Hickory Run State Park

The most notable feature of Hickory Run State Park is the huge boulder field located in the northeast corner of the park.^[5] The boulder field can be reached by car on Boulder Field Road or by hiking the 3.5-mile (5.6 km) long Boulder Field Trail from the trailhead on SR 534. The field comprises about 720,000 square feet (67,000 m²) (16.5 acres (6.7 ha) or 0.026 square miles (0.067 km²)) in area (1,800 feet (550 m) east-west by 400 feet (120 m) north-south). The top of the boulder layer is virtually level with the approaching path. The immense weight of the boulders has compressed the underlying soil 12 feet (3.7 m) or more. The boulder field was created about 20,000 years ago during the most recent glacial period. The boulders consist of the sandstone and conglomerates identical to those capping the ridges that surround the field on three sides (theMississippian Pocono Formation). The creation of the boulder field was by the continual freeze thaw process in the ridges southwest of the field. As the ridges broke apart into angular boulders, they accumulated on clays, sands, and ice at the base of the ridges. During summer months, the ice in the mass would melt and carry the boulders and finer sediment down the valley to the location of the boulder field today. As the glaciers receded and melted, the drainage flowed through the field and took the sand and clays with it, leaving behind the stack of boulders. This process occurred several times over the thousands of years of glacial melt, which is why the field is so large. Many visitors cannot resist hopping from boulder to boulder across the field. This unique geological landscape is a National Natural Landmark.^[4]

• http://en.wikipedia.org/wiki/Hickory Run State Park
• Page 158 - Dicka, A. B., 2012, 101 American Geo-sites you've gotta see: Mountain Press Publishing Co., 250p.