LATE PALEOARCHAIC OCCUPATION OF THE OLD RIVER BED DELTA, BONNEVILLE BASIN, WESTERN NORTH AMERICA

During the regressive phase of Lake Bonneville, the two major sub-basins of the Bonneville basin were connected by a river that channeled overflow from the Sevier Basin northward into the Great Salt Lake Basin in what is now the Great Salt Lake Desert of western Utah. Beginning about 12,500 ¹⁴C yr BP, the river in the Old River Bed (ORB) was a relatively large, high-energy river composed essentially of enlarged versions of all the rivers and streams that now flow into the Sevier Basin. Until about 11,000 ¹⁴C yr BP, this river formed “gravel channels” that are straight to curved, digitate features with abrupt bulbous ends, composed of fine gravel and coarse sand. In the area of the ORB delta these channels are topographically inverted (i.e., stand higher than the surrounding mudflats). From about 11,000-8800 ¹⁴C yr BP flow in the ORB was reduced, forming “sand channels” with well-developed meander-scroll morphology that is truncated by deflation of the mudflat surfaces. These meandering channels flowed through an extensive marsh/wetland ecosystem, up to 600 km² in size.

During the “sand channel” period, the ORB delta was occupied by Paleoarchaic foragers who used the topographically inverted “gravel channels” to reach and utilize the marsh resources in the delta wetlands. Surveys of 52 km of more than 200 linear km of gravel and sand channels on Dugway Proving Ground (DPG) have identified 51 Paleoarchaic sites. Together with work north of DPG, these surveys suggest the ORB delta may contain as many as 500 or more Paleoarch Late Paleoarchaic Occupation of the Old River Bed Delta, Bonneville Basin, Western North America aic sites. The sites are characterized by Great Basin Stemmed points and crescents, many of which are extensively reworked. Basalt tools are also common. These are composed primarily of large cores and bifaces from which flakes were struck, apparently for use in processing marsh resources. Toolstone sources are limited in comparison to other Great Basin Paleoarchaic sites and mobility patterns also appear to have been much different. Whereas movement within the ORB wetlands may have been frequent, movement away from the delta was probably infrequent relative to the mobility characteristic of Paleoarchaic foragers elsewhere.