Lecture One - Plate Tectonics and Surface Processes

Question 1

What can be said about the relative ages of oceanic and continental crust?

Answer 1

Oceanic crust is generally younger, as it is constantly recycled by subduction under continental crust.
190 million years old is the oldest oceanic crust.

Question 2

How is it that the Moon and Earth have been equally hit by meteorites, but the Earth shows very little evidence of this.

Answer 2

Because of plate tectonics, and the movement of the Earths surface, which removes or obscures the marks left by impacts.
Also, erosion, and the fact that many impacts occur in the ocean.

Question 3

What are the movements of the plate tectonics in Africa.

Answer 3

There is currently a spreading plate boundary forming the Red Sea, and another forming the great lakes.

Question 4

What causes deeper oceans ridges?

Answer 4

Magmatism.

Question 5

How do the solid rocks in the mantle move?

Answer 5

The hot rocks move up and cold rocks move down.

Very viscous, deformations, so that the rocks ‘flow.’

Question 6

How are granite, gneiss and mylonite related?

Answer 6

All began as a granite, as they are heated and placed under greater stress, a gneiss is formed, then under greater heat and pressure, a mylonite.