A Resource for Information on the Commonwealth's Geology
Finding bedrock outcrop in the Piedmont of Southside Virginia can be challenging. Much of the terrain is covered by soil and saprolite, and geologists interested in this region must search high and low for outcrop. The image above illustrates a ‘good’ natural outcrop in the Piedmont, likely the result of a relatively resistant rock that […]
This exposure in a pasture near Cuckoo exposes a poly-deformed hornblende and plagioclase-rich gneiss. Foliation in the gneiss has been refolded. Another interesting feature is the presence of garbenschiefer or “feather amphibolite.” This unusual texture is defined by stellate and featherlike hornblende clusters in the plane of foliation. Three amphibole species occur in this rock […]
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.
Many of the highest peaks in Shenandoah National Park (including Hawksbill, Stony Man, and Hightop Mountain, just to name a few) are underlain by distinctive bluish-green rocks that were once ancient lava flows (Virginia is for Lavas!), and are part of a geologic unit known as the Catoctin Formation. From the presidential retreat at Camp David to Jefferson’s […]