Tectonic Development of the Appalachian—Ouachita—Marathon Mountain Range (3 of 3)
map of the world showing location of continents today
"Today"—Atlantic Ocean and Gulf of Mexico Open. The modern oceans originated about 200 million years ago when Europe, Africa and South America ripped away from North America. Fragments of the collision zone mountains were left on three continents: the Appalachians in North America, the Atlas in Africa, and the Caledonides in Europe. The Atlantic continues to widen along the Mid-Atlantic Ridge. The Gulf of Mexico ceased opening about 100 million years ago, when tectonic activity shifted eastward to the Caribbean region. Continental collision is occurring today where Africa and India ram into Europe and Asia, forming the Alpine-Himalayan chain.
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Modified from “Parks and Plates: The Geology of our National Parks, Monuments and Seashores,” by Robert J. Lillie, New York, W. W. Norton and Company, 298 pp., 2005, www.amazon.com/dp/0134905172.