a wild and deep gorge carved by the south fork of the south branch of the potomac river, the smoke hole canyon is one of the most unique features of the central appalachian mountains. It is home to many rare and endangered plant and animal species, and the rock outcroppings along its rim are exposures of 400 million year old ordovician limestone which are full of scallop-like brachiopod shells. There are many places in this strata where the rocks are literally made of these shells, the children of a warm, shallow sea many ages ago...