Cleal, C.J. & Thomas, B.A. 1996 British Upper Carboniferous Stratigraphy. Geological Conservation Review Series No. 11, JNCC, Peterborough, ISBN 0 412 72780 3. The original source material for these web pages has been made available by the JNCC under the Open Government Licence 3.0. Full details in the JNCC Open Data Policy
Webster's Claypit
Highlights
Webster's Claypit is the only available exposure of alluvial plain deposits of the Enville Formation, and is the best British site for Upper Palaeozoic Walchia-like conifers remains.
Introduction
This is an extensive exposure of part of the Enville Formation in the Warwickshire Coalfield, on the west side
Description
The exposed sequence is about 28 m thick, and shows strata formed in a distal alluvial plain setting
The only fossils reported from here are branches of conifers, preserved on the weathered surfaces of the sandstones (Vernon, 1912, pl. 59, fig. 10; see also Dix, 1935). Vernon identified them as Walchia imbricata Schimper, but as pointed out by Visscher et al. (1986) this is a poorly defined taxon. The Coventry material is in clear need of revision. For many years, no new specimens had been reported. Recently, however, H. Williams (pers. comm., 1989) found some further conifer remains at this site on large blocks of sandstone. Unfortunately, the blocks were too large to move and, on his return, they had been destroyed.
Interpretation
Although widely distributed in the English Midlands, this is the only known exposure of the Enville Formation in what Besly (1988) terms the ephemeral fluvial association. The sedimentology suggests that this association was formed in an alluvial-plain setting, in which most of the discharge was concentrated in large flood-events. It contrasts with the more conglomeratic facies of the alluvial fan association, such as seen at Gospel End Road Cutting, which is normally associated with the Enville Formation. The latter association is more localized and represents a more proximal position within the delta system, but is less vulnerable to erosion and thus tends to outcrop more often.
This is also the best known British site for Upper Palaeozoic Walchia-like conifers. At one time, such fossils were thought to be strong evidence of a Permian age for the beds (e.g. Dix, 1935). However, it is now accepted that they are merely an indication of drier substrates, and that conifers are now well documented from strata as low as the mid-Westphalian (see Lyons and Darrah, 1989, for a review). Their presence in the alluvial sediments of the Enville Formation thus supports the sedimentological evidence, that the Enville Formation represents significantly drier conditions than the Productive Coal and Halesowen formations.
Conclusions
Webster's Claypit is the only available exposure of sandstones of the Enville Formation, about 305 million years old. They are probably the remains of alluvial plain deposits laid down in relatively dry, possibly sub-desert conditions. This is also the best site in Britain for fossils of Late Palaeozoic Walchia-like conifers.