The Geomorphology of Irish submarine canyons

The Geomorphology of Irish submarine canyons.Thomas Mackle. B00616287

Ulster University: Coleraine campus.

BSc Hons Marine Science

The Geomorphology of Irish submarine canyons.

Thomas Mackle B00616287

Supervisor: DR Sara Benetti

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Formatted for the Scientific Journal: Marine Geology.


Contents.

1.0 Abstract2.0 Introduction

2.1 Glaciation2.2 Erosion 2.3 Slope failure2.4 Canyon Geomorphology 2.5 Site location

3.0 Methodology 4.0 Bathymetric and slope analysis of continental margin

4.1 Canyon Analysis5.0 Turbidity currents present upon Irish continental margins

5.1 Erosion present upon the canyon system5.2 Glacial forcing/scarring5.3 Similarities between canyons upon the Irish continental margin.5.4 Conclusions 5.5 Acknowledgements

6.0 References.

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1.0 Abstract

Submarine canyons are common features upon continental margins around the world. There are many theories surrounding the formation of these canyons and how these canyons evolve over time. This paper will deal exclusively with submarine canyons found upon the Irish continental margin using bathymetric data which was then analysed through ArcGIS to produce bathymetric charts of the region so that canyons can be properly analysed. This report will provide insight into the geomorphology of the submarine canyons and the processes which occur upon these canyons, namely glaciation, sedimentation dispersal though turbidity currents, and erosion upon the canyon walls. When the full analysis of the canyons in question was completed it was determined that the canyons that have formed along the continental margin all have similar characteristics in regards to geomorphology as well as the processes occurring upon the canyons. It was also determined that glaciation was indeed the main factor that went into the formation of canyons along the Irish continental margin and that subsequent evolution was being carried out by a variety of processes occurring on the continental shelf.

Keywords: Geomorphology, Turbidity currents, Glaciation, Erosion, Sediment deposition, Canyon evolution.

2.0 Introduction.

Extensive research has been carried out upon continental margins throughout the last century. This research has been undertaken due to the importance of continental margins throughout the globe (Bott, 1971, Burk, 1974, Muller-Karger, 2005). With this in mind, features of continental margins have received significant attention within the scientific community. Features such as submarine canyons have received considerable amounts of attention due to their importance within marine systems. Submarine canyons can be found upon continental margins throughout the world (Harris, 2011) and have intricate roles to play within shelf dynamics. It is because of this attention, that the formation (Shepard, 1981, Burke, 1972) as well as the development (Pratson, 1994, Morris, 1988) of canyons, as well as the processes that occur upon these canyons (Baker, 1986, Allen, 1981, Canals, 2006). Physically different to marine trenches in that canyons occur upon the continental slope whilst marine trenches are found at areas of the world where tectonic plates collide with one another. These deep incisions found that are present within continental margins bear similar physical characteristics to canyons formed by rivers over millions of years upon the terrestrial environment (sawyer, 2007). Similar to terrestrial canyons submarine canyons too have taken millions of years upon the continental shelf.

2.1 Glaciation.

The formation of these canyons has widely been a subject that has been up for debate. One such theory is that canyons are formed through the processes of glacial activity during the late Holocene (Laursen, 2002). This theory works with the idea of glacial forcing and retreat, whereby glaciers pushing up the continental shelf, causing deep scars within the shelf. This scaring was then exacerbated by the subsequent glacial retreat, whereby glaciers began to retreat from the continental margins bringing with them vast amounts of sediment from the shelf (Shepard,1952,Embley, 1976, Herzer,1979). It was from these theories that the term glacial scarring was recognised. This theory also works on the idea that during the Holocene, global sea levels were at an average of 125m lower than current global levels (Clark, 1978). This would subsequently mean that terrestrial rivers were able to flow into the edges of continental margins, and would allow for these rivers to deposit sediment much further down the continental shelf than modern standards.

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This theory could work due to the fact that it considers canyons contained within close proximity to major world rivers (Liu,2002,Palanques,2006), however there have been canyons observed to depths of and greater than 3000mdepth (Babonneau,2002, Tyler,2009). Canyons at depths as great as these present problems within this theory, as global sea levels would have never dropped below this level at any point throughout history (Shackleton, 1987). With this information in mind there will then have to be other factors that have to be taken into consideration when looking at deeper canyon formations.

2.2 Erosion.

The theory of canyon erosion can then be considered that may be thought to be responsible for the formation of canyons found deeper upon continental margins (May, 1983, Pratson, 1996). Considering that submarine canyons are thought to be major sediment deposits upon continental margins (Nardin, 1979, Arzola, 2008). Taking into consideration that submarine canyons contain considerable amounts of sediment, this can lead into marine landslides (Moore, 1989) as well as the idea of turbidity currents that occur within canyons (Lowe, 1982). Turbidity currents, which are triggered by marine landslides upon the shelf (Hampton, 1972), are high concentrations of currents which are densely filled with fine sediments in suspension (Bagnold,1962) from the continental slope which flow downwards within the canyons. This downward flow allows for the removal of sediment from the upper reaches of the canyon system and over time this process has the potential to create deep canyons along the plains of continental shelves around the world. This theory of erosion would mean that there is a constant process occur on submarine canyon systems, as erosion itself is a constantly occurring process, and with this in mind it is possible that erosion of the continental shelf could lead to extensive canyon formation. This formation however would indeed take thousands upon thousands of years for any major or significant canyons to exhibit themselves upon the continental shelves. This theory still works as there have been thousands of years of erosion occurring on continental shelves throughout the world as was the case on continental shelves upon North American continental margins (Orange, 1999,McAdoo, 2000, Cacchoine,2002).

2.3 Slope Failure

The idea of slope failure can also come into canyon formation (Dugan,2000). Similar to marine landslides, whereby there are vast movements of sediment upon the continental shelf. This mass movement of sediment causes large gorges within the continental shelf, which in turn give rise to canyon walls along the margin (Schwab,1988, Driscoll,2000). This slope Failure arises due to excessive sediment weight on the slopes critical base (Kvalstad,2003). With this in mind, slope failure can tie into the two previous theories described, in that sediment arrives from rivers within the vicinity of the terrestrial environment, and then at this point turbidity currents carry sediment along the continental shelf, this sediment can then build up and up until critical weight mass of sediment occurs and induces slope failure upon that section of the continental shelf, essentially developing the canyon further into the shelf. However it has also been hypothesised that slumping upon the continental shelf can be caused by loose sediment that has come loose during earthquakes (Lewis,1971).

2.4 Canyon Geomorphology

The overall aim of this paper is to discuss the geomorphology of Irish submarine canyons through the examination of their characteristics. Features such as the canyon slope, glacial scarring and sediment build ups upon the Irish continental shelf will ultimately be analysed through a range of techniques using previous studies as examples (Bourillet, 2003, 2006, Mitchell, 2005, Sachetti,

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2012,). While many papers tend to deal with canyons around the globe rather than the Irish continental margins, the research that has went into these canyons can be applied to the Irish continental shelf, much in the way that formation of canyons follows a similar pattern around the world. While some canyons from different to others there will always be similarities within the geomorphology of two canyons found at opposite ends of the globe and this will show how processes occurring on canyons are indeed similar throughout continental margins. When considering that the processes that occur within submarine canyons are at a scale several times larger than those occurring upon the terrestrial environment, it is important that analysis of these processes occur so that a greater understanding of how formation and subsequent evolution occurs. Terrestrial canyons are indeed similar to submarine canyons and so analysis of formation of those upon the continental shelf can aid the analysis of those found upon land, albeit at a smaller scale. Study of canyons is essential so that the future evolution of submarine canyons can be analysed and assessed. The hypothesis for this report is as follows

Canyon formation upon the Irish continental shelf will have occurred through the processes of Glacial scarring/forcing as well as through the deposition of sediment from turbidity currents occurring within the pre-existing canyons.

Canyons upon the Irish Continental shelf will have similar characteristics as well as similar processes occurring upon the canyons.

2.5 Site location

This paper will deal exclusively with submarine canyons that are situated around the Irish continental margin. Over the past few decades there have been extensive studies undertaken upon the Irish continental margins (Bailey, 1975, Westley, 2011, Sacchetti, 2012). These studies have been able to take place partly due to the vast amounts of data that is readily available due to the Joint Irish bathymetric survey (JIBS). The region of interest within this report is upon the North Coast of Ireland, within close vicinity to Rockall trough. There have been previous studies within this region such as the Sacchetti (2012) paper which dealt with the entire Irish margin. From looking at the formation of these submarine canyons and the processes which occur upon these canyons could potentially provide an idea of what could possibly happen to the continental shelf in the future as well as possibly giving an idea of what the shelf region looked like before these processes occurred, though this may be difficult due to the long time period that the formation of canyons required.

3.0 Methods.

The data for this study was collected through the use of Multi-beam echo sounders mounted onto RV Bligh. The data was collected by the Geological survey of Ireland between the years 2000 and 2001 through the Irish National seabed survey. The

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Figure 1 A map created through ArcMap’s GIS software of the whole study area relative to its position in the UK


Multi-beam echo sounder that was used on board the RV Bligh was the Simrad EM120 which was set to frequencies of 11.75-12.75 kHz. Once the raw data from the multi-beam echo sounders had been collected the hydrographic package CARIS Hips&Sips v.7.0 was selected for the processing of said data. During the processing of the raw data there was attention given to the removal of specific noise within the data, such as movement of the research vessel, jumps within the vessels navigation, erroneous soundings that had been recorded as well as velocity refraction. Raw backscatter data which was obatained through the use of echo-sounders was processed through IVS Fledermaus V.7.0, using the geocoder algorithm. It is important to note that the digital numbers registered within the Simrad sonar records are not the final normalised values relative to backscatter strength. The purpose of the Geocoder algorithm was to remove all gains that had been used during the actual collection of the raw data and this in turn will apply a series of radiometric and geometrical corrections to the raw data so that the final product is a reliable value that represents backscatter strength. The raw data was then used to create maps of the study area through the use of ESRI’s arcmaps GIS. To do this the raw data was added as a raster image and its projected co-ordinate system was set to WGM 1984 29N so that all points were relative to their real location. Using the spatial analyst tools within Arcmaps, a hillshade wad added to the raw data and set for a stretched value of standard deviation to improve the visibility of the canyons upon the continental shelf. A slope map was then created to show the decline in angle of the canyons as they advanced further into the continental shelf. The paper by Sacchetti (2012) was used to help with interpretation of canyons features found within the study area and would be the backdrop for the overall canyon analysis that occurred upon the data collected. The measuring tool within Arcmaps so that the overall length and minimum and maximum widths of the canyons could be determined. Similarly the 3D analyst interpolation tool within Arcmaps was employed to create graphs which exhibited the rise and fall within the canyons and give an overall profile shape to each canyon analysed.

4.0 Bathymetric and slope analysis of continental Margin.

The initial analysis of the data has shown that there are a series of canyons found upon the continental margin, forming sporadically along the continental margins off of the Irish coast. The results were presented in a series of bathymetric charts, cross-section graphs of canyons and tables containing information on the canyons analysed.

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Figure 2 Bathymetric map of the study area with canyon sections highlighted upon the map. Included on the map is a slope map for the entire study area.

Figure 2 is a composite image of the whole study area. As is evident from figure two there are canyons formed along the whole of the study area. The canyon begin at a depth of 17m below the surface of the water for the majority of the continental shelf. The mouth of the all canyons tends to end around the depth of 1500-2000m below sea level where these canyons open up onto the greater continental shelf. Area’s marked out on figure 2 in red represent canyons that have been formed upon the continental shelf. From looking at figure 2 it is clear that canyon formation has occurred along the entire length of the study area with several canyons connecting with one another along the length of the canyon run. Though with this in mind there are several canyons that do not merge with one another along their entire run from the source of the canyon until the mouth of that canyon. Also included in figure 2 is a slope map that highlights higher angles found upon the study area. As is evident from the slope analysis the area where canyons have been highlighted in red upon the bathymetric chart also exhibit higher slope values upon the slope map. The higher slope values correlating with the digitised canyon boundaries indicate that canyon formation has occurred within these regions. This is further highlighted by looking at the areas between the canyon boundaries. The value for depth is lower between these digitised boundaries which highlight the presence of the canyon walls along the continental slope. These canyon wall are further highlighted the further down the slopes run where there is a clear change in depth values, indicating that the canyon has reached its full extent and opened up into the canyon mouth upon the continental shelf.

4.1 Canyon Analysis.

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Slope AnlysisHigh : 76.3434

Low : 0

A

B

C


Figure 3 Bathymetric map as well as a slope map of a Digitised canyon within the study area.

Figure three is a digitised map of the first section of canyons that have been selected for analysis. The canyon Gully axis has been highlighted in red along the site. This highlights the walls of the canyon along the study area for the entire run of the canyons found within this section of the study area. The bathymetric data has shown that the depth values around the site vary between two sections of canyon wall, whereby the area between two walls has a value correlated to a lower depth value than the surrounding area. Highlighted in green are areas along the continental slope where escarpment has occurred. These areas of escarpment are backed up by the results of the slope analysis, whereby the areas highlighted in green correlate with areas that have high slope values. Highlighted in brown are sediment lobes, areas where sediment has been deposited down toward the mouth of the canyons, this is relative of the downward flow of sediment downward through the canyon system (Canals, 2006) due to turbidity currents occurring within the canyon. Along with the downward sediment flow, canyon drainage is observed as beginning at the start of each canyons run which then continue downwards toward the mouth of the canyons. This drainage corresponds with the movement of sediment downwards through the canyon. This indicates that sediment moves down through the drainage basin of the canyon and down towards the mouth of the canyon where is collects upon the continental shelf. Before the beginning of each canyon there is evidence of glacial forcing observed which has occurred over several thousands of years. The evidence of forcing occurs just as canyons are about to begin and could provide evidence that the canyons formed are the result of glacial scarring upon the region during glacial retreat.

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A


Figure 4 bathymetric chart of section B of the study area. Included is a slope map for the canyon section.

Figure 4 is also a map created using ArcGIS using bathymetric data. Similar to figure 3 canyon gully axes have been highlighted by red lines throughout their run. Within these canyons the tributaries which run into the greater canyon run and subsequently feed into the mouth of the canyons opening up into the greater continental shelf. The different values for depth provide evidence for the canyon walls, where a canyon wall has been highlighted, it has shown a depth value indicative of a higher formation upon the continental shelf. Along with this the slope analysis provided further evidence for the presence of presence of canyons. The areas in which canyons have been highlighted also exhibit high slope values typical of canyon walls. This leads into areas where escarpment has occurred upon the continental shelf, these areas where steep rise and fall has occurred are evidenced by their high slope values indicated within the slope analysis. The canyon drainage basin has been highlighted within the canyons walls and has been shown to run from the canyon source to the canyon mouth for the entire canyon run. Correlating to the drainage basin of the canyons, there are sediment lobes exhibited towards the mouth of the canyons present within the continental shelf typical of submarine canyons along continental shelves. Turbidity currents have caused sediment to be dispersed downwards toward the bottom of the canyon run at the mouth of the canyon where these large sediment lobes have been formed. Along the continental shelf there are several areas outside of the canyon mouths which indicated high slope values, these could be indicative of sediment build ups that have been deposited from the canyons due to turbidity currents. Towards the source of the formed canyons, once again there was evidence of glacial forcing exhibited along the continental shelf, along with the close proximity to the canyons run, this is evidence of canyon formation due to glacial scarring.

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B


Figure 5 bathymetric chart of section c of the canyon study area. A slope map is included within the map for slope analysis.

Figure five is a bathymetric map produced using ArcGIS software. The map has canyon gully axis’s highlighted in red, these are indicative of canyon walls. The Walls can be seen with ease when looking at the depth values for bathymetric values, between two highlighted canyon walls there the area between has depth values greater than the surrounding wall, these of course are typical of submarine canyons. The walls are highlighted further by the slope analysis which is presented in the form of a slope map. The areas containing higher slope angle values, indicated in red, correlate with the highlighted canyon walls along the continental shelf. Areas of escarpment are found sporadically along the continental slope. These areas of escarpment, highlighted in green are backed up by the slope analysis, which correlates with highlighted areas of steep slope values. The drainage for the canyon has also been highlighted upon the map. The drainage for the canyon begins at the canyon source and extended the entire length of the canyon all the way down to the canyon’s mouth. It is at the canyon mouth where sediment lobes, indicated by brown are located, these lobes can be seen as build ups of sediment which have caused high slope values, as indicated by the slope analysis in red. Along the continental shelf just before the source of the canyons, there is evidence of glacial forcing which has been indicated upon the map, the close proximity of the scarring upon the continental slope would also provide evidence of scarring within the canyons themselves which could be a cause for their formation.

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C


Figure 6 Three cross section graphs of canyons that have been analysed within the report, each individual graph represents a different canyon section.

Figure 6 is a composite image of three cross sections for each section of canyons which had been analysed. Of all three canyons there is no overall uniform shape and the while canyon A has only two typical rise and falls, section B exhibited several more rise and falls throughout the entire study area. Section C is similar to A in that there are only two rise and falls, though it is the only section which displayed a significant gap between the two canyons between the 10,000 and 20,000 point upon the graph.

Canyon Section Greatest canyon length (m)

Narrowest canyon point (m)

Widest canyon point (m)

A 22,148.94 965.64 5,437.04B 30,770.54 572.38 8,113.36C 22,164.29 158.75 10.081.58

Table 1: table containing information for each of the canyons analysed within the report.

Table one shows the values for the canyons regarding the overall length of each canyon, as well as the canyons widest and narrowest points. As is evident from the table section B contained the longest running canyon with an overall length of 30,770.54m, Canyon A being the shortest with 22,148.94m for the entire run. While canyon C had the narrowest point at its source it had the widest mouth of all three canyons with 10.081.58m in overall length while at its most narrow it was analysed at 158.75m in length.

5.0 Turbidity currents present upon the Irish continental margin.

While the results physically do not show the presence of turbidity currents. The way that there are sediment lobes are present at the mouth of every canyon system, shows evidence that there are currents moving sediment downward from the continental shelf. The currents have collected sediments from the canyon at various point along the channel and have deposited sediments at the

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A B

C


mouth of the canyons (khripounoff, 2003). This deposition of sediment can give clues to canyon formation. The removal of sediment over several thousands of years could cause canyons to form within areas where high rates for sediment deposition are common (Lowe, 1982). This process could also be seen as a cause for canyon evolution. Considering that these currents are a continuous process and for this reason surely over time, these currents will be able to drag enough sediment away from the canyon system and onto the continental shelf (Piper, 2009). Though it is unlikely that the initial formation of canyons on the Irish submarine canyons, the continuation of turbidity and the subsequent deposition of sediment from within the pre-existing canyons could cause enough sediment to be dispersed that the evolution of these canyons will continue long down into the continental shelf.

Similarly the removal of sediment from the canyon system could be attributed as the main cause of slope failure within the canyon systems. The removal of sediments from the system causes overpressure upon the canyon system, which then subsequently leads to slope failure and the formation of escarpments along the continental shelf (Dimakis, 2000). These subsequent slope failures can also lead to the evolution of canyons upon the Irish continental margins. This over pressuring of the canyon system could possibly have led to the initial formations of the canyons along the continental margin though it is more likely that slope failures are more of a cause of evolution rather than for initial formation.

When the canyon had been analysed, and the areas of sediment deposition was indicated, it was observed that the depositional lobes of sediment were found to be at the mouths of the canyon runs , which also correlate with the ending of canyon drainage systems. This can back up the theory of sediment deposition as it can be shown that sediment is in fact being removed from the canyon system and being moved down toward the canyons mouth and out onto the greater continental shelf. The slope analysis showed areas adjacent to the canyon mouth that indicated high slope values along the continental shelves, this can been interpreted as the build-up of sediments that have been previously deposited along the shelf. This sort of interpretation proves the existence of currents within the region as well as the movement of sediment from the canyon’s run.

5.1 Erosion present upon the canyon system.

While the results displayed within this are of one moment in time and therefore could not represent the process of erosion over time. The process of erosion upon the Irish continental margin could well be a process that has led to the formation and subsequent evolution of canyons upon the Irish continental margin. While signs of slope failure and escarpment may indicate previous signs of erosion upon the continental shelf, the sediment of such erosion would indeed be removed from the canyon system by turbidity currents within the region (Pratson, 1994). Certainly the process of erosion could explain the formation of deeper areas of Irish submarine canyons, as a result of glacial forcing typically only being the cause for canyons in shallower regions upon continental margins rather than deeper regions of continental shelves. (Tyler, 2009). This process would be better viewed as a form of evolution rather than the initiation of formation of canyons.

Due to the potential for deep water erosion upon canyons it is possible that evolution of canyons is being caused by erosion of canyon walls throughout the canyon’s run. When considering that erosion is a continually on-going process, it could be entirely possible that erosion is the main cause for evolution upon the Irish continental margins. The process of erosion could also be coupled with turbidity currents due to the nature of the currents. Once erosion sets in and frees up sediments within the canyon, this free sediment is then collected within a turbidity current and moved downward through the canyons where it is eventually deposited at the mouth of the canyon. Over

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several thousands of years these two processes could have led to the formation of canyon walls along the shelf as well as the subsequent evolution that would occur upon the canyons over the years (McAdoo, 2000).

5.2 Glacial forcing/scarring

Upon all the sections of canyons analysed there were areas surrounding the canyons source that showed signs of glacial forcing. Considering that the continental margin within this region shows signs of glacial forcing (Dahlgren, 2005). Considering that during the last mass ice age there would have indeed been glaciers over the area that is being analysed it is very likely that glaciation was the cause for canyon formation within the region. The initial forcing of the glacier has pushed up into the continental shelf and then during the subsequent retreat of the glacier the loosened sediment that was freed during the initial forcing was then pulled back from the areas where the canyons are now present. When looking at the areas highlighted upon the maps that indicate glacial scarring are all within close proximity to the formed canyons along the shelf it is quite likely that during the time that the shelf was formed, the canyons present upon the shelf were also formed at this time due to glacial scarring (Sacchetti, 2011).

When considering that the majority of the Irish shelf exhibits signs of glacial forcing, it would make sense that the canyons within the region were formed by the same processes that formed the rest of the continental shelf. It is quite possible that the initial formation of canyons was caused by the process of glaciation, but since the melting of glaciers upon the ocean’s surface, the subsequent evolution upon the canyon, could be down to the processes previously mentioned such as erosion along with turbidity currents. The only draw-back to the theory of glaciation is that there are deeper canyons found upon the region are found at great depths towards the mouth of the canyon. When considering that glaciation is a much more common process in shallower bodies of water along continental margins. This would mean that for deeper regions of Irish continental margins there would need to be another process occurring so that the formation towards the canyon mouths are formed.

5.3 Similarities between canyons upon the Irish continental margin.

When looking over the analysed sections of the study area it is clear that for the majority of the canyons that have formed upon the Irish submarine canyons are highly similar in regards to geomorphology, and in regard to the process that occur upon the canyons themselves. This similarity could be explained by the close proximity of the canyons with one another, with the study area being less than 200km long. When the similarities of the canyons geomorphology and processes are taken into account it could possibly be assume that the canyons exhibited within this study were all formed in a similar manner to each other and the process that are currently occurring upon these canyons are similar to one another.

5.4 Conclusions

In conclusions it can be assessed that while the initial formation of canyons upon the Irish continental shelf were caused by the processes of glaciation. Subsequent canyon evolution has been the product of a combination of processes, namely erosion, slope failure and the activity of turbidity currents upon sediment within the canyons. With this in mind both of the hypothesis for this study can be accepted, as canyon formation was determined to be caused mostly by the processes of glaciation with evolution being furthered by other processes such as sediment deposition and the action of turbidity currents within the region. The second hypothesis can be accepted based on the fact that all three sections of canyons analysed shared significantly similar characteristics with one

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another. If there were to be a repeat of this experiment, higher resolution data were available would be beneficial for an analysis of the canyons to greater accuracy. As well as this data providing information on turbidity currents and their direction within the canyons examined would be useful to help better understand the dispersal of sediments upon the continental shelf. Finally access to Fledermaus for the actual canyon analysis would be beneficial for the creation of better results.

5.5 Acknowledgements

This project was carried out as a final year dissertation project. First thanks go to DR Sara Benetti of the University of Ulster for the help provided when working on this project, without whose help the report could have never been fully completed. Thanks to the Data collection team upon the RV Bligh who had collected the initial data used within the project. Special thanks go out to the University of Ulster, School of Environmental Sciences, through whom all training for this project was completed with.

6.0 References.

Allen, S. E., Vindeirinho, C., Thomson, R. E., Foreman, M. G., & Mackas, D. L. (2001). Physical and biological processes over a submarine canyon during an upwelling event. Canadian Journal of Fisheries and Aquatic Sciences, 58(4), 671-684.

Arzola, R. G., Wynn, R. B., Lastras, G., Masson, D. G., & Weaver, P. P. (2008). Sedimentary features and processes in the Nazaré and Setúbal submarine canyons, west Iberian margin. Marine Geology, 250(1), 64-88.

Babonneau, N., Savoye, B., Cremer, M., & Klein, B. (2002). Morphology and architecture of the present canyon and channel system of the Zaire deep-sea fan. Marine and Petroleum Geology, 19(4), 445-467.

Bagnold, R. A. (1962). Auto-suspension of transported sediment; turbidity currents. Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences, 315-319.

Bailey, R. J. (1975). The geology of the Irish continental margin and some comparisons with offshore eastern Canada.

Baker, E. T., & Hickey, B. M. (1986). Contemporary sedimentation processes in and around an active west coast submarine canyon. Marine Geology, 71(1), 15-34.

Bott, M. H. P. (1971). Evolution of young continental margins and formation of shelf basins. Tectonophysics, 11(5), 319-327.

Bourillet, J. F., Reynaud, J. Y., Baltzer, A., & Zaragosi, S. (2003). The ‘Fleuve Manche’: the submarine sedimentary features from the outer shelf to the deep sea fans. Journal of Quaternary Science, ‐18(3 4), 261-282.‐ Bourillet, J. F., Zaragosi, S., & Mulder, T. (2006). The French Atlantic margin and deep-sea submarine systems. Geo-Marine Letters, 26(6), 311-315.

Burk, C. A., & Drake, C. L. (1974). Geology of continental margins, edited by Creighton A. Burk and Charles L. Drake.

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Burke, K. (1972). Longshore drift, submarine canyons, and submarine fans in development of Niger Delta. AAPG Bulletin, 56(10), 1975-1983.

Cacchione, D. A., Pratson, L. F., & Ogston, A. S. (2002). The shaping of continental slopes by internal tides. Science, 296(5568), 724-727.

Canals, M., Puig, P., de Madron, X. D., Heussner, S., Palanques, A., & Fabres, J. (2006). Flushing submarine canyons. Nature, 444(7117), 354-357.

Clark, J. A., Farrell, W. E., & Peltier, W. R. (1978). Global changes in postglacial sea level: a numerical calculation. Quaternary Research, 9(3), 265-287.

Dahlgren, K. T., Vorren, T. O., Stoker, M. S., Nielsen, T., Nygård, A., & Sejrup, H. P. (2005). Late Cenozoic prograding wedges on the NW European continental margin: their formation and relationship to tectonics and climate. Marine and Petroleum Geology, 22(9), 1089-1110.

Dimakis, P., Elverhøi, A., Høeg, K., Solheim, A., Harbitz, C., Laberg, J. S., & Marr, J. (2000). Submarine slope stability on high-latitude glaciated Svalbard–Barents Sea margin. Marine Geology, 162(2), 303-316.

Driscoll, N. W., Weissel, J. K., & Goff, J. A. (2000). Potential for large-scale submarine slope failure and tsunami generation along the US mid-Atlantic coast. Geology, 28(5), 407-410.

Dugan, B., & Flemings, P. B. (2000). Overpressure and fluid flow in the New Jersey continental slope: implications for slope failure and cold seeps. Science, 289(5477), 288-291.

Embley, R. W., & Jacobi, R. D. (1977). Distribution and morphology of large submarine sediment slides and slumps on Atlantic continental margins. Marine Georesources & Geotechnology, 2(1-4), 205-228.

Hampton, M. A. (1972). The role of subaqueous debris flow in generating turbidity currents. Journal of Sedimentary Research, 42(4).

Harris, P. T., & Whiteway, T. (2011). Global distribution of large submarine canyons: Geomorphic differences between active and passive continental margins. Marine Geology, 285(1), 69-86.

Herzer, R. H. (1979). Submarine slides and submarine canyons on the continental slope off Canterbury, New Zealand. New Zealand journal of geology and geophysics, 22(3), 391-406.

Khripounoff, A., Vangriesheim, A., Babonneau, N., Crassous, P., Dennielou, B., & Savoye, B. (2003). Direct observation of intense turbidity current activity in the Zaire submarine valley at 4000 m water depth.Marine Geology, 194(3), 151-158.

Lewis, K. B. (1971). Slumping on a continental slope inclined at 1–4. Sedimentology, 16(1 2), 97-110.‐Liu, J. T., Liu, K. J., & Huang, J. C. (2002). The effect of a submarine canyon on the river sediment dispersal and inner shelf sediment movements in southern Taiwan. Marine Geology, 181(4), 357-386.

Lowe, D. R. (1982). Sediment gravity flows: II Depositional models with special reference to the deposits of high-density turbidity currents. Journal of Sedimentary Research, 52(1).

May, J. A. (1983). Role of submarine canyons on shelf break erosion and sedimentation: modern and ancient examples.

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McAdoo, B. G., Pratson, L. F., & Orange, D. L. (2000). Submarine landslide geomorphology, US continental slope. Marine Geology, 169(1), 103-136.

Mitchell, N. C. (2005). Interpreting long-profiles of canyons in the USA Atlantic continental slope. Marine Geology, 214(1), 75-99.

Morris, W. R., & Busby-Spera, C. J. (1988). Sedimentologic evolution of a submarine canyon in a forearc basin, Upper Cretaceous Rosario Formation, San Carlos, Mexico. AAPG Bulletin, 72(6), 717-737.

Muller Karger, F. E., Varela, R., Thunell, R., Luerssen, R., Hu, C., & Walsh, J. J. (2005). The importance ‐of continental margins in the global carbon cycle. Geophysical Research Letters, 32(1).

Nardin, T. R. (1979). A Review of Mass Movement Processes Sediment and Acoustic Characteristics, and Contrasts in Slope and Base-of-Slope Systems versus Canyon-Fan-Basin Floor Systems.

Orange, D. L. (1999). Tectonics, sedimentation, and erosion in northern California: submarine geomorphology and sediment preservation potential as a result of three competing processes. Marine Geology, 154(1), 369-382.

Palanques, A., de Madron, X. D., Puig, P., Fabres, J., Guillén, J., Calafat, A., & Bonnin, J. (2006). Suspended sediment fluxes and transport processes in the Gulf of Lions submarine canyons. The role of storms and dense water cascading. Marine Geology, 234(1), 43-61.

Pratson, L. F., & Coakley, B. J. (1996). A model for the headward erosion of submarine canyons induced by downslope-eroding sediment flows. Geological Society of America Bulletin, 108(2), 225-234.

Piper, D. J., & Normark, W. R. (2009). Processes that initiate turbidity currents and their influence on turbidites: a marine geology perspective. Journal of Sedimentary Research, 79(6), 347-362.

Pratson, L. F., Ryan, W. B., Mountain, G. S., & Twichell, D. C. (1994). Submarine canyon initiation by downslope-eroding sediment flows: evidence in late Cenozoic strata on the New Jersey continental slope. Geological Society of America Bulletin, 106(3), 395-412.

Sawyer, D. E., Flemings, P. B., Shipp, R. C., & Winker, C. D. (2007). Seismic geomorphology, lithology, and evolution of the late Pleistocene Mars-Ursa turbidite region, Mississippi Canyon area, northern Gulf of Mexico. AAPG bulletin, 91(2), 215-234.

Schwab, W. C., & Lee, H. J. (1988). Causes of two slope-failure types in continental-shelf sediment, north-eastern Gulf of Alaska. Journal of Sedimentary Research, 58(1).

Shackleton, N. J. (1987). Oxygen isotopes, ice volume and sea level. Quaternary Science Reviews, 6(3), 183-190.

Shepard, F. P. (1952). Composite origin of submarine canyons. The Journal of Geology, 84-96.

Shepard, F. P. (1981). Submarine canyons: multiple causes and long-time persistence. AAPG Bulletin, 65(6), 1062-1077.

Tyler, P. A., Amaro, T., ARzoLA, R., Cunha, M. R., dE STIgTER, H., Gooday, A., & Wolff, G. (2009). Europe's Grand Canyon: Nazaré submarine canyon. Oceanography, 2009, vol. 22, num. 1, p. 52-57.

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Westley, K., Quinn, R., Forsythe, W., Plets, R., Bell, T., Benetti, S., & Robinson, R. (2011). Mapping submerged landscapes using multibeam bathymetric data: a case study from the north coast of Ireland. International Journal of Nautical Archaeology, 40(1), 99-112.

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The Geomorphology of Irish submarine canyons

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