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Landslides and coastal erosion at Sidestrand, Norfolk

Sidestrand location

Sidestrand is situated 1.3 km south-east of the village of Overstrand on the Norfolk Coast. The cliff faces north-east and the beach is very wide and sandy (Figure 2).

Active deep-seated rotational landslides and mudslides predominate and BGS has been collecting data from this site since 2001. National Landslide Database ID 16350/1.

Sidestrand is part of a programme of work monitoring coastal erosion and landsliding at several sites around the coast of Great Britain.

The Sidestrand coastal section © Mike Page, SkyView

Geology described in detail

A considerable amount of work has been carried out on the local geology (Banham, 1988; Hart and Boulton, 1991; Lunkka, 1994; Hamblin, 2000; Lee et al., 2004), and to a much lesser extent the geotechnical properties of the tills of North Norfolk (Kazi and Knill, 1969; Hutchinson, 1976).

The current geological interpretation is that of Lee et al., (2004), shown in Figure 2. This scheme equates the Lowestoft Till with the Second Cromer Till.

Coastal section taken from Lee et al., 2004.

Important features of the landslide site and neighbouring cliffs are the glaciotectonically-controlled syncline and large-scale shears (Lee et al., 2004). The deposits within the platform and lower part of the cliff consist of the matrix-dominant dark grey Happisburgh Till Member of the Happisburgh Formation (Figure 3). This till has been subjected to small-scale folding, glaciotectonic in origin and, as with most tills of this type, is regularly jointed. The folding is observed in freshly eroded or landslide-exposed sections in the cliff, and also in the platform.

Happisburgh Till Member showing 'chevron folding'. The ranging rod is 1 m long.

The deposits in the mid part of the cliff are largely obscured by landslides. They consist of the Ostend Clay Member (Happisburgh Formation), the Walcott Till Member (Lowestoft Formation), and the lower and central components of the Sheringham Cliffs Formation, viz. the Mundesley Sand Member, Ivy Farm Laminated Silt Member, and the Bacton Green Till Member.

In the upper part of the cliff the exposure is good (Figure 4). Here the uppermost part of the Sheringham Cliff Formation (Trimingham Clay and Weybourne Town Till Members) is seen. This is overlain by the Stow Hill Sand and Gravel Member of the Briton's Lane Formation.

Virtually the entire thickness of the Briton's Lane and Sheringham Cliffs Formations has been subject to glaciogenic thrusting (Lee et al., 2004). Distinguishing syn-depositional and post-depositional thrust/shear features from modern landslide features is difficult in some cases. Some shear features visible in marine-eroded cliff sections are clearly the basal and side-shears of modern mudslides. The Happisburgh Till Member is a 3 to 6 m thick, massive yellow-brown sandy till, while the Walcott Till Member is a stiff blue-grey chalky, flinty till.

Landslides


Trimingham Clay Member (TCM), Weybourne Town Till Member (WM), and Stow Hill Sand & Gravel Member (SHM)

The landslides at the Sidestrand test site are complex, consisting partly of large-scale, deep-seated landslides and partly of mudslides and debris flows. The deep-seated movements tend to have a dominant rotational component, but are in part translational. In some cases these extend to depths several metres below platform level, but are more usually entirely within the cliff. The landslides form deeply incised embayments which are arcuate in plan. The backscarps at the cliff-top tend to be sharply defined vertical features which persist after the landslide event. Deep-seated landslides tend to rotate to angles of 10 to 20 degrees and break up during failure transport, producing large debris aprons which spread across beach and platform. These are short-lived as the debris is readily removed by the sea. Such large events are followed by many mudslides and mudflows.

The level of activity during the survey period has been high, particularly during the winter of 2000/01, and has included various types of movement at beach level (Figure 5), and a large-scale debris flow, which ran-out across the beach and persisted for two years (Figure 6 and Figure 7). Active beach thrusting and deep-seated rotation have been observed periodically.

Survey results

As part of a cliff monitoring programme at BGS, data has been collected from the cliffs at Sidestrand annually for six years. The principal method of survey is long-range terrestrial laser scanning (terrestrial LiDAR) — see Terrestrial LiDAR Survey Techniques.

The annual surveys results are processed to provide data for models of coastal recession. The data collected in the field by laser scanning and GPS are entered into a modelling package. The resulting computer model enables volume calculations and observations to be made as to the way in which the coast is eroding.

Photo gallery

References

Banham, P.H., 1988, Polyphase glaciotectonic deformation in the contorted drift of Norfolk, in Croot, D.G., ed., Glaciotectonics; Forms and Processes: Rotterdam, Balkema, p. 27-32.

Hamblin, R.J.O., 2000, A new glacial stratigraphy for East Anglia: Mercian Geologist, v. 15 (1), p. 59-62.

Hart, J.K., and Boulton, G.S., 1991, The glacial drifts of Norfolk, in Ehlers, J., Gibbard, P.L., and Rose, J., eds., Glacial Deposits in Great Britain and Northern Ireland: Rotterdam, Balkema,, p. 233-243.

Hutchinson, J.N., 1976, Coastal landslides in cliffs of Pleistocene deposits between Cromer and Overstrand, Norfolk, England, in Janbu, N., Jorstad, F., and Kjaernsli, B., eds., Laurits Bjerrum Memorial Volume, Contributions to Soil Mechanics: Oslo, Norwegian Geotechnical Institute, p. 155-182.

Kazi, A., and Knill, J.L., 1969, The sedimentation and geotechnical properties of the Cromer Till between Happisburgh and Cromer, Norfolk: Quarterly Journal of Engineering Geology, v. 2 63-86.

Lee, J.R., Booth, S.J., Hamblin, R.J.O., Jarrow, A.M., Kessler, H.K.E., Moorlock, B.S.P., Morigi, A.M., Palmer, A., Pawley, S.J., Riding, J.B., and Rose, J., 2004a, A new stratigraphy for the glacial deposits around Lowestoft, Great Yarmouth and Cromer, East Anglia, UK: Bulletin of the Geological Society of Norfolk, v. 53 3-60.

Lunkka, J. P., 1994, Sedimentation and lithostratigraphy of the North Sea Drift and Lowestoft Till Formations in the coastal cliffs of northeast Norfolk, England: Journal of Quaternary Science, v. 9 (3), p. 209-233.

Further reading

Banham, P.H., 1968, A preliminary note on the Pleistocene stratigraphy of northeast Norfolk: Proceedings of the Geological Association, v. 79 507-512.

Banhan, P.H., 1988, Polyphase glaciotectonic deformation in the contorted drift of Norfolk, in Croot, D.G., ed., Glaciotectonics; Forms and Processes: Rotterdam, Balkema, p. 27-32.

Banham, P.H., and Ranson, C.E., 1965, Structural study of the Contorted Drift and disturbed Chalk at Weybourne, North Norfolk: Geological Magazine, v. 102 (2), p. 165-174.

Bell, F.G., 2002, The geotechnical properties of some till deposits occurring along the coastal areas of eastern England: Engineering Geology, v. 63 49-68.

Bell, F.G., and Forster, A., 1991, The geotechnical characteristics of the Till deposits of Holderness. In:. (eds.). pp . . in Forster, A., Culshaw, M.G., Cripps, J.C., Little, J.A., and Moon, C.F., eds., Quaternary Engineering Geology, Engineering Geology Special Publications, Volume 7: London, Geological Society, p. 111-118.

Buckley, S.J., Howell, J.A., Enge, H.D., and Kurz, T.H., 2008, Terrestrial Laser scanning in geology: data acquisition, processing and accuracy considerations: Journal of the Geological Society of London, v. 165 625-638.

Cambers, G., 1976, Temporal scales in coastal erosion systems: Transcripts of the Institute of British Geographers, v. 1 246 - 256.

Cameron, T.D.J., Crosby, A., Balson, P.S., Jeffery, D.H., Lott, G.K., Bulat, J., and Harrison, D.J., 1992, UK offshore regional report: The geology of the southern North Sea: Keyworth, British Geological Survey.

Clayton, K.M., 1989, Sediment input from the Norfolk cliffs, Eastern England - a century of coast protection and its effects: Journal of Coastal Research, v. 5 (3), p. 433-442.

Clayton, K.M., McCave, I.N., and Vincent, C.E., 1983, The establishment of a sand budget for the East Anglian coast and its implications for coastal stability, Shoreline Protection: University of Southampton, Thomas Telford Ltd, p. 91-96.

Hamblin, R.J.O., 2000, A new glacial stratigraphy for East Anglia: Mercian Geologist, v. 15 (1), p. 59-62.

Hart, J.K., and Boulton, G.S., 1991, The glacial drifts of Norfolk, in Ehlers, J., Gibbard, P.L., and Rose, J., eds., Glacial Deposits in Great Britain and Northern Ireland: Rotterdam, Balkema,, p. 233-243.

Hobbs, P., Humphreys, B., Rees, J., Tragheim, D., Jones, L., Gibson, A., Rowlands, K., Hunter, G., and Airey, R., 2002, Monitoring the role of landslides in 'soft cliff' coastal recession, in McInnes, R.G., and Jakeways, J., eds., Instability Planning and Management: Isle of Wight, Thomas Telford, p. 589-600.

Hobbs, P.R.N., Pennington, C.V.L, Pearson, S. G., Jones, L.D., Foster, C., Lee, J. R. & Gibson, A. (in press), Slope Dynamics Project Report: Norfolk Coast (2000-2006), British Geological Survey Open Report OR/08/018.

HR Wallingford, 2002, Southern North Sea Sediment Transport Study Phase 2: Sediment Transport Report, Report produced for Great Yarmouth Borough Council by HR Wallingford, CEFAS/UEA, Posford Haskoning and Dr Brian D'Olier, Report EX 4526.,

Hutchinson, J.N., 1976, Coastal landslides in cliffs of Pleistocene deposits between Cromer and Overstrand, Norfolk, England, in Janbu, N., Jorstad, F., and Kjaernsli, B., eds., Laurits Bjerrum Memorial Volume, Contributions to Soil Mechanics: Oslo, Norwegian Geotechnical Institute, p. 155-182.

Kazi, A., and Knill, J.L., 1969, The sedimentation and geotechnical properties of the Cromer Till between Happisburgh and Cromer, Norfolk: Quarterly Journal of Engineering Geology, v. 2 63-86.

Klein, A.H.F., and Menezes, J.T., 2001, Beach morphodynamics and profile sequence for a headland bay coast: Journal of Coastal Research, v. 17 (4), p. 812-835.

Knight, J., 2005, Formation of thrust structures in front of coastal landslides: The Journal of Geology University of Chicago, v. 113 107-114.

Lee, J.R., 2001, Genesis and palaeogeographic significance of the Corton Diamicton (basal member of the North Sea Drift Formation), East Anglia, UK: Proceedings of the Geologists' Association, v. 112 43-67.

Lee, J.R., Booth, S.J., Hamblin, R.J.O., Jarrow, A.M., Kessler, H.K.E., Moorlock, B.S.P., Morigi, A.M., Palmer, A., Pawley, S.J., Riding, J.B., and Rose, J., 2004a, A new stratigraphy for the glacial deposits around Lowestoft, Great Yarmouth and Cromer, East Anglia, UK: Bulletin of the Geological Society of Norfolk, v. 53 3-60.

Lee, J.R., Rose, J., Hamblin, R.J.O., and Moorlock, B.S.P., 2004, Dating the earliest lowland glaciation of eastern England: a pre-M1512 early Middle Pleistocene Happisburgh Glaciation: Quaternary Science Reviews.

Lee, J.R., Rose, J., Riding, J.B., Hamblin, R.J.O., and Moorlock, B.S.P., 2002, Testing the case for a Middle Pleistocene Scandinavian glaciation in Eastern England: evidence for a Scottish ice source for tills within the Corton Formation of East Anglia, UK: Boreas, v. 31 345-355.

Lunkka, J.P., 1988, Sedimentation and deformation of the North Sea Drift Formation in the Happisburgh area, North Norfolk, in Croot, D., ed., Glaciotectonics: Forms and Processes: Balkema, Rotterdam, p. 109-122.

-, 1994, Sedimentation and lithostratigraphy of the North Sea Drift and Lowestoft Till Formations in the coastal cliffs of northeast Norfolk, England: Journal of Quaternary Science, v. 9 (3), p. 209-233.

McCave, I.N., 1978, Grain-size trends and transport along beaches: examples from Eastern England: Marine Geology, v. 28 M43-M51.

-, 1987, Fine sediment sources and sinks around the East Anglian coast (UK): Journal of the Geological Society of London, v. 144 (1), p. 149-152.

Miller, L., and Douglas, B.C., 2004, Mass and volume contributions to twentieth-century global sea level rise: Nature, v. 428 406-409.

Mills, J.P., Buckley, S.J., Mitchell, H.L., Clarke, P.J., and Edwards, S.J., 2005, A geomatics data integration technique for coastal change monitoring: Earth Surface Processes & Landforms, v. 30 (6), p. 651-664.

Moorlock, B., Hamblin, R., SJ, B., Woods, M., Kessler, H., and Hobbs, P., 2002, Geology of the Cromer District: a brief explanation of the geological map sheet 131 Cromer, British Geological Survey.

Ohl, C., Frew, P., Sayers, P., Watson, G., Lawton, P., Farrow, B., Walkden, M., and Hall, J., 2003, North Norfolk - a regional approach to coastal erosion management and sustainability practice, in McInnes, R.G., ed., International Conference on Coastal Management 2003: Brighton, Thomas Telford, p. 226-240.

Poulton, C.V.L., Lee, J.R., Jones, L.D., Hobbs, P.R.N., and Hall, M., 2006, Preliminary investigation into monitoring coastal erosion using terrestrial laser scanning: case study at Happisburgh, Norfolk, UK: Bulletin of the Geological Society of Norfolk, v. 56 45-65.

Reid, C., 1882, The geology of the country around Cromer, Sheet 68., British Geological Survey, 137 p.

Rowlands, K., Jones, L., and Whitworth, M., 2003, Photographic Feature: Landslide Laser scanning: a new look at an old problem: Quarterly Journal of Engineering Geology, v. 36 (2), p. 155-158.

Short, A.D., and Masselink, G., 1999, Embayed and structurally controlled beaches, in Short, A.D., ed., Handbook of beach and shoreface morfodynamics: Chichester, Wiley, p. 142-161.

Thomalla, F., and Vincent, C.E., 2003, Beach Response to Shore-Parallel Breakwaters at Sea Palling, Norfolk, UK: Estuarine, Coastal and Shelf Science, v. 56 203-212.

Contact the Landslide Response Team

British Geological Survey
Keyworth
Nottingham
NG12 5GG
E-mail: Landslides team
Telephone: 0115 936 3143
Fax: 0115 936 3276