nature.net
May 2004
Moving Mountains
By Robert Anderson
A summary of the processes that make mountains rise can be found at www.physicalgeography.net, a Web site created by Michael J. Pidwirny, a geographer at Okanagan University College in Kelowna, British Columbia. (On the home page click on “Fundamentals: Online Textbook” from the menu bar at the top; in “Chapter 10: Introduction to the Lithosphere,” click on “Mountain Building.”) For an overall view of how colliding tectonic plates transform the planet, go to Dynamic Earth, developed by Robert Butler, a geologist at the University of Leeds.
Illustrations of the way tectonics has changed the distribution of land and sea can also be found at a Web site run by Christopher R. Scotese, a geologist at the University of Texas at Arlington. For thirty years, Scotese and his collaborators have been working on a series of paleogeographic atlases. The latest of them, the Global Plate Tectonic Model, is available at PALEOMAP Project. From the home page you can choose 3-D movable paleoglobes and paleogeographic animations that show the positions of the continents and the shapes of the ocean basins for various periods of geological time. Select “Earth History” from the menu at the left on the home page. There you’ll find full-color maps depicting details such as mountain ranges, shorelines, and active plate boundaries during those same periods—beginning with the breakup of the first supercontinent, Rodinia, and extending through the present and into the future for 250 million years, when the supercontinent Pangea Ultima will trap what is now the Atlantic Ocean in a small, inland basin.
Antonio Schettino, a geologist in Milan, Italy, worked with Scotese to re-create plate motions in the Mediterranean region. The accompanying QuickTime animation provides an excellent graphic explanation of how the Alps arose. A similar presentation of tectonic processes at the Northern Arizona University site shows the ancient mountain chains in greater regional detail. Click on “Popular Departmental Links” and look at the three items created by Ronald C. Blakey, a geologist at Northern Arizona University. The site Geological History of Jamestown, Rhode Island provides a rundown of the northern Appalachian chain’s geological history, which stretches back a billion years.
Geologists can now watch mountains grow, thanks to new satellite and radar technologies that measure minute movements of the Earth’s crust and slight changes in the stresses that cause earthquakes. Go to the Active Tectonics site, run by a group from the University of California, Berkeley, for more information.
Robert Anderson is a freelance science writer living in Los Angeles.
Copyright © Natural History Magazine, Inc., 2004