Subterranean Fishes of the World

5182

2004

Journal of Cave and Karst Studies

113

66

Sinking Valley, Blair County, Pennsylvania, is a 17-kilometer-long anticlinal valley. It has the shape of an inverted V, open to the northeast and bounded on the east and west sides by Brush Mountain which follows the plunging fold of the anticline to form the apex of the V. The northern boundary, crossing the open end of the V, is the Little Juniata River which crosses the structure at right angles and defines regional base level. Upper Ordovician cavernous limestone outcrops along the base of the mountain. Mountain runoff sinks along the perimeter and drains internally to Arch Spring, the head of Sinking Run. Tytoona Cave is a master trunk consisting of segments of open channel connected by sumps. Dye tracing shows a connection between Tytoona Cave and Arch Spring and also a connection directly to the Juniata River. Analysis of surface drainage, channel and cave profiles, the dye trace, and reports of divers, indicate a complex history for Tytoona Cave: first a master conduit, then an abandoned upper level, then reactivation to its present use as an overflow route. Evidence for a previous dry phase is provided by stumps of massive stalagmites now nearly buried in the sediment of the active stream. Divers have found the final sump to descend to at least 25 meters, close to regional base level. A lower level flooded conduit is predicted, extending to the Juniata River, 3 kilometers away. What seemed to be a simple master trunk system has a much more complex history.

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