WOODGATE HOUSE, AYLSHAM, GEOPHYSICS PHASE 4 · PDF filewoodgate house, aylsham, geophysics...

WOODGATE HOUSE, AYLSHAM, GEOPHYSICS

PHASE 4

DETAILED MAGNETOMETER SURVEY

Report Number: 1139 February 2017

© Britannia Archaeology Ltd 2015 all rights reserved Report Number: 1139

WOODGATE HOUSE, AYLSHAM, GEOPHYSICS PHASE 4

DETAILED MAGNETOMETER SURVEY

Prepared for: Suffolk County Council Archaeology Services

Bury Resource Centre Hollow Road

Bury St Edmunds IP32 7AY

By:

Matthew J. Baker MA, BA (hons)

Britannia Archaeology Ltd Unit 2, The Old Wool Warehouse

St Andrews Street South Bury St Edmunds

Suffolk IP33 3PH

T: 01449 763034 [email protected] www.britannia-archaeology.com

Registered in England and Wales: 7874460

September 2016

Site Code - NGR

618200 326000

Event Number -

Planning Ref.

n/a

OASIS

pending

Approved By:

Date

February 2017

mailto:[email protected]

http://www.britannia-archaeology.com/

Woodgate House, Aylsham, Geophysics Phase 4 Detailed Magnetometer Survey

Project Number 1167

3 ©Britannia Archaeology Ltd 2017 all rights reserved Report Number: 1139

DISCLAIMER

The material contained within this report was prepared for an individual client

and solely for the benefit of that client and the contents should not be relied

upon by any third party. The results and interpretation of the report cannot be

considered an absolute representation of the archaeological or any other

remains. Britannia Archaeology Ltd will not be held liable for any error of fact

resulting in loss or damage, direct, indirect or consequential, through misuse

of, or actions based on the material contained within by any third party.


Project Number 1167


CONTENTS

1.0 INTRODUCTION

2.0 SITE DESCRIPTION

3.0 ARCHAEOLOGICAL BACKGROUND

4.0 PROJECT AIMS

5.0 METHODOLOGY

6.0 RESULTS

7.0 CONCLUSIONS

8.0 PROJECT ARCHIVE AND DEPOSITION

9.0 ACKNOWLEDGEMENTS

BIBLIOGRAPHY

Figure 1 General Location Plan 1:5000

Figure 2 Grid Plan 1:2000

Figure 3 Grayscale Data Unprocessed 1:2000

Figure 4 Trace Plot 1:2000

Figure 5 Grayscale Processed 1:2000

Figure 6 Interpretation Plan 1:2000


Project Number 1167


1.0 INTRODUCTION From 2014 to 2017 Britannia Archaeology Ltd (BA) undertook four phases of geophysics, with the latest phase being run as a community project, on land at Woodgate House, Cawston Road, Aylsham, Norfolk (NGR 618200 326000). 2.0 SITE DESCRIPTION

The site is located 1km to the south west of Aylsham town centre, between Cawston

Road and Stonegate Lane. It lies within the parish boundary of Aylsham and the

Broadland District of Norfolk. The site straddles the east-west orientated valley of Mary’s

Beck, which is a tributary of a larger stream called The Mermaid. Mary’s Beck has its

source 40m north of the western boundary of the site, and the size of the valley suggests

it was more substantial at some point in the past. The northern half of the site slopes

down to the south; the southern half slopes down to the north. The centre of the site is

situated just below 30m aOD and the far northern and south-western extents just touch

35m aOD.

The north-east corner of the site is currently used for arable farming and a large kitchen

garden is present north of the main house. The site is bounded to the north and west by

Cawston Road. A new housing development is under construction to the north, but the

western boundary remains woodland. Stonegate (Lane) forms the eastern boundary with

agricultural fields beyond, and the southern boundary comprises a chain-link fence and

hedgerow with agricultural fields beyond.

The underlying bedrock is described as Wroxham Crag Formation sand and gravel,

sedimentary bedrock formed up to 2 million years ago during the Quaternary Period

when the local environment was dominated by swamps, estuaries and deltas periodically

inundated by the sea (BGS, 2016).

The superficial deposits are described as mid-Pleistocene glaciofluvial deposits of sand

and gravel when the local environment was dominated by ice age conditions (BGS,

2016).


Project Number 1167


3.0 ARCHAEOLOGICAL BACKGROUND

A full desk-based assessment was undertaken for the site in November 2014 by Britannia

Archaeology, Land at Woodgate House, Cawston Road, Aylsham, Norfolk – Desk-Based

Assessment, (Adams, MC. 2014: R1069). The summary of this investigation was as

follows:

The assessment has identified a very high potential for Roman remains relating to high

status villa settlement activity on the site. The quantity and quality of Roman material

recovered by Mr Purdy over the years, suggests the presence of a substantial, high

status villa complex, probably focused in the area of the Kitchen Garden and immediate

surroundings, with outlying industrial areas to the north-east and agricultural areas to

the south and north.

The potential for all other periods is considered to be low, however the site appears to lie

on the periphery of the town’s medieval field system and so the potential here is

moderate. It has also been subject to significant landscaping as well as farming activity

during the post-medieval period so the potential for features or finds dating to this

period is considered high.

The wider area shows evidence of occupation activity since the Neolithic period with

significant settlement activity identified to the north-west of Aylsham in the Bronze Age

(outside the search area), at Brampton to the south-east in the Roman period, and in

Aylsham itself from the Anglo-Saxon period onwards.

The cartographic sources suggest significant remodelling of the plots around Woodgate

House between the late 18th and late 19th century AD. A system of old track ways are

clearly visible in both the cartographic sources and the geophysics results in the southern

half of the site.

4.0 PROJECT AIMS

The aims of this phase of the Aylsham Roman Project are to undertake non-intrusive

geophysical survey to expand on previous surveys, conducted in the north-east and


Project Number 1167


south-east fields, to further define magnetic anomalies identified in previous geophysical

surveys.

• To further enhance our understanding of the archaeological potential of the site;

• To characterise the development, phasing, spatial organisation, character,

function, and the nature of social, economic and industrial activities on site;

• Place the evidence for Roman activity at the site in context with known remains of

a similar date around Aylsham and the wider region;

• Undertake analysis of the survey data leading to appropriate forms of public

dissemination.

5.0 METHODOLOGY

The survey grid was be set out to the Ordnance Survey OSGB36 datum to an accuracy of

±0.01m using a Leica Viva Glonnass Smart Rover GS08.

A Bartington Dual Grad 601-2 fluxgate gradiometer was used to undertake the survey,

because of its high sensitivity and rapid ground coverage. The soils and underlying

geology are receptive to magnetometer survey, but good results are heavily dependent

on the contrast between the fills of a feature (with humic and charcoal rich deposits

providing the best results) and the relative weakness of the local magnetic background

field.

Only minimal processing of the datasets has been undertaken, data processing allows for

the correction of errors introduced during the survey and instrument errors. The survey

data has been processed using TerraSurveyor software V3, where the following data

processes were applied:

Destripe: Removes striping effects from the raw data caused by discrepancies

between different sensors and walking directions caused by alternate zig-zag

traverses.

Destagger: Corrects the displacement of anomalies caused by alternate zig-zag

traverse.

Clip: The range of the data can be set to specified maximum and minimum values

in order to improve the contrast of weaker anomalies within the data.


Project Number 1167


Compress: Weak anomalies were further enhanced by applying an arctangent

weighing to the data.

Grad. Shade: The overall appearance of the data was improved

The raw and processed greyscale plots have been produced for comparison. An XY trace

plot consisting of the processed data will be used in combination with raw and processed

greyscale data. An interpretation plan characterising the anomalies has been produced

based on the evidence collated from the greyscale and XY trace plots.

6.0 RESULTS (Figs. 2-6)

The unprocessed data from the magnetic surveys are shown in figure 2. Figure 2 is

displayed as a greyscale plot with the maximum and minimum readings for each survey

highlighted in red and blue. The processed data, following the application of the data

processing methodology described above. The processed data has revealed a number of

responses of archaeological significance, the interpretation of which is described below.

6.1 Interpretation

Kiln Field (FIG.5)

The most notable features within this field are 1000 which are two discrete positive

anomalies with negative responses, there is no separation between the two polarities.

These two anomalies are the two kilns excavated during the 2016 summer excavation,

the magnetic signal produced by the two kilns has masked the presence of features in

the immediate area.

The majority of anomalies identified in the survey of the kiln field have been low

amplitude positive linear anomalies, which are indicative of infilled ditch type features.

Which possibly represent some form of field boundary. Immediately to the south of the

two kilns are a series of positive linear anomalies with associated negative anomalies

1001. Which could represent bank and ditch type features. Possibly relating to the

ditches excavated in area 2 (1002).

The kiln field data has revealed several discrete positive anomalies, ranging in size from

c.1-3m. The anomalies are present through the survey area, with a concentration of six


Project Number 1167


anomalies in the eastern area of the survey 1003. The shape and size of these

anomalies are consistent with those resulting from infilled pit type features.

Modern disturbance

Three areas of increased magnetic noise can be seen in the data 1002, 1004 and 1005.

Anomaly 1002 corresponds with the location of area 2 and relates to the backfilling of

this excavated area. Anomaly 1004 is located to the south-west of the kiln excavation

area and is the result of some brick debris on the ground close to the excavation area 1.

The origin of disturbance 1005 is currently unknown, however, due to the high

amplitude of the signal it is most likely the spread is modern in origin.

Around the perimeter of the survey area are several areas of increased magnetic

disturbance 1006, these have been produced by a fence surrounding the field. The ‘halo’

effect produced by the fence has the possibility to mask magnetic anomalies.

Numerous high amplitude magnetic spikes can be seen in the data 1007. Each of these

discrete magnetic spikes consists of a well defined dipolar response. There high

amplitudes suggests the presence of ferrous debris in the topsoil.

North-east field (FIG.5)

The anomalies present within the survey are very weak positive linear anomalies. On the

western limit of the survey three low amplitude positive trending linear anomalies 2000

were identified, these anomalies run parallel to one another for c.14-24m with a north-

west to south-east orientation. On the eastern edge of the survey area, two more low

amplitude positive trending linear anomalies can be seen, these run parallel to one

another c.14m apart, with an east to west orientation and are visible in the data for

c.30-42m.

A concentration of discrete low amplitude positive anomalies, the shapes of anomalies

are largely irregular suggesting that these anomalies could be natural in origin, possibly

tree root boles. However, the more regular oval shaped anomalies could be

archaeological in origin.

The low signal strength of the positive anomalies in this field suggests the features have

been heavily truncated by modern ploughing.


Project Number 1167


Along the eastern edge of the survey area is a negative trending linear anomaly which is

c.120m in length with a north to south orientation. The anomaly follows the edge of the

field and is most likely the result of modern ploughing in the field.

Modern disturbance

The northern-most corner a fence and trackway have produced a slight distortion to the

earth’s magnetic field 2004. The northern half of the survey area has identified

numerous discrete magnetic spikes 2005, their high amplitude suggests ferrous debris in

the ploughsoil.

Lake field (FIG.6)

South of the lake sees an increase in anomalies. Most of the anomalies appear as

positive linear anomalies. Many of these anomalies have associated negative linears.

These anomalies appear to form enclosures 3000, 3001, 3002 and 3003.

Enclosure 3000, is sub-rectangular in form and c.48m in width, the anomaly is displayed

in the data as a series of positive and negative linear anomalies. Multiple linears

orientated north to south appear off of the main east to west linear, which could suggest

multiple phases of recutting or multiple subdivisions of the main enclosed area. The

enclosed area appears to have internal features 3004, which appear to be infilled pit

type features. However, the larger amorphous anomalies might be natural in source.

Adjoining enclosure 3000 is another enclosure 3001. This anomaly appears in the data

as two curvilinear positive anomalies with associated negative internal response, possibly

representing a ditch with internal bank. Enclosure 3001 is sub-oval in shape and c.20m

in width. Immediately to the east of the aforementioned enclosure is another sub-

rectangular enclosure 3002. This enclosure is formed of positive linear anomalies with

associated negative linear anomalies. The enclosure is c.24m in width, with possible

internal features. It is possible that this enclosure has internal divisions, or is cutting or

cut by another enclosure.

Anomaly 3003 has been truncated by modern service pipe 3008. Formed of curvilinear

positive anomaly it is c.18m in width and has some internal features.

All the enclosures appear to be associated with a linear anomaly 3005, which consists of

two positive linear trending anomalies running parallel c.6m apart from one another.

Between these two positive anomalies is a weakly negative intermittent linear anomaly.


Project Number 1167


The negative response given by anomaly 3005 may represent a metalled surface.

Therefore 3005 could be a form of trackway that enclosures 3000 – 3002 are aligned

off of. Running north-east to south-west is another anomaly 3006 which is similar in

appearance to anomaly 3005. This may be the remnants of another trackway.

To the north of the lake another survey area has discovered more positive and negative

linear anomalies 3007, these anomalies have a similar form and orientation to the

anomalies south of the lake. These anomalies have been truncated by the construction of

the lake.

Modern disturbance

A strong magnetic liner anomaly 3008 has been identified running north-west to south-

east in the southern survey area. This anomaly is a buried fence. This anomaly has

masked part of enclosure 3003.

An area of increased magnetic noise has been identified in the southern survey area.

This area has been interpreted as an area of disturbed ground 3009, possibly relating to

the construction of the lake. Several areas of magnetic disturbance can be seen on the

edges of the southern survey area, these have been caused by a metal fence which has

produces a distortion in the local magnetic field.

The most numerous anomaly in the southern most survey area were discrete magnetic

spikes. These consist of a high amplitude magnetic spike in the data which most likely

represent buried ferrous debris within the topsoil.

Conclusion

The geophysical surveys have so far identified numerous anomalies which appear to be

of archaeological origin. The majority of anomalies present within the survey areas have

been positive linear anomalies, which are synonymous with infilled ditch type features. A

large quantity of these anomalies have associated negative linears, which may indicate

the presence of remnant bank material, possibly indicating bank and ditch type features.

The varying signal strengths of some of these anomalies, particularly in the two northern

fields, is suggestive of the features being intermittently truncated or disturbed at the

source.

The survey area south of the lake has revealed numerous anomalies which appear to

form enclosures. These enclosures appear as positive responses with associated low


Project Number 1167


amplitude negative responses, which is indicative of ditches and banks. These enclosures

appear to be related to a linear anomaly formed of a low amplitude negative response

between two low amplitude positive linear anomalies suggesting that this anomaly could

be a trackway with a metalled surface.

The magnetic contrasts seen in the data indicates the underlying geology was suited to

magnetic geophysical survey. However, the magnetic contrast is clearer in the

southernmost survey areas where the land has not been subjected to modern ploughing.

8.0 PROJECT ARCHIVE AND DEPOSITION

A full archive will be prepared for all work undertaken in accordance with guidance from

the Selection, Retention and Dispersion of Archaeological Collections, Archaeological

Society for Museum Archaeologists, 1993. Arrangements will be made for the archive to

be deposited with the relevant museum/HER Office, in this case will be the Norwich

Castle Museum.

9.0 ACKNOWLEDGEMENTS

Britannia Archaeology Ltd would like to thank Mr Peter Purdy for commissioning the work

and for allowing access to the land. Britannia Archaeology would also like to thank the

volunteers of the Aylsham Roman Project for their help in conducting the surveys.

The survey was undertaken by volunteers of the Alysham Roman Project and Britannia

Archaeology.


Project Number 1167


Bibliography Ayala. G. et al. 2004. Geoarchaeology; Using Earth Sciences to Understand the Archaeological Record. English Heritage. Chartered Institute for Archaeologists. 2014. Standard and Guidance for Geophysical Survey Clark. A. J. 1996. Seeing Beneath the Soil, Prospecting Methods in Archaeology. BT Batsford Ltd, London. David. A. 1995. Geophysical Survey in Archaeological Field Evaluation: Research and Professional Services Guidelines. No.1. English Heritage. David. A. et al. 2008. Geophysical Survey In Archaeological Field Evaluation, Second Edition. English Heritage. Department for Communities and Local Government, 2012.National Planning Policy Framework (NPPF) English Heritage, 2008. Geophysical Survey in Archaeological Field Evaluation. Research and Professional Service Guideline No 1, 2nd edition. Gaffney. C, Gater. J. and Ovenden. S. 2002. The Use of Geophysical Techniques in Archaeological Evaluations. IFA Technical Paper No. 6. Gaffney. C. and Gater. J. 2003. Revealing the Buried Past, Geophysics for Archaeologists. Tempus Publishing Ltd. Gurney, D. 2003. Standards for Archaeology in the East of England, East Anglian Archaeology Occasional Paper 14. Institute for Archaeologists. 2011. Standard and Guidance for Archaeological Geophysical Survey. Linford. N. 2006. Notes from an English Heritage Seminar. Schmidt. A. 2001. Geophysical Data in Archaeology: A Guide to Good Practice. Archaeology Data Service. Oxbow Books. Whitten. D.G.A. 1978. The Penguin Dictionary of Geology. Penguin Books Ltd. London. Witten. A.J. 2006. Handbook of Geophysics and Archaeology. Equinox Publishing Ltd. London.


Project Number 1167


Websites The British Geological Survey, 2016, (Natural Environment Research Council) – Geology of Britain Viewer - www.bgs.ac.uk/opengeoscience/home.html?Accordion2=1#maps

http://www.bgs.ac.uk/opengeoscience/home.html?Accordion2=1#maps

33.3m

Nursery

The

Lodge

C

a

w

s

t

o

n

R

o

a

d

Dra

in

Woodgate Cottages

30.6m

Path (um)

Woodgate

House

B

1

1

4

5

ST

ON

EG

AT

E

Water

The Round

Pond

Pond

33.3m

Pond

Path

(um

)

30.1m

T

r

a

c

k

M

a

rrio

tt's

W

a

y

Nursery

The

Lodge

FB

2

1

T

r

a

c

k

T

ra

c

k

ESS

PEABODY ROAD

W

O

O

D

G

A

T

E

W

A

Y

8

10

15

2

12 17

1

11

2

11

12

Ppg Sta

14

20

H

O

BA

R

T LA

N

E

4

2

8

16

40

50

PUMPHREY WAY

17

19

5

9

Nelson

Close

1

4

7

6

1

8

5

6

11

9

25

7

23

ST

ON

EG

AT

E

ST

ON

EG

AT

E

UNIT 2

THE OLD WOOL WAREHOUSE

ST ANDREWS STREET SOUTH

BURY ST EDMUNDS

SUFFOLK

IP33 3PH

1

MJB

N

FIGURE:

326000

Norfolk

Suffolk

Essex

Cromer

Kings

Lynn

Thetford

SITE

NORWICH

Reproduced on plans supplied by the client

from the Ordnance Survey map with the

permission of the controller of Her Majesty’s

Stationery Office. Licence number:

100052663.

© CROWN COPYRIGHT 2017.

SITE

BRITANNIA ARCHAEOLOGY LTD

T: 01449 763034

E: [email protected]

W: www.britannia-archaeology.com

AUTHOR:

APPROVED:

DATE: PLOT: VERSION:

FEB 2017

DPM

DESCRIPTION:

GENERAL LOCATION AND GRID PLAN

PROJECT:

CLIENT:

© Copyright Britannia Archaeology Ltd 2017

WOODGATE HOUSE, AYLSHAM,

GEOPHYSICS PHASE 4

AYLESHAM ROMAN PROJECT

618200 326000

NGR: REF:

P1167

A3 1

618200

Site Boundary

0 100m

1:2500

1:2500

33.3m

Nursery

The

Lodge

C

a

w

s

t

o

n

R

o

a

d

Drain

Woodgate Cottages

30.6m

Woodgate

House

B

1

1

4

5

ST

ON

EG

AT

E

Water

Pond

Pond

33.3m

Pond

30.1m

T

r

a

c

k

Nursery

The

Lodge

FB

2

1

T

ra

c

k

ESS

PEABODY ROAD

W

O

O

D

G

A

T

E

W

A

Y

8

10

15

2

12 17

1

11

2

11

12

Ppg Sta

14

20

H

O

BA

R

T LA

N

E

4

2

8

Close

9

23

The Round

UNIT 2



BURY ST EDMUNDS

SUFFOLK

IP33 3PH

2

MJB

N

FIGURE:





100052663.



T: 01449 763034



AUTHOR:

APPROVED:


NOV 2016

DPM

DESCRIPTION:

NON-PROCESSED DATA PLAN

PROJECT:

CLIENT:



GEOPHYSICS PHASE 4

AYLSHAM ROMAN PROJECT

618200 326000

NGR: REF:

P1167

0 100m

1:2000

A3 1

Site Boundary

1:2000

+100nT

-100nT

33.3m

Nursery

The

Lodge

C

a

w

s

t

o

n

R

o

a

d

Drain

Woodgate Cottages

36.5m

30.6m

Woodgate

House

B

1

1

4

5

ST

ON

EG

AT

E

Water

Pond

Pond

33.3m

Pond

30.1m

T

r

a

c

k

Nursery

The

Lodge

2

1

T

ra

c

k

FB

ESS

PEABODY ROAD

W

O

O

D

G

A

T

E

W

A

Y

8

10

15

2

12 17

1

11

2

11

12

Ppg Sta

14

20

H

O

BA

R

T LA

N

E

4

2

8

40

Nelson

Close

1

46

9

23

The Round

UNIT 2



BURY ST EDMUNDS

SUFFOLK

IP33 3PH

3

MJB

N

FIGURE:

+ nT

- nT





100052663.



T: 01449 763034



AUTHOR:

APPROVED:


FEB 2017

DPM

DESCRIPTION:

PROCESSED DATA PLAN

PROJECT:

CLIENT:



GEOPHYSICS PHASE 4


618200 326000

NGR: REF:

P1167

0 100m

1:2000

A3 1

Site Boundary

1:2000

33.3m

Nursery

The

Lodge

C

a

w

s

t

o

n

R

o

a

d

Drain

Woodgate Cottages

36.5m

30.6m

Woodgate

House

B

1

1

4

5

ST

ON

EG

AT

E

Water

The Round

Pond

Pond

33.3m

Pond

30.1m

T

r

a

c

k

Nursery

The

Lodge

2

1

T

ra

c

k

FB

ESS

PEABODY ROAD

W

O

O

D

G

A

T

E

W

A

Y

8

10

15

2

12 17

1

11

2

11

12

Ppg Sta

14

20

H

O

BA

R

T LA

N

E

4

2

8

Close

9

23

UNIT 2



BURY ST EDMUNDS

SUFFOLK

IP33 3PH

4

MJB

N

FIGURE:





100052663.



T: 01449 763034



AUTHOR:

APPROVED:


FEB 2017

DPM

DESCRIPTION:

INTERPRETATION PLOT

PROJECT:

CLIENT:



GEOPHYSICS, PHASE 4


618200 326000

NGR: REF:

P1167

0 100m

1:2000

A3 1

Site Boundary

1:2000

Kiln

Negative Anomaly

Positive Anomaly

Service pipe

Magnetic disturbance

Strong magnetic noise

Discrete magnetic spike

Nursery

C

a

w

s

t

o

n

R

o

a

d

ST

ON

EG

AT

E

The Round

Nursery

UNIT 2



BURY ST EDMUNDS

SUFFOLK

IP33 3PH

5

MJB

N

FIGURE:





100052663.



T: 01449 763034



AUTHOR:

APPROVED:


FEB 2017

DPM

DESCRIPTION:

INTERPRETATION PLOT

PROJECT:

CLIENT:



GEOPHYSICS, PHASE 4


618200 326000

NGR: REF:

P1167

A3 1

Site Boundary

1000

1001

1002

1003

1005

1004

1006

1006

1006

1007

1007

1007

2000

2001

2002

2003

2004

2005

2005

2005

2005

2005

0 50m

1:1000

1:1000

Kiln

Negative Anomaly

Positive Anomaly




30.6m

Pond

UNIT 2



BURY ST EDMUNDS

SUFFOLK

IP33 3PH

6

MJB

N

FIGURE:





100052663.



T: 01449 763034



AUTHOR:

APPROVED:


FEB 2017

DPM

DESCRIPTION:

INTERPRETATION PLOT

PROJECT:

CLIENT:



GEOPHYSICS, PHASE 4


618200 326000

NGR: REF:

P1167

A3 1

Site Boundary

3000

3002

3003

3001

3004

3005

3005

3006

3008

3007

0 50m

1:1000

1:1000

Negative Anomaly

Positive Anomaly

Service pipe




WOODGATE HOUSE, AYLSHAM, GEOPHYSICS PHASE 4 · PDF filewoodgate house, aylsham, geophysics...

Documents

Transcript of WOODGATE HOUSE, AYLSHAM, GEOPHYSICS PHASE 4 · PDF filewoodgate house, aylsham, geophysics...