ABSTRACT
This chapter discusses the relationships between the shape of the ground surface the outcrops, and the structure in idealised models in which layers are constant in rock type and in thickness over the area of the map. A geological map is an Ordnance Survey map, showing locations and topography, on which is superimposed geological information. Large geological departments in commercial companies and government scientific bodies, such as the British Geological Survey (BGS), have a prescribed set of geological symbols for use in their reports and maps. Dating a geological event with reference to the geological timescale is like dating human history by dynasties. The description of strata in reports, for example BGS District Memoirs, is also arranged according to stratigraphic order, with the oldest group of rocks described first. Information about seismicity and seismic risk is obtainable by referring to the Global Seismology Unit of the BGS in Edinburgh.
