We can't go to the Earth's core, so how do we know how hot it is?
The hidden layers deep beneath the Earth's crust.
The geological forces which sculpt our landscape.
How was the Grand Canyon formed, and what does it tell us about the past?
How the Earth's moving plates cause earthquakes, volcanoes and tidal waves.
How tall are the tallest mountains?
How did early land masses change and converge to form the continents we know today?
How did mountain ranges like the Alps and the Himalayas form?
What can humans use the steep, rocky terrain of fold mountains for?