Ancient Discoveries

By Julie Francis

SUBLETTE COUNTY — Some wildlife biologists have suggested that migration of pronghorn from the Green River Basin to Jackson Hole dates to modern times, but archaeological evidence clearly shows that the Trappers Point corridor has been used for at least 7,000 years.

The narrow ridge between the Green and New Fork rivers provides an ideal setting for intercept hunting, especially during the migration seasons, and Native Americans took full advantage of the bottleneck, as revealed by abundant remains of the butchering and processing of pronghorn along the Trappers Point ridge system.

A rare combination of geologic factors has lead to the preservation of this evidence. Most of the upland surfaces along the Green River have been severely deflated by the strong western and southwesterly winds which often rage across the basin. As these winds hit the north-south Trappers Point ridge, windblown sands accumulate on the leeward side. Formation of this sand shadow began as early as 9,000 years ago and continual accumulation of sand has buried the archaeological remains.

During the early 1990s, excavations in advance of WYDOT construction at Trappers Point uncovered broken and battered pronghorn bone, hearths used for marrow and grease extraction, and points, tools, and lithic debris, all left at the site between 7,800 to about 3,000 years ago.

Pronghorn fetal remains found in one of the levels indicate that the animals were killed in the spring, coinciding with the modern migration period.

Projectile points found in the bone bed and near hearths exhibit a variety of styles typical of the southwestern Wyoming, Utah and the western slope of Colorado. The stone from which these tools were made also came from a variety of sources around the margins of the Green River Basin, suggesting that ancient people gathered in this area for spring hunting for thousands of years.

Though no specific evidence of a trap or corral was found, the steep slope of the leeward side of the ridge, loose sand, and snow drifts could have been used to trap animals as they moved along the slope during their migration.

Other sites investigated prior to highway construction paint a much different picture of human usage of the upper Green River Basin. Prior to modern agriculture, the wet meadows of the floodplains would have supported significant quantities of roots and tubers such as wild onion, biscuit root, yampa and death camas.

Thousands of deflated hearths and scatters of firecracked rock on the upper terraces give testament to intensive usage of these plants. Once baked, the roots are easily dried and stored for future use. One extremely well-preserved hearth, dated to about 4,000 years old, contained large amounts of charred roots. Assuming biscuit root was baked in this huge pit, one use could have provided about 12% of the calories for a family of four for a year.

All told, these ancient discoveries point to the extremely important role the resources of the upper Green River Basin held for the ancient hunter-gatherers of the region.