111-40 - GY 111 Lecture Notes D. Haywick (2007-08) 1 GY 111...

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GY 111 Lecture Notes D. Haywick (2007-08) 1 GY 111 Lecture Note Series Mountain Building 1: The Basics Lecture Goals A) Distribution of mountain belts (the return of plate tectonics) B) Isostacy C) The Rock Cycle again (or what goes around, comes around; the return of igneous, sedimentary & metamorphic rocks) Reference: Press et al., 2004, the whole book; Grotzinger et al., 2007, the whole book A) Distribution of mountain belts If you have ever looked at a decent map of the world (one that shows topography), you would have quickly recognized that mountains are neither randomly distributed nor do they occur as isolated features. They occur in belts that are frequently pretty linear. If you stripped the Earth of water (something that the best maps also do), you would have seen that most of the world's most impressive mountain belts occur beneath the surface of the ocean. We didn't even know they existed before the 1940's. By now, you should understand that all of these mountain belts are the result of plate tectonics. The most impressive mountain belts occur where plates collide with one another. The Cordilleran Mountains 1 of western North America and the Andes of western South America are the result of oceanic-continental plate collisions. The Himalayas are the result of a continent-continent collision (India-Asia). Transform plate boundaries also result in impressive mountains as anyone in southern California ( Sierra Nevada Mountains ) or New Zealand (Southern Alps) would tell you. Mid-oceanic ridges like the Mid-Atlantic Ridge or the East Pacific Rise , as well as the divergent plate boundary in eastern Africa called the East African Rift are all mountain belts that are as much the result of heat (thermal expansion) as they are deformation. All in all, there are a lot of very impressive mountain belts on the surface of the Earth. Sadly, none of them are within driving distance to Mobile. Yes, I am aware that a 3 hour drive up Interstate 65 will get you to the Appalachian Mountains, but I don't consider them overly "impressive", at least from a topographic point of view. Consider the cross-sectional cartoon of the Cordilleran Mountains and the southern Appalachians between Birmingham and Atlanta that occurs at the top of the next page. 1 Many people call the Cordilleran Mountains the "Rockies", but this isn't entirely correct. The Rocky Mountains are just one component or range of the Cordilleran Mountains. Other ranges include the Cascades (Washington State, Oregon), the Front Ranges (Alberta), the Coastal Ranges (British Columbia) and the Olympic Mountains (Washington State)
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GY 111 Lecture Notes D. Haywick (2007-08) 2 The Cordilleran Mountains are tall -- the highest mountains exceed 6500 m above sea level (e.g., Mt. McKinley in Alaska) -- and rugged. In contrast, the Appalachian Mountains are relatively short (most less than 2000m in height) and "rounded" (i.e., they have gentle slopes). If you examine the mountains portrayed in the cartoon map of the Earth on the previous page, you will
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This note was uploaded on 02/04/2012 for the course GLY 111 taught by Professor Haywick during the Fall '11 term at S. Alabama.

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111-40 - GY 111 Lecture Notes D. Haywick (2007-08) 1 GY 111...

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