Archbald Pothole, Lackawanna County
Location: Lackawanna County, Carbondale 7.5-minute quadrangle; approximately 41º 30' 42" latitude and 75º 34' 26" longitude.
Size: The pothole area covers less than an acre.
Geology: The Archbald Pothole, 38 feet deep and 42 feet in maximum diameter, lies in a small valley on a hillside in northeastern Pennsylvania. Discovered by anthracite miners in 1884, it is cut (from top down) into sandstone, shale, and coal of the Pennsylvanian-age Llewellyn Formation. The pothole became a local tourist sensation as soon as it was cleared of its gravel plug. A year later, miners encountered another pothole of similar size about 1000 feet to the northeast—but it was never cleaned out. In 1961 Archbald Pothole State Park was established at the site of the first pothole.
Two main hypotheses for the origin of the Archbald Pothole surfaced soon after its discovery. The explanation of the first on-site investigator of the pothole, John C. Branner, was that it had formed as a plunge pool at the base of an inclined moulin waterfall. Two years later, Charles Ashburner put forward the idea that the pothole had been carved mainly by subglacial meltwater.
Read more on the origin of the Archbald Pothole at our Geology of PA abstracts page.
Heritage status: Site is secure as part of a state park but could be potentially threatened if vandalism occurs. The sides of the pothole are slowly eroding and are covered in ferns and lichens.
How to get there: Visit the DCNR State Parks web page on Archbald State Park.
Heritage value: Site is scenic, educational, and scientific. Displays an erosional remnant, a geological curiosity, and a scenic periglacial feature of Pennsylvania.
Facilities: State park facilities are available.
References: Fleeger, G. M., Braun, D. D., and Inners, J. D., 2002, Plunge into the past or go with the flow: multiple hypotheses for the origin of the Archbald Pothole, Lackawanna County, Pennsylvania: Geological Society of America Abstracts with Programs, v. 34, no. 1, p. 27.
For information regarding geologic features and PNHP, contact Jim Shaulis of the Pennsylvania Geological Survey at 717–702–2037.