REMARKS: A long narrow "train" of angular blocks (often called a boulder field), about one-half mile long and ranging in width from 200 to 600 feet, on the southern slope of Blue Mountain. It was formed by solifluction or creep in the periglacial climate of the Wisconsinan glaciation, after which removal of fine-grained material occurred. Blue Rocks and adjacent rubble depostits closely resemble solifluction sheets in Alaska.
REFERENCE: Potter, Noel, Jr., and Moss, J. H. (1968), Origin of the Blue Rocks Block Field and adjacent deposits, Berks County, Pennsylvania, Geological Society of America Bulletin, v. 79, p. 255-262.
REMARKS: The Hardyston Quartzite (Cambrian age) has been thrust faulted over the limestone valley at this site. This "rootless slice" of Hardyston Quartzite contains an isolated peak, Cushion Peak, rising more than 800 feet above the Great Valley to the north; an excellent view of the Great Valley from the peak.
REFERENCE: MacLachlan, D. B., Buckwalter, T. V. and McLaughlin, D. B. (1975), Geology and mineral resources of the Sinking Spring 7 1/2-minute quadrangle, Berks and Lancaster Counties, Pennsylvania, Pennsylvania Geological Survey, 4th ser., Atlas 177d, 228 p.
REMARKS: A basal conglomerate in the Hardyston Quartzite (Cambrian age) is so extremely hard and resistant to weathering that individual peaks stand topographically above the surrounding granite gneiss (Precambrian age); Devils Hump, Owl Head (325), and Pinnacle Point (326) are three of the highest.
REFERENCES: Buckwalter, T. V. , Pre-Cambrian geology, Boyertown quadrangle, Pennsylvania Geological Survey, 4th ser., Atlas 197, 15 p.
REMARKS: Several outstanding geologic features are present in the immediate area: the North Lookout (222) on Hawk Mountain and Dans Pulpit (223) on Blue Mountain are in East Brunswick Township, Schuylkill County; South Lookout (224), Cobble (225), River of Rocks (226), Hemlock Heights (227), and Owls Head (228) are in Albany Township, Berks County. Towering outcrops and joint blocks of the Tuscarora quartzite (Silurian age) are exposed. The North Lookout is a massive outcrop of Tuscarora sandstone, 1520 feet above sea level; from this site, one may view a truly majestic 70-mile vista of the Great Valley and Blue Mountain. South Lookout is 1340 feet above sea level. The River of Rocks, a boulder field formed during the Ice Age, is 1 mile long and several hundred feet wide. Dans Pulpit is formed from outcrops of the Tuscarora quartzite standing in vertical columns. They are spectacular, and the scenic view to the south across the Great Valley is magnificent. The Appalachian Trail is adjacent to these geologic features. The area has been designated a National Natural Landmark.
REMARKS: A scenic drive along the ridge of Mount Penn at an elevation of 800 to 1000+ feet. Along the drive are the Pagoda and a lookout tower, which provide an excellent view of the Reading Prong and Great Valley.
REMARKS: Outcrops of hard, resistant quartzite (Tuscarora Formation, Silurian age) are exposed at the apex of a tight fold in the mountains. Weathering has produced a "spire" of quartzite; an excellent view of the Great Valley.
REMARKS: Erosion of a sharp fold (bend) in the Tuscarora quartzite (Silurian age) of Blue Mountain has produced a rock feature resembling a "pulpit."
REMARKS: An outstanding example of a water gap in Blue Mountain; an exceptional exposure of the quartzites of the Tuscarora Formation (Silurian age) and a major fault which causes this formation to repeat.
REFERENCES: Burner, Roger, Weaver, Richard, and Wise, Donald , Structure and stratigraphy of Kittatinny Ridge at Schuylkill Gap, Pennsylvania, Pennsylvania Academy of Science Proceedings, v. 32, p. 141-145.
REMARKS: This small topographic hill has been the site of a raging geologic controversy for more than 40 years. The hill lies in the middle of the Martinsburg Shale (Ordovician age), but some geologists since 1934 have said that it is limestone conglomerate of Triassic age, a synclinal outlier of Triassic rocks. Today geologists have identified fossils (brachiopods and graptolites) that date the rocks as Late Ordovician; they are now thought to be part of the Juniata and Bald Eagle Formations.
REFERENCES: Platt, L. B., Loring, R. B., Papaspyros, Athanasios, and others , The Hamburg klippe reconsidered, American Journal of Science, v. 272, p. 305-318.
Whitcomb, Lawrence , Spitzenberg Conglomerate as a Triassic outlier in Pennsylvania, Geological Society of America Bulletin, v. 53, p. 755-764.
Whitcomb, Lawrence and Engel, J. A. , The probable Triassic age of the Spitzenberg Conglomerate, Berks County, Pennsylvania, Pennsylvania Academy of Science Proceedings, v. 8, p. 37-43.