A Resource for Information on the Commonwealth's Geology
This micrograph colorfully illustrates deformed quartz grains in a well-cemented quartz sandstone from the Cambrian Antietam Formation, a prominent geologic unit in the Blue Ridge geologic province. Many of the individual sand grains are elongated (~horizontal orientation), but not recrystallized. Photo taken in cross polarized light with the gypsum plate inserted.
Photomicrograph of fault breccia in the Cambrian Antietam Formation, Blue Ridge province. Breccias form when rocks are extensively fractured in fault zones and are cemented together when minerals precipitate in the cracks and fractures. Note the angular fragments (fr) of quartz sandstone in a matrix of fine-grained iron oxide cement (ic). Field of view 4 […]
In Virginia the Appalachian Plateau province is not particularly ‘plateau-like’, rather the region is characterized by rugged topography and steep slopes. It is a well-dissected upland, and streams draining the region have a classic dendritic drainage pattern. The featured image of Buchanan County (and the surrounding areas of Kentucky and West Virginia) is a shaded relief map […]
When large quantities of magma intrude and solidify in the Earth’s crust they form bodies of intrusive igneous rock known as plutons. The featured image nicely illustrates the edge (geologic contact) of a granitic pluton in the Blue Ridge Mountains of central Virginia. The granite is part of the 706 ± 4 million year old […]