A regional engineering geological study of the London Clay in the London and Hampshire basins

The study was devised to investigate certain regional relationships between geological and engineering index properties of the London Clay. Geological data including lithology, bed thickness and structural contours and an important new sedimentological and palaeontological zonation system of the London Clay were related to the detailed mineralogy of the clay. The mineralogical and lithological characteristics (mainly grading) were found to have a fairly close relationship to engineering index properties of the clay and from this various geological and geotechnical properties were linked. Geological data were mainly gathered from published information and geotechnical data from several Firms and Organizations working in the London and Hampshire Basin areas. Mineralogical data were obtained by analysis of over 300 samples from 22 field sections of the London Clay. Examples on a regional scale of computer and manual plots of clay zones are given as well as maps showing palaeogeography, mineralogy and engineering property distributions. Examples of the geological and geotechnical depth profiles which were used to establish relations between lithology, zonation, mineralogy and geotechnical properties are also given. The results of some laboratory experiments to study the processes and effects of sediment deposition, erosion and weathering are discussed and related to the field work. Although the work can only be considered as a pilot study the results in the form of maps, sections and general conclusions indicate that future development of the techniques should be of geological and geotechnical interest and value in predicting the general engineering conditions in new sites within the area.