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

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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 apart Rock 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.

Faults A fault is a break in the earth’s crust. Fault’s occur along plate boundaries where forces push and pull the earth’s plates.

* 1. Strike-Slip Fault: occurs when rock on either side of the fault moves past each other in opposite directions There is no up or down motion Shearing stress causes this type of fault Example: 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 fault Creates valleys

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

* Strike Slip Fault!

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