Well-exposed columnar joints in the Ediacaran Catoctin Formation. These columns formed as cooling cracks as 570 to 550 Ma lava flows solidified. Exposure on Compton Mountain in Shenandoah National Park.
Catoctin Columns
August 5, 2016 by ·
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Highland County Geologic Map
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 […]
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Virginia is for Lavas- The Catoctin Formation
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 […]