Steven Dutch, Professor Emeritus, Natural and Applied Sciences,
University of Wisconsin - Green Bay
Geologic map of Shanandoah National Park (outlined in white, above). Lambert Conformal Conic, standard parallels at 30 and 50 N, 100 meters per pixel. Grid lines at 0.1 degree intervals, north to upper right. Yellow is snadstone, mostly Devonian and Silurian, brown is shale, mostly Ordovician. Light blue is carbonate rocks, mostly Ordovician. Yellow-green is Cambrian quartzite. Other green units are metamorphic, with darker denoting higher grade. Pink is granitic. Dark blue are cataclastic rocks. Purple lines are faults. Light blue lines are Interstates, red are US highways, magenta are other roads.
The Blue Ridge Mountains have a core of Precambrian metamorphic and igneous rocks. These rocks are mostly Grenvillean, about a billion years old. West of the Blue Ridge are the folded rocks of the Valley and Ridge Province. The intricate faults in the diagram above are gently dipping thrust faults. Most of the rocks on the skyline drive are metamorphic.
Topographic map of Shanandoah National Park (outlined in light blue). Lambert Conformal Conic, standard parallels at 30 and 50 N, 100 meters per pixel. Grid lines at 0.1 degree intervals, north to upper right.
What a difference a day makes. My first and only visit to shenandoahNational Park, for a long time, was in 1970 on a gray and hazy day |
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Then in 2016, I made the drive again on a bright and crystal clear day. | |
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Created 04 September 2012, Last Update 09 June 2020