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20 terms

Harcourt Science 6, Unit D, Cycles in Earth and Space (Ch. 1, Ls. 1-3)

Earth Science
STUDY
PLAY
crust
the Earth's outermost layer
mantle
the layer directly beneath Earth's crust
core
the Earth's innermost layer
lithosphere
the cool, solid portion of Earth that includes all of the crust and part of the upper mantle
asthenosphere
a zone of partially melted rock in the upper mantle of the Earth
plate tectonics
the theory scientists use to explain the movements of plates on the Earth's surface
divergent boundary
a boundary where crustal plates move way from each other
convergent boundary
a boundary were crustal plates collide with each other
transform fault boundary
a boundary where crustal plates grind past each other
mid-ocean ridge
the place where plates of the Earth's crust along the ocean floor are being split apart and molten rock pushes up to form new ocean floor and a mountain range
rift
a deep ocean valley formed where two crustal plates move apart
sea-floor spreading
a process in which magma is slowly pushed up through cracks in a rift and then cools to form new sea floor
earthquake
the sudden movement of rock along a fault which releases energy vibrations
focus
the point in the Earth's crust where the first major movement of an earthquake fault occurs
epicenter
the point on the earth's surface directly above the focus of an earthquake
P wave
a primary wave or "push-pull" wave of released energy in the Earth's surface that causes a back and forth vibration in the same direction that the wave moves
S wave
a slower kind of energy wave released by an earthquake that causes vibrations at right angles to the wave's direction of travel
surface wave
an energy wave from an earthquake that travels only at the surface and moves less quickly than P wave and S waves but makes the ground roll and sway
Richter scale
a scale that measures the amount of energy released during an earthquake
volcano
a mountain that may form around an opening in the Earth's surface where an eruption of molten rock occurs