REMARKS: This large boulder balanced on two small ones is a special example of spheroidal weathering. Chemical and mechanical weathering processes attacked this igneous rock, called diabase (Triassic age), and "rounded" it. The rock was first formed from molten magma, and, as it cooled, its volume shrank and shrinkage or cooling cracks were formed. These cracks later aided in the weathering and rounding of the blocks.
REFERENCES: Hoskins, D. M. , Gifford Pinchot State Park: Diabase, Pennsylvania Geological Survey, 4th ser., Park Guide 10.
Pinchot State Park - Visitation info, etc. [07/05/10]
Friends of Pinchot State Park - [07/05/10]
REMARKS: The highest point on a ridge of the Hellam Conglomerate Member of the Chickies Formation (Early Cambrian age); the oldest sedimentary rock in Pennsylvania. The conglomerate has weathered into spectacular pinnacles that stand 30 feet above the crest of the ridge.
REFERENCES: Stose, G. W., and Jonas, A. I. , Geology and mineral resources of York County, Pennsylvania Pennsylvania Geological Survey, 4th ser., County Report 67, 199 p.
PHOTO: ©2009 Randy E. Newcomer.
UPDATE: PRIVATE PROPERTY. Trespassing is not tolerated. Arranged visits for donation are welcome. See the link below for contact information.[09/02/09]
www.seechimneyrock.org - Site and visitation information. [09/02/09]
REMARKS: This area is limited to the steep west wall of the Susquehanna River north of the Holtwood Dam. There are scenic waterfalls on Counselman Run, Duncan Run, and Oakland Run, all tributaries of the Susquehanna.
REMARKS: Outcrops of Lower Cambrian Chickies Quartzite on the Pigeon Hills; an excellent north overlook across the Piedmont Uplands; the Blue Ridge province is in the background. Trails through the pines and rock outcrops are extremely scenic.
REMARKS: An outcrop of quartzite of the Antietam Formation (Cambrian age) has weathered to a shape resembling a head. Lookout (314) on Long Mountain (Cumberland County, South Middleton Township) is a nearby similar outcrop (not similar in shape) along the Appalachian Trail.
REMARKS: Fantastic 12-mile view of the Susquehanna River valley to the Safe Harbor Dam; there is a view of the Chickies Rock anticline to the north. The site, which is 865 feet in elevation, is one of the highest in the area.
REMARKS: The extremely scenic ruggedness of the gorge makes this one of the outstanding natural areas in Pennsylvania. Outcrops of schist (Wissahickon Formation, Precambrian(?) age) line the walls of the gorge.
REMARKS: Outcrops of Lower Cambrian Chickies Quartzite on the Pigeon Hills; provides a southern overlook across the Piedmont province in winter, when there is no summer foliage. A U. S. Coast and Geodetic Survey trig-station bronze plaque (dated 1942) is atop Pulpit Rock; a U. S. Coast and Geodetic Survey trig-station is a first order horizontal and vertical control point in the national topographic land survey.
REMARKS: A wild and scenic gorge on the north flank of the Hellam Hills. Wildcat Falls (384) is a spectacular feature within the gorge. Vertical cliffs up to 150 feet high of quartzite (Chickies Formation, Early Cambrian age) line the gorge and the Susquehanna River near the mouth of the run. Round Top (385), a prominent topographic feature located 2 miles to the east near Hellam Point (386), and Schulls Rock (387) located 2 miles to the west, are also underlain by this hard, weather-resistant quartzite. Schulls Rock and Wildcat Falls are two of the most scenic features in York County. Fossil animal trails or burrows called "scolithus tubes" are present in the Chickies Quartzite.
REFERENCE: Stose, G. W., and Jonas, A. I. (1939), Geology and mineral resources of York County, Pennsylvania, Pennsylvania Geological Survey, 4th ser., County Report 67, 199 p.