Even more specialized is the geochemist. Geomorphologists study the causes and effects of Earth processes and investigate the nature and origin of landforms. Volcanologists study geologic phenomena associated with volcanic activity. The structural geologist is concerned with the arrangement of rock masses in the Earth's crust and the types of forces that may have affected them. There are also specialized branches of geology for those who study Earth history.
Paleontologists use fossils to describe the nature and development of life through geologic time.
They use their knowledge to describe the environments in which these ancient life forms lived. Stratigraphers investigate the thickness, shape and the distribution of layered rocks in addition to their mineral and fossil content. Geochronologists calculate the rate of decay of certain radioactive elements to determine the age of certain rocks. Recent advances in science have produced new areas of specialization for geologists. The astrogeologist or planetary geologist uses knowledge of the Earth's geology to study surface conditions on the moon and other planets.