Transcript VIRGINIA GEOLOGY

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