The Pleistocene deposits of the area between Coventry, Rugby and Leamington and their bearing upon the topographic development of the Midlands

Abstract

The sequence of drift deposits in an area between Leamington and Warwick has been established by mapping following an extensive programme of auger drilling. There is a broad differentiation into Older Drift now capping the higher land and Newer Drift forming terraces along the upper Avon and Learn. The Older Drift includes relics of an ancient glaciation correlated with the First Welsh (Berrocian) or Mindel phase, and thick deposits belonging to the Great Eastern and Second Welsh (Catuvelaunian) or Riss episode. Details of the lithology, disposition and fauna of both the Older and Newer Drifts are given. Suggested correlations with neighbouring areas are made. The deposits of the Catuvelaunian episode are shown to be largely of clay or sand laid down in a lake whose extent is traced over a wide area of the Midlands. To it the name ‘Lake Harrison’ has been given. It is shown that it formed in a great pre-glacial valley of very gentle slope which ran from the region of Bredon Hill down towards Leicester, forming part of the Trent system, and which was impounded at each end by Welsh and north-eastern ice respectively. The lake was eventually overridden by the north-eastern ice which went as far south as Moreton-in-the-Marsh. Not until this ice retreated was the Avon river system developed. Associated with this great and very recent change of drainage pattern are others of less importance affecting the Tame and Soar basins.