Plate Tectonics

Plate Tectonics

Court Monroe

Chapter 17, pages 443 - 463

Alfred Wegener, father of continental drift

Wegener thought that the continents were once connected.

Continents fit into each other

Landforms, like mountains

Fossils of continents meshed in key areas





People did not go along with theory, because they could not figure out what force would be strong enough to move a continent.

Continents would crack if pushed through ocean

Gravity would not make them go “downhill”

Spin of the Earth was not fast enough





People did not go along with theory, because they could not figure out what force would be strong enough to move a continent.

Continents would crack if pushed through ocean

Gravity would not make them go “downhill”

Spin of the Earth was not fast enough

Wegener died on expedition to Greenland

Probably died by falling into a crevice

When digging in Greenland, when you are are deep as you are going to go, one yells “I’ve found Wegener”.

Theory widely accepted in early 1960’s

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

www.vulkaner.no/v/vulkinfo/ tomtech/etomtech.html



http://pubs.usgs.gov/publications/graphics/Fig2-5globes.gif



www.astro.umn.edu/~john/ Ast1001/earth/Earth.html



oak.cats.ohiou.edu/.../ Diversification.htm



www.ucmp.berkeley.edu/ tectonics/quakecenters.html

http://www.classzone.com/books/earth_science/terc/content/visualizations/es0806/es0806page01.cfm?chapter_no=visualization

http://www.wwnorton.com/college/geo/egeo/animations/ch2.htm

http://education.sdsc.edu/optiputer/flash/hotSpots.htm

http://www.wwnorton.com/college/geo/egeo/animations/ch2.htm

Plates can also slide past each other (transform).

When plates converge, one of three things can happen.

1. A continental plate (granite) can collide with oceanic plate (basalt), and the more dense goes under (subducts).




1. A continental plate (granite) can collide with continental plate (granite), and it crumples (mountains)




1. An oceanic plate (basalt) can collide with an oceanic plate (basalt), and it make an island arc (Japan)



1. The ocean comes apart at ridges. Most of these are in the middle of oceans.

2. Fig 4.12

1. We know that the plates come apart here (called Sea Floor Spreading), because of magnetic anomalies.http://www.uwsp.edu/geo/faculty/ritter/glossary/s_u/sea_flr_spread.html



http://www.uwsp.edu/geo/faculty/ritter/glossary/s_u/sea_flr_spread.html

Break it down (Old School Style)

Plates come together at PLATE BOUNDARIES

CONVERGENT (Where they come together)

a. Continent to continent (mountains like Himalayas)

b. Ocean to Ocean (Island arcs like Japan, with TRENCH)

c. Continent to Ocean (Rockies and Andes, with TRENCH and MOUNTAINS)

DIVERGENT (Where they come apart)

a. RIDGE (small hump where lava comes up)

b. RIFT (where the canyon is between plates)

c. SEA FLOOR SPREADING (where Ridges and Rifts are)

d. NEWEST (land is born here)

TRANSVERSE (Where they slide past each other)

a. L.A. and San Francisco

b. Crooked sidewalks

All of this is energy driven

a. Convection currents

b. Heat from birth of Earth, gravitational pressure, radioactive decay

Plate Tectonics

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