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 […]
Cedar Island is one of Virginia’s barrier islands that separates the Eastern Shore from the Atlantic Ocean. Barrier islands are dynamic environments that respond quickly to environmental changes. Over time barrier islands move, and their shorelines migrate. During the past two decades shoreline change at the south end of Cedar Island has been dramatic. Compare the 1994 […]
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 […]