1. The Layers of the Earth
© Copyright 2006.  M. J. Krech. All rights reserved.

2. The Four Layers The Earth is composed of four different layers.
The crust is the layer that you live on, and it is the most widely studied and understood.
The mantle is much hotter and has the ability to flow.
The outer core and inner core are even hotter, with pressures so great you would be squeezed into a ball smaller than a marble if you were able to go to the center of the Earth!

3. The Crust
The Earth's Crust is like the skin of an apple. It is very thin in comparison to the other three layers.
The crust is only about 3-5 miles (8 kilometers) thick under the oceans (oceanic crust) and about 25 miles (32 kilometers) thick under the continents (continental crust).

4. The Crust
The crust is composed of two main rock types (both are igneous):
The continental crust is mostly a rock called granite.
The oceanic crust is mostly a rock called basalt.

5. Igneous Rocks
Intrusive Igneous Rocks: magma pushes into surrounding rock below the Earth’s surface
Extrusive Rocks: forms when magma erupts onto the Earth’s surface (lava), cools quickly with very small or no crystals formed

6. What elements make up the crust?
Only 8 elements are common in the rocks that make up the Earth’s crust.
Together, they make up more than 98% of the mass of the crust.

46.6% Oxygen (O)
27.7% Silicon (Si)
8.1% Aluminum (Al)
5.0% Iron (Fe)

3.6% Calcium (Ca)
2.8% Sodium (Na)
2.6% Potassium (K)
2.1% Magnesium (Mg)

7. The Lithosphere
The crust and an upper layer of the mantle together make up a zone of rigid, brittle rock called the Lithosphere.

8. The Mantle The Mantle is the largest layer of the Earth.
Once you get past the top layer of the mantle, the rock becomes very hot and dense.
It is solid, but can flow and bend, like taffy.
The name for this part of the mantle is the asthenosphere.
Mantle

9. The Outer Core
The core of the Earth is like a ball of very hot metal. The metals are nickel (Ni) and iron (Fe).
The outer core is so hot that the metals in it are all in the liquid state.

10. The Inner Core
The inner core of the Earth has temperatures and pressures so great that the metals are not able to move about like a liquid, but are squeezed into a solid.