Lecture 3 (January 11): Plate Tectonics II
Brief outline of this lecture:
1. Convergent plate boundaries
2. Transform plate boundaries
3. Hot spots
4. The world as plates
5. Possible driving forces for plate tectonics
Main points of this lecture:
Convergent plate boundaries can be divided into three types, oceanic-oceanic, oceanic-continental, and continental-continental.
Continental lithosphere cannot be subducted because of its lesser density than that of oceanic lithosphere and of mantle material.
Transform plate boundaries occur at offsets in the Mid-Ocean Ridges and other places where plates move past each other.
Hot spots (sources of magma from the mantle) cause chains or strings of volcanic rock where plates have passed over the hot spots.
The Earth's surface can be divided into several different named tectonic plates, of which the North American Plate is one and the Pacific Plate is the largest.
There are several possible driving mechanisms for plate tectonics, but no one of them is very convincing.
Figures used in this lecture:
New Convergent plate boundaries sketches
Transform plate boundaries sketches - sketched in class; drafted here.
A map showing ages of the Hawaiian Islands
A diagram explaining hotspots
A diagram showing an alternate model to the hotspot model
A diagram showing possible driving forces for plate tectonics
Reading assignment: Chapter 3.
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