The majority of research in geology is associated with the study of rock, as rock provides the primary record of the majority of the geologic history of the Earth.
Geologists also study unlithified material, which typically comes from more recent deposits.
Geology can also refer generally to the study of the solid features of any celestial body (such as the geology of the Moon or Mars).
Geology gives insight into the history of the Earth by providing the primary evidence for plate tectonics, the evolutionary history of life, and past climates.
Geology is important for mineral and hydrocarbon exploration and exploitation, evaluating water resources, understanding of natural hazards, the remediation of environmental problems, and for providing insights into past climate change.
This rock can be weathered and eroded, and then redeposited and lithified into a sedimentary rock, or be turned into a metamorphic rock due to heat and pressure that change the mineral content of the rock which gives it a characteristic fabric.
The sedimentary rock can then be subsequently turned into a metamorphic rock due to heat and pressure and is then weathered, eroded, deposited, and lithified, ultimately becoming a sedimentary rock.
Sedimentary rock may also be re-eroded and redeposited, and metamorphic rock may also undergo additional metamorphism.
All three types of rocks may be re-melted; when this happens, a new magma is formed, from which an igneous rock may once again crystallize.
Geology also plays a role in geotechnical engineering and is a major academic discipline.
There are three major types of rock: igneous, sedimentary, and metamorphic.