Ch. 1 Sec. 3 – Forces of Earth

Objectives

• Describe the layers found within the earth.• Discuss the forces that change

the earth’s surface.

Earth’s Layers

Inside our Earth

3 layers: Crust, Mantle, and Core.Core can be split up into two parts: outer and

inner core.

Crust

• Uppermost part of the Earth, includes continents and ocean floors.

• Approx. 31 to 62 miles deep.

Crust

Mantle

• Mantle is below crust, or the outside part of Earth.

• The mantle is made up of rock material, and is 1,800 miles thick.

• The mantle has two layers. The outer layer is mostly in a liquid state of hot magma, and the inner is a solid state. The magma is just under the crust, which causes our plates to move.

Mantle layers

• Inner and outer layers of mantle• Liquid magma is the outer layer.• Rock is the inner layer.

Liquid hot magma!

Mantle

Core

• Under the mantle is the core, which is made up of hot iron and other metals and rocks.

• The inner core is solid, but the outer core is liquid because the temperatures are so hot and have melted the metals.

Core

Why does our Earth move?

• Plate Tectonics: The earth is made up of plates that are under continents and ocean floors that are moving on magma in the mantle.

Pangaea and the Plate Tectonic Theory

• At one point, all the continents were one super continent, all connected, and they drifted apart.

This was called Pangaea.

Pangaea

Different movements in plate tectonics

Transform Boundary

• occur where plates slide or, grind past each other along transform faults.

• The San Andreas Fault in California is an example of a transform boundary exhibiting dextral motion.

San Andreas Fault

Divergent Boundary

• Divergent boundaries occur where two plates slide apart from each other.

• Mid-ocean ridges (e.g., Mid-Atlantic Ridge) and active zones of rifting (such as Africa's Great Rift Valley) are both examples of divergent boundaries.

Divergent Boundary

Convergent Boundaries

• occur where two plates slide towards each other commonly forming either a subduction zone (if one plate moves underneath the other) or a continental collision (if the two plates contain continental crust).

• Examples of this are the Andes mountain range in South America and the Japanese island arc.

Andes Mountains

Japanese Island Arc