A geologist studies the earth, rock forms, and strata.
A geologist is a scientist who studies the structure of the earth (or other planets), together with its origin and development, especially by examination of its rock. A geologist studies fossils, soil and earth processes such as earthquakes, mountain formation, landslides, volcanic eruptions, tsunamis and floods. They prevent damage from natural disasters (such as earthquakes) by predicting when an earthquake might occur and how to prepare for it.