1. Earth's Interior
Summarize the three layers of Earth- crust, mantle, core- on the basis of relative position, density, and composition.

2. Objectives:
1.What do geologists do?
What are the characteristics of Earth's crust, mantle, and core?
geologists- scientists study forces that make and shape Earth.
chemical/ physical makeup of rocks
map location of types of rock on Earth
describe landforms
search for clues about Earth's history
Earth looks very different today!

3. Constructive forces- shape surface by building mountains
Destructive forces- wear away mountains and landmasses (wind, water- ocean waves)
200 years ago- what geologists knew:
Earth is a sphere
6,000 km radius
7 continents
made up of rock

4. What's inside the Earth?
deepest mine in the world 3.8 kilometers (6,000 km to center of Earth)
Indirect method to find out Earth's interior
Seismic waves- waves of energy produces by Earthquakes.
Geologists study:
1. how the waves travel
2. speed of the seismic waves
3. paths that the waves take
** determined that Earth's interior is made up of many layers

5. Journey to the Center of the Earth!
Temperature
surface rock cool, 20 meters down it is warmer
After 40 meters decent, 1°C increase
Pressure- force per unit of area
force pushing on a surface or area
weight & pressure of rock increases as descend

6. Crust, Mantle, Core
Crust-
"outer skin"
5 to 40 km thick
Basalt- dark, dense rock under oceans, fine texture
Granite- less dense continental rock, coarse texture

7. Mantle-
lithosphere- "lithos" Greek for stone
layer of mantle that is solid rock
100 km thick
asthenosphere- Greek for weak soft flowing rock
rock bends like plastic due to high heat and pressure
lithosphere floats on top of asthenosphere
mantle is km thick

8. Core-
outer core- molten iron and nickel, behaves like thick liquid
inner core- extreme pressure forms solid iron and nickel
inner and outer core slightly smaller than the moon! 1/3 Earth's mass
Earth's Magnetic Field
iron and nickel very magnetic- responsible for producing Earth's magnetic field

9. Middle layer, thickest layer; top portion called the lithosphere
Position
Density
Composition
Crust
Outermost layer, thinnest under the ocean, thickest under the continents; crust and top of mantle called the lithosphere
Least dense layer overall; oceanic crust=dense basalt, continental crust=less dense granite
Solid rock
Mantle
Middle layer, thickest layer; top portion called the lithosphere
Density increases with depth because of increasing pressure
Hot softened rock; contains iron & magnesium
Core
Inner layer; consists of two parts- outer core & inner core
Heaviest material; most dense layer
Mostly iron & nickel; outer core- slow flowing liquid, inner core- solid