A Resource for Information on the Commonwealth's Geology
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 […]
The level of the sea has been measured at Sewells Point, Virginia continuously since 1928. In 1928 the mean level of the sea was ~45 cm ( ~18″) lower than it is in 2016. Sea level rise and regional land subsidence is creating an ever-growing problem in Hampton Roads and most of coastal Virginia.
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 […]