The sedimentation and geotechnical properties of the Cromer Till between Happisburgh and Cromer, Norfolk

Kazi, A.; Knill, J.L.

doi:10.1144/gsl.qjeg.1969.002.01.05

Cited by 39 publications

(14 citation statements)

References 11 publications

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“…Banham (1988), Hart (1990) and Hart & Boulton (1991) have concluded that the glacial sediments were deposited on land, although they recognized that the associated thick fine sediment units are of glacio-lacustrine origin (Hart 1992). In contrast, several authors have concluded that some of the tills are waterlain and the meltwater sediments represent delta and lake-bottom deposits (Kazi & Knill 1969;Banham 1970Banham , 1988 1980; Lunkka 1988Lunkka , 1991Lunkka , 1994Hart 1992;Eyles et al 1989). Indeed Eyles et al (1989) considered the sequence to be of glacio-marine origin.…”

Section: Southern North Seamentioning

confidence: 99%

The formation of the Strait of Dover

Gibbard

1995

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The Strait of Dover (Pas-de-Calais) is a narrow sea passage that links the North Sea and the English Channel between Britain and France. Much evidence suggests that the Dover Strait did not exist throughout most of the Pleistocene. Instead, a Chalk barrier was present, formed by the Weald-Artois anticline. Advance of the continental ice-sheet across the North Sea in the Middle Pleistocene Elsterian/Anglian Stage apparently dammed the southern part of the basin and water discharging into it was prevented from reaching the Atlantic to the north. The resulting lake apparently drained by spilling over the barrier and initiated the gap. This scenario is supported by sediments at Wissant, France. This theory contrasts with one, proposed by French geologists, that favours a structural origin.Overflow from the lake has been interpreted as having been catastrophic. This was invoked to explain the origin of the complex anastomosing system of valleys or channels that occurs on the floor of the Channel cut into bedrock, predominantly of Mesozoic age. These valleys are interlinked to form a drowned drainage system and can also be linked to present rivers that enter the Channel on both the British and French sides. However, it is highly probable that the drowned valley system is multigenetic, resulting from repeated fluvial and marine erosion and deposition rather than representing a single, short-lived event. The valley system probably originated in the late Early to early Middle Pleistocene as a consequence of uplift of the Weald-Artois region.Once the Dover Strait was formed, the rivers Thames and Scheldt were deflected through the gap and into the Channel River system during periods of low relative sea-level. Subsequently these rivers were probably joined by the Maas and Rhine, diverted by glaciation in the Drenthe Sub-stage (Saalian/Wolstonian Stage). The narrows seem to have been progressively enlarged by marine tidal scour and coastal erosion during high sea-level events.The island of Great Britain is separated from France by the Strait of Dover (Pas-de-Calais) ( Fig. 1). This sea passage is 34km wide at its

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Section: Southern North Seamentioning

confidence: 99%

The formation of the Strait of Dover

Gibbard

1995

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“…Where the recession of temperate glaciers reveals a surface of subglacially-deposited till or other unlithified sediment, it is not, as has been commonly supposed (Kazi and Knill, 1969), hard and overconsolidated, but extremely soft and with a high water content (Baranowski, 1975 ;Boulton and Paul, 1976) . This is not merely a feature of the glacier margin but has been found to occur subglacially some distance from the glacier front.…”

Section: Sediment Deformation Beneath Glaciersmentioning

confidence: 99%

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

Boulton¹,

Jones²

1979

J. Glaciol.

105

117

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. 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 ...

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“…A subglacial consolidation model It has been generally assumed (Rominger & Rutledge 1952, Harrison 1968, Legget 1962, Kazi & Knill 1969) that the consolidation pressures to which subglacial materials are subjected is merely given by the pressure due to the overlying ice column. Harrison (1958) has claimed to have deduced the maximum thicknesses of glacier ice which had overridden a series of lake sediments from determinations of their preconsolidation pressures.…”

Section: Consolidation Of Subglacial Tillmentioning

confidence: 99%

The influence of genetic processes on some geotechnical properties of glacial tills

Boulton

Paul²

1976

QJEGH

174

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The principle characteristics of debris in transport by glaciers are described and the way in which this material is subsequently deposited as till. Three principal types of till are described, lodgement till, melt-out till and flow till, which can be related to typical sediment/landform models and which can form a good basis for site investigation planning. A proglacial/subglacial sediment association and land system is defined, in which lodgement till and proglacial outwash are the principal sediments, and in which drumlins, fluted moraines and push moraines, and kettle holes and eskers are the principal landforms. A supraglacial sediment association and land system is also defined, in which a suite of supraglacial sediments and landforms are superimposed on the subglacial/proglacial land system. The sediments comprise flow till, melt-out till and supraglacial outwash sediments, and the landforms largely comprise kame moraines. A third land system, the glaciated valley land system comprises chiefly medial and lateral moraines, in which the till is derived supraglacially from flanking valley sides, and kame terraces.Till genesis influences the geotechnical properties of tills through its control on several important characteristics: grain-size distribution and its spatial variation; the stress history of the till; the nature of the sequence in which the till lies, e.g. the presence of stratified horizons; and jointing in the till. Post-depositionaI processes which change these characteristics are also important. The processes considered are: post-depositional wetting and drying; freezing and thawing; remoulding; and downward percolation of fines.

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The sedimentation and geotechnical properties of the Cromer Till between Happisburgh and Cromer, Norfolk

Cited by 39 publications

References 11 publications

The formation of the Strait of Dover

The formation of the Strait of Dover

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

The influence of genetic processes on some geotechnical properties of glacial tills

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