spelaean

This region is part of a Spelean province composed by Neoproterozoic carbonatic rocks known as Serra da Ibiapaba, originating in the Upper Neogene-Quaternary according to Auler et al.

When the level dropped, the stalagmites formed from water drops from the cave ceiling (spelean calcite).

You can sit on a bench, pick up another receiver, and have Sonnabend's whole theory laid out for you through a series of haunting dioramas of variously intersecting (and compoundingly complexifying) cones and planes, complete with a representation of such technical subtleties as the perverse and obverse experience boundaries, the Spelean Ring Disparity, "the Hollows," and, perhaps most provocatively, the Cone of Confabulation.