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21 Cards in this Set

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  • Back
  • 3rd side (hint)
What is plate tectonics?
The theory that pieces of Earth's lithosphere move slowly on top of the asthenosphere.
The theory that...
What does the theory of plate tectonics explain?
The formation and movement of Earth's plates.
The formation and movement of...
What did Alfred Wegener do?
He hypothesized that the continents were once joined in a single supercontinent, which then moved into pieces that moved apart (Pangaea).
He hypothesized that...
What is continental drift?
A process in which continents move slowly on the Earth's surface.
A process in which...
What is a mid-ocean ridge?
A chain of underwater mountains.
A chain of...
What did Harry Hess do?
He proposed the idea of sea-floor spreading.
He proposed...
What happens as pieces of ocean floor move apart?
Magma from the mantle wells up and solidifies to form new oceanic crust.
Magma from the mantle...
What is subduction?
A process in which old oceanic plates sink into the mantle.
A process in which...
What happens during subduction?
Gravity slowly pulls the dense edges of oceanic plates into the mantle, destroying old ocean floor.
Gravity slowly pulls...
What is a trench?
A depression in the ocean floor that forms when a plate bends as it sinks through a subduction zone.
A depression in...
What did geologists find about underwater rocks?
Rocks near the mid-ocean ridge were younger and those farther away were older.
Rocks near the mid-ocean ridge...
What does sea-floor spreading do?
It creates new oceanic crust at mid-ocean ridges. Sunduction destroyes old oceanic crust at subduction zones.
It creates new...
What force moves the plates?
Convection currents form in the mantle as hot rock rises at mid-ocean ridges, cools and spreads horizontally as ocean lithosphere, and then sinks back into the mantle at subduction zones.
Convection currents...
At what rates do plates move?
Very slowly (about 10 to 0.1 cm per year)
How do plate motions relate do mantle convections?
They are the visible part of it.
They are...
What are the types of plate boundaries?
Divergent boundaries, convergent boundaries, and transform boundaries.
What is a divergent boundary?
Where plates move away from each other
Where plates...
What is a convergent boundary?
Where plates come together or collide.
Where plates...
What is a transform boundary?
Where plates slide past each other, moving in oppositre directions.
Where plates...
Where do most mountains form?
Along plate boundaries.
How do mountains form?
As plates collide, the crust buckles, folds, and thickens, pushing up mountains.An oceanic plate collides with a continental plate. Two plates diverge and magma wells up and solidifies as mountains (mid-ocean ridge).
3 things