The geophysical investigation of Quaternary geological environments

Abstract

Abstract There is a considerable Variation in the lithology and thickness of glacial and fluvial Sediments in Western Europe. This wide range of materials is associated with significant engineering problems and considerable economic interest from the extractive industries. Geophysical techniques are widely applied to map and investigate areas with glacial deposits and fluvio-glacial sands and gravels. There are sheet-like outwash deposits, some with buried and therefore unpredictable Channels, and smaller fissure and pocket deposits in rock. An assessment of the geometry of a deposit can be accurately achieved with geophysical methods, and electrical techniques have been particularly successful. The nature of the deposit, layering within the deposit, lateral Variation of lithology, thickness and depth to bedrock may all be established quickly and with great cost effectiveness. Numerous other problems occur with Quaternary environments particularly alteration and contamination of rock masses. Electrical techniques are also a powerful investigative tool in these situations. The success of these techniques depends upon the geophysical properties of the material to be investigated and the geophysical properties of the underlying sediment or bedrock, the technique actually selected, professional field practice and interpretation. These factors will be discussed and illustrated with reference to a number of case studies.