Cultural Dynamics and Transitions in the Northern Southwest

Animas-La Plata Archaeological Project
1992-1993 Investigation in Ridges Basin, Colorado

Editors
Susan A. Gregg
Francis E. Smiley

The U.S. Department of the Interior, Bureau of Reclamation, Animas-La Plata Project entails the construction of a large water impoundment in the Ridges Basin, south of Durango, Colorado. The construction involves building a dam across Basin Creek, removing previous dam fill material from Blue Mesa, tree clearing and removing impervious dam fill material from Ridges Basin, flooding all cleared lands in the basin lying below the elevation of approximately 7000 feet ASL, and several ancillary activities. The construction will destroy or damage archaeological sites in all parts of the project's primary impact zone; other activities may eventually affect sites in a large, surrounding zone of secondary impacts.

Surveys and excavations in the project area have identified 98 prehistoric archaeological sites within the primary impact zones in Ridges Basin or on Blue Mesa. An additional 54 sites occur within secondary impact zones inside the project boundaries in Ridges Basin. These 152 sites contain a minimum of 179 components of Archaic, Basketmaker II, puebloan, and protohistoric. occupation. Other sites are present on Blue Mesa as well, but will not be impacted by the project and so are not considered further here. Our research design specifically concerns all sites within the project takeline in Ridges Basin and all sites within the primary impact zones on Blue Mesa.

Nineteen sites lie in areas where construction will begin first; these are designated as Priority I sites by Reclamation. The remaining 79 sites in the primary impact zones are designated as Priority 2. The 54 sites in the secondary impact zones within Ridges Basin are hereafter referred to as Priority 3 sites. The site survey data for the overall project area have been evaluated several times (CASA n.d.; Fuller 1989; Ware 1986) (Bureau of Reclamation Determination of Eligibility) with some variation in assigning site ages and identifying multiple components. We have used Attachment A of the Reclamation Solicitation and the State of Colorado site files (CASA n.d.) as our primary guides for identifying site ages and the presence of multiple components.

The 179 components among the 152 sites considered in this research design have the following characteristics: 31 sites have components of probable Archaic age, including four Priority 1 sites, nine Priority 2 sites, and eighteen Priority 3 sites mostly in the northern and western portions of Ridges Basin. Sixteen sites have components of probable Basketmaker II age, including two Priority 1 sites, ten Priority 2 sites, and four Priority 3 sites also mostly located along the north side of Ridges Basin. One-hundred-nineteen sites have components of Pueblo I age, including 15 Priority 1 sites, 70 Priority 2 sites, and 34 Priority 3 sites. There are also five possible components of other, later puebloan ages (Pueblo II or III), including one Priority I site, two at Priority 2 sites and two at Priority 3 sites. Eight sites have protohistoric components, including one in Priority 1, three in Priority 2 and four in Priority 3.

Overall, 132 sites show surface remains from only one period of use; 14 have surface remains from two periods of use; and 6 have surface remains from at least three periods.

The Archaic components in the total project area probably date primarily to the Late Archaic period, specifically between ca. 2000 B.C. and A.D. 100, based on recent work at similar sites adjacent to the project area (Fuller 1988a) and in the Dolores River valley (Kane 1986a). However, projectile points of Early, Middle, and Late Archaic age have been recorded in the overall project area (CASA n.d.; Ware 1986).

The precise ages of the Archaic components need to be determined. Previous investigations on lands immediately northeast of the project area and in the Durango area in general (Fuller 1988a) indicate that the Basketmaker 11 components probably date between A.D. 200 and 400, again with considerable room for chronological refinement. These same recent investigations (see also Gooding 1980) and a long history of research in the area also indicate that the Pueblo I components probably date to a narrow time span between A.D. 750 and 825-or A.D. 840 at the very latest. The protohistoric sites may date to the late fourteenth/early fifteenth century entry of the Athapaskans into the Southwest; but more likely are the remnants of more recent Ute use of the area.

The temporal distribution of components in the project area presents an unusual opportunity to examine at least two discrete lifeways with an archaeological record that is only minimally blurred by successive occupations at particular sites. Furthermore, the brevity of the Pueblo I occupation presents a rare opportunity to develop a detailed picture of life within a single community during a fascinating period in regional prehistory. Once its dating has been improved, the Basketmaker 11 period of occupation may turn out to offer a similar research opportunity.

Overall, the four temporal components identified within the project area span a time of significant changes in both the cultures and the natural environment of the region. These changes provide opportunities for several lines of archaeological and paleoenvironmental research. The remainder of Part II, below, summarizes the history of comparable research in the region. This summary is intended as background information, to place the Ridges Basin Project in an historical context. Part III then focuses on the issues and opportunities raised by this previous research, which we will pursue in our research program.