sea-floor spreading and continental drift review

Front

What is sea-floor spreading?

Back

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

Front

What is continental drift?

Back

The theory that continents have moved over geological time from one location to another.

Front

What evidence supports sea-floor spreading?

Back

Magnetic patterns on the ocean floor, age of oceanic rocks, and the presence of mid-ocean ridges.

Front

What are the alternating magnetic patterns on the ocean floor?

Back

They are bands of normal and reversed magnetic polarity that show the history of Earth's magnetic field changes.

Front

Who proposed the theory of continental drift?

Back

Alfred Wegener.

Front

What is Pangaea?

Back

A supercontinent that existed around 200-300 million years ago, where all continents were joined together.

Front

What types of evidence did Wegener use to support his theory?

Back

Fossils, landforms, and climate evidence.

Front

How do tectonic plates move?

Back

They move due to convection currents in the Earth's mantle.

Front

What is the significance of mid-ocean ridges?

Back

They are underwater mountain ranges where sea-floor spreading occurs.

Front

What is the age of the oldest oceanic crust?

Back

Approximately 200 million years old.