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.
Marine geologists investigate the oceans, continental margins, and coastal environments.
Environmental geologists rely on skills and data to solve problems with pollution and urban development and to guard against hazards such as flooding and erosion. Engineering geologists use their geologic knowledge along with engineering principles to advise those involved in construction projects such as dams, tunnels and highways, thereby avoiding possible disasters from landslides, poor foundation conditions, expansive soils and other geologic conditions. Those are just a few of the geological fields being used to strengthen the world economy and improve the quality of human life. Geologists may be found sampling the deep ocean floor or collecting rock specimens on the moon. They usually divide their time between working in the field, the laboratory and the office.