Earth's Layers, Pangaea & Continental Drift

What are Earth’s four layers from outside to centre?

Crust, mantle, outer core, inner core.

What is the crust?

Earth’s thin, solid outermost layer where we live.

What is the mantle?

The thick layer of hot rock between the crust and core; its material can slowly deform and flow.

What is the outer core?

A liquid layer mainly made of iron and nickel; its movement helps generate Earth’s magnetic field.

What is the inner core?

Earth’s solid innermost layer, mainly made of iron and nickel, kept solid by immense pressure.

Which is Earth’s thickest layer?

The mantle.

Which Earth layer is liquid?

The outer core.

Why is the inner core solid despite its extreme temperature?

Extreme pressure prevents it from melting.

What is Pangaea?

An ancient supercontinent that joined almost all present-day continents together.

What happened to Pangaea?

It gradually broke apart, and its fragments moved toward their present-day positions.

Approximately when did Pangaea begin breaking apart?

Roughly 200 million years ago.

What is continental drift?

The idea that continents have moved over geological time from earlier positions.

Who proposed continental drift?

Alfred Wegener, a German scientist.

When did Wegener propose continental drift?

1912.

What is continental fit evidence?

The coastlines of continents, especially South America and Africa, appear to fit together.

How do fossils support continental drift?

Identical fossils on continents separated by oceans suggest those continents were once connected.

How do rocks and mountain ranges support continental drift?

Matching rock layers and mountain belts across oceans suggest they once formed continuous geological structures.

How does climate evidence support continental drift?

Ancient glacial evidence in now-warm areas suggests continents were once in different positions.

What were Wegener’s four types of evidence?

Continental fit, fossil evidence, matching rocks and mountains, and climate evidence.

Did scientists initially accept Wegener’s theory?

No. Many rejected it because he could not convincingly explain how continents moved.

What later helped support continental drift?

Evidence of seafloor spreading and the development of plate tectonic theory.