They are complete only to the extent that they preserve the things you most want to know, and Mammoth Cave’s archive has a fundamental gap at the most important point.

The minerals are gone.

The gypsum, the mirabilite, the epsomite — these did not survive in the cave in the form of the miners’ product.

The caches of processed mineral that the miners presumably carried back to the surface, the containers they used to transport it, the uses to which it was put once it arrived above ground — all of this is absent from the archaeological record.

The archive preserved the tools and the waste and the travel evidence, but not the purpose.