bouldnor 2 appears to be a previously undescribed peat accumulation, that is, with no local counterparts (but tentatively correlating with YAR:2). Initial thoughts are that the Bouldnor sequence is clearly a sediment unit which has been more sensitive to environmental (eustatic) changes than other areas investigated. The somewhat thinner peat of unit 2 must represent a shorter standstill phase than the upper and lower peat units This is further indicated by the fact that whereas Wootton-Quarr foreshore peats developed in a reed swamp habitat which had time to progress naturally to damp oak woodland by the middle Bronze Age. The peat at Bouldnor 2 demonstrated only development of a monocot. peat forming habitat.

The presence of the ‘submerged cliff’ at Bouldnor is somewhat unusual given the open sea and strong tidal action in the western Solent. The morphology of this feature has been examined, demonstrating the spatial extent of the submerged peat and sediment sequence. Clearly, the mechanism of deposition of the peats and intercalated mineral sediment is important to our understanding of the eustatic changes discussed above (and in Scaife and Long in Volume 1). Radiocarbon dating of the peat/sediment interfaces and calculation of the OD heights has added accurate datum points to the Solent sea-level altitude/date graph. The new radiocarbon dates and Ordnance datum heights when plotted against the sea-level graph for the Solent in general follow the same boad ‘curve’ of sea-level change of the last 7 Ka. This fact and the compact, stratified character of the peat and root boles demonstrates that the sediment profile at the point of sampling is in situ whereas, other parts of the submarine cliff may have been subject to mass movement/collapse.

In order for this deep sediment sequence to accumulate it is necessary to invoke a mechanism whereby such fine grained sediments could be deposited in a lesser energy environment than esists today in the Solent. It can be seen that the peat horizons at Bouldnor correlate broadly with the Yarmouth Spit profile in having similar thicknesses of grey marine/brackish water silts and clays. The peat horizons clearly represent standstill phases of relative sea-level (RSL), or even negative eustatic change allowing peat forming plant communities to grow in wet marsh conditions. The intercalated grey sediments are most likely to have formed in brackish water and/or salt marsh conditions. It seems most plausible that the area of Bouldnor was in the past, an extension of the salt marsh and estuarine habitat seen today at Yarmouth and analogous to the extensive salt marshes at Pennington on the other side of the Solent. Continued middle and late Holocene relative sea-level rise (with the standstills and peat accumulation noted) would have produced conditions favourable for the constant and progressive sediment build up against the hard rocks (Tertiary) of the coastline of North West Wight ultimately giving sediment thicknesses more typical of the eastuarine (ria valleys) of the River Yar, Newtown Creek and Wootton Creek. Final marine inundation seen around the Solent and Southampton water flooded the marginal peat forming communities during the late-prehistoric period (Bronze Age). This resulted in marine inundation to possibly, more or less the present coastline causing destabilisation of the cliff line.

It is suggested that the Bouldnor sequence provides a model for future changes in coastal dynamics. As noted in Volume 1, continued positive sea-level rise through global warming may be expected to have a similar effect on the extensive salt marshes at Lymington (Pennington) with marine inundation occurring once sediment accretion rates are exceeded. Based on the evidence offered by analyses of the Yarmouth and Bouldnor cores the past history of coastal change may be summarised as follows:-

· Early Holocene rising sea-levels (post-glacial eustatic changes).

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK · Formation of a freshwater lake/lagoon and peat-forming fen in the West

Solent/Yarmouth area and in other areas of Southampton Water during the late- Boreal period (Fl. Ic).

· Marine inundation of deeply incised channels (Solent, Yar, Medina, Newtown).

· Mid-Holocene periods of standstill and peat formation.

· Stabilisation and peat development under freshwater reed/sedge fen from the latter part of the Atlantic period (i.e. c. 5,680 BP) until c.4,700 BP in the early Sub- Boreal period.

· Principal marine inundation during the early Sub-Boreal (i.e. at 4,700 BP).

· Possible truncation of the peat.

· Establishment of the spit at the sample site sealing marine sediments. Date?

11. BIOSTRATIGRAPHICAL MARKERS AND THEIR APPLICATION TO COASTAL SEDIMENTARY DYNAMICS

11.1 Introduction to biostratigraphical markers

The absence of coastal peat formed during the last 2500 years poses problems for reconstruction of relative sea-level rise during this most recent period. Furthermore, this has meant that short-term estimates of future change are difficult being based largely on the interpolation of sea-level altitude/age graphs derived from earlier Holocene data. Clearly, rates of sea-level rise and coastal/salt marsh sedimentation are of importance to any understanding of the effects of global warming and resultant sea-level rise over and above the estimates derived from standard sea-level change data. Integration of long and short term records of sea-level change and coastal sedimentation has become an increasingly important concern of researchers in eustatic change. Whilst tide gauge data is available from Portsmouth which demonstrates a rise in sea-level of 5.0 mm yr (+/- 0.5mm) since AD 1962 (Woodworth 1987). However, local tectonic subsidence in the English Channel (Emery and Aubrey 1985) suggests that this may be anomalous and that there may be substantial variation between late Holocene sea -level rise during the last century (Long and Tooley 1995). Radiocarbon dated peat/organic deposits usually provide the means of establishing positive and negative eustatic change. As noted, the absence of such material dating to the last two millenia negates such a data/techniques. Other forms of absolute dating (for example 210 Pb; 137 Cs) have been used to calculate the rates of salt marsh sediment accretion (Cundy and Croudace 1996). This research has produced evidence for an acceleration in the rate of sea-level rise during the late Holocene.

Microfossils and especially pollen, diatoms and foraminifera are valuable sources of environmental data and furthermore, may be used as proxies for studying other wider aspects of environmental change such as climate, salinity/sea-level change and as a potential dating technique where radiometric techniques are not possible/available. This contribution examines the value and role of specific pollen types and their stratigraphical change in the salt marsh environment of the Solent region and, in particular, the use of two biostratigraphical markers are examined (Pinus and Spartina anglica) which may date the levels of salt marsh accretion in the last two centuries.

11.2 Pollen analysis of salt marsh sediments

Typically, pollen analysis is used as a method for studying past vegetation and vegetation environmental changes. Such studies are usually undertaken on lake sediments, peat and buried soils under archaeological structures. Where such sediments occur in the coastal zone, such analyses are invaluable to an understanding of coastal environmental change. In the South coast studies such as Godwin (1940), Long (1992) and in the Solent (Long and Tooley 1995; Long and Scaife (in press); Long and Scaife (1996). Pollen analytical

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK techniques have rarely been used to examine the typically largely inorganic salt marsh sediments which have accreted along the depositional, ria coastlines of the region. This lack of interest is undoubtedly due to the problems of interpretation caused by the complex taphonomy of pollen (and diatoms) in this depositional environment. Such difficulties are brought about by the factors which influence the dispersal and deposition of the pollen including the vicinity of the plants to the sedimentation site, the size and specific gravity of the pollen and flotation characteristics, air and water transport vectors and preservation potential at the site of deposition. There is also the possibility of reworking of older material from unconsolidated sediment (Groot 1966; Brush and Brush 1994; Long et al. 1999). Long et al. (1999) have identified three additional factors which require understanding for the analysis of pollen from inter-tidal salt marsh and mud-flat sediments. These include (i) the rate of net sediment accumulation (ii) the rates of vegetation change in the pollen catchment (iii) the time span between successive pollen levels/intervals.

11.3 Pollen as biostratigraphical markers in recent sediments

Prior to the development of radiocarbon dating, pollen was frequently regarded as a technique for dating sediments. With radiocarbon dating, pollen is clearly a tool for reconstructing past vegetation communities and changes in them resulting from climate, human and other factors. With radiocarbon dating, this has allowed the establishment of regional vegetation chronologies where specific changes in vegetation, such as the ‘lime decline’ or prehistoric ‘elm decline’ and the various vegetation communities present have been established for the Holocene. With undated samples, some indication of age can be gauged from comparison with the regional chronology. In geological contexts, pollen/microfossil analysis remains an important stratigraphical tool for broadly dating and correlating borehole sequences.

Three palynological phenomena may be of particular use for providing biostratigraphical age/markers within recent inorganic sediment sequence. These include increases in the pollen of pine, elm and Spartina anglica.

(i.) First, is the marked rise in pine pollen which is evident in the upper-most levels of many terrestrial pollen diagrams from throughout the country and in southern England (Haskins 1978; Scaife 1980, 1987; Barber 1981; Waton 1982). This expansion of coniferous woodland and thus pine pollen was the result of plantation in private estates after publication of Sylva by John Evelyn and later for forestry. Plantations are well documented for Dorset, Hampshire and the Isle of Wight and reviewed (Flower 1977; Haskins 1978; Scaife 1980; Waton 1983). The abundance of wind dispersed pollen produced by pine has resulted in the widespread incorporation of pine pollen in a range of sediments and especially more open marshes, fens and bogs. Whilst there is some local variation in the supposed date of the pine pollen expansion due to plantation at different times, the broad

range is from AD 1700-1800 and in the Isle of Wight at c. 1800 (Scaife 1980). This phenomenon is clearly seen in a number of recent studies undertaken on the south coast where it has been used a biostratigraphical market used to enable rates of sedimentation to be ascertained.

(ii.) Spartina anglica is interesting in that after its introduction into Hythe on Southampton Water in AD 1870, this salt marsh plant hybridized and spread rapidly along the south coast. The large pollen grains of Spartina anglica associated with on-site growth and sediment macrofossils similarly produces a useful marker for the close of the 19th Century. This development had a profound effect on coastal sedimentation, apparently causing rates to increase due o trapping of transported material (Long, Scaife and Edwards 1999) in Poole Harbour and Southampton Water (Long and Scaife 1996). With recent ‘die-back’ of Spartina, such sedimentation rates have bee reduced. This has important implications for future management of coastal, fringing salt marsh in view of future expected relative sea- level rise (see below).


iii.) Less well represented are other introduced taxa which include Ulmus glabra (wych elm) into hedgerows with the enclosure movement and other exotic conifers including Picea (spruce) and Abies (fir). These taxa may be present in some pollen profiles but are less evident because they are not growing on-site and/or do not produce large quantities of anemophilous pollen as does pine.

11.4 The Yarmouth Marsh study area Pollen biostratigraphical markers have been used successfully to establish age/sediment thickness’ and changing sedimentation rates in Pollen Harbour (Long, Scaife and Edwards 1999) and Southampton Water (Long and Scaife 1996). The replicability of such studies is still questioned. Hazel (1998 unpublished) has, however, demonstrated a degree of replicability in an adjacent borehole transect in the Poole Harbour salt marshes studied by Long et al. (1999). Given the availability of salt marsh habitats within the region, the absence of other dateable material and the relevance of salt marshes as a coastal barrier protection to the low lying drowned river valleys (rias), a further study of the extensive salt marsh at Yarmouth was undertaken. The location of a 1 metre core obtained for this study is given in Figure P1.11(b) which also shows the location (s) of boreholes used in establishing the earlier Holocene/Prehistoric vegetation, environment and sea-level change. The core taken from the central area of the estuarine salt marsh has been pollen analysed at 10cm intervals in order to delimit the biostratigraphical markers discussed above-especially the anthropogenic pine rise and colonisation of the marsh by Spartina. From these, estimates of sediment accumulation depths/rates might be achieved.

Pollen and spores were successfully extracted from these typical grey, salt marsh sediments and the pollen spectra obtained provide information on the background regional vegetation as well as the on-site (autochthonous) plant communities. The taphonomy is complex with pollen derived directly from airborne sources and also fluvially and from the possible reworking of older sediment (i.e. factors noted above in the introduction). Briefly, the former (regional) vegetation comprised largely Quercus (oak) and Corylus avellana (hazel) woodland which was most likely coppice managed. Fagus (beech), Fraxinus (ash) were also present but are less well represented because of lesser/poorer pollen production levels. Juglans (walnut) is an interesting occurrence of this tree introduced into western Europe during the Roman period. Where it occurs in terrestrial mires it is also a useful biostratigraphical marker of c.2000 years ago. In coastal sediments this may also apply although it has been suggested that earlier (Bronze Age) records in Poole Harbour may derive from long distance marine transportation from North America (Scaife in Long et al. 1999). Given the recent time-span of this 1 metre sequence, as expected, there is evidence of human activity in the form of agriculture-both arable and pastoral and also interesting records of Fagopyrum (buck-wheat) and possibly Cannabis sativa (hemp).

It is, however, the biostratigraphical markers discussed above and the on-site salt marsh development which are here relevent.

The pine rise: From 90cm, there is a progressive expansion of pine to highest values at the top of the profile. The magnitude of this expansion is not as great as witnessed in other pollen diagrams from the Island (Scaife 1980) or from the coastal sediments of Southampton Water (Long and Scaife 1996) or Poole Harbour (Long et al. 1999. Hazel 1998 unpublished). This may be due to the dominance of ‘on-site’ plants such as Chenopodiaceae and Poaceae which are here calculated within the pollen sum and with high values will reduce the relative percentages of other taxa (including Pinus). However, the expansion from 90cm suggests a date of c. AD 1800 for this level/horizon.

The Spartina rise: Whilst Spartina pollen is less readily recognised to species or genus/level than pine, the very substantial expansion of ‘large Poaceae’ is associated with

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK macrofossil remains in the sediments representing local/on-site colonisation. The pollen morphology is frequently described as cereal type being >45u. However, ‘large’ halophytic grasses such as Elymus and Spartina anglica have large similarly large grains but without the thick exine and large pore/annulus diameter and ratio. As such they are readily differentiable from the smaller wild grasses. The introduction and hybridization and spread of Spartina anglica from Hythe in 1870 resulted in colonisation on the Isle of Wight at the end of the 19th Century (Colin Pope pers. comm.). This expansion, therefore, provides a second useful datum point in the sediment profile.

Other biostratigraphical indicators: As expected, pine and Spartina are the main elements of interest. However, the conifers, Picea (spruce) and Abies (fir) are also present. Whilst derived Tertiary pollen contained similar types, these sporadic or individual records were in a state of preservation comparable with the Holocene pollen. It is thought that these occurrences, as with pine, derive from exotic/plantations.

11.5 Saltmarsh development The first evidence of the hybridised Spartina (S. anglica) was found at Hythe on Southampton Water in 1870. Typically with introduced taxa, initial spread and colonisation was rapid along Southampton Water and the Solent. This prompted several articles and papers to be written in scientific and local journals. Here, Groves (1927) provides information on the early colonisation with comments relating to Lymington marshes. Lord Beaulieu of Lymington describes the way in which Spartina was responsible for the stabilisation of Lymington Marshes by 1927 contrasting this beauty with the ‘foul smelling mud flats’ present some 50 years earlier. This is an early indication of the potential value of Spartina in protecting the lowland/submerging coastline of Southern Britain in the future. As with Ammophila arenaria (marram grass) stabilisation of dunes, Spartina may not only stabilise the mud-flats against erosion but also be responsible for increased sediment accretion which may keep pace with rising sea-level. Without this, there will clearly be increased erosion and also inundation of the marshes due to rising sea-level due to global warming.

The Yarmouth Marsh pollen profile demonstrates the change from open mud flat to Spartina dominated salt marsh. The pine rise at 95-90cm is placed at AD 1750-1800 while the Spartina rooting and pollen evidence is for stabilisation at a depth of c.40cm at a date estimated at c.1900-1920 at this site. When the Yar Marsh data are compared with data from Pollen Harbour and Southampton, it appears that the salt marsh sediment thickness’ which have accrued during the last c. 200 years is broadly similar at each of the sites examined. Overall, depths of some 60-90cm are represented but with differing accretion rates of sedimentation clearly occurring according to Spartina colonisation and later ‘die- back’ (Long et al. 1999).

11.6 Summary and conclusions

Pollen bio-stratigraphical analysis of recent sediments has rarely been undertaken. Absence of typical, peat accumulation in the coastal zone during the past 2 millenia has posed the problem of obtaining/delimiting the standard datum points for changing sea-level during this period and the rates of sediment accretion in coastlines of deposition. Estimates of relative sea-level rise have generally been based upon extrapolations of earlier Holocene sea-level change data. Biostratigraphical markers such as the anthropogenic pine pollen rise and Spartina colonisation have provided useful information on sediment depths and accretion rates which are not available using radiocarbon dating/measurements (although 210Pb is of use). Whilst apparently broad, the estimated ages of these biostratigraphical indications are comparable with standard errors for radiocarbon measurements. Where these biostratigraphical data are backed by historical documentation for these events, the accuracy may be great and the results may be used to test existing extrapolated data and determine the overall sediment accretion rates noted above. At Yarmouth Marsh, both the

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK Spartina and the pine rise have been identified and are at depths comparable with studies undertaken in Poole Harbor and Southampton Water. Spartina colonisation had a profound impact on the ecology of salt marshes along the south coast in stabilising large areas of unstable mud-flat and increasing sedimentation rates which keep pace with rising sea-level. Die back has occurred and their has been increased erosion of these delicate habitats. The ability to re-introduce and/or preserve Spartina may have important implications for future coastal protection and management. This may be especially pertinent since there is clear evidence for accelerated sea-level rise as a consequence of global warming.

11.7 Bibliography for pollen analytic studies

Nb. Please refer to this list also for pollen studies in Study Area P2.

Andersen, S.Th. 1970 'The relative pollen productivity and pollen representation of North European trees, and correction factors for tree pollen spectra'. Danm. Geol. Unders. Ser I I96,99pp

Andersen, S.Th. 1973 'The differential pollen productivity of trees and its significance for the interpretation of a pollen diagram from a forested region In Birks, H.J.B and West, R.G. Quaternary Plant Ecology Blackwell, Oxford. pp.109-115.

Barber, K.E. 1981 ‘Pollen-analytical palaeoecology in Hampshire: Problems and potential’. In I. Shennan and T. Schadla-Hall, (eds.). The archaeology of Hampshire, Hampshire Field Club and Archaeological Society. Monograph Series No. 1 pp.91-94.

Barber, K.E. and Clarke. M.J. 1987 'Cranesmoor, New Forest: Palynology and macrofossil stratigraphy' in K. E. Barber, (ed.), Wessex and the Isle of Wight, Field Guide. Cambridge: Quaternary Research Association. pp.33-44.

Battarbee, R.W,. 1986. ‘Diatom analysis’. In B. E. Berglund, (ed.) Handbook of Holocene Palaeoecology and Palaeohydrology. Chichester: John Wiley and Sons, pp 527-570.

Bennett, K.D., Whittington, G. and Edwards, K.J. 1994 'Recent plant nomenclatural changes and pollen morphology in the British Isles'. Quaternary Newsletter 73,1-6

Birks, H.J.B., Deacon, J. and Peglar, S. (1975) 'Pollen maps for the British Isles 5000 years ago'. Proceedings of the Royal Society B. 189, 87-105.

Birks, H.J.B. (1989) 'Holocene isochrone maps and patterns of tree spreading in the British Isles'. Journal of Biogeography 16, 503-540.

Brush, S. and Brush L.M. 1994. ‘Transport and deposition of pollen in an estuary: signature of the landscape’. In A. Traverse, (ed.). Sedimentation of Organic Particles. Cambridge University Press, Cambridge.

Cundy, A, and Croudace, I.W. 1996 ‘Sediment accretion and recent sea-level rise in the Solent, southern England: inferences from radiometric and geochemical studies’. Estuarine, Coastal and Shelf Science 43, 449-467.

Denys, L. 1992. A Checklist of the diatoms in the Holocene deposits of the Western Belgian Coastel Plain with a survey of their apparent ecological requirements: I. Introduction, ecological code and complete list. Service Geologique de Belgique. Professional Paper No.246. pp 41.

Devoy, R.J.N. 1972 Environmental changes in the Solent area during the Flandrian. Unpublished B.A. dissertation, Department of Geography, University of Durham.

Devoy, R.J.N. 1979 'Flandrian sea-level changes and vegetational history of the Lower Thames estuary'. Philosophical Transactions of the Royal. Society B 285, 355-407.

Devoy, R.J.N. 1980 'Post-glacial environmental change and man in the Thames estuary: a synopsis'. pp.134-148 in F.H. Thompson (ed.) Archaeology and Coastal Change Occasional paper Soc. Antiqs. New Ser. 1.

Devoy, R. 1987 ‘The estuary of the Western Yar, Isle of Wight: sea-level changes in the Solent’. in K. E. Barber, (ed.), Wessex and the Isle of Wight, Field Guide. 156-180. Cambridge: Quaternary Research Association. pp.115-122

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK Emery, K.O and Aubrey, D.G. 1985 ‘Glacial rebound and relative sea-levels in Europe from tide gauge records’. Tectonophysics 120,239-255.

Flower, N. 1977 ‘Forestry and land-use in the New Forest’. PhD. thesis of University of London, Kings’ College.

Girling, M.A. (1988) 'The bark beetle Scolytus scolytus (Fabricius) and the possible role of elm disease in the early Neolithic'. pp.34-38 in M. Jones, (ed.) Archaeology and the flora of the British Isles. Oxford: Oxford University Committee for Archaeology.

Godwin, H. and M. E. 1940 'Submerged peat at Southampton. Data for the study of post- glacial history V'. New phytologist 39,303-307.

Godwin, H. 1945 ‘A submerged peat in Portsmouth Harbour’. New phytologist 44, 152- 155.

Godwin, H 1956 The History of the British Flora 1st Edition Camb. Univ. Press

Godwin, H. 1975 The history of the British flora. 2nd Edit. Camb. Univ. Press.

Greig, J.R.A. 1982 'Past and present lime woods of Europe'. in M. Bell and S. Limbrey (eds.), Archaeological Aspects of Woodland ecology. Assoc. Environ. Arch. Symposia Vol 2 B.A.R.(Int. Ser.) 146. pp.23-55

Groot, J.J. 1966 ‘Some observations on pollen grains in suspension in the estuary of the Delaware River’. Marine Geology 4,409-416.

Groves, J. 1927 ‘The story of our Spartina.’ Proceedings of the Isle of Wight Natural History and Archaeological Society 1,.509-513.

Haskins, L.E. 1978 The Vegetational History of South-East Dorset. Unpubl. Ph.D. University of Southampton, Department of Geography.

Hartley. B,. 1996 An Atlas of Britsh Diatoms. Biopress.

Hendy, N.I,. 1964 An introductory account of the Smaller Algae of British Coastal Waters. Part V. Bacillariophyceae (Diatoms). MAFF, Series IV. HMSO.

Husdedt, F,. 1957. Die Diatomeenflora des Fluss-systems der Weser im Gebiet der Hansestadt Bremen. Ab. naturw. Ver. Bremen 34, 181-440.

Janssen, C.R. 1969 'Alnus as a disturbing factor in pollen diagrams'. Acta Bot. Neere. 8,55- 58.

Long, A.J. 1992 Coastal responses to changes in the East Kent Fens and southeast England, UK over the last 7500 years'. Proceedings of the Geologists Association 103,187-199.

Long, A.J. and Innes, J.B. 1993 'Holocene sea-level changes and coastal sedimentation in Romney marsh, southeast England, UK. Proceedings of the Geologists Association 104,223-237.

Long, A.J and Tooley, M.J. 1995 'Holocene sea-level and crustal movements in Hampshire and Southeast England, United Kingdom'. Journal of Coastal Research Special Issue No.17,299-310.

Long, R.G. and Scaife, R.G. 1996 Pleistocene and Holocene Evolution of Southampton Water and its Tributaries. Environmental Research centre, Department of Geography, University of Durham.

Long, A.J., Scaife, R.G and Edwards, R.J. 1999 ‘Pine pollen in intertidal sediments from Poole Harbour, UK; implications for late-Holocene sediment accretion rates and sea- level rise’. Quaternary International 55,3-16.

Long. A.J., Scaife, R.G. and Edwards, R.G. 2000 ‘Stratigraphical architecture, relative sea- level and models of estuarine development in southern England; new data fro Southampron Water’. pp. 253-279 in K. Pye and J.R.L. Allen (eds.) Coastal and estuarine environments: sedimentology, geomorphology and geoarchaeology. Geol Society Special Publications Vol. 175.

Mangerud, J., Andersen, S.T., Berglund, B.E. and Donner, J.J. 1974 'Quaternary stratigraphy of Norden, a proposal for terminology and classification'. Boreas 3, 109- 128.


Moore, P.D. (1977) 'Ancient distribution of lime trees in Britain.' Nature, London 268, 13-14.

Moore, P.D. and Webb, J.A. 1978 An illustrated guide to pollen analysis. London: Hodder and Stoughton.

Moore, P.D., Webb, J.A. and Collinson, M.E. 1991 Pollen analysis Second edition. Oxford: Blackwell Scientific.

Nicholls, R.J and Clarke, M.J. 1986 Flandrian peat deposits at Hurst Castle Spit’. Proceedings of the Hampshire Field Club and Archaeological Society 42,

Scaife, R.G. 1980 ‘Late-Devensian and Flandrian palaeoecological studies in the Isle of Wight'. Unpubl. Ph D thesis. University of London, King's College.

Scaife, R.G. 1982 'Late-Devensian and early Flandrian vegetation changes in southern England.' in S. Limbrey and M. Bell (eds.) Archaeological aspects of woodland ecology. B.A.R (Int. Ser.) 146, 57-74.

Scaife, R.G. 1987a 'The Late-Devensian and Flandrian vegetation of the Isle of Wight'. in K.E. Barber(ed.), Wessex and the Isle of Wight, Field Guide. 156-180. Cambridge: Quaternary Research Association. pp.156-180.

Scaife, R.G. 1987a 'A review of later Quaternary plant microfossil and macrofossil research in southern England; with special reference to environmental archaeological evidence'. pp 125-203 in H.C.M. Keeley (ed..), Regional environmental archaeological reviews. Publ. English Heritage Commission.

Scaife, R.G. 1988 'The elm decline in the pollen record of south east England and its relationship to early agriculture". In M. Jones (ed.), Archaeology and the flora of the British Isles. Oxford University Committee for Archaeology. Monograph No.14.

Scaife, R.G. and Burrin, P.J. (1992) 'Archaeological inferences from alluvial sediments: some findings from southern England'. in S. Needham and M. Macklin (eds.), Alluvial Archaeology in Britain. Oxbow Monograph 27. pp.75-91.

Scaife, R.G. 1994 ‘Testwood Lakes: An early Holocene pollen sequence’. Unpublished report for Wessex Arcaheology, Salisbury.

Scaife, R.G 1998 ‘Mountbatten Park, Southampton: Pollen analysis of the Holocene peat and sediment sequence’. Unpublished Report to Southampton City Council.

Scaife, R.G. (forthcoming/in press) ‘The changing vegetation and environment’. in Tomalin, D.J., Loader, R. and Scaife R.G. Wootton Haven: Coastal and port archaeology in a dynamic envirnment. English Heritage.

Shennan, I. 1982 ‘Interpretation of the Flandrian sea-level data from the Fenland, England’. Proceedings of the Geologists Asssociation 93,53-63.

Shennan, I. 1986 ‘Flandrian sea-level changes in the Fenland II: Tendencies of sea-level movement, altitudinal changes and local and regional factors’. Journal of Quaternary Science 1,155-179.

Shennan, I. 1989 ‘Crustal movements and sea-level changes in Great Britain Journal of Quaternary Science 4,77-89.

Shennan, I. 1994 ‘Models of coastal sequences’. In M. Waller (ed.), The Fenland Project, Number 9 Flandrian Environmental Change in the Fenland. East Anglian Archaeology 70.

Sidell, J., Scaife, R., Tucker, S. and Wilkinson, K. 1995 'Palaeoenvironmental investigation at Bryan Road, Rotherhithe'. London Archaeologist 7,(11),279-285.

Sidell, J., Wilkinson, K., Scaife, R.G. and Cameron, N. 2000 The Holocene Evolution of the London Thames. Museum of London Monograph 5. ISBN 1 901992 10 1. 144pp.

Smith, A.G. (1970) 'The influence of Mesolithic and Neolithic man on British vegetation: a discussion.' in D. Walker and R.G. West (eds.), Studies in the vegetational history of the British Isles. Camb. Univ. Press.

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK Smith, A.G. and Pilcher, J.R. (1973) 'Radiocarbon dates and the vegetational history of the British Isles'. New Phytologist 72,903-914.

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Stockmarr, J. 1971 'Tablets with spores used in absolute pollen analysis'. Pollen et Spores 13, 614-621.

Sutherland, F.M.J. 1984 Flandrian sea-level changes on the South Coast of England. Unpublished M.Sc. dissertation of Geography Ddepartment, University of Durham.

Tooley, M.J. 1978 ‘Sea-level changes in North-west England during the Flandrian Stage’. Clarendon Press, Oxford.

Tooley, M.J. 1979 ‘Sea-level change during the Flandrian stage and the implications for coastal development’. in K. Suguio et al. (eds.) Proceedings of the International symposium on coastal evolution in the Quaternary’. Sao Paulo, Brazil (1978). pp.502- 533.

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Waton, P.V. 1982. A palynological study of the impact of man on the landscape of central southern England, with special reference to the chalklands. Unpubl. Ph.D. thesis of University of the Southampton, Department of Geography.

Waller, M. 1994 'The Tilia decline and paludification in southern England'. The Holocene 4, 430-434.

Woodworth, P.L. 1987 ‘Trends in U.K. mean sea-level’. Marine Geology 11, 57-87

12. ARCHAEOLOGICAL AND PALAEO-ENVIRONMENTAL INVESTIGATIONS AT THE RIA INLET OF NEWTOWN HARBOUR

Newtown Harbour is a drowned river basin in which a dendritic pattern of four shallow valleys has been occupied by the sea. These arms of the harbour system reach a maximum distance of 3km inland where they are fed by minor streams.

Newtown enjoyed a brief period of prosperity in the early Middle Ages when it was chosen by the de Redvers family as a promising site for the development of a specifically planned coastal town and port. The neighbouring Solent ports of Lymington, Yarmouth and Newport were also planned by this powerful Norman family. Each town was laid out according to a rectilinear pattern in which a parrallel arrangement of a minor streets were set at right- angles to one or more central axial streets.

Newtown grew slowly but steadily until the mid 14th century after which it entered into a rapid and irreversible decline. The cause was a disastrous French raid which, in AD 1377, left the town a burnt ruin. Prior to this date the town was recorded as harbouring 'some 500 souls' but after the raid it seems that many families never returned and as a consequence houses were not rebuilt and burgage plots were left unoccupied.

Newtown is a significant cultural heritage site because it is one of the few English medieval port towns which has shrunken to virtual extinction while still retaining its ancient urban land boundaries. These boundaries are now hedgerows which follow the lines of the old streets and burgage plots. These are surprising centred upon a town hall which stands incongruously within a surrounding of fields. The entire 'town' and its surroundings are almost entirely managed by the National Trust and it has become an important asset to the 'green tourism' economy of the Isle of Wight. There are also highly sensitive bird habitats within the natural setting of the harbour and these are protected by Ramsar and other appropriate designations


The history of Newtown has made it an important archaeological and palaeo-environmental resource in a sensitive coastal zone. The arms, or reaches, of the natural harbour have never been dredged and this means that the archaeological and palaeo-environmental horizons below water level have escaped disturbance. The waterside margins are important breeding habitats for the protected bird population. They are also significant sources of archaeological and palaeo-environmental information. Figure P1.12 provides an indication of thenpalaeo- environmental potential of Newtown Harbour. The history of the town shows that a former area of riverside pasture was embanked as a protection against increased flooding during the early post-medieval period. This was about the same time that the brewers in the neighbouring town of Newport were being accused of drawing 'salty beer' when high tide was affecting their waterside taverns.

For the present and future management of the harbour the most important feature is the nature of the river mouth. Historically, it seems that this has always been naturally protected by opposed shingle spits which have very effectively confined the entrance. These are known as the East and West Spits and they are sited on an old saltmarsh surface. One of the studies included in this LIFE study has been an appraisal of the archaeological evidence and geomorphological evidence at the mouth of the harbour. An investigation by the Isle of Wight County Archaeological Service and the School of Ocean and Earth Sciences identified a concealed palaeochannel below old saltmarsh sediments on the seaward side of the East Spit. The presence of this channel demonstrated that the course of the river had changed very little throughout the Holocene period although it might be assumed that the spits had retreated upstream as the wave planation had advanced. A Pleistocene ancestry for this river chaneel could also be demonstrated by the recovery of notable numbers of mammal bones from interglacial silts which could be approached at low tide in the intertidal zone.

To establish the evolutionary history of the harbour and its spits two lines of investigation were pursued. A single Cobra auger core was sunk on the offshore margin of the East Spit. This penetrated the underlying saltmarsh sediments to reveal a long history of similar environmental conditions broken at relatively brief intervals by episodes of peat formation. A significant peat horizon could be attributed to the Neolithic period when human activity could also be detected in the area of former saltmarsh which now lay offshore. The second line of investigation had been intertidal archaeological survey and this had identified two Neolithic wooden trackways which had been laid at a level of 1.6 metres below Ordnance Datum when waterlogging was being experienced during the 3rd millennium BC. One of these trackways was dated at 2920-2500 cal. BC (GU-5341).

The course of the Pleistocene/Holocene palaeo-channel was traced for a short distance offshore by the School of Ocean and Earth sciences by means of sub-bottom profiling. The sub-bottom images show an eastward trending channel which appears to be a feeder to the East Solent estuarine system. Consequently, it might be suspected that marine changes permeated the ancient valley from this quarter. See Figure P1.13.

On the north side of the East Spit some remnant s of relatively recent saltmarsh was still being eroded by the sea. Some scatters of Mesolithic and Neolithic flint tools could be found within this surface and this indicated that wave attack had not arrived here until at least post -Neolithic times. Some in-situ pits filled with intensely burnt flint waste attested prehistoric cooking or boiling activities on the margin of the old river channel but unfortunately these features did not produce carbonised material suitable for absolute dating. Position of the shingle spit on top of these saltmarsh deposits suggests that spit formation has advance just ahead of coastal eroson and has sheltered the interior of the harbour system over a very long period. The sedimentological evidence from the Cobra core also suggests that the environment of the river channel has always been sheltered. The current regimes of wave attack and spit depletion has presented a marked contrast with both the short-term and long-term palaeo-environmental record. This begs comparison with changes in the sediment path from the East Solent shingle bank. This was a potential natural supply of shingle to the spits prior its exploitation for mineral aggregate dredging in

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK the 1960s and 1970s. It has been in the post-dredging era that local concern has arisen over the marked diminution of the spits. The implications for the future management of the sensitive habitats of the harbour have yet to be assessed and the cessation of offshore mineral dredging at this location must be seen as a positive advantage. Currently the shoreline management plan for this section of coast is unresolved.

13. RECENT INVESTIGATION OF DEEPLY SUBMERGED HUMAN OCCUPATION ON THE FLOOR OF THE WESTERN SOLENT AT BOULDNOR CLIFF

13.1 Identifying the submerged Middle Holocene landscape at Bouldnor Cliff

The geomorphological evolution of the coastline at Bouldnor Cliff in the western Solent has resulted from climatic changes and sea-level fluctuations in the Pleistocene and Holocene periods. The cliff is subject to instability which is res[ponsible for an active landslide complex. Surprisingly,, some 500m offshore, a drowned landscape can be identified where past periods of accretion and sedimentation have occurred. Here, three three layers of peat have been been found interclated with alluvium. These deposits attest marine inundation which has been interrupted by episodes of falling or static sea-level during which some parts of the shoreline have been allowed to advance and reclaim land from the sea. The archaeological and palaeo-environmental evidence found within these drowned deposits provides a temporal framework for climatic and environmental events. This site is a prime example of geomorphological adaptations which are coincident with climatic change. The presence of both palaeo-environmental and archaeological material at this site has provided both relative and absolute fixes for placing these events within a calculable timeframe.

The submerged forest was first identified in 1976 when local fishermen dredged up peat and tree fragments. A preliminary appraisal by David Tomalin and Rob Scaife led to a number of diving sweeps seeking the source of this disturbed material. Eventually, in 1985, this source was finally traced to the foot of an underwater cliff by John Cross, of the Coastal Research Unit of the University of Southampton Department of Oceanography. This discovery was concurrent with an underwater survey of the Yarmouth Roads anchorage by the Isle of Wight Maritime Heritage Project. Members of the project team then turned their attention to further exploratory dives off Bouldnor and this led to the in situ examination of tree boles and roots on a submerged land surface which was subject to active erosion. Later, with the help of English Heritage, an absolute date was obtained of 6430–6120 calendar years BC (GU-5420) for a tree in this basal peat deposit.

In 1991 this same section of the Solent coast was revisited by the diving team of the Hampshire and Wight Trust for Maritime Archaeology (HWTMA) and mapping of the submerged land surface was pursued. In 1997 further seabed archaeological inspections by the Trust and its trainee underwater surveyors identified a particular location in this submerged landscape where deposits of Mesolithic flint tools had been disturbed by burrowing lobsters. This site was subsequently chosen as a research topic for the European LIFE Project. In 1998 and 1999 the LIFE investigations were successful in recovering monoliths of peat and sediment for palaeo-environmental analyses. The diving team was also able to identify in-situ scatters of Mesolithic tools, confirming that human habitation had once occurred in this now drowned landscape.

The date of the basal peat lies within the Mesolithic period when local communities were adapting to the changing environmental conditions brought about by post-Glacial climatic and sea-level changes. Studies of Mesolithic settlement patterns elsewhere in Europe have shown a common interest in the subsistence resources of the coast. This affinity with the maritime zone often resulted in the siting of human occupation at locations which were vulnerable to the rise and advance of the sea. The archaeological features within the basal

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK peat at Bouldnor provide tangible evidence of the response of the local population to a rise in sea-level during the mid-Holocene period.

13.2 Underwater investigations off Bouldnor Cliff The archaeological task within the LIFE project has been conducted in conjunction with a team led by Dr J Dix of the School of Ocean and Earth Sciences (SOES), University of Southampton. The key objectives were:-

· To characterise the morphology of the submerged cliff by conducting geophysical surveys and to compare the morphology of the submerged cliff with the present terrestrial cliff.

· To investigate the relative stability or instability of the submerged cliff.

· To explore the implications for the history of Holocene transgression in the Western Solent.

To aid the SOES team, the Trust conducted a number of dives on the Bouldnor coast to collect monolith and gouge core samples from the submerged landscape. A considerable number of dives were needed to establish the most representative section of the cliff suitable for coring. The chosen sector of the submerged cliff-face comprised silty clays in interspersed with peat. Some of these deposits were exposed in a vertical section which was subject to erosion. A seam of peat protruded from the top of the cliff and another lay a metre below. The total height of the submerged cliff was over 7m. The peat-capped crest was set 4.1 m below Ordnance Datum. Below this the profiledropped steeply before levelling off. At 9m below OD, the slope of the cliff changed to a 2m vertical drop. The base of the cliff lay at an average depth of -11.1m OD. It this point the foot of the cliff was an expanse of in-situ peat and ancient timber. This basal peat deposit extended for about 15m to the north before being terminated by a miniature cliff at 12m below Ordnance Datum. This final break in slope bordered the main channel of the Western Solent which at this point was covered with shingle/cobble, oyster shells and sand.

13.3 Methods employed of coring underwater At Bouldnor, the aim of the LIFE project was to gain samples from the full height of the submerged cliff by coring. Three methods of core sampling were employed. All were manual and necessitated a diving personnel. The requisite tools were a 20mm auger or gouge core, a 40mm enclosed core with acetone liner and Monolith sampler. The auger core was relatively quick and efficient so it was primarily used to identify the submerged stratigraphy. The 40mm enclosed core and the monolith sampler were used to collect samples for radio carbon dating, diatom analysis and pollen analysis.

A datum was established at the foot of the cliff on the surface of the lower peat deposit. Secondary datums were positioned to the south at the top of the cliff and to the north at the edge of the peat platform. A 36m baseline was finally laid linking all proncipal points. Gouge core samples were taken at intervals along the tape measure and these were bored as deeply as possible. The cores were transported to the surface via a messenger line for recording and sampling and returned to the diver in the water. The depth at each core was recorded as well as the total length of penetration. The next core was taken down the slope to a depth of about 0.5m above the deepest penetration of the previous core. This gave a continuous series of overlapping cores down the cliff.

Monolith cores were used to collect samples from peat/alluvium interfaces in the verticle sections of cliff. The cores were all extracted in long rectangular boxes with one side open. The box was pushed into the deposit and excavated to leave an undisturbed sample in the

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK core. This method is very useful where thestratigraphy is clearly exposed in the face of the deposit.

Datum depths were first recorded with Aandera! WLR7 depth meters. These depths were calibrated against a local tide gauge in the mouth of Lymington River and against an intertidal benchmark. This benchmark was positioned directly inshore from the submerged cliff and positioned with an RTK differential Global Positioning System (DGPS), The tide guage calibrations and the DGPS were kindly provided by New Forest District Council.

13.4 Results produced by coring Core samples were taken along the cliff to a maximum depth of 2m. The angle of cliff slope averaging about 30 degrees, however, made it possible to obtain representative samples from almost every depth. For the purpose of the LIFE Project, pollen and diatom analyses of the cores were carried out by the University of Southampton, Dept of Geogrraphy (Scaife, this report). This work sought to determine past vegetation environments, cliff formation processes and the progression of sea-level rise.

13.5 Survey of the peat platform below the submerged cliff On completion of the coring, an area of the basal peat seabed was surveyed, recording the larger tree remains and any archaeological features. Underwater survey in this difficult environment presents many challenges. With each turn of the tide, water flows across the site at over 2 knots. Slack water lasts only a few minutes. Visibility averages about 1.5m but can be reduced to zero when the sediment load increases on the ebb tide. Visual difficulties are compounded by the dark peat seabed, which absorbs light. Consequently, many dives by many divers were necessary to complete the survey. Five, 3m wide lanes in a 30m long strip running east west were searched. This covered the total width of the peat platform at this point, where the 'corridor search' technique was used (Dean, et al., 1992). The results revealed a platform inlaid with fallen tree trunks and in-situ boles and associated root systems reaching into the underlying substrate. The deposit lies about 11.5m below Ordnance Datum at the foot of a 1.8 metre vertical section of submerged cliff. Within the area surveyed, 13 tree stumps, extensive pieces of timber and 9 substantial boles were plotted (Fig. 5). One trunk, orientated south to north, measured over 12 metres in length. At its southern end, where it emerged from below the cliff, its full diameter, including bark was intact. Degradation of the timber increased with distance from cliff. This implies that the peat had been sealed in an anaerobic environment, prior to the progressive erosion of the cliff. A sample of oak timber sapwood, removed from the seabed , provided good evidence of active biological degradation. Two hazelnuts over 8,000 years old were embedded in the underside of this fallen tree. These demonstrated the preservational qualities of the peat and the fact that the fallen tree had remained entirely undisturbed after the floor of its woodland habitat had been submerged. (Fig. 6).

On the northern edge of the platform, scour around tree stumps was found to be undercutting the peat creating overhanging ledges up to 1.5m high. These were subject to failure and collapse. This eroding boundary was very well defined in the survey area. Consequently a drift dive was conducted to quantify continuity. The dive traced the platform for over a kilometre west. The band of peat was found to be unbroken in a laterally consistent deposit running roughly east-west.

13.6 The discovery of human occupation as attested by lithic remains

During the corridor search, flint tools and flint waste were discovered in the south west corner of the site at the bottom of the cliff. Here the diving team first observed that a number of flints had been up-cast from the peat or the underlying clay by burrowing lobsters. A lack of marine growth on the flints testified recent exposure by these creatures.


In total, 50 flints showing signs of human industry were found in two discrete locations lying 5m apart at the entrance to lobster burrows. 35 humanly-struck flints were present, 8 pieces showed evidence of burning and a further 7 small flakes were those which might be produced by knapping. The worked flints comprised one implement, 3 cores and 31 waste flakes. As the flints were not found in a stratified sequence their provenance could not be verified so during their initial discovery it was still suspected that they might have been washed into this position from a deposit further up the cliff. To help resolve this question the site was searched a second time looking specifically for lithics. A sampling strategy was also undertaken where metre quadrats were set in each corridor at evenly distributed points around the site. The quadrats were surveyed and recorded before all the loose cobble was removed for further scrutiny on dry land. However, no more worked material was found exposed on other areas of the seabed. This tended to suggest that all of the lithics had been truly up-cast from a sealed layer which had been intercepted by the lobsters.

In addition to the surface sampling, two small 200mm deep cores were taken from the peat near the lobster burrows. Both cores contained small amounts of flint, one piece being a small flake. From this evidence it appeared that flint was lying in situ within the peat. The analysis of this peat presented in this LIFE report indicates an environment which was responding to a rising sea-level and a ponding-back of the local river system. These changes created anaerobic conditions which were suited to organic accumulation. The pollen spectra recovered from this basal peat has now confirmed that the local vegetation at this time was wet fen with colonising alder and oak and hazel on the drier margins.

13.7 Identification of a stratified cultural deposit Following the discovery of worked flints in 1999, a project was organised between the 23rd and 30th May 2000. The principle aim was to confirm the existence of stratified Mesolithic material located at the foot of the cliff. Here, a sample of wood collected during the coring was C14-dated to 6615-6395 cal. BC (Beta-140104).

The Western Solent is not the easiest location in which to conduct a diving operation. Despite the shelter afforded by the Isle of Wight, the wind seldom abates and the tide only slackens for the shortest of windows. To maximise productivity in these circumstances, the project was run from a 23m vessel operated by Flat Holm, Coastline Surveys. This was moored over the site to provide a home for eight diving archaeologists, and additional experts and volunteers.

The excavation was conducted using surface supply diving equipment (SSDE) with air lifts, trowels and purpose made coring boxes in an area delineated by a stainless steel grid, built specifically for the project by Analytical Engineering. All the work was recorded on a head mounted Seahawk camera system provided by Kongsberg Simrad. This linked the dive supervisor and archaeological director with the excavator.

When sections of the seabed were collected in the core-boxes they were lifted to the surface for examination. The artifacts within the core boxes were then excavated and recorded on deck. The overwhelming majority of lithics were located in a dark sandy/silt context below the basal peat deposit. Analysis of their distribution revealed an increase in concentration towards the eastern end of the excavated trench. This suggested a centre for the Mesolithic occupation site. To date, over 300 humanly worked or burnt pieces of flint have been identified. Despite the assemblage being relatively small, the technology compares favourably to that of the early to mid Mesolithic.


In addition to the archaeological and palaeoenvironmental studies, 8 samples of timber were sawn from trees within the peat. These were sent for dendrochronological analysis by Nigel Nayling of the University of Wales, Lampeter. The samples were of excellent quality, providing a 280 year sequence over 8,000 years old.

Following the excavation, further monitoring was conducted towards the end of the summer when the site was revisited and the rate of erosion in the surrounding peat deposit was recorded. This was achieved by measuring calibrated rods that had been placed at selected locations across the site 10 months earlier. From the results it was clear that material from the peat platform was indeed being lost, this was most evident to the north of the archaeological site where 160mm of erosion was recorded at the outermost edge of the basal peat deposit.

The methods employed during the LIFE project proved very successful and enabled the main outcomes to be realised by demonstrating that worked lithics were stratified within the seabed. The project has been unique in the UK, and it has demonstrated the potential value the archaeological and palaeo-environmental material which has been deeply submerged on the former margins of the European coastline.

13.8 Coastal sites of the Mesolithic in southern England

Submerged palaeo-landscapes are a diminishing and irreplaceable resource. They represent an archive of information relating to previous glacial low sea-levels, as well as sea-level which has risen during the Holocene period. Peat deposits and evidence of human activity at known depths can reveal information about sea-level and local environments at that time.

The formation processes of the deposits and spatial relationships between them, can show rates of change (Long et al., 1999; Scaife, 1982). Archaeological investigation can indicate habitation responses to these circumstances (Flemming, 1998) and their impact on the landscape

At the opening of the Mesolithic period, the sea would have been many kilometres from the modern coastline of lowland southern England. Sea-levels began to rise steeply about 8,500 BP when Britain was severed from mainland Europe by inundation (Mithen, 1999). By the end of the Mesolithic, about 6,000 years ago, levels were just a few metres lower than today (Devoy, 1982; Scaife, 1980) but some notable regional variations were also occurring.

The coastal Mesolithic communities of Europe successfullyadapted to the changing environment of the early and middle Holocene and exploitation of the coastline became a significant subsistence strategy (Palmer, 1977; Price 1989; Grigson 1989). Not too far the Solent study area, on the coast of the Massif Armoricain in northwest France, investigators have identified an array of submerged prehistoric sites (Prigent, 1983). Evidence of coastal use can also be found in Scotland where a number of coastal middens have been saved from submergence by uplift (Mellars, 1987). Scotland however, possessing a harsher environment than England was one of the last areas of Europe to be infiltrated by Mesolithic communities (Wickham-Jones, et al., 1998). In southern England evidence of large coastal sites is rare but this may be partly due to a history of coastal submergence which may have removed many sites from view. Simmons (1996:194), sums up the value of the coast to the Mesolithic, 'Coasts exert a very strong pull force in terms of available resources, to the point where no society would ignore them unless prevented by other human groups from gaining access to them.' All the evidence suggests the optimum sites in southern England would have been adjacent to the coast.


The the occupation of Warren Hill, Hengistbury Head (Cunliffe, 1987), hints at the potential for coastal occupation in the south. However, this site lies on a raised promontory which has ensured its survival. The remains of a Mesolithic midden, partially submerged in the intertidal zone at Westwood Ho! (Churchill, 1965), and sites found below the high water mark in the Severn Estuary (Wilson, 1998) seem to provide better clues as to human occupation on the earlier coastal margins of southern England. Here, a number of peat-

filled palaeo-channels have been investigated.Channels such as these have been attributed dates from the Mesolithic to the Bronze Age. All are below Ordnance Datum and all have contained archaeological remains.

Based on the present evidence it can be assumed that Mesolithic communities exploited the southern British coastline before this territory was lost to the advance of sea water. Successive camps would have been constructed as previous sites were abandoned and if certain location were favoured for their natural resources then the discovery of one submerged occupation site may well lead to otherr.Many of these sites would have been eroded and destroyed by contemporary coastal processes but investigations at Bouldnor have demonstrated that others were buried and protected underwater. For the archaeologist of the 21st century these submerged locations should not present a problem; indeed they offer distinct advantages. The preservation of organic materials in anaerobic conditions within a submerged site can be superior to sites of comparable date on land. Where a coastal site has been inundated and quickly encapsulated in sediment, a greater array of archaeological and palaeo-environmental material will survive. Not only can these be well preserved, but since they rest in an environment which is free from many of the terrestrial compaction stresses, deformation can be greatly reduced. Such conditions have been witnessed in discoveries in the Danish Storebaelt: However, due to the isostatic realignment of the forebulge, the contemporary southern coastline of Britain has mostly been submerged to a greater depth. The period when the coastline played accommodated the greatest density of Mesolithic people would have been in the later Mesolithic period when populations grew and landmass diminished. In Denmark, many late Mesolithic sites appear in the intertidal zone while along the English south coast, a greater proportion of similar sites would have been submerged by the sea. This means that particular care is needed in the management of the sub-tidal zone where archaeological and palaeo-environmental resources can be preserved and covered by sediment in the manner which has now been observed by the LIFE project at Bouldnor.

14. SUCCESSES AND PROBLEMS IDENTIFIED BY THE LIFE PROGRAMME

This case study has been particularly valuable because it has been able to examine a multi- disciplinary approach to an area of coastline where the submerged topogaphy of the Middle Holocene coastline can be compared with the on-shore topography of an actively eroding cliff-line. The successes of this project have been the high level of coastal behaviour evidence obtained from underwater exploration and the sinking of cores. The period covered by this evidence has been substantial and it has been able to set a base point for onset of inundation and the genesis of coastal erosion in the Western Solent. A high level of local support and amateur diving input has been a further successful feature of this project.

The problems identified in the study have concerned the omission of intertidal and sub-tidal research from the the Shoreline Management Plan. This has arisen because this particular section of coast has been assigned a do nothing management option on the grounds of low property values while the off-shore archaeological and palaeo-environmental resource has a broader value concerning the recognition of timescale and processes that affect a wide range of individual management units throughout the Western Solent. A further potential problem can be identified where the research carried out on this site has stemmed entirely from the goodwill and interest of local fishermen. Where areas of the European coastline are subject to fishing by non-local fleets this type of interest and reporting cannot be

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK expected. This raises the question of just how many seabed archaeological and palaeo-environmental sites are currently being trawled, damaged, dispersed and ignored.

15. SOCIAL INCLUSION AND COMMUNITY INVOLVEMENT

This case-study examined the imput of a number of different groups The primary responsibility for the discovered of the submerged landscape at Bouldnor lay with members of fishing ccmmunity of the Western Solent who had observed the reported the first artifacts from the seabed. Without this critical input none of the subsequent work would have gone ahead. The input by the sports diving community was equally critical as well as the organisational abilities of the Hampshire and Wight Trust for Maritime Archaeology which co-ordinated the activities of the amateur diving teams. While the first survey was carried out by the Maritime Heritage Project of the Isle of Wight, a remarkable groud swell of public support was provided by the residents of Yarmouth. This included the loan of substantial onshore premises for a two year period, free milk supplies for the ssame period, free and unlimited photcopying by the local estate agent and endless boat and engine repairs. The support of the Isle of Wight Council was similarly generous, the whole reflecting the very high regard which the local community held for its coastal heritage.

16. CONCLUSION AND KEY ISSUES

The discovery of the submerged site off Bouldnor Cliff has presented new and promising prospects for combining the study of Mesolithic coastal activity with the calibration and reconstruction of past and ongoing changes in sea-level. Unfortunately, in the past, this potential for interpreting Britain’s drowned landscape does not seem to have been fully recognised and consequently safeguards amongst regulating and sectoral bodies have been minimal (Tomalin, 1997).Sites below mean low water mark are undoubtedly being lost as a result of ignorance, neglect and the progression of human impacts. This is an issue which is only being weakly comprehended as both archaeologists and coastal managers are beginning to recognise a commonality of interests (Tomalin 1993). most important of these revelations is the realisation that many gaps in our understanding of coastal change could be answered with the investigation of well-preserved archaeological sites underwater.

Some of the key management principles have been laid out in the Policy Statement in England’s Coastal Heritage: A survey for English Heritage and the Royal Commission on the Historic Monuments of England. This states that:

‘Although archaeological remains situated in intertidal and sub-tidal areas may be less visible and accessible than remains on dry land, this does not affect their relative importance and they should be managed in accordance with the principles which apply to terrestrial archaeological remains.’ (Fulford et al, 1997).

Unfortunately, in England these principles have yet to be applied.

As a result of this current LIFE programme the partners have reviewed similar issues, questioning:

‘whether; present proposals for coastal management and protection can demonstrate wisdom drawn from a long term understanding of past natural and human events on the relevant coastline.’

They have also questioned whether:


‘new fields information will be required on past natural and human events, before such a question can be answered’.

In the future the task should be twofold. Firstly, there is a need to locate areas where submerged habitation sites have survived and to ascertain their scientific potential Secondly, there remains a need to develop effective legislation which can protect these resources in a sustainable manner and will avert needless destruction. There is also a need

to ensure that adequate archaeological and palaeo-environmental recording is conducted in advance of the approval or licensing of destructive practices.

17. BIBLIOGRAPHY

Alley, R.B., Meese, D.A., Shuman, C.A., Gow, A.J., Taylor, K.C., Grootes, P.M., White, J.W.C., Ram, M., Waddington, E.D., Mayewski, P.A. and Zieginski, G.A., 1993. ‘Abrupt increase in Greenland snow accumulation at the end of the Younger Dryas event’, Nature 362: 527-529.

Allen, L.C.& Gibbard, P.L., 1993. ‘Pleistocene evolution of the Solent River of Southern England’. Quaternary Science Review. 12: 503-528.

Allen, M. J. & Gardener, J. (forthcoming). Our changing coast; an archaeological survey of Langstone Harbour. Hampshire CBA Research report, no. unassigned.

Barton, N., 1999. ‘The Lateglacial or Late and Final Upper Palaeolithic colonisation of Britain’, in J. Hunter & I. Ralston (eds), The archaeology of Britain. Routledge. London. 13-34.

Bradley, R. & Hooper, B., 1973. ‘Recent discoveries from Portsmouth and Langstone Harbours: Mesolithic to Iron Age’. Proceedings of the Hampshire Field Club Archaeological Society. 30: 17-27.

Christensen, C. Fischer, A. & Mathiassen, D. R. 1997. ‘The great sea rise of the Storebaelt’, in L. Pedersen, A. Fischer & B. Aaby (eds), The Danish Storebaelt since the Ice Age - man sea and Forest. 45 - 54. The Storebaelt Publications.

Churchill, D.M., 1965. ‘The kitchen midden site at Westward Ho!, Devon, England: Ecology, age and relation to changes in land and sea-level’. Proceedings of the Prehistoric Society. 31: 74-84.

Clark, J. G. D., 1954. Excavations at Star Carr. Cambridge: Cambridge University Press.

Coles, B. J., 1998. ‘Doggerland: a Speculative Survey’. Proceedings of the Prehistoric Society. 64: 4

Clutton-Brook, J. & Noe-Nygaard, N., 1990. ‘New osteological and C-isotope evidence on Mesolithic Dogs: companions to hunters and fishers at Star Carr, Seamer Carr and Kongemose’, Journal of Archaeological Science 17: 643-653.

Cunliffe, B., 1987. Hengistbury Head, Dorset, Volume 1. Oxford University Committee for Archaeology, Oxford.

Day, S. P. & Mellors, P., 1994. 'Absolute' dating of Mesolithic human activities at Star Carr, Yorkshire: new palaeoecological studies and identification of the 9600 BP radiocarbon plateaux’, Proceedings of the Prehistoric Society 60, 417-422.

Dean, M., Ferrari, B., Oxley, I., Redknap, M. & Watson, K., (eds), 1992. Archaeology Underwater. The NAS guide to principles and practice. Nautical Archaeology Society.

Denker, J., 1997. ‘Stone-age settlements in the middle of natures larder’, in L. Pedersen, A. Fischer & B. Aaby (eds), The Danish Storebaelt since the Ice Age - man sea and forest. 87-92. The Storebaelt Publications.

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK Devoy, R. J., 1982. ‘Analysis of the geological evidence for Holocene sea-level change in south east England’, Proceedings of the Geological Association 93, 65-90.

Dyer, K. R., 1975. ‘The buried channels of the Solent River, Southern England’. Proceedings of Geological Association of London. 86: 23 9-246.

Everard, C.E., 1954. ‘The Solent River: a geomorphological study’. Transactions of the Institute of British Geographers 20, 41-58.

Fischer, A. (ed.) 1995. Proceedings of the Man, Sea and Mesolithic conference, Horsholm. Oxford: Oxbow Monograph 53.

Fischer, A., 1997. ‘People and the sea - settlement and fishing along the Mesolithic coasts’, in L. Pedersen, A. Fischer & B. Aaby (eds.), The Danish Storebaelt since the Ice Age - man sea and forest 63 - 77. The Storebaelt Publications.

Flemming, N., 1998. ‘Archaeological evidence for vertical movement on the continental shelf during the Palaeolithic, Neolithic and Bronze Age Periods’. in I. S. Stewart & C. Vita-Finzi (eds). Coastal Tectonics. Geological Society, London, Special Publications, 146: 129-146.

Fox, W., 1862. ‘When and how was the Isle of Wight severed from the mainland’? The Geologist 5, 4

Fulford, M., Champion, T. & Long, A. (eds.) 1997. England's Coastal Heritage. RCHME & English Heritage. Archaeological Report 15. London.

Gendel, P. A., 1984. Mesolithic social territories in north western Europe. Oxford; B.A.R. International Series 218.

Hodson, F., & West, I. M., 1972. ‘Holocene Deposits of Fawley Hampshire, and the development of Southampton, Water’. Proceedings of the Geological Association 83 (4), 421-441

Loader, R., Westmore I.. & Tomalin, D., 1997. Time and Tide; an archaeological survey of the Wootton-Quarr coast. Isle of Wight Council, Newport.

Long, A.J. & Tooley, M.J., 1995. ‘Holocene sea-level and crustal movements in Hampshire and Southeast England, United Kingdom’. In Jr. Frinkl (ed.), Holocene Cycles: Climate, Sea-levels and Sedimentation. Journal of Coastal Research, Special Issue 17: 299-210.

Long, A. J., Scaife, R. G., & Edwards, R. J., 1999. ‘Pine pollen in the intertidal sediments from Poole Harbour, UK; implications for late Holocene sediment accretion rates and sea-level rise’. Quaternary International 55: 3-16.

Mathiassen, D. R., 1997. ‘The changing landscapes of the Storebaelt, from the retreat of the ice to the sea flood’, in L. Pedersen, A. Fischer & B. Aaby (eds), The Danish Storebaelt since the Ice Age - man sea and forest. The Storebaelt Publications. 13 - 21.

Mellars, P.A., 1987. Excavations on Oronsay: prehistoric human ecology on a small island. Edinburgh: Edinburgh University Press.

Mithen, S., 1999. ‘Hunter-gatherers of the Mesolithic’, in J. Hunter & I. Ralston. (eds), The archaeology of Britain. Routledge. London. 35-57.

Palmer, S., 1977, Mesolithic cultures of Britain, Dolphin Press, Poole, Dorset

Palmer, S., 1990. ‘Culverwell - Unique opportunities for studying the intra-site structure of a Mesolithic habitation site in Dorset, England’, Contributions to the Mesolithic in Europe. Leuven University Press. 87-91.

Prigent, D., Visset, L. Morzadec-Kerfourn. N. T. & Lautrido, J. P., 1983. ‘Human occupation of the submerged coast of the Massif Armoricain and post glacial sea-level changes’, in P. M. Masters & N. C. Flemming (eds), Quarternary coastlines and marine archaeology. London. Academic Press. 303 – 324.

Rowley-Conwy, P., 1983. ‘Sedentary Hunters: the Ertebølle example’, in G. Bailey (ed) Hunter-Gatherer economy in pre-history. A European prospective. Cambridge University Press, 111-126.

Scaife, R. G., 1980. Late-Devensian and Flandrian palaeoecological studies in the Isle of Wight. Unpublished Ph D thesis. University of London, King's College.

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK Scaife, R. G., 1982. ‘Late Devensian and early Flandrian vegetation changes in southern England’, in S. Limbrey and M. Bell (eds), Archaeological aspects of woodland ecology. B.A.R. (Int. Ser.) 146: 57-74.

.Shilling, H., 1997. ‘The Korsor Nor site; the permanent dwelling place of a hunting and fishing people in life and death’, in L. Pedersen, A. Fischer & B. Aaby (eds), The Danish Storebaelt since the Ice Age - man sea and forest. 93-98. The Storebaelt Publications.

Simmons, I., 1996. The Environmental Impact of Later Mesolithic Cultures. Edinburgh University Press, for the University of Durham.

Shore, T.W. & Elwes, J.W., 1889. ‘The New Dock excavation at Southampton’. Proceedings of the Hampshire Field Club 1, 43-56.

Tolan-Smith, C., 1998. ‘Radiocarbon chronology and the lateglacial and early postglacial resettlement of the British Isles’. Quaternary International. Elsevier Science Ltd. 49/50: 21-27.

Tomalin, D.J., 1993. ‘Maritime archaeology as a coastal management issue’, Proceedings on the Standing Conference on the Problems Associated with the Coastline; Semina on regional coastal groups-after the House of Commons report, SCOPAC. Isle of Wight County Council, 93-112.

Tomalin, D.J., 1997. ‘Bargaining with nature; considering the sustainability of archaeological sites in the dynamic environment of the intertidal zone’. Preserving archaeological remains in situ: Proceedings of the conference of 1st – 3rd April 1996 at the Museum of London. Museum of London and the University of Bradford, 144-158.

Tomalin, D.J., 2000. ‘The geomorphological evolution of the Solent seaway and the severance of Wight: a review’, in M..B. Collins & K. Ansell (eds), Solent Science – A review. Proceedings in marine science 1, Elsevier: 9 – 19.

Tomalin, D.J., Loader. R and Scaife, R.G., (forthcoming), Wootton Haven: Coastal and port archaeology in a dynamic environment. English Heritage monograph.

Velegrakis, A. F., Dix, J.K. & Collins, M.B., 1999. ‘Late Quaternary evolution of the upper reaches of the Solent River, Southern England, based upon marine geophysical evidence’. Journal of the Geological Society, London, 156: 73-87.

Wilson, K., 1998. ‘An investigation of Holocene peat and intertidal stratigraphy on Shapwick Heath, Somerset: preliminary results. Archaeology in the Severn Estuary 9, 87-90.

Wickham-Jones, C.R., and P.C. Woodman., 1998, ‘Studies on the early settlement of Scotland and Ireland’. Quaternary International. Elsevier Science Ltd. 49/50: 13-20.

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18. ACKNOWLEDGEMENTS

For its work on the submerged archaeological and palaeo-environmental site at Bouldnor, the Hampshire and Wight Trust for Maritime Archaeology acknowledges the pioneer work carried out at this off-shore location by the County Archaeological Unit of the Isle of Wight Council and its former Maritime Heritage team. Academic contributions were made by John Cross of Coastal Research Section and the Remote Seismology Group of the School of Ocean and Earth Sciences, University of Southampton. The help of Matthew Hosey and Andrew Colenutt of the New Forest District Council has also been greatly appreciated.

Figure P1 Coastal archaeological sites in the Solent region, south coast, UK. Sites from the combined Hampshire and Wight Trust for Maritime Archaeology SMR (yellow) and the Isle of Wight SMR (blue). The 13 Solent region Study Areas are shown (red boxes), P1 to P13. The +5m contour and the -10m contour are also shown.

Figure P1.2 The location of long-shore and cross-shore Chirp and side-scan sonar lines acquired fromBouldnor submerged cliff, Isle of Wight, UK.

TRACK PLOT OF SIDESCAN SURVEY (28 JULY 1998)

EASTING

NO

RT

HIN

G

4320

00

90000

91000

92000

93000

94000

95000

96000

4330

00

4340

00

4350

00

4360

00

4370

00

4380

00

4390

00

4400

00

4410

00

4420

00

Figure P1.3 Digital Terrain Model of the submerged Bouldnor Cliff.Colour scale depth in metres OD.

Figure P1.4 Two-dimensional contour plot of Bouldnor Cliff. The Mesolithic site investigated by theHWMTA is located by the box outline. Base Map ©OS.

Figure P1.5 Selected profiles along Bouldnor submerged cliff.

Dep

th r

elat

ive

to O

.D.

Dep

th r

elat

ive

to O

.D.

Dep

th r

elat

ive

to O

.D.

(Profiles 1-3 vertically exaggerated, 1m vertical: 10m horizontal)

Distance along profile (m)

438492, 91463

437432, 91007

436892, 907844307010, 90408

437580, 90620

438610, 91241

PROFILE 1

PROFILE 2

PROFILE 3

Figure P1.6a Seismo-stratigraphicColumn of Sequence 1derived from theChirp data.

Figure P1.6b Litho-stratigraphic Columnbased on existing literature

Figure P1.7 A geo-rectified aerial photograph of the Hamstead Ledges and their expression in the offshorebathymetry. (Aerial photograph courtesy of the Environment Agency).


Plate P1a Extensive tree debris litters the intertidal zone at the base of the current cliff section at Bouldnor

Plate P1b An aerial photograph of Bouldnor coastline following a major landslide (EA)

Figure P1.9a Pollen diagram from the lower peat layer in Bouldnor submerged cliff, Isle of Wight, UK (Rob Scaife 2000).

Figure P1.9b Pollen diagram from the lower peat layer in Bouldnor submerged cliff, Isle of Wight, UK (Rob Scaife 2000).

Figure P1.9c Pollen diagram from the middle peat layer in Bouldnor submerged cliff, Isle of Wight, UK (Rob Scaife 2000).

Figure P1.9d Pollen diagram from the upper peat layer in Bouldnor submerged cliff, Isle of Wight, UK (Rob Scaife 2000).

Figure P1.11a Pollen diagram from the deep peat layer at Yarmouth Spit, Isle of Wight, UK (Rob Scaife 2000).

Figure P1.11b Pollen diagram from the modern peat layer in Yarmouth Marsh, Isle of Wight, UK (Rob Scaife 2000).


Plate P1c Section through a large oak tree (70cm wide) within the drowned landscape below Bouldnor Cliff

Plate P1d Lithics and mammoth tusk recovered by fisherman , Michael White, in the West Solent

CORE 3B

CORE 3A

MESOLITHIC OCCUPATION

FLOOR OF THE MAIN SOLENT CHANNEL

TREE

UPPER PEAT BED C. (Bouldnor 1)

LOWER PEAT BED A. (Bouldnor 3)

LAKE SEDIMENTS

4m

6m

8m

10m

12m

MIDDLE PEAT BED B. (Bouldnor 2)

SILT

MARINE CLAY

WITH BRACKISH

DIATOMS

?

??

Figure P1.15 General profile of the submerged cliff at Bouldnor, Isle of Wight, UK,showing Holocene peats and submerged landsurface. See Figure P1.8.

Exposed basal sediment

Peat platformwith tree stumps

trunks and branches

Peat platform

Submergedcliff-face

5m

Figure P1.16 Plan of the basal peat layer at Bouldnor.

Mesolithicflint

artifacts fromlobster burrows


Plate P1e Worked flints (foreground) in the upcast of a lobster burrow beneath a submerged fallen tree.

Plate P1f This palaeolith attests Pleistocene human activity on the floor of the Western Solent (recovered and reported by local fishermen)

Palaeo-environmental Study Area P1 North-west coast (Yarmouth-Bouldnor-Newtown), Isle of Wight, UK Plate P1g Diver entering the water from survey vessel Flat Holm

Plate P1h Divers working on site with air lift


Plate P1i Excavation of core boxes on the survey vessel

Plate P1j A range of worked flints from the stratifies deposits recovered in the cores

PALAEO-ENVIRONMENTAL STUDY AREA P1 NORTH-WEST COAST (YARMOUTH

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