How the earth Was Made--From Molten Rock to Green Planet

Front

What was the temperature of Earth's surface during its early formation?

Back

8,000 degrees Fahrenheit.

Front

How long did Kelvin estimate it would take for the molten Earth to cool to its present temperatures?

Back

20 million years.

Front

What did Lord Kelvin believe about the Earth's temperature over time?

Back

It was slowly cooling down.

Front

What is the relationship between the density of oceanic crust and continental crust?

Back

Oceanic crust is denser and heavier.

Front

Where is geologist Gary Stevens climbing on some of the oldest continental rock?

Back

South Africa.

Front

What is the primary composition of the Earth's crust?

Back

The Earth's crust is primarily composed of rocks and minerals.

Front

What is the process called when molten rock cools and solidifies?

Back

Crystallization.

Front

What are tectonic plates?

Back

Tectonic plates are large sections of the Earth's crust that move and interact with each other.

Front

What is the theory of plate tectonics?

Back

The theory that explains the movement of the Earth's plates and how they shape the Earth's surface.

Front

What is the difference between oceanic and continental crust?

Back

Oceanic crust is thinner and denser, while continental crust is thicker and less dense.