This is the paradox at the center of the Mammoth Cave archaeological story.

The cave preserved everything except the thing you most want to understand: why these minerals mattered enough to justify three thousand years of sustained underground effort.

The hypotheses — ritual use, trade, medicine, pigment, agricultural amendment — are all consistent with what the evidence allows.

None of them is established by direct evidence.

The minerals were important; they were collected in large quantities over a very long time; they were taken to the surface and presumably used for specific purposes; and those purposes have left no trace in the archaeological record that current methods can read.

George Crothers, the state archaeologist for Kentucky, and Ed Jakaitis, the cultural resource manager at Mammoth Cave National Park, have worked to document and interpret the cave’s archaeological record in ways that acknowledge this fundamental uncertainty.