Continental Crust av. 32 km Oceanic Crust av. 8 km

The Earth’s crust moves as a result of the stress or forces within the Earth.

Which brings us to Chapter 10 The Movement of the Earth’s Crust

Stress are forces that push and pull on the Earth’s crust causing it to undergo deformation.

As rocks under go stress They slowly change shape and volume Also, they move up and down The movement causes the rocks to break, tilt, and fold. Deformation is the breaking, tilting, and folding of rock.

Stress Causes rocks to slowly change shape and volume.

3 Types of Stress CompressionTensionShearing

Compression Tension Shearing

Compression,tension, and shearing of rocks can cause the rocks to Fracture or crack.

FaultBreak or crack along which rocks moveLarge faults within the Earth’s crust result from the movement of tectonic plates

A Normal Fault occurs when tension or pulling apart acts on a fault. The hanging wall will move down relative to the foot wall.

Tension

A Reverse Fault occurs when compression or pulling apart acts on a fault causing the hanging wall to move up relative to the foot wall.

Compression

Thrust Fault is a special type of reverse fault that is formed when compression causes the hanging wall to slide over the foot wall.

A lateral fault occurs when shearing acts on a fault which causes blocks of rock to slide horizontally past each other left or right.

Shearing

Fault-block mountains are formed by blocks of rock uplifted by 2 normal faults. Example: Cordilleran Mountains in Western USA

Fault Block Mountain

Rift Valleys are formed by 2 normal faults sliding down Example: Death Valley, California USA

Nearly five and a half million years ago, what we today call Baja California used to be part of the Mexican mainland, and then it began pulling away as tectonic forces underneath split the land apart. Now, Baja California is slowly moving northwest. Some geology experts say that the northernmost extension of this rift, or tear, is the area we call Death Valley, while others claim it to be in the Salton Sea. There is even some plausible scientific evidence to support the idea that this tearing of the land could extend as far north as southern Oregon. There are those who refer to this phenomenon as the Baja Rift.Salton SeaBaja Rift

A fold is a bend in rock. Anticline is an upward fold. Syncline is a downward fold.

Factors that will determine whether rocks will fault or fold Temperature Hotter: Folds Pressure Greater: Fold Rock type Brittle: Fault Ductile: Fold How Stress Applied Gradually: Fold Suddenly: Fault

Plateau may be formed by: Slow flat topped fold Appalachian Plateau Vertical faulting Colorado Plateau Molten lava flows on surface of Earth layer by layer Rivers often carve a large plateau into smaller plateaus Grand Canyon in Colorado Plateau

Magma – molten rock beneath the Earth’s Surface Lava - molten rock beneath the Earth’s Surface Dome – oval or circular uplift by rising magma, fluid collects beneath the surface and pushes up like a blister Dome Mountains – domes that have been worn away in some places leaving separate peaks