It is not known whether he reached bedrock or a large boulder.
In any case, the deepest known deposits consist of stream-rolled gravels, suggesting that the shelter was periodically flooded prior to the formation of the site's earliest known bone beds.
Apart from the roof blocks, the most prominent topographic feature in Bonfire Shelter is the cone-shaped debris pile ("talus cone") directly beneath the notch in the cliff.
Many of the buffalo in Bone Bed 3 landed atop the talus cone and tumbled into the cave.
Follow the contour lines down from the high point and you will see that the lowest part of the original surface of Bonfire Shelter is actually at the back of the shelter, rather than at the front as is often the case with most rockshelters.
Archeological excavations have only penetrated through the upper 13 feet (4 meters) of the shelter's deposits, but landowner Jack Skiles drove an iron rebar down nearly 10 feet (3 meters) before encountering impenetrable rock.The fallen rocks formed a natural barrier or wall that closed in the mouth of the shelter.Because of this feature, Bonfire Shelter is practically invisible from the canyon floor.The contour lines are shown only for the parts of the shelter that had buried deposits; the stippled roof blocks at the front of the shelter jut up from the "floor" as can be seen in the photographs.The most dramatic topographic feature shown by the contour lines is the talus cone situated directly under the cleft in the cliff above the shelter.Because of the roof blocks and the talus cone as well the brush and small trees growing around these features, Bonfire Shelter is all but invisible from the canyon floor below.