I’m in Cortez, Colorado, for the Pecos Conference, an annual gathering focused on southwestern archaeology which moves from place to place. On my way up here I stopped at Chimney Rock, one of the most interesting of the Chacoan outliers and one that I had not been to before.
The main reason for both those things is Chimney Rock’s location. It’s the furthest known outlier to the northeast of Chaco, near Pagosa Springs, Colorado, and there are no other outliers very close to it. The great house is perched in a bizarre position up on top of a high, steep mesa, and further down the mesa ridge there are many smaller sites, most of them having a distinctive architectural style suggesting that they are basically above-ground pithouses (perhaps because on the mesa there wasn’t enough soil to dig into to create regular pithouses). There are also more typical pithouses, possibly from a slightly earlier period, further down on the banks of the Piedra River. While the great house is distinctive in being very “Chacoan” in style, more so than many closer outliers, the small sites on the mesa seem to have more similarities to the architecture of the Gallina culture to the south.
Because of its odd location and distance from Chaco, Chimney Rock has been the subject of considerable research over the years, and the University of Colorado has just started a major new research project there headed by Steve Lekson that has already gotten quite a bit of press coverage. The theories about Chimney Rock’s relationship to Chaco itself vary, and aren’t really that different from theories positing various roles of outliers in general. The main theories about the founding of the Chimney Rock great house (among those who agree that it was founded by Chacoans at all rather than being an indigenous development) fall into two main groups: resource-procurement and astronomical observation. The resource-procurement theories emphasize Chaco’s need for wood and the possibility that by the time Chimney Rock was founded in the AD 1070s closer sources such as the Chuska Mountains had been largely exhausted. The astronomical theories, on the other hand, focus on the two large geological features, known as Chimney Rock and Companion Rock, that give the site its name. Protruding from the mesa, they have a small gap between them when viewed from the great house that appears to align perfectly with the northernmost moonrise at the lunar major standstill, which only occurs every 18.6 years and did in fact occur around the time the great house was first built, and again when it was expanded or renovated in the 1090s. This theory has been pushed largely by Kim Malville, an astronomer at the University of Colorado, and investigated thoroughly by Ron Sutcliffe, an engineer and surveyor in Pagosa Springs who has also worked at Chaco.
Given my skepticism about the idea of floating beams down the Piedra River to Aztec or Chaco, it may come as no surprise that I much prefer the astronomical explanation. While it’s certainly possible that some wood used in great houses elsewhere (more likely in the Totah area than in Chaco itself) came from the Chimney Rock area, there has not been any clear evidence yet establishing this, and if they were carried overland rather than floated, as was apparently the case, upstream areas like Chimney Rock wouldn’t have had any particular advantages over other, closer areas with similar vegetation for procurement purposes. The procurement scenarios make sense on a general level, but when applied to Chimney Rock specifically they leave many questions unanswered. Why would the great house need to be way up on top of the steep mesa if the point was to harvest trees? Why weren’t there any other procurement outliers nearby? And why so far away?
All these questions are easily addressed by the theory that Chimney Rock was a preexisting religious site based on astronomical observations through the gap between the rocks (probably from various locations throughout the local area). If the Chacoans were aware of this site, they may well have wanted to integrate it into their system, whatever it was, particularly if astronomical knowledge was an important aspect of the ritual authority that allowed them to put the system together in the first place, which it may have been. While some archaeoastronomy can get a little too speculative for my taste, this Chimney Rock theory seems like one of the most clear-cut and useful examples of the archaeoastronomical approach as applied to Chacoan sites. And, indeed, it seems that the astronomical theory has been winning out lately in both scholarly and interpretive circles. Certainly the tour guide I had today talked about it a lot and didn’t mention wood procurement much.
In any case, it’s a fascinating place, well worth a trip, and hopefully the new research there will soon begin to shed more light on it. With Lekson in charge, I have no doubt that the findings will, at the very least, be entertainingly described.