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Provinces of Virginia. Differences Among Provinces Physiography : landforms change and the countryside has a different appearance Rock Type : igneous,

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Presentation on theme: "Provinces of Virginia. Differences Among Provinces Physiography : landforms change and the countryside has a different appearance Rock Type : igneous,"— Presentation transcript:

1 Provinces of Virginia

2 Differences Among Provinces Physiography : landforms change and the countryside has a different appearance Rock Type : igneous, sedimentary and/or metamorphic Rock Structure : flat or folded & faulted Geologic Ages of the rocks

3 Coastal Plain Location from Atlantic Ocean on east to fall line at west continues underwater to continental slope Physiography Flat & often marshy Low slopes, barrier islands & salt marshes

4 Coastal Plain Rock Type: Sedimentary Layered by sediments left when area was flooded & by sediments eroded from Appalachian Mtns transgression: when sea level rises & floods the land regression: when sea level drops, exposing the land All sedimentary rocks at surface Many oceanic fossils Oblique aerial view of Passmore Creek and marsh, Jamestown Island, James City County

5 Coastal Plain Structure Fairly low-relief, but dips slightly toward ocean Geologic Age Youngest of VA provinces Started forming when Atlantic Ocean opened in late Triassic

6 Coastal Plain Fossils Common seashell fossils Whale fossil from Miocene Eastover Fm., New Kent County

7 Coastal Plain – Chesapeake Bay The Chesapeake Bay was created about 5000 to 6000 years ago when the area was flooded as meltwater from glaciers raised sea level. Continuing sea level rise and shoreline erosion caused the bay to grow further.

8 Piedmont Physiography Outer Piedmont (Eastern) gently rolling upland erosion flattened the surface of the folded bedrock beneath Inner Piedmont (Western) rugged terrain erosion hasn’t smoothed the folded metamorphic rock small broken belt of mountains Location from fall line at east to mountains (Blue Ridge province) on west

9 Piedmont Rock Type: Metamorphic Metamorphic rocks (from Precambrian) folded during the Paleozoic when North America and Africa hit Igneous intrusions (granite & basalt) from rifting when Pangaea broke apart Soil at surface is red & clayey from oxidation of rocks below Montpelier anorthosite exposed in the Virginia Piedmont

10 Piedmont Structure Deeply weathered folded bedrock More resistant outcrops are seen nearer the Blue Ridge Scattered old volcanic arcs, faults & intrusions Geologic Age late Proterozoic through Paleozoic

11 Piedmont Resources Virginia Slate(above) and Gold (below) Dinosaur footprint (left) found in Culpeper Basin sandstone quarry, above

12 Blue Ridge Location thin province extending from Piedmont to east, Valley & Ridge to west Physiography Average height of area ~3000ft above sea level VA’s two highest peaks in southwest corner of Blue Ridge

13 Blue Ridge Rock Type: Igneous & Metamorphic Complexly folded & faulted granite & metamorphic rock dating from Precambrian age – original North American basement rock (Grenville) Thrust upward during collision between N Amer & Africa in late Paleozoic The northern Blue Ridge of Virginia, as seen from Shenandoah National Park

14 Blue Ridge Structure Folded & faulted Steep mountains, high relief Geologic Age Mid-Proterozoic through Cambrian

15 Blue Ridge Resources Catoctin Greenstone – Skyline Drive Beautiful views which draw tourists

16 Valley & Ridge Location Extends from Blue Ridge to east, Appalachian Plateau to west Physiography Folded mountains, which have been eroded leaving valleys & ridges

17 Valley & Ridge Rock Type: Sedimentary Thick folded sedimentary rock deposited during Paleozoic Resistant sandstone caps the ridges; limestone is eroded to form valleys (differential erosion)

18 Valley & Ridge Structure Folded bedrock Steep mountains, high relief Geologic Age Paleozoic

19 Valley & Ridge Resources Well-developed Karst topography Luray Caverns

20 Appalachian Plateau Location Smallest, southwestern corner of Virginia Continues into WV Physiography High plateau Somewhat flat, but eroded by many rivers

21 Appalachian Plateau Rock Type: Sedimentary Thick folded sedimentary rock deposited during Paleozoic Deeply cut by many rivers

22 Appalachian Plateau Structure Similar rocks to Valley & Ridge, but weren’t folded – still horizontal Geologic Age Pennsylvanian (late Paleozoic)

23 Appalachian Plateau Resources Coal seams exposed along Keen Mountain, Buchanan County. Each seam is approximately 0.5 m. Petroleum

24 Virginia Relief

25 Bibliography


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