Geological data presented cartographically fall into three general types: direct observational data, indirect data obtained by transformation of observational data by operational procedures, and interpretative data obtained by inference from direct
and indirect data. Geological maps are divided on subject-matter basis into the following types: geologic maps, stratigraphic maps, tectonic maps, palinspatic maps and paleogeographic maps, hydrogeological maps, engineering geology maps, geochemical maps