Development of a Theory

Front

What are mid-ocean ridges?

Back

Vast mountain ranges deep below the ocean's surface.

Front

Where is new ocean crust continually formed?

Back

At mid-ocean ridges.

Front

True or False: Magma is less dense than Lava.

Back

True.

Front

What does the theory of plate tectonics state?

Back

Earth's surface is made of rigid slabs of rock, or plates, that move with respect to each other.

Front

What best explains the age of oceanic crust and ocean-floor features?

Back

Seafloor spreading.

Front

What is seafloor spreading?

Back

The process by which new oceanic crust is formed at mid-ocean ridges and older crust is pushed away.

Front

What are tectonic plates?

Back

Large, rigid pieces of Earth's lithosphere that move and interact at their boundaries.

Front

What is subduction?

Back

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

Front

What is the difference between magma and lava?

Back

Magma is molten rock beneath the Earth's surface; lava is magma that has reached the surface.

Front

What are ocean trenches?

Back

Deep underwater troughs formed by the subduction of one plate beneath another.