A large variety of sophisticated laboratory instruments are used, including x-ray diffractometers, which determine the crystal structure of minerals, and petrographic microscopes for the study of rock and sediment samples. The locations and intensities of earthquakes are determined using seismographs, instruments which measure energy waves resulting from movements in the earth's crust. Geologists also apply geological knowledge to engineering problems in constructing large buildings, dams, tunnels, and highways. Some administer and manage research and exploration programs, and others become general managers in petroleum and mining companies. Geology and geophysics are closely related fields, but there are some major differences.
Geologists study the composition, structure, and history of the earth's crust.
They try to find out how rocks were formed and what has happened to them since their formation. Geophysicists use the principles of physics and mathematics to study not only the earth's surface, but its internal composition, ground and surface waters, atmosphere, and oceans as well as its magnetic, electrical, and gravitational forces. Both, however, commonly apply their skills to the search for material resources and to solve environmental problems. The analysis and classification of rocks to learn their origin and history. The study of the deformation of rocks and the forces that cause deformation.