chapter 15.4 deforming the earth’s crust
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Chapter 15.4Chapter 15.4Deforming the Earth’s CrustDeforming the Earth’s Crust
stressstress• a force that acts on rock deforming it’s
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
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
AAnticlinenticline • fold in rock layers that forms an Arch
Syncline
• fold in rock layers that bends down to form a bowl –SMILEY FACE!
Anticline & syncline
Anticline & syncline
Monocline
• Rock layers are folded so that both ends of the fold are horizontal.
3 typesof faults
strike-slip normal reverse
caused by shearing
caused bytension
caused bycompression
Hanging Wall/Footwall
Normal fault
hanging wall
footwall
hanging wall moves down relative to the footwall
Normal Faults
Reverse faulthanging 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 fault-block mountainmountain
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)
plateauplateau= 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
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
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
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