Ailstone Old Gravel Pit

Also within

Warwickshire County

Condition (Natural England)

Geology & landscape

Geological Period: Quaternary

Description

Description The old gravel pit at Ailstone exposed sands and gravels deposited by the Stour a tributary of the Warwickshire Avon which contained an extremely important Pleistocene interglacial molluscan fauna. The importance of this fauna lies in its use in establishing a Pleistocene terrace stratigraphy in the Avon basin. The deposits at Ailstone underlie the 4th Terrace of the Stour, but have been considered to represent the same interglacial as shelly sediments underlying the lower 3rd Terrace elsewhere in the Avon basin. This view places both these terraces in the Ipswichian stage. This is despite a number of differences in the faunal assemblages between the lower, Terrace 3 sites and that at Ailstone. The latter site is the only one in the 4th Terrace from which unequivocal interglacial fossil molluscs have been obtained. Current research on the Avon terraces is seriously challenging the established chronology, in which the Terrace 4 deposits are stratigraphically younger than those of Terrace 3, the reverse of normal terrace stratigraphy. The recently developed technique of amino stratigraphy, which enables the relative dating of molluscan shells on the basis of the progressive decay of their contained amino acids, will hopefully provide sound evidence to confirm or refute the established terrace dating. If the Ailstone molluscs are found to be older than the Ipswichian stage they will almost certainly represent a new, as yet undefined, warm period. Evidence that such a period may have existed is accumulating from elsewhere in Britain, but Ailstone may be the first site in the Midlands where it can be identified. Whatever the outcome, Ailstone is of critical importance for understanding the Avon terrace sequence, since it is the only site yielding warm climate molluscs from the 4th Terrace.