Ch. 2Ch. 2Sec. 1 Forces in Earth’s CrustSec. 1 Forces in Earth’s Crust

stressstress• force that acts on rock to

change its shape or volume

3 typesof stress

shearing tension compression

pushes rock in

opposite directions

pulls on cruststretches rock so that it becomes

thinner in the middle

squeezes rock until it folds or breaks

YouTube video-Bill Nye Stress

3 typesof faults

strike-slip normal reverse

caused by shearing

caused bytension

caused bycompression

Demonstrating Compression WavesDemonstrating Compression Waves

• Materials: Slinky

2. Two students hold the Slinky at the 2 ends pulling & stretching it slightly.

4. One student pushes the Slinky, slowly watching the Compression wave as it rolls from one end of the Slinky to the other.

In a normal fault

hanging wall

footwall

hanging wall lies above / footwall lies below

Animation of a reverse fault

footwall

hanging wall

What kind of fault is this?strike-slip fault

San Andreas fault

Example of a strike-slip fault

fault-block mountain

• mountain formed when normal faults uplift a block of rock

Sierra-Nevada mountain range

- fault block mountain- fault block mountain

Mountains formed by folding

Folded Mountains

• fold=

bend in rock that forms when compression shortens & thickens part of Earth’s crust

aanticline nticline • fold in rock layers that forms an arch

syncline

• fold in rock layers that bends down to form a bowl

Anticline & syncline

Anticline & syncline

plateauplateau= large area of flat land elevated high above sea level

• 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

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 uplift a block of rock ?

Sierra-Nevada mountain range

aanticline nticline

• 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 ?

shearing tension compression

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

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

tensiontensionWhat type of stress pulls on the

crust, stretching the rock so that it becomes thinner in the middle ?

B. shearingB. shearing

• What type of stress pushes rock in opposite directions?

A. tensionA. tension

What are the 3 types of faults?What are the 3 types of faults?

1. strike-slip2. normal3. reverse

What type of fault is caused by shearing?

A.A. Strike-slipStrike-slipB.B. NormalNormalC.C. ReverseReverseD.D. Fault-blockFault-block