Geologists study the Earth, including Earth's surface and interior. Geologists study the origin, history, and structure of Earth and the processes that shape it over time. A geologist is a contributor to the science of geology. Geologists study the physical structure and processes of the Earth. Their undergraduate training typically includes significant coursework in chemistry, physics, mathematics and possibly biology, in addition to classes offered through the geology department; volcanology, hydrology, and rock and mineral formation are among the many areas of study. Most geologists also need skills in GIS and other mapping techniques. Geologists survey the rock and mineral structure of an area which can assist in finding water supplies, oil, gas, mineral resources and faults amongst other things. This information can be useful to mining companies, government agencies, construction companies and so on.