Reading the ground: Morphology and geology in site appraisal

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 futu re competence in this area are outlined. It acknowledges the world-wide sco pe of this activity, but employs mainly the narrower canvas of mass movemen ts in NW European conditions to illustrate its nature. Some basic tools whi ch can assist in this process are first noted, good databases, the techniqu es of initial site appraisal, comprising desk study, site reconnaissance an d mapping (with the aid of stereoscopic air photo interpretation and other remote sensing techniques), terrain modelling and the use of associated wel l-logged and sampled trial trenches. The importance of the classification o f mass movements, not least to develop an agreed terminology, is touched up on and the great value, even at this early stage, of the influence line app roach in assessing rapidly the effects of proposed cuts and fills is noted. An attempt is then made to identify the relevant vocabulary for reading th e ground, that is those physical phenomena which bear on site appraisal. Th ese 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, h ydrogeological features and glacial, periglacial, fluvial and marine erosio nal and depositional features, Abandoned cliffs and inland scarps in chalk and some clays are then identified as characteristic landforms, and their n ature and development are also explored. Case records of successful and uns uccessful earthworks on clayey scarps are also reviewed, in relation to the quality of initial site appraisal undertaken. in conclusion, significant w eaknesses 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.