The Mesa Verde region, which is generally considered to correspond to southwestern Colorado and southeastern Utah, or alternatively to the northern portion of the San Juan River watershed, has been one of the most intensively studied parts of the prehistoric southwest. This is due to a variety of factors over the decades, most importantly the early work of the Wetherills and the more recent work of the Crow Canyon Archaeological Center. The seventh chapter of The Prehistoric Pueblo World, about this region, draws mainly on the work of the latter, which sponsored the conference from which the book originated. The authors are Mark Varien, Bill Lipe, Michael Adler, Ian Thompson, and Bruce Bradley, all of whom have been associated with Crow Canyon in various ways and to various degrees over the years.
This chapter takes a somewhat broader perspective than that taken by many of the others in the volume. In addition to the rather large geographical area covered, the authors look at the evolution of settlement patterns over a much longer time period than the “Pueblo III” or “Post-Chaco” period, roughly AD 1150 to 1350, that is the main focus of all of the chapters. This long view functions mainly as context for the discussion of Pueblo III developments, to be sure, but that’s important context to have in a region with such a long and complicated history of occupation.
The main issues of importance during the Pueblo III period in the Mesa Verde area are aggregation and abandonment. As the authors of this chapter observe, neither is an entirely new development; aggregation into villages, some of which were quite large, was a notable feature of the Pueblo I period here, and those villages also seem to have been abandoned rather abruptly around the beginning of the Pueblo II period. It’s not clear exactly what happened, but the whole region apparently underwent a rather severe decline in population at this time. Of the various explanations offered for this, the authors of this chapter prefer the scenario in which the inhabitants of the aggregated villages moved south to the area of Chaco Canyon, where they were instrumental in the rise of the Chaco Phenomenon at around the same time. This would certainly explain both the sudden population growth at Chaco in the early Pueblo II period and the many parallels between the nature of that growth and the earlier development of the northern villages.
In any case, however the rise and fall of the Pueblo I villages is interpreted, it’s quite clear that it happened, which shows that the aggregation and later abandonment of the whole region during Pueblo III was novel only in scale. The authors of this chapter see the key to understanding aggregation in community structure, and particularly in the persistence of communities over time. They present considerable evidence that the Pueblo II period in the Mesa Verde region was a time of dispersed settlement that was nonetheless characterized by organization into defined communities, some (but not all) of which construction Chaco-style great houses in the late eleventh century, rather late in the Chacoan era. Whether they had great houses or not, these communities consisted of loose clusters of small houses or unit pueblos.
In the early Pueblo III period, after the decline of the Chacoan system (whatever it was), these communities began to aggregate, at first just by bringing the dispersed small houses closer together. Later, communities aggregated even more, often into compact, walled compounds surrounding springs or canyon heads. This resulted in the famous cliff dwellings of Mesa Verde and other locations, along with the towers of Hovenweep and other sites that are generally taken as typical of the Mesa Verdean tradition. These impressive, large sites, however, were occupied quite briefly, generally being constructed in the early or mid-thirteenth century and abandoned by 1300.
This process of increasing aggregation culminating in sudden abandonment is seen in other regions, but it is most pronounced here in the north. Various explanations have been offered for it, often focusing on the clear environmental changes taking place in the 1200s that may have caused problems for settled communities dependent on runoff agriculture. These include the “Great Drought” of AD 1276 through 1299, along with a possible shortening of the growing season due to the beginning of the Little Ice Age in the mid-1200s and increased variability in rainfall from year to year. Any or all of these factors may have impacted the established communities in the Mesa Verde area.
However, as the authors note, these environmental problems were not actually enough to entirely explain the process of aggregation and abandonment. Aggregation in particular is difficult to explain by deteriorating environmental conditions, given that it involves more intensive use of the increasingly limited resources in a given location, but even the regional abandonment was clearly not due entirely to the changes. Studies of the carrying capacity of the Mesa Verde region have shown that on a regional level the prehistoric population couldn’t have come close to maxing out the available resources. This region was and is very fertile and, unlike many other parts of the southwest, is a primarily agricultural area even today. Indeed, as the authors point out, a dry year at Mesa Verde is still wetter than a wet year at Chaco or Hopi.
This is not to say that environmental factors are entirely beside the point here. Part of the “in situ” model of aggregation that the authors posit involves substantial traditions of use-rights to particular lands, with the community serving in part as the mechanism for determining the extent of those rights. The upshot of this in a time of deteriorating climatic conditions would be to artificially limit the amount of productive land (whether for farming or for hunting and gathering) available to a given household or community at a given time. The overall result could very well be to make the increasingly large and immobile communities that developed as population increased overly dependent on the resources in a small area and unable to adapt to a series of bad years. While it would be theoretically possible for such unlucky people to move to a different part of the region that was doing better, in practice they may not have had the social right to do so if the land “belonged” to someone else. As a result, local-level environmental problems could end up having regionwide effects, culminating in regionwide abandonment.
As this scenario shows, given the facts at hand even a primarily environmental explanation for abandonment has to take into account social factors such as land-use histories. Another possible social factor, which the authors of this chapter mention but don’t fully explore, is warfare, which could of course ultimately be driven by environmental changes either locally or more broadly. As Steven LeBlanc has argued, the process of aggregation seen in many parts of the Puebloan world, including Mesa Verde, in the Pueblo III period is strongly suggestive of defensive considerations becoming paramount in the minds of the people building the settlements, and the increasingly fortress-like layout of the Mesa Verdean communities toward the end is particularly notable. There is even a certain amount of direct evidence for warfare in the form of burned communities and human remains showing signs of violent death. While the authors of this chapter certainly don’t ignore warfare entirely as a possible cause of the patterns they describe, they don’t give it the kind of centrality that LeBlanc does either. Given the weakness of other explanations, however, I think the possibility of both aggregation and abandonment being primarily warfare-driven deserves serious consideration.
There’s a lot more in this chapter than I have mentioned in this post, and it’s definitely one of the most useful and accessible in the book. One of the main purposes of the book and the conference at Crow Canyon whence it arose was to collect data in an accessible place for future research, and this chapter is a good example of a successful effort to do just that.