1. Layers of the Earth
Crust
Mantle
Outer Core
Inner Core

2. Crust Avg. thickness- 35 km 2 kinds 1. Continental
20-90 km thick; known as sial; contains older rock, primarily granite; less dense than oceanic crust
2. Oceanic
5-10 km thick; known as sima; younger rock, primarily basalt; more dense crust

3. Crust Cont. All life exists in the crust of the Earth.
Approximately 90 different elements are found in the crust, but 5 make up 90% of the crust- oxygen, silicon, aluminum, iron, & calcium
Sodium, potassium, & magnesium are the most common elements in the remaining 10%

6. Mantle
Earth’s mantle contains 80% of Earth’s volume & 67% of Earth’s mass.
Common elements found in the mantle are: silicon, oxygen, aluminum, iron, & magnesium.
The mantle consists of solid rock, except for the asthenosphere.
Density increases in the mantle as depth increases

7. Layers of the Mantle The mantle is divided into 3 sections.
Lithosphere- consists of the uppermost part of the mantle (rigid rock) & the crust. Average thickness is 100 km.
- Moho’s discontinuity- boundary separating crust from mantle; discovered in 1909 using seismic data; found approximately 30 km from Earth’s surface

8. Layers of the Mantle cont.
2. Asthenosphere km deep; more fluid layer, but not liquid
3. Mesosphere- lowest layer; rigid rock; km deep
-temperature increases with depth, as does density

10. Core
Diameter of the total core is 6960 km = to approximately the diameter of Mars
The core is 1/6 of Earth’s volume & 1/3 of its total mass

11. Outer Core Approximately 2270 km thick
Temperature approximately º Celsius
Liquid; very dense molten iron & nickel
Believed to create Earth’s magnetic field; similar to the magnetic field around a magnet

12. Inner Core Temperature is about 5000º Celsius
Believed to be solid; very dense iron & nickel
Remains solid due to immense pressure (may be 2 million times stronger than normal pressure exerted on Earth’s surface); molecules can not spread out & become liquid