Abstract
The Outer Hebrides Platform extends west from the present island chain towards the Atlantic continental shelf edge and represents a fragment of Archaean crust (Lewisian gneiss) that was differentially uplifted during the Palaeogene and tilted westwards during the Neogene. An extensive planation surface developed close to sea level in the Pliocene and was subsequently modified by Pleistocene marine and glacial erosion to form an extensive, partly submerged strandflat. During Pleistocene cold stages the Outer Hebrides supported an independent ice cap, but mainland ice periodically over-ran the extremities of the island chain and flowed through the sounds separating individual islands. Ice-roughened knock-and-lochan terrain is extensive across lowland areas, but during the last (and probably earlier) glacial stage(s) the Outer Hebrides Ice Cap remained cold-based and non-erosive above 450–700 m and on lower ground in NW Lewis, permitting the preservation of summit blockfields and over-ridden raised beach gravels. During the last glacial stage (~35 to 14 ka) the ice cap fed the Minch and Hebrides Ice Streams and extended westwards across the shelf but did not reach St Kilda, which supported only small cirque glaciers. Readvance of glaciers during the Loch Lomond Stade (~12.9 to 11.7 ka) was limited to the mountains of North Harris and SW Lewis, and resulted in the deposition of end, lateral and multiple recessional moraines. Postglacial sea-level rise drowned the structurally guided and glacially modified coastline, creating numerous rocky inlets; on Atlantic coasts, large volumes of sediment were moved shoreward onto beach, dune and machair (calcareous shell sand) land systems. The beach, dune and machair features of the Outer Hebrides and the exceptionally high sea cliffs and stacks of St Kilda represent some of the most iconic coastal scenery in Scotland.
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References
Amin A (2020) A study of the tectonic and geomorphic history of Scotland using a joint apatite fission track and (U-Th-Sm)/He analysis approach. PhD thesis, University of Glasgow
Angus S, Hansom JD (2004) Tir a’mhachair, tir nan loch? Climate change scenarios for Scottish machair systems: a wet future? In: Delivering sustainable coasts: connecting science and policy. Proc Littoral Conf 2004, vol 2. Cambridge Publications, Cambridge, pp 565–569
Angus S, Hansom JD (2021) Enhancing the resilience of high-vulnerability, low-elevation coastal zones. Ocean Coast Man 200:10514
Ballantyne CK (2006) Loch Lomond Stadial glaciers in the Uig Hills, western Lewis, Scotland. Scot Geogr J 122:256–273
Ballantyne CK (2007) Loch Lomond Stadial glaciers in North Harris, Outer Hebrides, North-West Scotland: glacier reconstruction and palaeoclimatic implications. Quat Sci Rev 26:3134–3149
Ballantyne CK, Hallam GE (2001) Maximum altitude of Late Devensian glaciation on South Uist, Outer Hebrides, Scotland. Proc Geol Assoc 112:155–167
Ballantyne CK, Harris C (1994) The periglaciation of Great Britain. Cambridge University Press, Cambridge
Ballantyne CK, McCarroll D (1995) The vertical dimensions of Late Devensian glaciation on the mountains of Harris and southeast Lewis, Outer Hebrides, Scotland. J Quat Sci 10:211–224
Ballantyne CK, Fabel D, Gheorghiu D et al (2017) Late Quaternary glaciation in the Hebrides sector of the continental shelf: cosmogenic nuclide dating of glacial events on the St Kilda archipelago. Boreas 46:605–621
Bradwell T, Stoker MS (2015) Submarine sediment and landform record of a palaeo-ice stream within the last British-Irish Ice Sheet. Boreas 44:255–276
Bradwell T, Small D, Fabel D et al. (2019) Ice-stream demise dynamically conditioned by trough shape and bed strength. Sci Adv 5:eaau1380
Bradwell T, Stoker MS, Larter R (2007) Geomorphological signature and flow dynamics of The Minch palaeo-ice stream, northwest Scotland. J Quat Sci 22:609–617
Callard SL, Ó Cofaigh C, Benetti S et al (2018) Extent and retreat history of the Barra Fan Ice Stream offshore western Scotland and northern Ireland during the last glaciation. Quat Sci Rev 201:280–302
Carter R (1992) How the British coast works: inherited and acquired controls. In: Stevens C, Gordon JE, Green CP, Macklin MG (eds) Conserving our landscape. English Nature, Peterborough, pp 63–68
Cave JAS, Ballantyne CK (2016) Catastrophic rock-slope failures in NW Scotland: quantitative analysis and implications. Scot Geogr J 132:185–209
Chandler BMP, Boston CM, Lukas S (2019) A spatially-restricted Younger Dryas plateau icefield in the Gaick, Scotland: reconstruction and palaeoclimatic implications. Quat Sci Rev 211:107–135
Chesher JA, Smythe D, Bishop P (1983) The geology of the Minches, Inner Sound and Sound of Raasay. Institute of Geological Sciences Report 83/6, HMSO, London
Clayton, KM (2003) Sea-level history. In: May VJ, Hansom JD (eds) Coastal geomorphology of Great Britain. Geological Conservation Review Series 28. Joint Nature Conservation Committee, Peterborough, pp 15–18
Cooper JAG, Jackson D, Dawson AG et al (2012) Barrier islands on bedrock: a new landform type demonstrating the role of antecedent topography on barrier form and evolution. Geology 40:923–926
Dawson AG, Dawson S, Cooper JAG et al (2013) A Pliocene age and origin for the strandflat of the Western Isles of Scotland: a speculative hypothesis. Geol Mag 150:360–366
Dawson AG, Dawson S, Mighall TM et al (2001) Intertidal peat deposits and early Holocene relative sea-level changes, Traigh Eileraig, Isle of Coll, Scottish Hebrides. Scot J Geol 37:11–18
Dawson S, Smith DE, Jordan J, Dawson AG (2004) Late Holocene coastal sand movements in the Outer Hebrides, NW Scotland. Mar Geol 210:281–306
Dove D, Arosio R, Finlayson A et al (2015) Submarine glacial landforms record Late Pleistocene ice-sheet dynamics, Inner Hebrides, Scotland. Quat Sci Rev 12:76–90
Earll R, Pagett RM (1984) A classification and catalogue of the sea lochs of the Western Isles. Nature Conservancy Council, Peterborough
Fabel D, Ballantyne CK, Xu S (2012) Trimlines, blockfields, mountain-top erratics and the vertical dimensions of the last British-Irish Ice Sheet in NW Scotland. Quat Sci Rev 55:91–102
Faithfull J, Timmerman M, Upton B, Rumsey M (2012) Mid-Eocene renewal of magmatism in NW Scotland: the Loch Roag Dyke, Outer Hebrides. J Geol Soc 169:115–118
Fettes DJ, Mendum JR, Smith DI, Watson JV (1992) Geology of the Outer Hebrides. British Geological Survey Memoir, HMSO, London
Franklin BSG (2013) Characterising fracture systems within upfaulted basement highs in the Hebridean Islands: an onshore analogue for the Clair Field. PhD thesis, Durham University
Geikie J (1877) The Great Ice Age, 2nd edn. Daldy and Isbister, London
Gibb F, Henderson C (1996) The Shiant Isles Main Sill: structure and mineral fractionation trends. Mineral Mag 60:67–97
Gilbertson DD, Schwenninger J-L, Kemp R, Rhodes EJ (1999) Sand-drift and soil formation along an exposed North Atlantic coastline: 14,000 years of diverse geomorphological climatic and human impacts. J Archaeol Sci 26:439–469
Godard A (1965) Recherches de géomorphologie en Écosse du Nord-Ouest. Masson, Paris
Hall AM (1995) Was all of Lewis glaciated in the Late Devensian? Quat Newsletter 76:1–7
Hall AM, Ebert K, Goodfellow BW et al (2019) Past and future impact of glacial erosion in Forsmark and Uppland. SKB-19-07. Svensk Kärnbränslehantering AB, 247 p
Hall AM, Krabbendam M, van Boeckel M et al (2020) Glacial ripping: geomorphological evidence from Sweden for a new process of glacial erosion. Geogr Ann. https://doi.org/10.1080/04353676.2020.1774244
Hansom JD (2001) Coastal sensitivity to environmental change: a view from the beach. Catena 42:291–305
Hansom JD (2003a) Loch Maddy–Sound of Harris coastline. In: May VJ, Hansom JD (eds) Coastal geomorphology of Great Britain. Geological Conservation Review Series 28. Joint Nature Conservation Committee, Peterborough, pp 94–97
Hansom JD (2003b) Machair. In: May VJ, Hansom JD (eds) Coastal geomorphology of Great Britain. Geological Conservation Review Series 28. Joint Nature Conservation Committee, Peterborough, pp 473–514
Hansom JD (2003c) St Kilda. In: May VJ, Hansom JD (eds) Coastal geomorphology of Great Britain. Geological conservation review series 28. Joint Nature Conservation Committee, Peterborough, pp 60–68
Hansom JD, Angus S (2006) Machair nan Eilean Siar (Machair of the Western Isles). Scot Geogr J 121:401–412
Hansom JD, Fitton JM, Rennie AF (2017) Dynamic Coast—national coastal change assessment: national overview. CRW2014/2. www.dynamiccoast.com
Hansom JD, Lees G, McGlashan DJ, John S (2004) Shoreline management plans and coastal sediment cells in Scotland. Coast Manage 32:227–242
Harding RR, Merriman RJ, Nancarrow PHA (1984) St Kilda: an illustrated account of the geology. Brit Geol Surv Rept 16/7. HMSO, London
Hibbert FD, Austin WEN, Leng MJ, Gatliff RW (2010) British Ice Sheet dynamics inferred from North Atlantic ice-rafted debris records spanning the last 175 000 years. J Quat Sci 25:461–482
Hiemstra JF, Shakesby RA, Vieli A (2015) Late Quaternary glaciation in the Hebrides sector of the continental shelf: was St Kilda overrun by the British-Irish Ice Sheet? Boreas 44:178–196
Hinchliffe S, Ballantyne CK, Walden J (1998) The structure and sedimentology of relict talus, Trotternish, northern Skye, Scotland. Earth Surf Proc Landf 23:545–560
Holliday NP, Yelland MJ, Pascal R et al (2006) Were extreme waves in the Rockall Trough the largest ever recorded? Geophys Res Lett 33:L05613
Hubbard A, Bradwell T, Golledge N et al (2009) Dynamic cycles, ice streams and their impact on the extent, chronology and deglaciation of the British-Irish ice sheet. Quat Sci Rev 28:758–776
Hughes ALC, Clark CD, Jordan CJ (2010) Subglacial bedforms of the last British Ice Sheet. J Maps 6:543–563
Jehu TJ, Craig RM (1934) The geology of the Outer Hebrides—Part V. North Harris and Lewis. Trans R Soc Edinb 57:839–874
Jones EJW, Mitchell JG, Perry RG (1986) Early Tertiary igneous activity west of the Outer Hebrides, Scotland: evidence from magnetic anomalies and dredged basaltic rocks. Mar Geol 73:47–59
Jordan JT, Smith DE, Dawson S, Dawson AG (2010) Holocene relative sea-level changes in Harris, Outer Hebrides, Scotland, UK. J Quat Sci 25:115–134
Krabbendam M, Bradwell T (2014) Quaternary evolution of glaciated gneiss terrains: pre-glacial weathering vs. glacial erosion. Quat Sci Rev 95:20–42
Lawrence K, Sosdian S, White H, Rosenthal Y (2010) North Atlantic climate evolution through the Plio-Pleistocene climate transitions. Earth Planet Sci Lett 300:329–342
Le Coeur C (1988) Late Tertiary warping and erosion in western Scotland. Geogr Ann 70A:361–368
Merritt JW, Hall AM, Gordon JE, Connell ER (2019) Late Pleistocene sediments, landforms and events in Scotland: a review of the terrestrial stratigraphic record. Earth Env Sci Trans R Soc Edinb 110:39–91
Peacock JD (1984) Quaternary geology of the Outer Hebrides. Brit Geol Surv Rept 16/2. HMSO, London
Peacock JD (1991) Glacial deposits of the Hebridean region. In: Ehlers J, Gibbard PL, Rose J (eds) Glacial deposits in Great Britain and Ireland. Balkema, Rotterdam, pp 109–120
Persano C, Barfod DN, Stuart FM, Bishop P (2007) Constraints on early Cenozoic underplating-driven uplift and denudation of western Scotland from low temperature thermochronometry. Earth Planet Sci Lett 263:404–419
Ramsay DL, Brampton AH (2000) Coastal cells in Scotland: Cells 8 and 9: The Western Isles. Scottish Natural Heritage Research, Survey and Monitoring Report No. 145
Ritchie JD, Hitchen K (1996) Early Paleogene offshore igneous activity to the northwest of the UK and its relationship to the North Atlantic Igneous Province. Geol Soc Lond Spec Publ 101:63–78
Ritchie W (1968) The coastal geomorphology of North Uist. O’Dell Memorial Monograph No. 1. Aberdeen University, Aberdeen
Sejrup HP, Hjelstuen BO, Torbjørn Dahlgren KI et al (2005) Pleistocene glacial history of the NW European continental margin. Mar Pet Geol 22:1111–1129
Selby IC (1987) Glaciated shorelines in Barra and Vatersay. Quat Newsletter 53:16–22
Small D, Benetti S, Dove D et al (2017) Cosmogenic exposure age constraints on deglaciation and flow behaviour of a marine-based ice stream in western Scotland. Quat Sci Rev 167:30–46
Smith DE, Barlow NLM, Bradley SL et al (2019) Quaternary sea level change in Scotland. Earth Env Sci Trans R Soc Edinb 110:219–256
Smythe DK, Kenolty N (1975) Tertiary sediments in the Sea of the Hebrides. J Geol Soc Lond 131:227–233
Spratt RM, Lisiecki LE (2016) A Late Pleistocene sea level stack. Clim Past 12:1079–1092
Steel RJ, Wilson AC (1975) Sedimentation and tectonism (?Permo-Triassic) on the margin of the North Minch Basin, Lewis. J Geol Soc 131:183–200
Stoker MS, Hitchen K, Graham CC (1993) The geology of the Hebrides and West Shetland shelves, and adjacent deep-water areas. Brit Geol Surv UK Offshore Regional Rept. HMSO, London
Stoker MS, Holford SP, Hillis RR et al (2010) Cenozoic post-rift sedimentation off northwest Britain: recording the detritus of episodic uplift on a passive continental margin. Geology 38:595–598
Stoker MS, Leslie AB, Scott WD et al (1994) A record of late Cenozoic stratigraphy, sedimentation and climate change from the Hebrides Slope, NE Atlantic Ocean. J Geol Soc Lond 151:235–249
Stone JO, Ballantyne CK (2006) Dimensions and deglacial chronology of the Outer Hebrides Ice Cap, northwest Scotland: implications of cosmic ray exposure dating. J Quat Sci 21:75–84
Sutherland DG (1984) The submerged landforms of the St. Kilda Archipelago, western Scotland. Mar Geol 58:435–442
Sutherland DG (1993) Glen Valtos. In: Gordon JE, Sutherland DG (eds) Quaternary of Scotland. Geological conservation review series 6. Chapman and Hall, London, pp 425–429
Sutherland DG, Walker MJC (1984) A Late Devensian ice-free area and possible interglacial site on the Isle of Lewis, Outer Hebrides. Nature 309:701–703
Sutherland DG, Ballantyne CK, Walker MJC (1984) Late Quaternary glaciation and environmental change on St. Kilda, Scotland, and their palaeoclimatic significance. Boreas 3:261–272
von Weymarn J (1974) Coastline development in Lewis and Harris, with particular reference to the effects of glaciation. PhD thesis, University of Aberdeen
von Weymarn JA (1979) A new concept of glaciation in Lewis and Harris. Proc R Soc Edinb 77B:97–105
Walker MJC (1984a) A pollen diagram from St Kilda, Outer Hebrides, Scotland. New Phytol 97:99–113
Walker MJC (1984b) Pollen analysis and Quaternary research in Scotland. Quat Sci Rev 3:369–404
Watson JV (1977) The Outer Hebrides: a geological perspective. Proc Geol Assoc 88:1–14
Whittington G, Hall AM (2002) The Tolsta Interstadial, Scotland: correlation with D-O cycles GI-8 to GI-5? Quat Sci Rev 21:901–915
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Hall, A.M., Ballantyne, C.K., Hansom, J.D. (2021). The Outer Hebrides and St Kilda. In: Ballantyne, C.K., Gordon, J.E. (eds) Landscapes and Landforms of Scotland. World Geomorphological Landscapes. Springer, Cham. https://doi.org/10.1007/978-3-030-71246-4_9
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