Deformation

Part 1: Deformation

http://www.youtube.com/watch?v=DppbibMhAXU

Earth’s Changing surface

I. Crust – the surface layer of the earthA. Continental: land not under the oceansB. Average of 32km, but can be as thick as

70kmII. Oceanic

A. Ocean floorB. Average of 8km thick

Review: Which one is denser?

a. The forces that pull and push on the earth’s crustb. Causes deformation – the tilting, breaking or folding of rock

III. STRESS

i. Compression

Compression – squeezes the rocks of the

crust, decreasing

volume, increasing

density

Think: Covergent

ii. Tension

Tension – pull the rocks of the crust, increasing volume,

decreasing density Think: Divergent

iii. Shearing

Shearing – the crust being pushed in opposite directions

causing the rocks to tear

and twistThink: transform

Review #1. Match the set of arrows to the 3 stress

a. Shearing

b. Tension

c. Compression

Fractures and Faults

c. Fracture – cracks in rocks

d. Fault – crack along which rocks move sideways, up, or down.i. Fault block mountains form from

the normal faults pushing up rockii. Rift valleys form when land

between normal faults slide down

San Andres

Folding

e. Folding – a bend in the rocki. Anticline – an upward foldii. Syncline – a downward foldiii. Appalachian mountains are made from folds

The Appalachians

f. Factors that affect faulting or folding

i. Higher temperatures will cause folding/lower temps. cause faultingii. Greater pressure causes folding/lower pressure causes faulting

Rock typeiii. Brittle rock will more likely faultiv. Ductile (bendable) rock will more likely foldv. Pressure applied gradually will cause folding/fast will cause faulting

Review #2

What’s the difference between anticline and

syncline folding?!