Sea-Floor Spreading

Front

What are mountain ranges at the bottom of the ocean called?

Back

Mid-ocean ridges.

Front

What causes the movement of Earth's tectonic plates?

Back

Convection currents in the mantle.

Front

True or False: Throughout Earth's history, the magnetic north and south poles have switched places several times.

Back

True.

Front

What did scientists discover about the ocean floor in the 1960s?

Back

That the ocean floor contains magnetic patterns.

Front

Why is older oceanic crust denser than new oceanic crust?

Back

Because it is cold.

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.

Front

What is the role of tectonic plates in sea-floor spreading?

Back

Tectonic plates move apart at mid-ocean ridges, allowing magma to rise and create new crust.

Front

What is a tectonic plate?

Back

A large, rigid piece of the Earth's lithosphere that moves and interacts with other plates.

Front

What is the significance of magnetic patterns on the ocean floor?

Back

They provide evidence for sea-floor spreading and the history of Earth's magnetic field.

Front

What is a mid-ocean ridge?

Back

An underwater mountain range formed by plate tectonics.