The central element is the 1:25,000 geological map; the rest are called peripheral elements. The peripheral elements are: the legend of the cartographic units, the conventional signs, the stratigraphic columns, the geological sections, the stratigraphic relationship diagram, the geological diagram and the complementary diagrams. The geological map shows the distribution of different types of rocks that emerge on the surface of the earth and their relative arrangement. It allows us to deduce much of the arrangement of rocks in the subsoil and to learn about the geological history of a region. It is a two-dimensional graphic representation that allows us to make extrapolations in three dimensions or, even, four if time is considered, depending on the level of reading that is made. It is formed by a set of cartographic units limited by contacts and by symbols that represent other geological elements: surface dip, folding structures, subsoil information (isopachs or isobaths of the Quaternary), slope of recent deposits, morphological indications, landslides and other recent processes, deposits, etc. It also includes symbols of various references (geological sections, drillings, names of major geological structures, etc.).