NATS 1750 Lecture 4: NATS 1750-Earth structure .pdf
13 Nov 2014
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1, 12: earth is dynamic active body, only the layer at the top is truly was we think of as solid", three main layers; core, mantle, crust. Post wwii with being able to probe the sea oor found the oceanic ridge system. Out of this in the 1960"s the theory of plate tectonics came into existence. Divergent boundaries: where two plates are separakng, material upwells from underlying mantle to create new rock. Also somekmes called spreading centers: most divergent boundaries are under oceans. The mid- oceanic ridges run more than 70,000 km in length throughout the world"s oceans. Along these ridges high level of volcanic ackvity (i. e. iceland sit on mid atlankc ridge. Ridges rise up to 2- 3 km above surrounding ocean basin osen with deep ris valley along axis. Convergent boundaries: where two plates are moving toward each other. Here one plate slides under the other.
