The usual countryside map is a helpful starter, showing roads, towns, railways, parks, simple topography and similar features. This is useful for planning the trip and accessing the site. A geological map is also needed. This is available for purchase from specialist map suppliers, or perhaps for loan or hire from a local dub or society. Geological maps show the general types and ages of rocks present or outcropping at the surface, as areas of lines and colours. Experts also employ
satellite images and remote sensing to locate and survey new sites.