Hi Ash - these are the columnals that make up the crinoid stem. Where did you find them? I recognise the cogwheel pattern and am interested. If you would like to know more about how we describe crinoid columnals please see Fig. 2 on page 50 [ probably more information than you want!].
Scripta Geologica, 136 (January 2008) F.E. Fearnhead: Towards a systematic standard approach to describing fossil crinoids, illustrated by the redescription of a Scottish Silurian Pisocrinus de Koninck
Fiona. All my Fossils have been found on Hornsea south Beach, and the Crinoids were found on the Foreshore.
Thanks for the added information it might come in handy , oh and if you want any more shots, higher magnification that's no problem.
Hi Ash - I contacted Prof. S. K. Donovan a crinoid expert in Naturalis Museum, Leiden, The Netherlands who assumes them to be ?Carboniferous crinoids. Although the rocks in Hornsea were formed during the Pleistocene, the features on your columnals are more characteristic of Carboniferous crinoids. I have seen this type of morphology on Silurian crinoids, however, there are no Silurian rocks exposed here, so Carboniferous seems likely.
For more information:
"The cliffs are dominated by deposits of till and boulder clays deposited during the Devensian glaciation period (Pleistocene age). Within these deposits, you will find many erratics, and it is these that contain the Jurassic, Carboniferous and Cretaceous fossils " [http://www.hornsea.ukfossils.co.uk/geology-guide.asp]
I hope this is helpful,
All the best,
Hi Fiona. Thanks for all this detailed information on the Crinoids, it will be very useful. Yes the cliffs here on Hornsea south beach erode very fast and i never know what i'll find next, unlike the north beach cliffs which have'nt eroded since the eighties.