Hull Geological Society

Mike Horne FGS

Unfinished Works

This is unfinished work that has not been edited or peer reviewed by the Society.

A thin Chalk layer at Gransmoor Quarry

by Mike Horne

   During a visit to Gransmoor Quarry ( grid reference TA113597 )  in May 1993, led by Barry Constantine and Richard Myerscough, I

noticed a layer of chalk rubble towards the top of the peat bed.

   The peaty beds at Gransmoor formed in a kettle hole, due to the melting of a large block of trapped ice, on the top of an esker. This was one of the many meres that were formed about the glacial deposits of Holderness, which have all filled up, with the exception of Hornsea Mere. The deposits at Gransmoor provide a record which spans the last 15,000 years (Ellis 1993).

   Fossil fish bones of Perch and Pike have been found in the beds as well as a harpoon point. Fish scales and pieces of wood are common in the deposits. In total there are just over 2 metres of the mere deposits,which overly glacial sands and gravels. The beds of peat and clay form a continuous sequence from the Late Devensian Lateglacial interstadial through the Loch Lomond (Younger Dryas) Stadial. A full description of the deposits, with dating of the pollen and coleoptera, will be published in the …Quaternary Science Review„   by M Walker, G Coope and J Lowe.

   The layer of Chalk was about 3 cm thick and the chalk was very  soft. The layer was quite persistent forming a noticable feature  and is recorded by Walker et al. as their bed no. 6, about 120cm above the sands and gravels. The bed consisted of small clasts of white chalk averaging 3mm in diameter and mostly flattened. because it was so soft, much softer than Yorkshire Chalk, I collected a sample to see if I could date the Chalk.

   On examining the sample after washing and sieving it, I found a well preserved microfauna which included the following :

References :

Ellis S [ed.] 1993. …Wetland Heritage. Humber Wetalands Project, School of Geography and Earth Resources, University

  of Hull. 181pp.

Walker MJC, Coope CR & Lowe JJ, (in press) 1994. The Late  Devensian (Late Weichselian) palaeoenvironmental record from

  Gransmoor, East Yorkshire, England. …Quaeternay Science Review.

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