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Chapter 10 Movement of the Earth's Crust
I. Earth's changing surface
A. Crust
1. Two major sections
a. Continental crust
b. Oceanic crust
2. Stress
a. Pushes and pulls on the crust
b. Causes change in shape and volume
c. Deformation
1.) Breaking
2.) Tilting
3.) Folding
B. Basic types of stress
1. Compression
a. Squeezes rocks
b. Rocks denser and smaller in volume
2. Tension
a. Pulls on rocks
b. Stretches rocks over larger area
c. Rock becomes thinner
3. Shearing
a. Pushes rocks in 2 opposite directions
b. Rocks twist or tear apart
c. Rocks bend or break apart
4. Fracture
a. Cracks in rock
b. Called joints - generally parallel to each other
C. Faulting
1. Break of crack along which rocks move
a. Hanging wall - block of rock above a fault
b. Foot wall - block of rock below a fault
2. Types of faults
a. Normal
1.) Hanging wall moves down
2.) Foot wall moves up
b. Reverse
1.) Hanging wall moves up
2.) Foot wall moves down
c. Thrust
1.) Special type of reverse fault
2.) Almost horizontal
3.) Hanging wall slides over the foot wall
d. Lateral
1.) Blocks slide past each other horizontally
2.) Caused by shearing
D. Faulted mountains and valleys
1. Fault-block mountains
a. Formed by blocks of rocks uplifted by normal faults
b. Cordilleran Mountain range
2. Rift valleys
a. Block of land between 2 normal faults slides down
b. Death Valley
E. Folding
1. Bend in rock
2. Downward fold - syncline
3. Upward fold - anticline
F. Determining factors for folding or faulting
1. Temperature (high temp. = fold)
2. Pressure (greater pressure = fold)
3. Rock type
a. Brittle (fault)
b. Ductile (fold)
4. How stress is applied
a. Gradual = fold
b. Sudden = fault
G. Plateaus
1. Large area of flat land
2. Raised above sealevel
3. Wide than it is tall
4. Surrounded by steep cliffs
5. Formation
a. Slowly - flat-topped fold
b. Vertical faulting
c. Series of molten rock flows
d. Rivers carve large plateaus into smaller ones
H. Domes
1. Raised area shaped like top half of sphere
2. Created by rising magma
II. Floating crust
A. Dense material beneath crust
B. Solid, rocky crust exerts downward force
C. Molten rock of mantle exerts upward force
D. Isostasy exists between two forces (balance)
1. Material added to crust - crust floats lower
2. Material removed from crust - crust floats higher