1. Layers of the Earth
Geology is the study of the Earth, the materials of which it is made, the structure of those materials, and the processes acting upon them.

2. Earth’s Interior

3. Interior of the Earth
Explored shallowly through mines and wells – deepest mines on Earth are only about 2.5 miles deep
Temperature and pressure increase with depth
Earthquake (Seismic) Waves
scientists are able to tell the density and composition of materials in the Earth by how these waves travel through the Earth
caused by earthquakes or manmade explosions
Magnetic Fields on Earth
created by massive circulation of the hot, liquid mantle beneath Earth’s surface

4. Earth’s Layers and Density
Differences in density resulted in materials within Earth forming layers
Crust – least dense
Mantle
Outer Core
Inner Core – most dense

5. Earth’s Layers – The Crust
the brittle, rocky outer layer of Earth
very thin compared to other layers, like the shell of an egg
composed of magnesium and iron
earthquake waves speed up through this layer because it is the least dense
Two types:
Oceanic Crust – crust under the oceans
Continental Crust – crust on land (3x thicker than oceanic)

6. Earth’s Layers – The Mantle
thickest middle layer in the solid part of the Earth
contains more iron and magnesium than the crust, making it more dense
first 50 miles believed to be very hard rigid rock
next 150 miles is super-heated solid rock that is weak from heat energy and can “flow”
next several hundred miles is
very solid, sturdy rock again

7. Parts of the Mantle Uppermost Mantle (Lithosphere) Asthenosphere
similar rocks to that of the crust
Asthenosphere
heated rocks begin to melt and flow slowly underneath the lithosphere
Upper Mantle
higher temperatures and pressure cause rocks to stop melting and become solid again
Lower Mantle
most dense part of the mantle
Lower Mantle – down to 1800 miles

8. Earth’s Layers – The Core
dense and metallic center of the Earth
composed mainly of iron and a small amount of nickel

9. Parts of the Core Outer Core Inner Core
higher temperatures outweigh the high pressure and makes the outer core a liquid, molten lava
discovered by analyzing earthquake wave data
high pressure outweighs the high temperatures and makes the inner core a ball of dense, solid iron with a bit of nickel
spins faster than the rest of Earth

10. Deepest Depth Reached Kola Superdeep Borehole in Russia
Drilling began on May 24, 1970
In 1989, reached 40,230 feet (7.5 miles)
Hole is only about 9 inches wide
Still holds record in 2012 for the deepest hole ever drilled. (longest hole is drilled on an angle)
Due to higher than expected temperatures at this depth and location, drilling deeper was stopped in 1994
Rocks taken from this depth date 2.7 billion years old

11. Layers by Density (approx. values in g/cm3)
Atmosphere (avg ~ decreasing with distance)
layer of gases/air surrounding earth
Continental Crust to 3.0
thin, rocky layer of the earth that forms the continents
Oceanic Crust 3.0 to 3.3
thin, rocky layer of the earth under the oceans
Mantle to 5.7 (increasing with depth)
part liquid rock, part solid rock layer of earth
Outer Core (liquid) 9.9 to 12.2
hot, dense, liquid, metal layer of earth
Inner Core (solid) 12.6 to 13.0
hot, dense, solid, metal layer of earth