At the end of the last Ice Age, around 11,000 years ago, the high plains of what is now west Texas and eastern New Mexico, called the Llano Estacado or the Southern High Plains, were covered by rich grassland savannas. The plains were dotted with playa lakes, that supported a wide array of animals and plant life, including water-loving species such as muskrat, turtles, ducks and fish, and larger animals including now-extinct megafauna such as bison, mammoth and horse.
The first human beings in the Llano Estacado were Clovis, who arrived in the region by 11,000 years ago at numerous waterholes throughout the region, such as the archaeological sites of Blackwater Draw, Lubbock Lake, San Jon and Plainview. According to the most recent studies, Clovis people followed a generalized hunter-gatherer strategy as a way of life, that in the southern high plains included but wasn't limited to now-extinct megafauna such as mammoth, mastodon and horse.
Hunting and gathering is a time-tested, extremely successful living strategy, because it relies on a wide variety of foods in a wide variety of environments, plants and animals both, and it can be easily adapted as conditions change and the availability of certain foods change.
Onset of the Altithermal
And about 7500 years ago, conditions did change. A continent-wide dry spell began, called the Altithermal by archaeologists, with sustained summer droughts and higher average temperatures. Climate change on such a wide scale was most extreme in the Llano Estacado, drying up streams and waterholes, dropping the water table by as much as three meters (nine feet) and turning the once fertile savannas into dry steppes. The bison left, and so did most of the people. Population density in the Llano Estacado plummeted.
But not everybody left. Human occupation in the Llano Estacado in the Archaic period is known to have occurred in a few areas. At some sites, such as Blackwater Draw (New Mexico), Mustang Springs (Texas) and McClellan Wash (Arizona), archaeologists have discovered evidence of hand-excavated wells, at least fourteen at Blackwater Draw, eight at McClellan Wash, and perhaps as many as sixty at Mustang Springs.
Dealing with Drought
The levels from which the Archaic period wells were dug reveal a drastically different climate from that of the post-Pleistocene, as shown by sandy wind-eroded soils with little vegetation. The wells are between 1.5 and 2 meters (4-7 feet) in depth, and have oval or rectangular openings between 75 and 100 centimeters (2-3 feet) in diameter. The wells have straight or nearly straight walls, although in some cases at Blackwater Draw steps were cut into the walls for easy access. The wells were either allowed to fill in naturally (at Mustang Springs), or were deliberately filled shortly after use. In at least two cases at Blackwater Draw, the wells were re-excavated and used a second time, their walls relined with red clay.
Reuse of wells is not in evidence at Mustang Springs, where excavator David Meltzer described finding over sixty pits of varying depths and sizes in a pattern he characterizes as a "wellfield", a place used specifically for obtaining water during the worst period of the Altithermal, a 200 year stretch somewhere between 6800 and 6500 years ago. In some of the wells at Mustang Springs, bore holes extended the well depth another 50 to 75 centimeters.
Technology of the Archaic People
Bear in mind that hunter-gatherers of the American high plains did not have access to metal implements. The wells had to have been dug by hand. Evidence for excavation strategies has been found at Mustang Springs where one of the well's walls retain marks of the digging stick used to excavate it, and a broken ground stone tool interpreted as a well-digging stone was recovered in the bottom of another well. Interestingly, at Blackwater Draw recent faunal analysis of the few bison bones found in levels dated to the Altithermal were desiccated and broken before burial; and eleven pieces of bison scapula (shoulder blades) were noted.
Elsewhere on the plains, bison scapula were used as digging implements. Unfortunately, the context and integrity of the bison bones precludes making this interpretation (of mine, admittedly) speculation at best.
The Drought Eases
Eventually, by about 4000 years ago, the drought conditions eased and people and fauna moved back into the now semi-arid Llano Estacado: most of the wells here were abandoned about that time. Interestingly, the McClellan Wash wells in southern Arizona were excavated about 3000 years ago, a thousand years after the easing of the drought: and scholars argue that they were dug to make water more reliable.
But the wells of the mid-Holocene period high southern plains speak to the resilience of the hunter-gatherer lifestyle, and the elastic human response to adverse conditions.
Sources
This glossary entry is a part of the About.com guide to the American Archaic Period, and the Dictionary of Archaeology.
At the Blackwater Draw site between Clovis and Portales New Mexico, an excavated Clovis period well is open to the public. Many thanks to David Meltzer (Southern Methodist University) and Joanne Dickenson (Eastern New Mexico State University) for their assistance with this article. Any errors are mine.
Cannon MD, and Meltzer DJ. 2004. Early paleoindian foraging: Examining the faunal evidence for large mammal specialization and regional variability in prey choice. Quaternary Science Reviews 23:1955-1987.
Evans GL. 1951. Prehistoric Wells in eastern New Mexico. American Antiquity 17(1):1-9.
Green FE. 1962. Additional notes on prehistoric wells at the Clovis site. American Antiquity 28(2):230-234.
Meltzer DJ. 1999. Human Responses to Middle Holocene (Altithermal) Climates on the North American Great Plains. Quaternary Research 52(404-416).
Meltzer DJ, and Collins MB. 1987. Prehistoric water wells on the Southern High Plains: Clues to Altithermal climate. Journal of Field Archaeology 14:9-28.
Wright DK, Waters MR, Loendorf C, Woodson MK, Miles WD, and Darling JA. 2013. Late Archaic wells on the Gila River Indian Community, Arizona. Journal of Archaeological Science 40(1):45-57.
