Deforming the Earth’s Crust: Faulting

Pg. 129

What is a FAULT? When rock layers

BREAK when stress is applied

One block of rock slides relative to another

What is the hanging wall,

Narrow base block of angled crust

the foot wall?

Broad base block of angled crust

see page 114

What is a normal fault? When the

hanging wall moves down relative to the footwall

Occurs when tectonic forces cause tension that pull the blocks of rock apart

A normal fault

What is a REVERSE FAULT? When the

Hanging wall moves up relative to the footwall

Occurs when tectonic forces push the blocks of rock together (Compression)

A reverse fault

What are STRIKE-SLIP FAULTS?

Form when opposing forces cause rock to break and move horizontally

Example: California’s San Andreas fault

A strike slip fault

Geologic Activity, http://www.nps.gov/pore/naturescience/geologicactivity.htm

Mountain Building

• Occurs because of tectonic plate movement

What are folded mountains?

Form at convergent

plate boundaries

Make the highest mountains in the world

Rock layers that are squeezed together

Folded mountain Layers that are squeezed together

Appalachian mountains

The Alps

Himalayan Mountains

What are some examples of folded mountains?

What are fault block mountains?

Tension causes large blocks of rock to drop down

Example: Teton Mountains, Wyoming

Fault block mountains

Grand Tetons Wyoming

Volcanic Mountains

What is uplift and subsidence?

Uplift—the rising of a region of the Earth’s crust

Subsidence—the sinking of a region of the Earth’s crust

What is Tectonic Letdown?

Sinking of a region of Earth due to tension

Rift zone – a set of deep cracks that form between two plates that are pulling apart

Formation of a Rift Valley

Sequence showing how movements deep under the Earth's Crust help to create a Rift Valley