Sinkhole may exhibit a visible opening into a cave below. In the case of exceptionally large sinkholes, such as the Minyé sinkhole in Papua New Guinea or Cedar Sink at Mammoth Cave National Park in Kentucky, an underground stream or river may be visible across its bottom flowing from one side to the other. Sinkholes are common where the rock below the land surface is limestone or other carbonate rock, salt beds, or in other soluble rocks, such as gypsum, that can be dissolved naturally by circulating ground water. Sinkholes also occur in sandstone and quartzite terrains. As the rock dissolves,
Devil's Sinkhole State Natural Area Devil's Sinkhole State Natural Area Devil's Sinkhole State Natural Area is a natural bat habitat near the city of Rocksprings in Edwards County in the U.S. state of Texas. Home to the Mexican free-tailed bat, access to the area is available only through advanced reservations. The Devil's Sinkhole is a vertical natural bat habitat. The opening drops down to reveal a cavern some below. The cavern was first discovered by local residents in 1876. H. S. Barber carved his name inside the cave in 1889. The area was transferred to the state of Texas in 1985, and open to the