Bald Eagle Mountain
Bald Eagle Mountain – once known locally as Muncy Mountain
Bald Eagle Mountain lies in the central portion of Centre County, the southern portion of Clinton County, and the southern portion of Lycoming County, and the ridge line forms part of the border between Blair County and Huntingdon County. It runs from the water gap formed with Brush Mountain by the Little Juniata River at Tyrone, to the bend in the West Branch Susquehanna River just east of Williamsport, a distance of approximately 60 miles (97 km).
The Julian and Unionville Pikes are paved roads that cross the ridge near State College, along with U.S. Route 322 and Interstate 99 which pass through the now enlarged wind gap known as "Skytop".[2] Most other major road crossings are through water gaps, including Interstate 80 which passes through Curtin Gap east of Milesburg. Other water gaps in the ridge are formed by Spring Creek on the south edge of Milesburg and by Fishing Creek at Mill Hall (where U.S. Route 220 crosses). U.S. Route 15 crosses through a wind gap south of Williamsport near Bald Eagle Mountain's eastern end.
Bald Eagle Ridge is popular with
A mature oak and hickory forest covers Bald Eagle Mountain.[4]
Geology
Bald Eagle Mountain is in the western part of the
During the
The Tuscarora Quartzite is more resistant to erosion than Bald Eagle sandstone, and both are more durable than the Juniata Shale sandwiched in between. Softer rock layers on either side of these eroded, leaving the double crested Bald Eagle Mountain ridge, with a depression between the higher western and slightly lower eastern ridge lines. On the neighboring ridges that formed the opposite slope of the ancient mountain, the same three rock layers are exposed in reverse order, with the oldest rocks near the hinge of the fold. Since the rock layers on these ridges are not vertical, the Tuscarora Formation underlies a much higher crest, and the Bald Eagle Formation creates a series of lower "terraces" broken by small ravines.[6]
The southeast slope of the ridge is underlaid by
The Bald Eagle sandstone is laced with pyrite veins, and when exposed to air and water, these minerals produce sulfuric acid, contaminating both surface runoff and groundwater. Construction of Interstate 99 where it crosses Bald Eagle Mountain has been delayed since 2004 by complaints from the Pennsylvania Department of Environmental Protection about acidic runoff from pyritic rock excavated from this formation. The planned I-99/I-80 interchange further north in the Nittany Valley at the foot of the ridge was redesigned to avoid excavating contaminated rock from the same formation.[8]
See also
References
- ^ Trego, C.B. (1843). A Geography of Pennsylvania. Philadelphia: Edward C. Biddle. p. 255.
- ^ Gold, David P. & Doden, Arnold G. "Geological Report on the Skytop Road Cuts". Geosciences: Feature Article. Pennsylvania State University College of Earth and Mineral Sciences. Retrieved 2008-01-26.
- ^ "The Conservation Fund". Archived from the original on November 20, 2008. Retrieved 2009-04-12.
- ^ "Pennsylvania State Parks - Bald Eagle - PA DCNR". Archived from the original on 12 January 2008. Retrieved 2008-01-26.
- ^ "Short Explanation of the Geological Structure of Pennsylvania". Archived from the original on 2007-04-20. Retrieved 2009-04-12.
- ^ "Description of the Geology of Centre County Pennsylvania". Archived from the original on 2006-12-09. Retrieved 2009-04-12.
- ^ "Explanation of Geologic Units" (PDF). Pennsylvania Geological Survey. Archived from the original (PDF) on April 22, 2003. Retrieved 2008-01-26.
- ^ "I-99". www.centredaily.com. Archived from the original on 2006-12-19. Retrieved 2008-01-26.
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