Sandstone is porous, allowing drainage that prevents waterlogging, which is one of the conditions most destructive to bone.

The sandstone’s calcium carbonate cement tends to create an alkaline microenvironment that inhibits the acid dissolution of bone mineral and slows the microbial degradation of collagen.

And the consolidation of the sandstone matrix around the burial materials provided some physical protection against the mechanical disruption that would otherwise occur as the overlying deposits shifted over millennia.

The red ochre coating on the bones and artifacts may have contributed to preservation as well.

Some experimental studies have suggested that ochre can inhibit microbial growth on bone surfaces and may help maintain the organic fraction of bone over time.