Chapter 3

Chapter 3 - they were ignored because scientists didn’t...

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Continental Drift and Spreading Oceans are old Oceans and continents don't move Mountains from contraction of earth like grape to raisin Glaciers move and shrink and grow The glacial scars all pointed in the same directions (north and down) It wasn’t until bout 1910 - 1925 that a climate scientist (Alfred Weigner) articulates the ideas on plate tectonics (interested in polar ice/ ice sheets) Rifting Initial rifting-when Africa and North America began to separate and water would go in- between them Redbeds- continental rocks on top f that is oceanic Fossil remains of mesosaurus have been found in Africa and South America Fossil remains of Cynognathus have been found in Africa and South America Glossopteris fossils have been found on all the southern continents Wegners ideas got ignored until about 1950-
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Unformatted text preview: they were ignored because scientists didn’t know how the weak continental crust could break through the oceanic crust- the continental crust was much lighter/ less dense ○ In the 1950s, there is bathymetric profiles and magnetic surveys of the ocean floor sonar scanners) ○ Mid atlantic ridge (mid- oceanic ridge)- middle pint inbetween the two continental areas underwater mountain range- mre heat flow from the underwater mountain range ○ Continental shelf, continental slope, continental rise ○ Hess's concepts of sea- floor spreading (spreading/ subductin) Magma seeps through wear parts of the crust and then it pushes stuff to the side and then it forms new crust ○ 19th century version of the world Chapter 3 Friday, February 04, 2011 10:22 AM Planet Earth Page 1...
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This document was uploaded on 05/05/2011.

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