Solid outer zone of the earth. It consists of oceanic crust and continental crust. Compare core, mantle.
divergent plate boundary
Area where earth’s lithospheric plates move apart in opposite directions. Compare convergent plate boundary, transform fault.
Shaking of the ground resulting from the fracturing and displacement of rock, which produces a fault, or from subsequent movement along the fault.
Process or group of processes by which loose or consolidated earth materials are dissolved, loosened, or worn away and removed from one place and deposited in another. See weathering.
Study of the earth’s dynamic history. Geologists study and analyze rocks and the features and processes of the earth’s interior and surface.
Rock formed when molten rock material (magma) wells up from the earth’s interior, cools, and solidifies into rock masses.
Compare metamorphic rock, sedimentary rock. See rock cycle.
Outer shell of the earth, composed of the crust and the rigid, outermost part of the mantle outside the asthenosphere; material found in earth’s plates. See crust, mantle.
Molten rock below the earth’s surface.
Zone of the earth’s interior between its core and its crust. Compare core, crust. See lithosphere.
Rock produced when a preexisting rock is subjected to high temperatures (which may cause it to melt partially), high pressures, chemically active fluids, or a combination of these agents. Compare igneous rock, sedimentary rock.
See rock cycle.
Any naturally occurring inorganic substance found in the earth’s crust as a crystalline solid. See mineral resource.
Theory of geophysical processes that explains the movements of lithospheric plates and the processes that occur at their boundaries. See lithosphere, tectonic plates.
Any material that makes up a large, natural, continuous part of the earth’s crust. See mineral.
Largest and slowest of the earth’s cycles, consisting of geologic, physical, and chemical processes that form and modify rocks and soil in the earth’s crust over millions of years.
Rock that forms from the accumulated products of erosion and in some cases from the compacted shells, skeletons, and other remains of dead organisms. Compare igneous rock, metamorphic rock. See rock cycle.
Area in which oceanic lithosphere is carried downward (subducted) under the island arc or continent at a convergent plate boundary. A trench ordinarily forms at the boundary between the two converging plates.
See convergent plate boundary.
Various-sized areas of the earth’s lithosphere that move slowly around with the mantle’s flowing asthenosphere. Most earthquakes and volcanoes occur around the boundaries of these plates. See lithosphere, plate tectonics.
Area where the earth’s lithospheric plates move in opposite but parallel directions along a fracture (fault) in the lithosphere. Compare convergent plate boundary, divergent plate boundary.
Series of large waves generated when part of the ocean floor suddenly rises or drops, usually because of an earthquake.
Vent or fissure in the earth’s surface through which magma, liquid lava, and gases are released into the environment.
Physical and chemical processes in which solid rock exposed at earth’s surface is changed to separate solid particles and dissolved material, which can then be moved to another place as sediment. See erosion.