VIRGINIA GEOLOGY
Virginia is divided into 5 provinces based on their geologic (rock) formations.
1. Coastal Plain Coastal = near the ocean, Plain = Flat region of land Fall Line The Coastal Plain includes a flat region of sedimentary strata (layers of sand, mud, & gravel) that extends east of the Fall Line for more than 100 miles where it meets the Chesapeake Bay and Atlantic Ocean.
The Coastal Plain runs from the fall line on the west, to the Atlantic Ocean on the east It is a terraced landscape (like stair steps down toward the ocean) It is the youngest VA province
What is the Fall Line? The Fall Line is a low east-facing cliff paralleling the Atlantic coast It is where the rocks transition from harder to softer. It separates metamorphic rocks of the Appalachian Piedmont to the west from the sedimentary rocks of the Coastal Plain.
Waterfalls on the Fall Line The edge of the Piedmont/Coastal Plain is marked by a line of waterfalls on the Fall Line, where various rivers move from harder to softer bedrock. Great Falls on the Potomac River
Sediments (sand, silt and clay) produced by erosion of the Appalachian Mts. covers the plain, including the beaches
Virginia Fossils Due to climate changes, sea levels rose and fell and fossils were left at various layers Fossils include various marine organisms like clams, scallops, sharks teeth, and other hard remains
Chesapeake Bay Impact Structure 35 million years ago a large meteorite crashed into the shallow sea and created a crater 90 km in diameter. It is now buried under 1.2 km of sediment.
2. Piedmont Pied = Foot, Mont = hill/mountain Piedmont means “foothills”
Piedmont Piedmont is the largest province and is separated from the Coastal Plain by a Fall Line, extending westward to the Blue Ridge Mountains.
Facts about the Va. Piedmont: It is an area of rolling hills underlain by ancient igneous and metamorphic rock It is the largest of the provinces
Mining the Piedmont High quality slate is mined from this area The Piedmont has one of the worlds largest kyanite mines ( see picture of kyanite )
Slate mine in the Piedmont Slate is used for billiard (pool) tables, Chalkboards, & roofs
3. Blue Ridge Blue Ridge consists of a long, narrow NE-SW trending mountain chain and is the oldest area of the state of VA.
Blue Ridge Facts: It is a high ridge separating the Piedmont from the Valley and ridge Province
Blue Ridge Facts: The billion year old igneous and metamorphic rocks are the oldest in the state Old Rag Granite is the oldest rock unit dated in Virginia at 1.2 billion years Highest point in Virginia is in the Blue Ridge Mount Rogers, In Grayson County
4. Valley & Ridge The Valley and Ridge includes the area between the Blue Ridge and Appalachian Plateau.
Valley and Ridge The Valley and Ridge Province is an area of long parallel ridges and valleys underlain by ancient folded and faulted sedimentary rocks (550 – 300 my old)
Cambrian Period algae fossils are found in the Valley & Ridge Province, which means this area was once a shallow sea!
Limestone outcrops are common in the Valley and Ridge Province
This area is also famous for Karst Topography. Karst is an irregular limestone region with sinkholes, caves, underground streams, and caverns
5. Appalachian Plateau The Appalachian Plateau is the western most province and it continues into West Virginia. A plateau is a plain with a high elevation.
Appalachian Plateau Facts: The Appalachian Plateau has rugged, irregular topography with deep narrow valleys and steep, rugged mountain sides caused by the down-cutting (erosion) of rivers and streams It is underlain by ancient, flat-lying sedimentary rocks
Virginia Coal Most of Virginia's coal is found in the Appalachian Plateau and is mined for energy. Coal is Virginia’s most profitable Natural resource. Like all fossil fuels, it is nonrenewable! These old sedimentary rocks contain many fossils and tons of coal.
Strip mining for coal Strip mining removes the mountaintop to get to the coal. It destroys ecosystems and pollutes the water Black Mountain, Wise, Virginia