A Resource for Information on the Commonwealth's Geology
This image illustrates part of the geological map of Highland County, Virginia in the Valley & Ridge province. Note the linear belts Paleozoic sedimentary rocks that are repeated by folding. From oldest to youngest these include O1 = lower Ordovician strata, O2 = upper Ordovician strata, S1 = Silurian strata, SD = Silurian-Devonian strata, D1 […]
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.
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 […]