The last British Ice Sheet: A review of the evidence utilised in the ...

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LGM are presently drawn at the feather edge of the Skipsea Till (previously mapped as Hessle Till; e.g. Suggate and West, 1959). The oldest glacial deposit recognized in this area is the Basement Till, which is overlain by the Skipsea (“Drab”) and Withernsea (“Purple”) tills along an extensive stretch of the Holderness coastline (Madgett, 1975; Madgett and Catt, 1978). Debate continues as to whether the Basement Till is Dimlington or pre-Devensian in age (e.g. Lamplugh, 1890; Catt and Penny, 1966; Eyles et al., 1994). However, radiocarbon dates of 18,500±400 years BP and 18,240±250 years BP obtained by Penny et al. (1969) on organics between the Basement and Skipsea Tills provide a maximum age for the onset of the Dimlington Stadial in the region (Rose, 1985). An additional date for the onset of the stadial of 17,500±1600 (16,600±1700 BP corrected and in calendar years) was obtained by thermoluminescence techniques from beneath the Skipsea Till on the Wolds dip slope (Wintle and Catt, 1985). Peacock (1997) has argued that the Skipsea till represents a readvance by North Sea ice as late as 15–14 ka radiocarbon years BP. A radiocarbon date of 13,045±270 on organics from a kettle hole at Roos provides a minimum for deglaciation (Beckett, 1981). A radiocarbon date of 16,713±340 from basal peat in a kettle hole on glacial outwash in Kildale provides a minimum age on deglaciation of the northern slopes of the Cleveland Hills (Jones, 1977). On the central Lincolnshire Wolds, a drift limit, marked by the edge of the “Lower Marsh Till”, occurs at 114 m and has been equated with an Early Devensian glaciation by Straw (1957, 1958, 1961, 1979). However, this Early Devensian age is refuted by Madgett and Catt (1978) based upon intensive studies on all the tills of Holderness and Lincolnshire. Lake Humber I has been dated to 21,835±1600 years BP by Gaunt (1974, 1976, 1981) using a bone fragment found at the base of lacustrine sediments near Brantingham. This date has been questioned by Straw (1979) as it refutes his Early Devensian age for Lake Humber 1 and associated tills and landforms, but it is generally regarded as a maximum age for lake initiation. A minimum age of 11,110±200 years BP for lake emptying has been obtained from a buried soil at the top of the lacustrine sediment (Gaunt et al., 1971). Gaunt (1981) suggests that the lower lake was dammed by the moraine in the Humber after ice had receded and it actually silted up rather than drained through this moraine. A minimum age of 11,205±120 years BP on the deposition of the Hogsthorpe moraine was reported by Suggate and West (1959) based upon basal peat in a kettle hole. 2.3.5. Northwest England and Irish sea basin In northwest England, the glacial deposits of the Blackpool area were reviewed by Wilson and Evans (1990), who emphasized a stratigraphy of upper and lower “boulder clays” separated by a thick sequence of stratified sediments that could record glacier recession followed by a readvance. This sequence has now been classified as the “Kirkham Formation” by Thomas (1999) and is correlated with the “Stockport Formation” of the Cheshire–Shropshire Lowlands (Maddy, 1999). Early deglacial dates in west Cumbria include one of 12,560±170 radiocarbon years BP from peat on the St Bees Moraine (Coope and Joachim, 1980) and another 45
of 14,623±360 radiocarbon years BP from Windermere (Coope and Pennington, 1977). A basal moss layer lying over glacial outwash at Glen Ballyre on the northwest coast of the Isle of Man yielded a radiocarbon age range of between 18,900 and 18,400 14 C years BP, providing an early deglacial date for the area (Shotton and Williams, 1971, 1973; Dackombe and Thomas, 1985). The late Quaternary deposits of the Isle of Man have been traditionally subdivided into two suites, an upland suite of locally derived periglacial materials and a lowland suite of foreign glacigenic sediments (Thomas, 1976, 1977; Dackombe and Thomas, 1991). The upland suite has been explained as a product of cold climate slope processes either during Devensian glaciation, implying that the Manx uplands were nunataks, or paraglacial reworking of glacigenic materials during ice sheet wastage. Dackombe and Thomas (1991) support the latter interpretation based upon the ice sheet model of Boulton et al. (1977). The lowland suite has been interpreted as the product of terrestrial glacial deposition by Thomas (1976, 1977) and Dackombe and Thomas (1985, 1991) and as glacimarine sediment by Eyles and Eyles (1984) and Eyles and McCabe (1991). Although Thomas (1976, 1977) and Pantin (1978) have acknowledged that the receding Irish Sea glacier margin on the Isle of Man may have been partially marine based, the 200 m water depths required by the Eyles and Eyles (1984) and Eyles and McCabe (1991) model cannot be reconciled with the sea level history of the Irish Sea Basin at the close of the Dimlington Stadial. The last glaciation of the island by Irish Sea ice is recorded predominantly in the Shellag Formation and Orrisdale Formation of the lowland suite of deposits in the north (Thomas, 1999). These overlie Ipswichian raised beach and locally derived slope deposits. The Shellag Formation records the initial advance and recession of glacier ice (Shellag Advance, Thomas, 1976) and is unconformably overlain by the Orrisdale Formation. The latter was deposited during the Orrisdale Readvance, during which the Bride Moraine was constructed. Subsequent short-lived oscillatory readvances are recorded by the northward offlapping Jurby Formation (Thomas, 1976, 1999). New dates and a revision of the lithostratigraphy suggest a more complex sequence of events with an extensive glacial phase followed by rapid oscillations of the ice margin during deglaciation and then a substantial ice advance (Thomas et al., 2004). 2.3.6. North Wales Considerable emphasis has been placed on the till sequences of the Lleyn Peninsula and their role in reconstructing the glacial advances in North Wales. Early work on glacial sediments revealed a tripartite sequence of two tills separated by stratified sediments (e.g. Jehu, 1909; Nicholas, 1915). This stratigraphy was used in conjunction with the drift morphology to propose multiple glaciations (e.g. Synge, 1963a, 1964), but more specifically it revealed that the Lleyn Peninsula was an area of coalescence between Irish Sea and Welsh ice. Sections on the north coast of the Lleyn record southerly flow of Irish Sea ice. Moreover, sites on the west of the peninsula contain evidence of Irish Sea till only, whereas sites between Gwydir Bay and Dinas 46
Page 1 and 2: White Rose Consortium ePrints Repos
Page 3 and 4: 1. Introduction It is apparent that
Page 5 and 6: Fig. 1(b) Map of Britain and outlin
Page 7 and 8: and Sutherland. Although this limit
Page 9 and 10: esearch papers only record the pres
Page 11 and 12: 1994). In the Yorkshire Dales, drum
Page 13 and 14: 1988; Klassen and Thompson, 1989; B
Page 15 and 16: Evidence for extensive glacier ice
Page 17 and 18: Fig. 3. Nadir view of a solar-shade
Page 19 and 20: moraine deposited by the Devensian
Page 21 and 22: of Evans and Rea (1999), strongly s
Page 23 and 24: The Linton-Stutton gravels occur ou
Page 25 and 26: Fig. 5 (b) Map of linear ridges bas
Page 27 and 28: A large number of moraines were ide
Page 29 and 30: northern edge of the Lake District.
Page 31 and 32: al., 1937; Williams et al., 2001).
Page 33 and 34: water on its surface. Once the Iris
Page 35 and 36: marked by hummocky moraine/kame and
Page 37 and 38: Usk glacier at Aberyscir as documen
Page 39 and 40: development of the second moraine.
Page 41 and 42: Bridge and Clunbury (Oaker Moraine)
Page 43 and 44: Lapworth. More recently the evoluti
Page 45: 22,480±300 years BP from glacimari
Page 49 and 50: the Gower is provided by glacitecto
Page 51 and 52: een traditionally regarded as the s
Page 53 and 54: south of 51820V prompted Wingfield
Page 55 and 56: Lateglacial when sub-Milankovitch s
Page 57 and 58: palaeo-surging has been reported fr
Page 59 and 60: Aveline, W.T., Hughes, T.McK., 1888
Page 61 and 62: Bowen, D.Q., 1984. Introduction. In
Page 63 and 64: Clapperton, C.M., 1968. Channels fo
Page 65 and 66: Derbyshire, E., 1962. Late glacial
Page 67 and 68: Firth, C.R., Haggart, B.A., 1989. L
Page 69 and 70: Goudie, A.S., Piggott, N.R., 1981.
Page 71 and 72: Huddart, D. 1970. Aspects of Glacia
Page 73 and 74: Kynaston, H., Hill, J.B., 1908. The
Page 75 and 76: Merritt, J.W., Connell, E.R., Bridg
Page 77 and 78: Peake, D.S., 1961. Glacial changes
Page 79 and 80: Scourse, J.D., Furze, M.F.A., 2001.
Page 81 and 82: Stone, J.O., Ballantyne, C.K., Fifi
Page 83 and 84: Thomas, G.S.P., Chiverrell, R.C., H
Page 85: Yates, E.M., 1955. Glacial meltwate

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