GEOL 104 Lecture Notes - Lecture 3: Mid-Atlantic Ridge, Transform Fault, Supercontinent Cycle
18 Apr 2016
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Continental drift: for theories to come about needed to have the technology to map out the world. Sailing around all the continents: had to make a map, and good enough to do it, first ideas of continental drift didn"t consider the continental shelf, alfred wagener. Had numerous evidence to support his theory. Identical fossil organisms are found on continents now separated by vast oceans. Doesn"t make sense in terms of physics: what forces could move whole continents over large distances. Thought the larger continents moved (ploughed) through thinner, smaller continents. 1930 he left for greenland to find evidence: died at 50, buried in snow. Theory debated for the next 30 years: breakup of pangaea. 180ma: rigid lithosphere overlies weak asthenosphere. The lithosphere is earths strong, outer layer. The asthenosphere is a hotter weaker region of the mantle under the lithosphere. Because difference in physical properties, the lithosphere is effectively detached from the asthenosphere.
