Chapter 9: Plate Tectonics and Ocean Floor

Front

What was the supercontinent called?

Back

Pangaea

Front

What is it called when new land forms over another, produced by a small chain of volcanic islands on top of one another?

Back

Volcanic island arc

Front

Alfred Wegener is best known for what?

Back

Continental drift

Front

How much of the ocean floor has been discovered?

Back

Less than 5 percent

Front

What was the main objection to Wegener's hypothesis?

Back

He could not describe a mechanism that could shift continental plates.

Front

What is plate tectonics?

Back

The theory that explains the movement of the Earth's lithosphere which is divided into tectonic plates.

Front

What is continental drift?

Back

The gradual movement of continents across the Earth's surface through geological time.

Front

What is subduction?

Back

The process by which one tectonic plate moves under another and is forced into the mantle.

Front

What are oceanic ridges?

Back

Underwater mountain ranges formed by plate tectonics.

Front

What is sea-floor spreading?

Back

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