There are several different kinds of geologists. Mineralogists, for example, study rocks, minerals, and precious stones. They classify them according to their composition and structure. Paleontologists work with biologists to determine what the world was like in prehistoric times. They study fossils and layers of rock. Engineering geologists help to determine where to construct dams, lay pipelines, and build roads. Some geologists also study ecology to incorporate protection of the environment in their work. Other geologists may work with geophysicists to predict earthquakes and volcanic eruptions.
Most of the geologists in the United States work in private industry, with the majority employed in the petroleum and natural gas industry. These geologists help find new sources of oil and gas by collecting samples of rock and soil. They compare these samples with rock and soil found near known deposits of crude oil and natural gas. This helps them to select locations for new wells. Because offshore oil resources are one of the main energy supplies of the future, geologists' ability to examine samples taken from the ocean floors is becoming increasingly important. Samples of rock and soil may also be useful to geologists who search for sources of fresh water or deposits of valuable minerals and ores.
Another group of geologists in the United States are teachers or researchers in schools and colleges. In high schools they teach earth science and general science. In colleges most geologists teach introductory and advanced courses in geology. Some also instruct students in ecology and environmental studies. Geologists working for colleges usually divide their time between teaching and research.
