The Bear Valley Strip Mine is an abandoned coal

strip mine Surface mining, including strip mining, open-pit mining and mountaintop removal mining, is a broad category of mining in which soil and rock overlying the mineral deposit (the overburden) are removed, in contrast to underground mining, in whic ...

located in Coal Township, Northumberland County, to the southwest of the town of Shamokin, Pennsylvania. It lies in the Western Middle Field of the Anthracite belt in the

Ridge-and-Valley Appalachians The Ridge-and-Valley Appalachians, also called the Ridge and Valley Province or the Valley and Ridge Appalachians, are a physiographic province of the larger Appalachian division and are also a belt within the Appalachian Mountains extending ...

, where the Pennsylvanian Llewellyn Formation is exposed. The property is owned by the

Reading Anthracite Company Reading Anthracite Company is a coal mining company based in Pottsville, Pennsylvania in the United States. It mainly mines anthracite coal in the Coal Region of eastern Pennsylvania. The company owns the Bear Valley Strip Mine in Northumberland ...

. Sequence of structural stages of the Alleghany orogeny at the Bear Valley Strip Mine, Shamokin, Pennsylvania. Nickelsen, R. P. (Dept. of Geology,

Bucknell University Bucknell University is a private liberal arts college in Lewisburg, Pennsylvania. Founded in 1846 as the University at Lewisburg, it now consists of the College of Arts and Sciences, Freeman College of Management, and the College of Engineering ...

)

Geological Society of America The Geological Society of America (GSA) is a nonprofit organization dedicated to the advancement of the geosciences. History The society was founded in Ithaca, New York, in 1888 by Alexander Winchell, John J. Stevenson, Charles H. Hitch ...

Centennial Field Guide—Northeastern Section, 1987

Structural geology

The coal and other overlying rock has been removed by mining down to a resistant sandstone bed, revealing the three-dimensional structures of

folding Fold, folding or foldable may refer to: Arts, entertainment, and media * ''Fold'' (album), the debut release by Australian rock band Epicure * Fold (poker), in the game of poker, to discard one's hand and forfeit interest in the current pot *Abov ...

and

faulting In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

caused by the Alleghany Orogeny. Students of geology have visited the location for decades due to the quality of exposures. The central

anticline In structural geology, an anticline is a type of fold that is an arch-like shape and has its oldest beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex up in which the hinge or crest is the ...

in the valley is often called the "Whaleback". The sequence of structural deformation is outlined as follows:

Gallery

File:Concretions Bear Valley.jpg,

Concretion A concretion is a hard, compact mass of matter formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. Concretions are often ovoid or spherical in shape, although irregular ...

s in the south wall File:Bear Valley east wall.jpg, View of the east wall from the Whaleback File:Bear Valley Slickensides.jpg,

Slickensides In geology, a slickenside is a smoothly polished surface caused by frictional movement between rocks along a fault. This surface is typically striated with linear features, called slickenlines, in the direction of movement. Geometry of slickens ...

on a fault plane, south wall. Lens cap 5.8 cm wide. File:Stigmaria Bear Valley upright.jpg, Upright ''

Sigillaria ''Sigillaria'' is a genus of extinct, spore-bearing, arborescent (tree-like) plants. It was a lycopodiophyte, and is related to the lycopsids, or club-mosses, but even more closely to quillworts, as was its associate ''Lepidodendron''. Fossil ...

'' in dipping sandstone and shale beds of the north wall. A so-called " Polystrate fossil". File:Bear Valley Whaleback DCP 0776.jpg, Another image of the south wall and Whaleback File:Stigmaria Bear Valley Strip Mine.jpg,

Stigmaria ''Stigmaria'' is a form taxon for common fossils found in Carboniferous rocks. They represent the underground rooting structures of coal forest lycopsid trees such as '' Sigillaria'' and '' Lepidodendron''. These swamp forest trees grew to ...

root fossils

References

Coal mines in the United States Geography of Northumberland County, Pennsylvania Mines in Pennsylvania {{geology-stub