Wind Cave National Park

This view shows detail of boxwork - an unusual pattern on the surface of the limestone roof. Calcite precipitated in fractures in the limestone. Later, as the caverns began to form by dissolution of the limestone, the calcite that had filled the fractures was more resistant. As the regional groundwater table slowly migrated downward, the caverns (with boxwork preserved) were left high and dry (Feldmann, 1997; NPS, 2009).