Site Taphonomy and Cultural Traditions in NW Colorado

A few weeks ago I presented a paper at the CCPA meetings in Alamosa (Bandy and Baer 2009). It was based on some work SWCA did in 2008 in the Piceance Basin in Rio Blanco County, northwestern Colorado. We block surveyed almost 140 square miles and recorded almost 400 prehistoric archaeological sites.

There is a low-level but persistent controversy concerning cultural traditions in the Piceance Basin during the Formative Era (400 B.C.E. to 1300 C.E., approximately; Reed and Metcalf 1999). The region is adjacent to major concentrations of Fremont culture settlement in lower elevation areas to the West, particularly in nearby Douglas Creek, but also in Dinosaur National Monument, and in the Uinta Basin and along the Green River in Utah. The Piceance Basin is located in middle elevations, between roughly 6000 and 8000 feet, and is too high for all but the most marginal maize cultivation. There were never any permanent Fremont farming settlements in the region as far as we can tell.

The question therefore arises: do the Formative Era sites in the Piceance Basin reflect seasonal use of the area by Fremont populations resident in farming settlements at lower elevations, or was there an indigenous population in the Piceance and similar areas that was contemporary with but distinct from the Fremont, and that possibly derived from local Archaic populations? Or do Formative Piceance Basin sites reflect some mixture of Fremont seasonal use and local hunter-gathers?

This question is as old as archaeological research in the Piceance Basin. Jennings (1976) proposed that Piceance Basin Formative sites were produced by a local, non-Fremont population with an Archaic-style hunter-gatherer adaptation. He posited an ethnic frontier between this unnamed local population and the Douglas Creek Fremont. This frontier would presumably have been located somewhere in the vicinity of Cathedral Bluffs. Reed and Metcalf (1999) offered a similar scenario, proposing a new term, the Aspen Tradition, to describe these Archaic-style hunter-gatherers living in northwestern Colorado (in the Piceance Basin and elsewhere).

On the other hand, Grady (1980) suggested that the Piceance Basin (and the Roan Plateau) was used seasonally by Fremont peoples who farmed at lower elevations (Douglas Creek, Dinosaur National Monument). In his scenario, the Fremont would have planted in the Spring in lower elevations, hunted and gathered in the late Spring/early Summer in the Piceance, spent the Summer in higher elevation areas such as the Roan Plateau, and returned in the Fall to the Piceance Basin and in the late Fall to their low-elevation fields for the harvest and the Winter. Byron Loosle has proposed a similar model for the Uinta Mountains of Utah, though the mobility he envisions is less transhumant and more logistically organized.

What interests me is the way in which these arguments are constructed and supported. In general, very little evidence is used. Grady, for example, bases his argument mainly on an abstract model of how humans should exploit the environment of northwestern Colorado. Reed and Metcalf (1999) assert that Formative Piceance Basin sites are "not Fremont" and therefore are related to a different archaeological culture: their Aspen Tradition. However, since Aspen Tradition peoples are postulated to have used small, corner-notched arrow points, identical to Fremont examples, as well as nondescript grayware ceramics, it is not clear what Reed and Metcalf's expectations would be for Fremont seasonal campsites. Apart from temporary campsites containing Fremont ceramics and projectile points, what more can reasonably be expected?

Reed and Metcalf's argument seems to be reducible to the single assertion that there is not much Fremont material culture in the Piceance Basin. This does not include Fremont-style projectile points which, of course, are abundant. They seem to be impressed mainly with the paucity of Fremont ceramics in the area. However, since the area never supported permanent agricultural settlements, Fremont sites in the area would all be impermanent campsites and resource extraction locales. Since ceramics have a long use-life (generally estimated at > 1 year for a cooking pot) and campsites have a short duration (probably a month or less), only a small percentage of Fremont campsites would be expected to contain ceramic sherds and therefore to be recognized as Fremont.

Several approaches to estimating the percentage of Fremont campsites that are aceramic converge on a figure of about 90%. That is, no ceramic vessels were broken or deposited at approximately 9/10 of Fremont seasonal campsites in the Piceance. When this is taken into consideration, the entire Formative Era occupation of the Piceance Basin can easily be accounted for by Fremont seasonal use. No sites remain unaccounted-for and the Aspen Tradition is therefore analytically superfluous. There is simply no reason to posit the presence of any cultural tradition in the Formative Piceance Basin apart from Fremont.

The importance of this kind of simple Middle Range Theory insight (derived from a recognition of the critical role played by a site's length of occupation in the formation of its artifact assemblage) is seldom appreciated in a hunter-gatherer context. And yet it is precisely in these contexts that the effects of short occupation spans will be most pronounced.

Here's the abstract:

Reed and Metcalf proposed the Aspen Tradition in order to account for Formative Era archaeological remains in the northern Colorado River Basin that seemed not fit into existing taxa such as Fremont or Anasazi. In their argument, they suggested that the Formative Era occupation of the Piceance Basin was dominated not by Fremont seasonal hunting camps (as had been proposed by Grady) but rather by highland-adapted groups similar to and perhaps directly descended from the region's Archaic Era inhabitants. In 2008, SWCA Environmental Consultants conducted extensive block surveys in the Piceance Basin, resulting in the recording of hundreds of archaeological sites representing all periods of regional prehistory. These data make possible a preliminary evaluation of the taxonomic affiliations of the region's Formative Era archaeological remains. Our analysis indicates that Fremont seasonal use can adequately account for the entire Formative Era archaeological record of the project area. The question must therefore be asked: is there any reason to postulate a poorly-defined taxonomic unit such as the Aspen Tradition when the archaeological record can be adequately explained without it?

References Cited:

Bandy, Matthew S. and Sarah Baer
2009 The Formative occupation of the Piceance Basin: Is the Aspen Tradition analytically superfluous? Paper presented at the Colorado Council of Professional Archaeologists annual meeting, Alamosa, CO, April 3.

Jennings, Calvin H.
1976 An assessment of the potential cultural resources of the proposed utility corridors for the C-b oil shale lease tract. Laboratory of Public Archaeology, Colorado State University, Fort Collins.

Grady, James
1980 Environmental Factors in Archaeological Site Locations. Bureau of Land Management Cultural Resource Series 9. BLM, Lakewood, CO.

Reed, Alan D. and Michael D. Metcalf
1999 Colorado Prehistory: A Context for the Northern Colorado River Basin. Colorado Council of Professional Archaeologists, Denver.