GEL 20 Lecture 4: Geology-Chapter4-2
Document Summary
Evidence for continental drift: past glacial regions and glacial striations match. They thought that the continents would have to scrape and grind across the rocky ocean floor. Age of the sea floor is symmetrical. The bottom of the ocean floor isn"t flat. Deep ocean trenches with deep earthquakes and nearby volcanoes; subduction zones. At subduction zones, old lithosphere goes back into the earth. Plate tectonics: the continents and ocean floor are made of rigid plates of rock (lithosphere) that can move above a slowly convecting (circulating), gooey interior. *most tectonic plates contain continental lithosphere and oceanic lithosphere. Lithosphere: contains crust and the upper rigid part of the mantle. Made of silicate minerals w/ iron and magnesium. Fe and mg silicates are dark-colored and heavy. Made of silicate minerals w/o iron and magnesium. These minerals tend to be light colored and light weight.
