Lecture13 tectonics&weathering

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