Humberside Geologist No. 14

Humberside Geologist Online

Abstracts for the "The Pleistocene World" meeting 13th October 2001

(with photographs by Gordon Binns)

 

A joint meeting of the Hull Geological Society and the Yorkshire Geological Society at Hull University, Department of Geography, starting at 1-30 am.

Introduction by Prof John Neale

This meeting is dedicated to the memory of Dr L F Penny (1920-2000) whose obituary was recently published in the Society's Proceedings. It is fitting that this meeting should be in Hull since Dr Penny spent all his working life in Hull and also that the papers should be on the theme of his principle research interest - the Quaternary. Professor Neale will introduce the meeting and say something of Dr Penny's life and work.

"The Pleistocene glaciations of Yorkshire" by Prof John Catt of Geography Department, University College London.

Lewis Penny's main contribution to Yorkshire geology was to clarify the county's complex glacial history by studies of till lithology and the fossil remains in associated deposits. Because of its mid-latitude position in Britain and the presence of both upland and lowland areas, Yorkshire has evidence for a more complete Pleistocene glacial history than any other part of Britain. However, the older (pre-Ispwichian) deposits are still very difficult to date precisely. The most extensive is the Basement Till of Holderness and other eastern coastal areas. This is overlain by the raised beach of the Ipswichian Stage (Marine Oxygen Isotope Stage (MOIS) 5e, 128,000 - 117,000 BP) at Sewerby, by the pre-Ipswichian Calcethorpe Till at Welton-le-Wold, Lincolnshire, and by boulders weathered in interglacial conditions at Warren House Gill, Co. Durham. Derived mammal remains and human artefacts in gravels beneath the till at Welton-le-Wold could be as old as MOIS 15 (565,000-620,000 BP), so the Basement was deposit ed during one of the cold stages from MOIS 14 to MOIS 6. Late Devensian (MOIS 2) amino acid dates for marine shells from the Basement Till at Dimlington are explained by intrusion during subglacial disturbance of the till's upper layers by the Late Devensian glacier. Other pre-Ipswichian glacial deposits occur as eroded and often strongly weathered remnants on interfluves from the Wolds and Yorkshire Moors westwards to the high Pennines. In the Leeds-Tadcaster-Harrogate area spreads of little-dissected and only moderately weathered till occurring on both high and low ground outside the accepted Late Devensian ice limit have been attributed to an early phase of the "Newer Drift" (i.e. MOIS 4?). As such they provide almost the only evidence for an Early Devensian glaciation in England, but until their relationship to Ipswichian deposits is clarified this status remains uncertain.

In coastal areas of Yorkshire the Skipsea and Withernsea Tills are both attributed to a short time interval in the Late Devensian, the Dimlington Stadial (MOIS 2). There is considerable evidence that they were deposited by a single surge of a two-tiered ice sheet. The lower (Skipsea Till) tier originated in SE Scotland and NE England, and the upper (Withernsea Till) layer in Lake District ice that crossed the Pennines via the Stainmore Gap and overrode the Skipsea Till glacier in the Lower Tees Valley area. Stainmore ice was also diverted southwards into the Vale of York, where it was joined by various ice streams from the Yorkshire Dales area. At the end of the Dimlington Stadial Yorkshire was ice-free by about 13,000 BP, but the climatic deterioration of the Loch Lomond Stadial (11,000 - 10,000 BP) led to formation of five small cirque glaciers in higher parts of the western Pennines.

"Late Quaternary relative sea-level, crustal rebound and the dynamics of the Greenland ice sheet" by Dr Antony Long of Dept of Geography, University of Durham

Late Quaternary relative sea-level, crustal rebound and the dynamics of the Greenland ice sheet Antony Long Spatial and temporal changes in the Greenland ice sheet are recorded by a range of glacial erosional and depositional features, but many of thee are difficult to date or relate directly to ice sheet mass change. However, the loading and unloading of the earth's crust associated with changes in ice mass is well constrained by the pattern of glacio-isostatic rebound which has occurred since deglaciation. This rebound may be mapped using relative sea-level (RSL) data, and previous analyses favour a two stage deglaciation with initial melting of the marine based portion of the ice sheet sometime before c. 11.5k years before present, followed by a slower retreat of the land-based ice sheet thereafter. This presentation details the results of efforts aimed at improving our understanding of the spatial and temporal dynamics of the Greenland ice sheet, based on the analysis of high resolution RSL histories from a range of sites in Disko Bugt, a large marine embayment on the west coast of the ice sheet. These new data point towards a much later and much faster deglaciation of the region, most probably associated with the rapid collapse of the Jakobshavn ice stream.

"Pleistocene mammals: a key to correlation" by Dr. Danielle Schreve of Dept of Geography, Royal Holloway, University of London.

Remains of fossil mammals are extremely common finds in a wide range of Pleistocene deposits and evidence from these former mammalian communities has proved to be a uniquely valuable tool in answering many of the questions concerning the nature and succession of the different climatic episodes now recognized for this period. The value of mammals as biostratigraphical indicators is based upon observed patterns of species turnover through origination and extinction events, the significant evolutionary trends displayed by many taxa, and the fluctuations in geographical distribution caused by intense and repeated environmental and climatic change. Using these lines of evidence, it has been possible to construct a mammalian biostratigraphical framework and to use this to identify and differentiate between the various temperate episodes of the Middle and Late Pleistocene in Britain and the rest of NW Europe. The mammalian story is also closely interlinked with that of our earliest ancestors and the established framework may further be applied to sites where there is evidence of early human occupation. This has helped to shed light on patterns of human colonisation, abandonment and settlement of Britain during the Pleistocene, highlighting different migration routes and the development of endemic technological traits during times of island isolation.

"Interpreting Pleistocene palaeoclimates using relict permafrost structures" by Prof. Peter Worsley of University of Oxford

During the Pleistocene the climate alternated between cold (glacial) and temperate (interglacial) modes. This forms the basis of the British stratigraphic classification based on climatic stages in the rock record. Although the glacial stages may have on occasion featured glaciation per se it is likely that most of the British landscape during the cold stages was periglacial in character. Indeed southern Britain appears never to have been glaciated.

Periglacial environments are normally associated with the presence of permafrost, i.e. mean annual air temperatures are below freezing. Unfortunately sedimentary evidence for the former presence of permafrost is often ambiguous. Despite this, the best evidence for past permafrost is in the form of ice and sediment wedge casts. Annual changes in the ground thermal regime of permafrost often causes cracking of the near surface sediments during the winter season and these cracks subsequently become infilled by materials such as snow, hoar frost, meltwater and sand. Overtime these crack infills grow into wedge shaped structures although the precise form is dependent upon the stability or otherwise of the ground surface. With the onset of climatic amelioration and the dissipation of the permafrost there is the potential for any ground ice to melt and be replaced by sediment.

The replacement process is variable and the sedimentary structures so created need careful examination if they are to be related to permafrost. Examples from contemporary arctic and former permafrost environments will be compared and contrasted.

Display - "Derived fossils from the Boulder Clays of Holderness" by Stuart Jones. Erratic fossils from Mappleton, Cowden and Aldbrough including: Hildoceras, Dactylioceras, Acroteuthis, Harpoceras, Rotularia, Pleuromya, Cardinia, Lima, Exogyra and Pholadomya.

Display - Specimens from the Lewis Penny Collection at Hull University. These included :- erratics from the Basement Till - red flint, Gryphaea, Carboniferous Limestone with corals, Jurassic ammonites, Brockram and Rhomb Porphyry; cemented chalk shingle overlying the Basement Till at Sewerby; shells from Easington - Macoma balthica, Scrobicularia plana and Cerastoderma edule; shells from Kelsey Hill - Turritella commune, Natica nana, Scala commune, Trophon clathratis, Amauropsis islandica, Nassa reticulata, Dentalium and Ostrea edulis; laminated silts from Barmston; till fabrics from Holderness; shells from the Bridlington Crag at Dimlington - Arctica islandica, Astarte, Nucula, Chlamys islandica, Turritella tricarinata, Turritella erosa, Panomya, Dentalium and Macoma; samples of the Bridlington Crag from the beach at Bridlington opposite Royal Crescent collected in 1964; samples of the Dimlington Moss Bed; and samples of the mere deposits at Skipsea Withow.

Display - "Pleistocene bones and shells from the Kelsey Hill Gravels" by Stephen Whitaker. Specimens colected from Keyingham including deer, horse, bison, mammoth; vertebrae of a teleost fish; and a large variety of shells including - Macoma balthica, Scrobicularia plana, Cerastoderma edule, periwinkle, Dentalium and a large oyster.

Display - "Some glacial erratics from the Holderness Coast" by Mike Horne on behalf of the East Riding Boulder Committee. Erratic rocks from Speeton, Aldbrough, Barmston, and Mappleton; including Brockram, Cannon Ball Limestone, Tilberthwaite Tuff, and ?Rasenia.

Display by Gordon Binns and Chris Blackhurst - Lonsdalaea and Gryphaea from Withernsea and Galerites and a large Nautilus from Hornsea.

Display - "A variety of erratics" by Ron Harrison. Erratic rocks and fossils from Holderness including: Lithostrotion, Polyptychites, Echinocorys, Stigmaria, Gryphea, Harpoceras, Asteroceras, Dactylioceras, Arnioceras, Nautilus, Pleuroceras, Brockram, Bunter Sandstone, Cannon Ball Limestone, jasper, flints, granites, serpentine, gneisses, quartzite, porphyries and Larvikite.

Display by Felix Whitham of shells from Kelsey Hill, Keyingham, Bridlington and Suffolk. The specimens from Kelsey Hill and Bridlington included - Cardium edule, Buccinum undatum, Trophonopsis clathratus, Nucella lapileus, Macoma blathica, Ostrea edulis, Scrobicularia fluminalis, Spisula arcuata, and Dentalium entalis. The specimens from the Bridlington Crag included - Littorina littorea, Trophonopsis clathratus, Astarte semisulcata, Astarte omalii, Turritella communis and Dentalium.

Display - "Microfossils from the Quaternary of Holderness" by Mike Horne. Specimens from the Bridlington Crag at Bridlington, lake deposits at Skipsea Withow Mere, varve-like clays at Barmston and Scrobicularia Clay (estuarine sediments) at Kilnsea.

Display - A large Crioceras from the Speeton Clay found at Speeton Beck by Steve Reed.

Poster Display - "Holocene environmental change at Jagger Howe Beck, North York Moors" by Clare Goldsmith of Hull University.

Poster Display by Wetlands Archaeology and Environment Research Centre of Hull University about Routh Quarry and Stone Carr.

Poster Display - East Yorkshire RIGS Group - list of sites.

Publications sales stands by the Quaternary Reserach Association and Humberside Geologist.

The meeting was hosted by Department of Geography University of Hull, and chaired by the President of the Yorkshire Geological Society and Chris Leach, the Vice-President of the Hull Geological Society. Catering was provided by Mrs Janet Binns and members of the Hull Geological Society. The meeting organisers were Martyn Pedley, Mike Horne and John Catt. These abstracts were compiled by Mike Horne with the help of John Catt.

Links to articles about Lewis Penny from Humberside Geologist :

LEWIS FREDERICK PENNY 1920-2000 By J W Neale

Student memories of Lewis Penny as Head of the Geology Department. By J.A.Catt

Lewis Penny Remembered.

 

(c) Hull Geological Society 1999 + 2007