Evidence for Younger Dryas global climate oscillation and human response in the American Southwest

Folsom on the Edge of the Plains: Occupation of the Estancia Basin, Central New Mexico

“…Refining the chronology of Lake Estancia and evidence for a YDC high-stand of the lake lends support to the idea of an attractive environment for human and animal populations. A YDC rebound in lake levels after 11,000 14 C yr BP, during Folsom occupation, would have opened up a suite of resources to Folsom not available to Clovis groups before or later occupations in central New Mexico (Ballenger et al 2011). Folsom sites associated with playa and draw features have been well documented throughout the Southwest and southern Plains (Holliday 1995;Judge 1973;Judge and Dawson 1972).…”

“…Waters and Stafford (2007) have constrained the Clovis period to between 11,500 and 10,900 14 C yr BP, which suggests that the earliest potential Clovis occupation of the Estancia Basin would have occurred when there was virtually no permanent surface freshwater in Lake Estancia. However, the record suggests a final lake high stand dating between 11,500 and 9700 14 C yr BP at ∼1865 m (Ballenger et al 2011). This recorded period of high-stand conditions would correspond to Folsom occupation of the basin, which dates from 10,900 to 10,400 14 C yr BP (Haynes et al 1992;Holliday 2000).…”

“…This calcareous mud deposition continued until ∼7000 14 C yr BP, suggesting that mountain front recharge and effective moisture had increased from the previous terminal Pleistocene levels during Clovis occupation. Finally, firm evidence for Holocene high-stands of Lake Estanica is a 14 C date of ∼9200 14 C yr BP of an aquatic snail (Succinea) found in a near-shore carbonate deposit (Ballenger et al 2011). These high-stands would have opened a range of resources to humans unlike any conditions in central New Mexico today.…”

“…Reitze and Kowler (reported in Ballenger et al 2011) have worked to refine the late Pleistocene chronology originally presented by Allen and Anderson (2000). Work by Reitze on the upland portion of the basin system through sediment cores from playa and draw records as well as more detailed radiocarbon dating of shell from beach deposits by Kowler and Reitze were conducted to further refine this record (Table 1) (Ballenger et al 2011).…”

“…Directly applicable to human occupation of the basin is a freshwater high-stand after a dry period of shallow, brackish water at a maximum elevation of ∼1875 m between 13,800 and 12,500 14 C yr BP (Ballenger et al 2011). Based on Allen and Anderson's (2000) 14 C age model this is followed by a period when the lake would have been fully desiccated likely by 11,500 14 C yr BP.…”