I continued my late November 2018 hike on the Alum Cave Trail from Arch Rock past Alum Cave and on to the halfway point at Gracie's Pulpit before returning to the trailhead on Newfound Gap Road.
Alum Cave is not an actual cave, but rather a concave bluff about 80 feet high and 500 feet long. It was the site of mining operations from 1838 to1854 by the Epsom Salts Manufacturing Company. During the Civil War, Confederate troops mined saltpeter for use in the manufacturing of gunpowder.
The Alum Cave Trail is a steep route with an average gradient of over 10% from the trailhead to Gracie's Pulpit. It has numerous stairs and steep dropoffs in some places. A couple of stream crossings require rock hopping, but most have a log footbridge. Several crossings near the trailhead have planked bridges wide enough to meet other hikers. Portions of the trail were rebuilt during 2015 and 2016 by a Trails Forever crew.
Part 1 covering the trail from the trailhead to Arch Rock can be found
here.