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Earth Science


the Earth's outermost layer


the layer directly beneath Earth's crust


the Earth's innermost layer


the cool, solid portion of Earth that includes all of the crust and part of the upper mantle


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


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


the sudden movement of rock along a fault which releases energy vibrations


the point in the Earth's crust where the first major movement of an earthquake fault occurs


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


a mountain that may form around an opening in the Earth's surface where an eruption of molten rock occurs

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