25 terms

chapter 7 Plate Tectonics

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Terms in this set (...)

crust
The thin and solid outermost layer of the earth above the mantle.
mantle
Layer of rock between earth's crust and core.
core
Central part of the earth below mantle.
lithosphere
Solid outer layer of earth that consists of crust and rigid upper part of mantle.
asthenosphere
Soft layer of mantle on which tectonic plates move.
mesosphere
Strong, lower part of mantle between asthenosphere and the outer core.
Tectonic Plates
Blocks of lithosphere that consists of crust and rigid outermost part of the mantle.
Seismic Waves
A wave of energy that travels through the earth and away from an earthquake in all directions.
Continental Drift
The hypothesis that states that the continents once formed a single landmass, broke up, and traveled to their present locations.
Sea-Floor Spreading
The process by which new oceanic lithosphere forms as magma rises towards the surface and solidifies.
Plate Tectonics
The theory that explains how large pieces of the earth's outermost layer move and change shape.
Convergent Boundary
The boundary formed by the collision of two lithospheric plates.
Divergent Boundary
The boundary between two tectonic plates that are moving away from each other.
Transform Boundary
The boundary between tectonic plates that are sliding past each other horizontally.
Compression
Stress that occurs when forces act to squeeze an object.
Tension
Stress occurs when forces act to stretch an object.
Folding
Bending of rock layers due to stress.
Fault
Break in rock body when one block slides relative to another.
Normal
A ___________ fault usually occurs when tectonic forces pull rocks apart because of tension.
Reverse
A ___________ fault forms when rocks are pushed together by compression.
Strike-Slip
A __________ fault is the third major type and forms when opposing forces cause rocks to break or move horizontally.
Uplift
Rising of regions of earth's crust to higher elevations.
Subsidence
Sinking of regions of earth's crust to lower elevations.
Rift Valley
A long, narrow valley that forms as tectonic plates separate. (pg. 385)
Convection Currents
The Sun is the initial energy source of the wind and currents. Because the sun heats the earth more in some places than in others, ___________ are formed.