Do Now for Wednesday, February 20th!Use your knowledge of the Law of Superposition to arrange the layers of Earth from oldest to youngest.

Stress and Faults**

An earthquake is the shaking and trembling that results from the movement of rock beneath the Earth’s surface.These forces are defined as stress!

Stress in the Crust

3 Types of Stress*

1. Compression: stress that pushes rock together

2. Tension: stress that pulls rock apartRock gets thinner in the middle

3. Shearing: stress that pushes rock in opposite directions

Any change in the shape of the Earth’s crust is called a deformation.

FaultsA fault is a break in the earth’s crust.

Fault’s occur along plate boundaries where forces push and pull the earth’s plates.

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1. Strike-Slip Fault: occurs when rock on either side of the fault moves past each other in opposite directionsThere is no up or down motionShearing stress causes this type of faultExample: San Andreas Fault, Cal.

3 Types of Faults

*2. Normal Fault: occurs when the rock above the fault (the hanging wall) moves down (along the footwall)Tension stress causes this type of faultCreates valleys

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3. Reverse Fault: occurs when rock above the fault (H.W.) move up (along the F.W.)Compression stress causes this type of faultCreates mountains

* Strike Slip Fault!

Mountain Building Two normal faults can form a fault block mountain.

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Grand Tetons - Wyoming

Mountains formed by folding

Folds are bends in rock that form when compression shortens and thickens part of the Earth’s crust. Folds can be a few centimeters across or hundreds of kilometers wide.

Himalayan Mountains are folded mountains!

*An upward fold in rock is called an ANTICLINE!*A downward bend in the middle of rock is called a

SYNCLINE!

Black Hills, SD

Plateau – A large area of flat, elevated land, high above sea level.

North Rim, Grand Canyon, AZ