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VIRGINIA GEOLOGY PHYSIOGRAPHIC PROVINCES MATHEMATICS & SCIENCE CENTER Courtesy of Virginia Division of Mineral Resources A mile-wide asteroid struck near the mouth of the Chesapeake Bay 35 million years ago. Courtesy of NASA THE COASTAL PLAIN • A region of sedimentary strata consisting of sands, muds, and gravels • Tidal waters occupy not only the Chesapeake Bay, but also lower portions of the James, York, Rappahannock and Potomac rivers • Extends inland for more than 100 miles and is monotonously flat Courtesy of Virginia Division of Mineral Resources THE PIEDMONT • Largest province extending from the Fall Line westward to the Blue Ridge Mountains • comprised of a complex of metamorphic and igneous rocks, overlain in a few places by Triassic-age sedimentary beds • Important rocks and minerals include pegmatites, slate, kyanite, gold and pyrite Courtesy of Virginia Division of Mineral Resources The Blue Ridge Mountain • A long narrow, northeast-southwest trending mountain chain • consists of old Precambrian-age sedimentary and volcanic rocks • Old Rag Granite is the oldest rock unit dated in Virginia at 1.2 billion years • The two highest mountains in the state, Mt Rogers (elevation 5,719 ft.) and White Top (elevation 5,520 ft.) are both in the southern Blue Ridge Courtesy of Virginia Division of Mineral Resources The Valley and Ridge • Composed of folded and faulted 550 to 300 million-year-old sedimentary rocks • Most ridges are held up by resistant sandstone, and most valleys are underlain by less resistant shale, limestone, and dolostone • Karst features, such as caves and sinkholes are common throughout this province Courtesy of Virginia Division of Mineral Resources Courtesy of Virginia Division of Mineral Resources The Appalachian Plateau • Contains deep narrow valleys and steep, rugged mountain sides caused by downcutting by streams • Consists of 320 to 280 million-year-old sandstone and shale with coalbeds • Most of the rock layers are relatively flatlying • Coal is Virginia’s most important mineral resource
