Archbald Pothole State Park, Geological state park in Archbald, Pennsylvania, US.

Archbald Pothole is a natural cylindrical depression carved into bedrock by glacial activity, located within a Pennsylvania state park. The formation displays an elliptical shape and sits as a dramatic hole in the landscape where visitors can observe the raw geological forces that shaped the region.

A coal miner named Patrick Mahon stumbled upon this hole in 1884 while expanding a shaft in his mine, when water and stones suddenly rushed into the excavation. The discovery eventually made it a key location for understanding how glacial activity shaped northeastern Pennsylvania.

The pothole served as a prominent research site for geologists studying glacial formations from the Wisconsin Period, dating back 15,000 years.

The site is easily accessible during warmer months with marked trails leading directly to the edge of the hole. Visiting between spring and fall offers the best experience, as the park closes during the colder season.

The hole became a major reference for geology studies because it represents one of the finest examples of glacial erosion in North America. Researchers traveled from across the region to examine this natural drill and learn more about the ice age period.