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.
Mount Rogers is the highest peak in Virginia, with its summit 1,746 meters above sea level (5,729 ft). The peak is located in the Blue Ridge province in southwestern Virginia on the border between Grayson and Smyth counties. Mount Rogers is underlain by Neoproterozoic rhyolite. The upper reaches of the mountain are cloaked in alpine forests of red […]
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 […]
This distinctive scallop is the state fossil of Virginia and is the first fossil described from North America in 1687. Chesapecten sp. are commonly found in strata exposed along Coastal Plain cliffs along major rivers in southeastern Virginia and eastern North Carolina. Chesapecten jeffersonius is the index fossil for the Lower Yorktown Formation, and is distinguished by the number […]
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 […]