Bear Valley Strip Mine
The Bear Valley Strip Mine is an abandoned strip mine located to the southwest of the town of Shamokin, Pennsylvania. It lies in the Western Middle Field of the Anthracite belt in the Valley and Ridge Province of the Appalachian Mountains, where the Pennsylvanian Llewellyn Formation is exposed. [1]
Due to the coal and other overlying rock being removed by mining down to a resistant sandstone bed, excellent three-dimensional structures of folding and faulting caused by the Alleghany Orogeny are clearly displayed.
The central anticline in the valley is often called the "Whaleback".
The sequence of structural deformation is outlined as follows<ref="Nickelsen">:
| Stage | Deformation event |
|---|---|
| I | Joint formation in coal |
| II | Joint formation with quartz fiber fillings in sandstone and ironstone |
| III | Pressure solution and primary crenulation cleavage |
| IV | Conjugate wrench and wedge faults form |
| V | Large-scale folding |
| VI | Extensional jointing and faulting |
Gallery
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Concretions in the south wall
References
- ^ Sequence of structural stages of the Alleghany orogeny at the Bear Valley Strip Mine, Shamokin, Pennsylvania. Nickelsen, R. P. (Dept. of Geology, Bucknell University) Geological Society of America Centennial Field Guide—Northeastern Section, 1987
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