Geology
The Shenandoah valley is underlain by limestone. The fertile soil made it a favored place for early settlement. It continues to be a major agricultural area of Virginia and West Virginia. Some karst topography is evident, and the limestone is honeycombed with caves. Several have been developed as commercial tourist attractions, including Luray Caverns, Shenandoah Caverns, and Skyline Caverns.
On the riverbank a few miles above Harper's Ferry is said to be a cave with an opening just large enough for a mounted rider to squeeze through. It widened in the interior to a spacious room where hundreds of Col. John Mosby's raiding troops are said to have hidden from pursuing Union cavalry.
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