Lower Cave

Crystal Caverns formed within Hupp's Hill after limestone strata were compressed when the North American and African tectonic plates collided about 265 million years ago, an orogeny that folded, warped, and cracked miles of rock while lifting the mountains and hills of the Shenandoah Valley. Perhaps as much as 50 million years ago, the limestone solution cave began forming in the warped strata, developing rooms and passages decorated with speleothems as slightly acidic water carrying carbonic acid dripped into the chambers and redeposited calcite taken from the limestone. In the Hall of Masonry, about 60 feet below this point, calcite filled tectonic fissures created during the folding and faulting, features geologists call tension gashes that reflect a rehealing of deformed rock. About 65 feet below the Civil War infantry trench lies the Ballroom, from which the deepest chamber of Crystal Caverns can be seen at or just above today's water table, about 95 feet below the surface; these chambers are thought to be the cave's oldest section and contain speleothems as much as two million years old. Alongside this geology, Hupp's Hill preserves the only surviving remnant of a mile-long Union infantry trench built in 1864, a sod-covered mound with a deep ditch, sharpened stakes, thorn brush abatis, and a revetment that gave Union infantrymen converging fields of fire against Confederate troops advancing up the hill. Civil War soldiers explored the cave, deserters hid there, and it also served as a field hospital and temporary prison pen. On the evening of 19 October 1864, in the last organized action of the Battle of Cedar Creek, a Confederate cavalry rear-guard action on Hupp's Hill held off Union troopers long enough for Confederate infantry to escape, though some artillery and wagons were abandoned after a bridge collapsed in Strasburg.

Strasburg, Virginia · United States