Records of sea levels during the Late Devensian

Synge, F. M.

doi:10.1098/rstb.1977.0107

Cited by 31 publications

(7 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A different interpretation, first suggested by Smith (1977) and Synge (1977), and developed by Flinn (1981) and Sutherland (1984), is that the uppermost shelly till is the product of an earlier glaciation than the inland till. This interpretation was given impetus by evidence suggesting that the last Scandinavian and Scottish ice sheets may not have been confluent in the northern North Sea basin (e.g.…”

Section: Southern Caithness and Eastern Sutherlandmentioning

confidence: 99%

The altitude of the last ice sheet in Caithness and east Sutherland, northern Scotland

Ballantyne

Hall

2008

SJG

View full text Add to dashboard Cite

SynopsisOn the mountains of southern Caithness and east Sutherland, geomorphological evidence for the upper limit of glacial erosion implies that, at the last glacial maximum (LGM), warm-based erosive ice extended up to altitudes of 410-600 m. Above the upper limit of glacial erosion is a cover of frost-weathered detritus, with tors on conglomerate bedrock. Kaolinite and gibbsite in soils on such terrain imply that it escaped significant glacial erosion at the LGM. This is confirmed by cosmogenic 10 Be exposure ages of (>) 146.6 15.1 ka and (>) 178.2 18.1 ka obtained for summit tors; sites below the upper limit of glacial erosion yielded deglacial ages of 16.6 2.1 to 18.5 2.4 ka. It is unlikely that glacially unmodified summits represent LGM nunataks, as the implied ice thickness is inconsistent with an ice sheet that extended across high ground on Orkney onto the Atlantic shelf; under conservative assumptions at least 70 m of ice must have covered the highest ground in southern Caithness at the LGM. We infer that the absence of evidence for glacial erosion on some summits and plateaux reflects cover by cold-based ice, frozen to the underlying substrate, that preserved the underlying tors and blockfields. This inference calls into question the use of similar evidence in NW Scotland to identify the maximum altitude of the last ice sheet.

show abstract

Section: Southern Caithness and Eastern Sutherlandmentioning

confidence: 99%

The altitude of the last ice sheet in Caithness and east Sutherland, northern Scotland

Ballantyne

Hall

2008

SJG

View full text Add to dashboard Cite

show abstract

“…However, reconstructed isobases for south-western Norway (Anderslilfi, 1960) and eastern Britain (Synge, 1977) appear to follow the respective coastlines and do not reflect the presence of a large ice mass in the North Sea. Thus, we have geological evidence for a widespread ice mass, but no evidence for a heavy load on the Earth's crust.…”

Section: Isostatic Evidencementioning

confidence: 99%

Stability of Temperate Ice Caps and Ice Sheets Resting on Beds of Deformable Sediment

Boulton¹,

Jones²

1979

J. Glaciol.

105

117

View full text Add to dashboard Cite

. Although theories of glacier movement ge n erally assume that glaciers flow over rigid rock beds, there are many places where glacie rs r est on beds of d eforma ble sedim e nt, a nd the great Pleistocene ice sheets which extend ed from time to time over much of Northern Europe a nd N orth America were largely underlain by such b eds. Observations sh ow that a large proportion of the forward movement ofa glacier lying on such a bed may be contributed by d eformation of the bed ra ther than the gl acier. A theory is d eveloped in which the glacier surface profile is rela ted to the hydraulic and strength prope rti es of potentially deformable bed materials. If these have a high hydraulic transmiss ibility, melt wa te r is readily discharged subglacially, the bed is stable, and the profile is a normal p a ra boli c one, governed by the rheologica l properties of ice. If bed transmissibility is low, wa ter pressures build up, the bed begins to d eform, and a lower equilibrium profile will develop, so tha t in a n extreme case the gl acier a pproxim a tes to a thin flat sheet, similar to an ice shelf. It is suggested tha t su ch behaviour may h ave occurred a t the m a rgins of large Pleistocene ice sheets over North America and Europ e, a nd evidence in support of this is dra wn from the reconstructed shapes of these ice margins, a nomalo usly sm all a mounts of isostatic rebound, a n o ma lously high retreat-rates, and the presence of glaciotectonic structures. R easons a re suggested to expl a in why this behaviour should have been important for Pleistocene glaciers which p en etra ted into currently te mperate latitudes but does not appear to be important in la rge m od ern glaciers. REsuME . Stabiliti de calottes de glace tempi ree reposant sur des lits de sidiments diformables. Bien que les theories sur le mouvem e nt d es glaciers supposent en general que les glaciers s'ecoule nt sur d es lits rocheux rigides, il arrive souvent que les glaciers reposent e n fait sur des sed iments deforma bles et la grande calotte glaciaire pleistocene qui s' es t pa rfois etendue sur la plus grande pa rti e de l'Europe du N o rd et de l'Amerique du Nord etait en gran de partie supportee p a r d e tels lits. Des o bservati ons montre nt qu'une fort e proportion des avancees de glacie rs r eposant sur un tellit peut et re le res ultat de la deform atio n du lit plus que d e glacier. On a developpe un e theorie selon laquell e le profil de la surface du gl acier es t mis en relation avec les proprietes hydrauliques et plastiques d es m a te ria ux d'un lit d e fo rma ble. S' ils o nt un e forte permeabilite, I'eau d e fonte est rapid ement tra nsmise so us le glacier, le lit est sta ble et le profil est normalement parabolique, conformement aux lois rheologiques d e la glace. Si la pe rm eabili te a I'eau est fa ible, la pression hydrosta tique croit, le lit commence a se deforme r et un profil d'equilibre plus bas en a ltitude se developpe d e sorte que, e n d es cas extre m es, le glacier ressembl e a un e feuille ...

show abstract

“…3). Subsequent workers identified the presence of more than one raised shoreline, distinguishing between the lower elevation 'post-glacial' raised beaches of sand, gravel and shell, and the higher elevation 'lateglacial' shorelines, commonly incised into till or outwash gravels and truncated by moraines (see Mitchell and Stephens, 1974;Synge, 1977aSynge, , 1977bCarter, 1982). Over time, various attempts were made to correlate between shoreline fragments to produce overall patterns of shoreline height.…”

Section: The Late-glacial and Post-glacial Shorelinesmentioning

confidence: 99%

“…At larger spatial scales the growing separation between a feature of interest and the material used to date it inevitably renders correlations more susceptible to error. For example, the age of the late-glacial shoreline near Carlingford is ultimately based on a radiocarbon date from a kettle hole on the Isle of Man (Synge, 1977b).…”

Section: The Late-glacial and Post-glacial Shorelinesmentioning

confidence: 99%

“…Complex shoreline correlation diagrams were developed, identifying a suite of late-glacial and post-glacial shorelines, each with different tilts and elevation ranges (e.g. Synge and Stephens, 1966;Synge, 1977aSynge, , 1977bDevoy, 1983). Whilst the details vary, the general pattern of decreasing shoreline height with distance west and south is a common feature of the reconstructions.…”

Section: The Late-glacial and Post-glacial Shorelinesmentioning

confidence: 99%

See 1 more Smart Citation