Report on Session 2b

Abstract

Introduction No part of geological time has had a more profound influence on the engineering characteristics of soils and rocks than the Quaternary period. Large areas of the earth’s surface are covered by superficial deposits of Quaternary age, and almost all surface soils and rocks affected by the changeds in climate which occurred in the Quaternary retain characteristics which have implications for engineering works at the present time. During the Quaternary period, at least five major glaciations occurred. During each glaciation, as the climate became colder, ice sheets spread from the poles and mountainous areas, to be followed by a retreat as warmer weather conditions prevailed during the inter-glacial periods. At the present time, in the Northern hemisphere, ice sheets cover approximately 10% of the total land area, but during the time of maximum glaciation in the Pleistocene, over 30% of the total land area was covered by ice. The volume of water taken up by the ice sheets caused significant variation in sea-levels. It has been estimated that the maximum and minimum sea-levels during the Quaternary were +200 m and -150 m 0D respectively. Indeed, following the main postglacial transgression at the end of the Devensian, the sea has been within 3 m of its present level for only the last 4000 or 5000 years. These large variation in sea-level significantly influenced the development and stability of slopes in coastal areas and inland.