A Resource for Information on the Commonwealth's Geology
This micrograph illustrates a mylonite from the Hylas Zone in the eastern Piedmont ~5 km west of Doswell, Virginia. The rock is characterized by a well-developed foliation with elongate quartz ribbons (transparent grains) and feldspar porphyroclasts. The rock originally was a granodiorite that was strongly deformed and sheared, under ductile conditions, into a mylonite. Checkout […]
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 […]
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 […]