lecture13 tectonics&weathering
Post on 06-Jul-2015
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Announcements
Exam 1 review session:Monday the 21st at 5pmHere in McG-S room 20
Bring questions!
Exam 1 itself: Wednesday the 23rd
Quiz #4
Question 6A B
Question 1
Linking Volcanism and Faulting to Plate Tectonics
Geologic Excitement at Tectonic Plate Boundaries
Hawaii?
World Hot Spots
Hot spots
= individual, stationary sites of upwelling from mantle
Hawaiian IslandsLots of basaltic volcanismIslands become older to the NW
Newer
Older
Oldest
Hot spot development over time
Hot spots: Hawaii
Pacific-North American Boundary
One tiny problem
We haven’t found good evidence for plumes yet…Maybe they’re too small for our technology to see. Maybe they don’t exist.
Big debate right now: plume theory vs. crack theory
Normal Faults: Basin and Range
Normal Faults: Basin and Range
GrabbenHorst
← Extension →
Why is Nevada pulling apart?
Why is Nevada pulling apart?
30+ m.y.a. Present
• All that pressure from subduction has been released. The continent is relaxing!
• There might be residual upwelling at the spreading center, and now North America is right over top of it.
Weathering
Bedrock to regolith to soil
Endogenic vs. exogenic
Internal vs. external systems
plate tectonics
folding
faulting
volcanism
weathering
water erosion
wind erosion
Building up Breaking downtug of war
glacial erosion
Denudation
= wearing away of landforms
Involves• Weathering• Mass wasting• Erosion
Agents: moving water, air, waves, ice
Weathering – breakdown of rock materialsErosion – transport of broken-down materials
Processes that weather/alter/destroy bedrock (Pw)
versus
Processes that expose bedrock (Pe)
Yosemite, California
Pw < Pe
Pw > PeWest Virginia
Champaign, France
Moab, Utah
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