GEO 1301 Lecture 10: Midterm 2 review
4 Apr 2016
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Plate tectonics: theory that lithospheric deformaion is caused by lithospheric plates that move on the asthenosphere. Unifying theory because it accounts for earthquakes, rock deformaion, mountain belts, volcanism. Wegener: coninents once formed a single landmass (superconinent) that broke up and drifed to their present posiions. Traces of ancient glaciaions: glaciaion in africa and india (can"t form at equator on that scale, glaciaion from sea onto land. Can"t low from sea to land: therefore, coninents started at south pole. Matching geological structures: shields on diferent coninents composed of same material, it. Spreading as a result of oceanic ridges and lava. Volcanic lavas record the earth"s magneic ield (strength and direcion) exising at the ime of their cooling (crystallizaion) As lava cools below the curie point, some iron-rich minerals become magneized in the direcion parallel to the exising magneic lines of force. Move in relaion to one another, loaing and riding on the asthenosphere.
