[2]: xii  The largest known cave along the North Fork, it is believed to have been carved by the river's flow; the reason for its diversion away from the alcove is unknown.

[1] Discovered by Cody resident Gene Smith in 1957,[5] it was first studied in 1962 and excavated by the Buffalo Bill Historical Center.

The site includes unusual amounts of perishable materials such as hide, feathers and wood, as well as the buried and mummified remains of an inhabitant, named by researchers "Mummy Joe," and dated to about AD 800.

[2]: 8 [4] The cave fill has accumulated for at least 10,000 years and appears to have originated from nearby debris fans formed where weathered material has flowed down channels in neighboring cliffs.

[2]: 31 The site had previously been disturbed by relic hunters, who had dug a 2.5 feet (0.76 m) deep pit in what turned out to be the most productive zone of the excavation.

The relic hunters appear to have stopped when they encountered a rock cairn that covered what proved to be a human burial site.

The excavation of Mummy Cave yielded a nearly continuous succession of artifacts, which span a period of over 9000 years.

[2]: 29 The earliest layers at Mummy Cave yielded a few prismatic stone blades dating to about 7300 BC.

[2]: 115  This implies that the inhabitants of Mummy Cave during this era were big-game hunters from the Great Plains who adapted to the mountain environment.

[2]: 118–19  The presence of such points suggests a connection with the Simonsen site in northeastern Iowa,[4] which has been dated to the Early Archaic period.

[2]: 118–19  Side-notched points recovered from layers 21, 24 and 28 imply a return of the previous inhabitants; the easterners had moved on to the central Columbian Plateau.

As at many other archeological sites in the region, significant numbers of Bighorn Sheep (Ovis canadensis) and deer from the genus Odocoileus were identified.

This anomaly has led researchers at UTEP to propose that the site was used as a home base for hunters to operate at higher altitudes.