After my talk Wednesday night to the Potomac Appalachian Trail Club, I got an email from PATC member Tom Johnson, with an extraordinary photo attached. It shows an exceptional outcrop of the Neoproterozoic Catoctin Formation, exposed atop Compton Peak in northern Shenandoah National Park, Virginia. The outcrop features enormous, well-preserved cooling columns from these ancient meta-lava flows.
Click on it for the full-size version (posted here with Tom’s permission). You know that I’ll be visiting this in person at the first possible opportunity.
Wow, what a fine example of columnar joints!
Here’s a gigapan look at the outcrop:
http://www.gigapan.org/gigapans/97851
I visited this formation today (with my dog), and was delighted. It’s at the end of the Compton Peak East Trail. From the Compton Gap parking area south of milepost ten, cross Skyline Drive, go the top of Compton Peak on the AT southbound and take the blue-blazed side trail to the left (to the south) and go down, down what you just climbed up, about 0.2 miles. At the end of the trail, take the trail around the left side of the outcrop even further down, and when that trail ends, there are the columns as pictured. It’s very much worth the climb there and back, which is high praise!