Plate Tectonics: Continental Drift & Seafloor Spreading

Front

What is sea-floor spreading?

Back

The process by which new oceanic crust is formed at mid-ocean ridges and gradually moves away from the ridge.

Front

Where does sea-floor spreading begin?

Back

At the mid-ocean ridge.

Front

What are the four geological time divisions in order from least to greatest?

Back

Epoch, Period, Era, Eon.

Front

What type of plate boundary occurs when two plates move apart?

Back

Divergent boundary.

Front

What happens at a convergent plate boundary?

Back

Two tectonic plates collide, which can lead to subduction or mountain formation.

Front

What is subduction?

Back

The process where one tectonic plate moves under another and sinks into the mantle.

Front

Why does oceanic crust sink below continental crust during subduction?

Back

Because oceanic crust is more dense than continental crust.

Front

What is a mid-ocean ridge?

Back

An undersea mountain range formed by the upwelling of magma at divergent plate boundaries.

Front

What is continental drift?

Back

The theory that continents have moved over geological time and were once joined together.

Front

What is a transform boundary?

Back

A plate boundary where two plates slide past each other horizontally.