Generalised directions of ice flow on the eastern side of Great Britain, interpreted from erratic finds and till characteristics.
Erratic finds on the east coast indicate that at various times ice from the Lake District and western Scotland flowed across the main watershed, on three main routes: via the Tweed Valley, the Tyne Gap and the Stainmore Gap. It is inferred that there was a powerful southward-flowing ice stream from Scotland very close to the current coastline.
I'm intrigued by the modelling done by Chris Clark and his colleagues for the latest paper which floats the idea of long-distance glacial transport of the Stonehenge Altar Stone.
The paper suggests that southwards transport of ORS material from the far NE of Scotland might well have been possible -- but that the "footprint" of the ice stream involved would have been rather far offshore, out in the middle of the North Sea. Probably the modelling showed ice from the Grampians and southern Scotland streaming down the east coast of England not far away from the present coastline. Further, the model might be based in part on the presence of lineations on the sea floor. We don't have a lot of detail on how the model was created.........
Anyway, one point of interest arising from this publication is the occurrence of Scandinavian and Scottish erratics in many locations on the east coast of England. More than a century ago it was believed that Scandinavian erratice were abundant -- but there was a lot of mis-labelling and mis-identifications in the early days of erratic studies, and many of the boulders vand cobbles thought to have come from Oslofjord and the south coast of Norway are now believed to have come from Stotland and even northern England.
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See the following:
Glaciodynamics of the central sector of the last British–Irish Ice Sheet
in Northern England
Stephen J. Livingstone, David J.A. Evans, Colm Ó Cofaigh, Bethan J. Davies, Jon W. Merritt,
David Huddart, Wishart A. Mitchell, David H. Roberts, Lynda Yorke
Earth-Science Reviews 111 (2012) 25–55
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Finds from till etc on the "Ice Age Coast" (Hull Geological Society):
https://hullgeolsoc.co.uk/erratics4.htmIgneous Rocks "Cheviot Porphyry"* (Cheviot Porpyrite of old surveys) - medium grained porphyry (smaller phenocrysts than Norwegian Porphyry) in a red, brown or black matrix. Always looks glossy as if it has been polished. Origin - ?Cheviot Hills.
Dolerite
Gabbro
Grey Granite
Larvikite - coarse grained dark rock, shines blue in sunlight when wet. May have been described as Augite-Syenite in early boulder survey publications. Origin - Larvik in Norway.
Norwegian Porphyry - yellowish phenocrysts up to 1cm in a red-brown matrix. Phenocrysts may be zoned. Origin - Oslo Fjord in Norway
Peterhead Granite - looks a bit like Shap Granite but the orthoclase phenocrysts are more of a tinned-salmon pink and not as domino shaped.
Rapakivi Granite - origin Aaland
Rhyolite - reddish-brown fine grained igneous rock. May exhibit flow banding and contain small phenocrysts. Origin - ?Cheviot Hills.
Shap Granite - pale granite containing distinctive large crystals of pale pink orthoclase (like pink dominoes), sometimes with obvious simple twinning. It is difficult to identify in small specimens because you need to see the phenocrysts, so it may be under-reported. Origin - Shap in Cumbria. There is a large boulder near the base of Sewerby Steps that can be seen when it is not covered with sand. In older publications it may be called Shap Fells Granite.
Tilberthwaite Tuff - green fine grained rock, sometimes with current bedding, fining upwards bedding and volcanic bombs. This is a volcanic ash that fell into water and was later metamorphosed (so it is an igneous, sedimentary and metamorphic rock in one!) - Origin - Lake District.
"Whin Sill" * (Whinstone of older surveys) - medium grained almost black. Origin - northern England.
Sedimentary RocksBlack Flint - hard, black, sharp if broken, may have a white cortex. Origin - Upper Campanian and Maastrictian of the North Sea and Holderness. "Rowe Formation". May containg fossils.
Black Shelly Carboniferous Limestone - pale brown shells in a black matrix which may weather to brown. Origin - midland valley of Scotland. Matrix may be bleached or weathered to a chocolate brown colour.
Brockram - a breccia, pieces of grey limestone (usually around 25mm across) in a dull red matrix.
Brown flint - dark gey brown, hard, breaks with a conchoidal fracture, with a paler brown cotex. Probably weathered Black Flint. Not so common in Yorkshire.
Brown ripple bedded sandstone - fairly fine grained pale sandstone with ripples picked out in darker brown
Carboniferous Limestone - dark grey limestone (Mountain Limestone in older surveys)
• Coral - packed with colonial corals
• Crinoidal
• ice scratched - polished and striated; evidence of grinding with other rocks within the glacier
Striated Carboniferous Limestone cobble
Carstone - phosphatic nodules from the Aptian, occasionally steinkerns of Jurassic fossils. . Found south of the Humber.
Cementstones - large (over 30cm), grey flattened nodules, usually septarian. Origin - mostly from the North Sea or Vale of Pickering.
• Kimmeridge* - darker grey than the Speeton Clay ones
• Speeton Clay - from the B Beds
Chalk - hard, very fine grained, white. Origin - Yorkshire Wolds or North Sea (see also Soft Chalk)
Dogger* - hard orange or red fine grained ironstone from the middle Jurassic often containing fossils
Flow banded porphyritic rhyolite (Dimlington)
Frosterly Marble - dark grey to black Carboniferous Limestone with numerous large solitary corals. May be under-reported because you need ta large enough specimen to recognise it. Origin - Lower Carboniferous of Weardale.
Green Lake District conglomerate (a.k.a. "Ingleton Granite" or Greywacke Grit of old surveys) - a conglomerate with rounded clasts of quartz and other minerals up to 1 cm in size in a green matrix
Green sandstone - medium grained,
Grey Flint - from the Yorkshire Chalk. Pale or very pale grey, hard, foes not break with the conchoidal fracture you would normally "expect" for flint. Origin - Yorkshire Wolds or North Sea.
Jurassic plant bed (Esturine Sandstone of old surveys or Deltaic Sandstone) - pale grey, well bedded, mpstly quartz grains with some black plant remains.
Kimmeridge Clay - a dark grey shale often containing flattened white ammonites. Origin - Vale of Pickering or North Sea
Magnesian Limestone - quite hard, fine grained, creamy yellow colour.
Oxford Clay - grey or dark grey clay. Occasionally seen as "rafts" on the beach or in the cliff in the area around Aldborough. Origin - probably from the North Sea.
"New Red Sandstone" - medium to fine grained, with some mica, brick red colour. Origin - Permo-Trias of north west England.
"Old Red Sandstone" - medium to coarse grained, dull blood red colour. Origin - Devonian, perhaps Scotland.
Orange brown coarse sandstone - bright rusty brown colour, grains about 1-2mm, poorly cemented, may contain Tertiary foraminifera. Origin - probably from the North Sea.
Phosphate nodules - small pale brown nodules from the Speeton Clay, may contain fossils.
"Pink Chalk"* - hard, very fine grained, pink. It may not necessarily be from the "Red Chalk Formation", you would need to see distinctive fossils to be sure. Origin - North Sea and Yorkshire Wolds.
Red flint - hard, reddish brown, sharp if broken, may have a white cortex. Origin - perhaps the Danian of Denmark
Rhaxella Chert - found in Trent Valley and Norfolk, said to be from the Jurassic of the Howardian Hills (not recorded in Holderness)
Septarian nodules ( "turtle stones" ) - (see also Cement Stones)
Shelly Jurassic Limestone* - darkish grey limestone with fossils including Gryphaea, Lower Jurassic. Origin - North Yorkshire or the North Sea
Soft Chalk - white, putty-like. Can be seen in "rafts" in the cliffs. Origin - Upper Campanian and Maastrictian of the North Sea and Holderness. "Rowe Formation"
Speeton Clay - seen as "rafts" on top of the Chalk of the Flamborough area.
Red Flint - very hard, red-brown, sharp when broken, may have white cortex. Origin - perhaps the Danian of the North Sea and southern Scandinavia.
Tilberthwaite Tuff (see above under Igneous Rocks)
Metamorphic rocks -
Garnet mica schist - hard rock with sparkly muscovite and small red garnets. Occasionally you may find a version which is mostly biotite and garnets that crumbles when you try to collect it.
Gneiss
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See also:
and
Busfield, M.E., Lee, J.R., Riding, J.B., Zalasiewicz, J., Lee, S.V. 2015. Pleistocene till provenance in east Yorkshire: reconstructing ice flow of the British North Sea Lobe. Proceedings of the Geologist’s Association 126, 86-99
Map from Busfield et al, 2015
The main point arising from all of this is that there is substantial evidence of long-distance erratic transport broadly southwards along the east coasts of Scotland and England. Since abundant Scandinavian erratics have ended up in the coastal till and fluvioglacial deposits, there must have been at least one episode during which the ice of the Fennoscandian Ice Sheet dominated the ice of the BIIS and entered the territory portrayed in the map above.
It would therefore not be particularly surprising if some material from NE Scotland found its way into a southwards-flowing North Sea ice stream.
But why does Doggerland and Dogger Island need to come into the frame at all? That is an unnecessary complication in the narrative, introduced entirely for the purpose of demonstrating some human involvement in the movement of the Altar Stone..........
