The Fourth Glossop Lecture

In this lecture, the process of reading the ground is explored, some of the necessary background is defined and ways of improving our present and future competence in this area are outlined. It acknowledges the world-wide scope of this activity, but employs mainly the narrower canvas of mass movements in NW European conditions to illustrate its nature. Some basic tools which can assist in this process are first noted, good databases, the techniques of initial site appraisal, comprising desk study, site reconnaissance and mapping (with the aid of stereoscopic air photo interpretation and other remote sensing techniques), terrain modelling and the use of associated well-logged and sampled trial trenches. The importance of the classification of mass movements, not least to develop an agreed terminology, is touched upon and the great value, even at this early stage, of the influence line approach in assessing rapidly the effects of proposed cuts and fills is noted. An attempt is then made to identify the relevant vocabulary for reading the ground, that is those physical phenomena which bear on site appraisal. These are divided into bedrock elements, of which lithology and tectonics are highlighted, and Quaternary elements, particularly those that occurred in areas of cold climate, i.e. past freezing and thawing, sea-level changes, hydrogeological features and glacial, periglacial, fluvial and marine erosional and depositional features. Abandoned cliffs and inland scarps in chalk and some clays are then identified as characteristic landforms, and their nature and development are also explored. Case records of successful and unsuccessful earthworks on clayey scarps are also reviewed, in relation to the quality of initial site appraisal undertaken. In conclusion, significant weaknesses in our current education and training in this area are identified, specifically a near-absence of geomorphology and insufficient Quaternary geology, and proposals made to remedy these.