Glossary of Geological Terms
Fault: a fracture in the Earth’s crust along which blocks of earth or rock have shifted relative to each other
Formation: a body of rock with specific lithic characteristics and stratigraphic position
Graben: a block of rock that has shifted down and is flanked by higher blocks
Horst: an uplifted block of rock flanked by blocks that have shifted down (see graben, above)
Plate: a segment of the Earth’s crust that generally moves horizontally and that meets other plates along zones of seismic activity
Rift: a long, narrow continental trough bounded by faults and marking a zone along which the entire thickness of the Earth’s crust has ruptured
Spur: a narrow ridge projecting from the crest or side of a hill or mountain
Talus: rock debris that has fallen from a cliff
Throw: the amount of vertical displacement along a fault