chapter  21
20 Pages

Geotechnical characteristics of weathering profiles in British overconsolidated clays (Carboniferous to Pleistocene)

WithD. J. Russell, N. Eyles

The British land mass was better defined in Oligocene and later times and became a source of muddy detritus for surrounding areas. The geological evolution of Great Britain has contrived to leave a considerable surface area underlain by overconsolidated clay soils. The most marked difference in origin within the overconsolidated clay group is perhaps that between the marine, dark-coloured mudrocks of Mesozoic and Cenozoic age, and the glacially-overconsolidated pebbly clays deposited by Quaternary glaciers. Liquidity index is a measure of the consistency of a clay soil, since it relates the in situ moisture content to the plasticity parameters. The increase in drained brittleness can be ascribed to a greater propensity for alignment of grains along a shear surface in the soils enriched by clay minerals. Significant changes in the physical properties of marine overconsolidated clays are caused by chemical weathering.