A single bundle probably lasted between thirty minutes and an hour — estimates based on the length of charred sections found in the cave and on experimental archaeology that has tried to replicate the conditions.

A round trip of several miles underground, in passages where the route involved climbing and scrambling and searching for mineral-bearing walls, would require multiple torch bundles.

Archaeologists have found caches of unburned torch material in passages deep inside the cave — reserves that miners brought in but never used, left behind when they departed or when the trip went wrong.

They have found the charred ends of burned torches discarded where they were dropped.

They have found sections of torchlight navigation recorded, in a sense, in the cave’s ceiling — passages where the soot from burning cane torches has blackened the rock above ancient routes, marking where people walked by the residue of their light.