Boneyard: Notice how the limestone here is riddled with holes like Swiss cheese. Explorers named this place "the Boneyard" because the rounded shapes of the rocks reminded them of old bones. When the cave was developing, weakly-acidic groundwater permeated cracks, or "joints," in the limestone. Many holes formed were acid dissolved the rock. After the cave drained, there must have been little dripping water here, because few stalactites or other speleothems formed.