Chapter 15.4 Deforming the Earth’s Crust

stress a force that acts on rock deforming it’s shape or volume

3 types of stress shearing pushes rock in opposite directions tension pulls on crust stretches rock so that it becomes thinner in the middle compression squeezes rock until it folds or breaks YouTube video-Bill Nye Stress

Stress causes rocks to either fold (bend) or fault (break).

Folding Folded Mountains fold- bend in rock that forms when compression shortens & thickens part of Earth’s crust – can create folded Mountains

Three Types of Folds Anticline Syncline Monocline

Anticline fold in rock layers that forms an Arch

Syncline fold in rock layers that bends down to form a bowl – SMILEY FACE!

Anticline & syncline

Monocline Rock layers are folded so that both ends of the fold are horizontal.

3 types of faults strike-slip caused by shearing normal caused by tension reverse caused by compression

Hanging Wall/Footwall

Normal fault hanging wall footwall hanging wall moves down relative to the footwall

Normal Faults

Reverse fault hanging wall moves up relative to the footwall footwall hanging wall

Reverse Fault

Strike-Slip Fault Faulting at a transform boundary – fault blocks slide past each other

What kind of fault is this? strike-slip fault

San Andreas fault Example of a strike-slip fault

Fault-Block Mountains mountains formed when normal faults cause large blocks of rocks to slip down due to tension Grand Teton mountain range

fault-block mountain

Uplift and Subsidence Vertical movements in the crust are divided into two types— –Uplift – the rising of regions of the Earth’s crust to higher elevations (mountains and rebound – slow movement back to normal level after weight is removed) –Subsidence – sinking of regions of Earth’s crust to lower elevations (rift zones and oceanic crust as it moves away from the ridge)

plateau plateau= large area of flat land elevated high above sea level (an area of uplift)

The Colorado Plateau is a 150,000 square mile region covering parts of Arizona, Utah, Colorado, and New Mexico.

syncline What is a fold in rock layers that bends down to form a bowl ?

syncline

fold What is a bend in rock that forms when compression shortens & thickens part of Earth’s crust ?

A fold is a bend in rock that forms when compression shortens & thickens part of Earth’s crust.

A fold is a bend in rock that forms when compression shortens & thickens part of Earth’s crust.

fault-block mountain What is a mountain formed when normal faults cause a block of rock to slip down? Sierra-Nevada mountain range

anticline What is a fold in rock layers that forms an arch ?

In a _____________ fault, the rocks on either side of the fault slip past each other sideways.

In a strike-slip fault, the rocks on either side of the fault slip past each other sideways.

What are the 3 types of stress ? shearingtension compression

The 3 types of stress are shearing, tension and compression.

tension What type of stress pulls on the crust, stretching the rock so that it becomes thinner in the middle ?

B. shearing B. shearing What type of stress pushes rock in opposite directions? A. tension

What are the 3 types of faults? 1. strike-slip 2. normal 3. reverse

What type of fault is caused by shearing? A. Strike-slip B. Normal C. Reverse D. Fault-block