Planetary geologists study the moon and other planets to understand the evolution of the solar system. Geochronologists determine the age of certain rocks by calculating the rates of decay of certain radioactive elements and thus help reconstruct the geologic history of the Earth. Geomorphologists study the effects of Earth processes and investigate the nature, origin and development of present landforms and their relationship to underlying structures. Glaciologists study the physical properties and movement of glaciers and ice sheets. Marine geologists investigate the oceans and continental shelves.
Mineralogists study the formation, composition and properties of minerals.
Paleontologists study fossils to understand past life forms and their changes through time and to reconstruct past environments. Petrologists determine the origin and genesis of rocks by analyzing mineral or grain relationships. Sedimentologists study sedimentary rocks and the processes of sediment formation, transportation and deposition. Stratigraphers investigate the time and space relationships of layered rocks and their fossil and mineral content. Structural geologists study deformation, fracturing and folding that has occurred in the Earth's crust.