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Chapter 21 - Structural Geology and Plate Tectonics

Terms in this set (28)

geology
The study of the planet Earth: its composition, structure, and history. Also, the study of the chemical and physical properties of other solar system bodies.
seismic wave
The waves generated by the energy release of an earthquake.
outer core
Part of the innermost region of the Earth , which is composed of iron and nickel in two parts; a solid inner core and molten, highly viscous outer core.
inner core
The innermost region of the Earth, which is solid and probably composed of about 85% iron and 15% nickel.
mantle
The interior region of the Earth between the core and the crust.
crust
The thin, rocky, outer layer of the Earth.
lithosphere
The outermost solid portion of the Earth, which includes the crust and part of the upper mantle.
asthenosphere
The part of the mantle that lies beneath the lithosphere and is essentially solid rock, but is so close to its melting temperature that it contains pocket of thick, molten rock and is relatively plastic.
continental drift
The theory that continents move on continental plates, drifting apart or together.
seafloor spreading
The theory that the seafloor slowly spreads and moves sideways away from mid-ocean ridges. Because the seafloor slopes downward and away from the ridges, the plates are pulled apart by gravity causing the plate to descend into the trenches.
remanent magnetism
The magnetization of rocks that form in the presence of an external magnetic field.
plate tectonics
The theory that the Earth's lithosphere is made up of a series of solid section or segments called plates that are constantly interacting with one another in very slow motion.
divergent boundary
A region where one plate of the lithosphere is moving away from one another and new oceanic rock is formed.
convergent boundary
A region where moving plates of the lithosphere are driven together, causing one of the plates to be consumed into the mantle as it descends beneath and overriding plate.
transform boundary
A region of the lithosphere where a moving plate slides along one side of another without creating or destroying rock.
isostacy
The depth to which a floating object sinks into underlying material depends on the object's density and thickness; the state of buoyancy between the Earth's lithosphere and asthenosphere.
subduction
The process in which one plate is deflected downward beneath another plate into the asthenosphere.
volcano
A vent from which hot molten rock (lava), ash and gases escape from deep below the Earth's surface, or the mountain or elevation created by solidified lava and volcanic debris that accumulates near the vent.
earthquake
The tremendous release of energy accompanying the rupture or re-positioning of underground rock and is manifested by the vibrating and sometimes violent movement of the Earth's surface.
faults
A break or fracture in the surface of a planet or moon along which movement has occurred.
focus
The point within the Earth at which the initial energy release or slippage of an Earthquake occurs.
epicenter
The point on the surface of the Earth directly above the focus of a earthquake.
tsunami
A Japanese word for a "harbor wave" - an unusually large sea wave produced by a sea-quake or undersea volcanic eruption.
fold
A folded rock layer that can form an arch or a trough as a result of compressional forces.
Pangea
The giant supercontinent that is believed to have existed over 200 million years ago.
volcanic mountain
Mountains that have been built by material ejected during volcanic eruptions.
fault-block mountain
Mountains that are built by normal faulting in which giant pieces of the Earth's crust were faulted and uplifted at the same time.
fold mountain
Mountains characterized by folded rock strata, with external evidence of faulting and internal evidence of high temperature and pressure changes; formed at convergent plate boundaries.
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