Geologists and geophysicists examine chemical and physical properties of specimens in laboratories. They study fossil remains of animal and plant life or experiment with the flow of water and oil through rocks. They use a variety of sophisticated laboratory instruments, including x-ray diffractometers, which determine the crystal structure of minerals, and petrographic microscopes, for the study of rock and sediment samples. Geoscientists also use seismographs, instruments which measure energy waves resulting from movements in the earth's crust, to determine the locations and intensities of earthquakes. Geoscientists working in the oil and gas industry sometimes process and interpret the maps produced by remote sensing satellites to help identify potential new oil or gas deposits.
Seismic technology is also an important exploration tool.
Seismic waves are used to develop 3-dimensional computer models of underground or underwater rock formations. Geologists and geophysicists also apply geological knowledge to engineering problems in constructing large buildings, dams, tunnels, and highways. Geology and geophysics are closely related fields, but there are 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.