Home |  PublicationsEncyclopedia |  Summers Site

The Encyclopedia of Oklahoma History and Culture


From 5000 B.C. to 1200 B.C. the Altithermal, a drought of a severity unimaginable to its modern inhabitants, beset the Great Plains. The southwestern Great Plains turned from grassland to desert, and there was very little evidence of human habitation of the region during this time. This Altithermal virtually depopulated western Oklahoma and adjacent parts of Texas for several thousand years.

The Summers Site, in Greer County, appears to be the earliest excavated post-Altithermal archaeological site on the southwestern Great Plains. A radiocarbon assay of woody charcoal from a rock-filled cooking pit, also containing bison bone, has been dated to about 2,900 years ago (circa 900 B.C.). Current geoarchaeological research in western Oklahoma has indicated that the canyon systems began rapidly filling with sediment about 1200 B.C. in response to increasing rainfall, so the radiocarbon date from Summers has been considered reasonable from that perspective.

However, chipped stone artifacts from Summers suggest a much later date for the site. Corner-notched dart points, bifacial knives and choppers, and simple, unifacial flake tools made of Ogallala quartzite, Alibates agate, and various cherts from Ogallala Formation gravels have been typical of Late Archaic cultures of the region.

Radiocarbon dates from well-documented Late Archaic sites in western Oklahoma and the Texas Panhandle indicated that people did not return to the area for a lengthy period after the Altithermal. Although there has been limited evidence of Late Archaic people killing bison at the Certain site as early as 400–350 B.C., most dates from southern plains Late Archaic sites fall in the time span 1–400 A.D. It is likely that the Summers Site actually dates around the time of the Christian era or slightly later.

John Peter Thurmond

Browse By Topic

Precontact Era



Learn More

Leland C. Bement and Kent J. Buehler, "Preliminary Results from the Certain Site: A Late Archaic Bison Kill in Western Oklahoma," Plains Anthropologist 39 (May 1994).

C. Reid Ferring, The Late Holocene Prehistory of Delaware Canyon (Denton: North Texas State University, Institute of Applied Sciences, 1982).

Jack L. Hofman, From Clovis to Comanchero: Archeological Overview of the Southern Great Plains (Fayetteville: University of Arkansas, Arkansas Archeological Survey, 1989).

J. Michael Quigg, "A Late Archaic Bison Processing Event in the Texas Panhandle," Plains Anthropologist 43 (November 1998).

J. Peter Thurmond, "Archeology of the Dempsey Divide, a Late Archaic/Woodland Hotspot on the Southern Plains," Bulletin of the Oklahoma Anthropological Society 39 (1991).

J. Peter Thurmond and Don G. Wyckoff, "The Calf Creek Horizon in Northwestern Oklahoma," Plains Anthropologist 44 (August 1999).

Don G. Wyckoff, "Archaic Cultural Manifestations on the Southern Plains," Journal of American Archaeology 5 (1992).


The following (as per The Chicago Manual of Style, 17th edition) is the preferred citation for articles:
John Peter Thurmond, “Summers Site,” The Encyclopedia of Oklahoma History and Culture, https://www.okhistory.org/publications/enc/entry?entry=SU006.

Published January 15, 2010

Copyright and Terms of Use

No part of this site may be construed as in the public domain.

Copyright to all articles and other content in the online and print versions of The Encyclopedia of Oklahoma History is held by the Oklahoma Historical Society (OHS). This includes individual articles (copyright to OHS by author assignment) and corporately (as a complete body of work), including web design, graphics, searching functions, and listing/browsing methods. Copyright to all of these materials is protected under United States and International law.

Users agree not to download, copy, modify, sell, lease, rent, reprint, or otherwise distribute these materials, or to link to these materials on another web site, without authorization of the Oklahoma Historical Society. Individual users must determine if their use of the Materials falls under United States copyright law's "Fair Use" guidelines and does not infringe on the proprietary rights of the Oklahoma Historical Society as the legal copyright holder of The Encyclopedia of Oklahoma History and part or in whole.