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Published byDiana Dawson Modified over 8 years ago
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Warm up! On a piece of notebook paper, define the following:
Chapters 19 & 20: Stress Topography Isostasy Take out your 18 study guide
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Mountain Building
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There are three main ways to make a mountain:
1) compression force collision boundary Examples: Himalayas, Appalachians
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There are three main ways to make a mountain:
2) tension stress Fault-block mountains Examples: Sierra Nevada (CA), Grand Tetons (WY)
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There are three main ways to make a mountain:
Rift valley 3) volcanoes divergent boundary subduction boundary hot spots New Island Forms Examples: Iceland, East African Rift trench volcanic mountains Examples: Cascades, Andes Example: Hawaii
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Plate Tectonics Review: Look for Mountains Forming in all 3 ways…
Wilson Cycle -
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Most mountains are along continental margins
continental margin – boundary between continental and ocean crust
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active margin – along a plate boundary (YES – mtn. building)
passive margin – not along a plate boundary (NO – mtn. building) Passive East Coast US Active West Coast US
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What forces and faults are involved in mountain building?
Shear Stress Tension Compression Squeezing Pulling Apart Sliding Past
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3 types of stress: 1) compression – push together (like a convergent boundary) Compression Squeezing
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3 types of stress: 2) tension – pull apart (like a divergent boundary)
Pulling Apart
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3 types of stress: 3) shear – pushed in two, opposite directions (like a transform boundary) Shear Stress Sliding Past
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What happens to rocks that are stressed?
They can bend into folds They can break along faults
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4 types of faults: 1) normal fault – caused by tension
hanging wall moves down
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4 types of faults: 2) reverse fault – caused by compression
hanging wall moves up
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4 types of faults: 3) thrust fault – caused by very strong compression
plane of the fault is not very steep
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4 types of faults: 4) strike-slip fault caused by shear stress
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Strike Slip Fault layers of rock slide by each other
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Review: Identify Each type of fault
1. Normal 2. Reverse 4. 3. Thrust Strike-Slip
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Folds in rock layers: anticline – top of a fold: looks like an “A”
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Folds in rock layers: syncline – bottom of a fold: looks like it “sinks” Sideling Hill, MD
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Folds in rock layers: limb – slope of a side of a mountain
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Compression
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Identify the 2 folds. syncline anticline
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Local Geology Which province has the most folds?
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Put it all together: On your own
Stress Description Fault Plate Boundary Arrows showing motion of plates 1. Reverse 2. Divergent Shear Push together convergent Thrust compression Pull apart tension normal Slide past horizontally Strike-slip transform
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Homework: Finish back of notes page on mountain building (review)
Next: The Rock Cycle
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