Archive for October, 2016


Room 33, Pueblo Bonito

In my post about the recent radiocarbon dating of macaw remains from Chaco Canyon, I mentioned another paper I’ve been meaning to post about. Published in 2010 by Steve Plog and Carrie Heitman of the University of Virginia, it takes a close look at burial practices at Chaco, particularly focusing on the northern burial cluster within Pueblo Bonito. Within that cluster it focuses on Room 33, the location of the most elaborate burial assemblages ever found in the Southwest.

Plog and Heitman take advantage of their Chaco Archive project, which is collecting and making available lots of archival material on excavations at Chaco that was previously very hard to access, to look back at the field notes from the excavators of Pueblo Bonito, particularly those of George Pepper, who excavated this part of the site in the 1890s as part of the Hyde Exploring Expedition. Pepper took very detailed notes, especially by the standards of the time, and particularly for the rooms in the northern burial cluster he kept track of artifact locations and the positioning of skeletal remains, which makes it possible for Plog and Heitman to plot the vertical and horizontal positions of the burials and grave goods in Room 33 to see what patterns there may be.

They find some interesting patterns in the burial and artifact locations, but the most important data they report are radiocarbon dates, directly on the bones, from ten of the burials, including the ones with the most elaborate funerary assemblages, known as Burials 13 and 14. Burials 13 and 14 had actually already been dated for a different study a few years earlier, which I have discussed before, but Plog and Heitman redated them to see if they the earlier results would be replicated. (They were.)

At this point I should back up and review some basic facts about Room 33 and its burials, as well as some assumptions that had seeped into the Chacoan literature over the years despite not being well-supported by evidence.


Type I Masonry in Room 33, Pueblo Bonito

Facts: Pepper found 14 identifiable individual burials in Room 33. He numbered them in order of discovery, which roughly corresponds to vertical distance from the roof beams, so 13 and 14 were the lowest. Burials 13 and 14 had the most elaborate grave goods by far, including vast numbers of turquoise beads and other ornaments. They were intact and undisturbed, and were separated from the higher burials by a “floor” of wooden planks. The burials above this floor were accompanied by grave goods, but they were mostly disarticulated and appeared to have been disturbed at some point after burial. Pepper proposed that they had been scattered by water flowing into the room at some point.

Assumptions: At some point over the years, the idea entered the literature that these burials dated to the time of the “florescence” of Chaco starting around AD 1030 and lasting for about 100 years. Despite the fact that Room 33 is in the oldest part of Pueblo Bonito and its masonry style indicates that it dates to early in the site’s construction, many archaeologists (starting with Pepper himself) have suggested that it was not originally constructed as a mortuary chamber, and that the burials reflect a reuse of a room that originally had a different purpose. I don’t know where the idea that this reuse coincided with the rise of Chaco as a regional power, or with the advent of monumental construction in the canyon at roughly the same time, originated, but it makes a certain amount of intuitive sense to see the establishment of a crypt with unusually elaborate grave goods would happen at the same time as the enormous labor effort reflected in the expansion of Pueblo Bonito and other early great houses, along with the building of many new ones. However, it’s important to note that there was never a rigorous argument made for a late dating of the burials, bringing in support from the pottery styles reflected in the grave assemblages or any other independent lines of evidence.

And, in fact, the most comprehensive study of Chaco burials to date, that of Nancy Akins as part of the Chaco Project in the 1970s, concluded that the pottery types in Room 33 covered a potentially long timespan, which could mean the burials themselves were deposited over a long period of time. On the other hand, it could also mean that certain “heirloom” vessels of styles that were no longer being produced but that had been kept around might be buried with particularly important people, so this evidence wasn’t dispositive about the late-burial theory.


Old Bonito from Above

Plog and Heitman’s radiocarbon dates, on the other hand, provide firm evidence that the burials do indeed date to a long period, more or less corresponding to the full span of Chaco’s importance as a regional center. Burials 13 and 14 both date to quite early in the history of Pueblo Bonito, with 95% confidence ranges of AD 682 to 870 and 687 to 870 respectively. When averaged with the dates from the earlier study, which were comparable but slightly later, the 95% ranges become AD 691 to 877 and 690 to 873.

That’s very early! It means that these two burials, at least, could easily have occurred at the same time as the initial construction of Room 33, which was likely in the late ninth century. One other burial above the plank floor dates to this period as well. (The bones got relabeled at some point and it’s not clear which sets correspond to which numbers assigned by Pepper, so it’s not possible to say for sure that this was one of the burials immediately above the floor, but it’s a reasonable surmise.) Despite the near-identical age determinations on Burials 13 and 14, the vertical distance between them is by far the highest in the room. This suggests strongly that the large amount of sand separating the two vertically was brought in deliberately rather than accumulating naturally, and they could well have occurred at exactly the same time, or nearly so, very early in the occupation of Pueblo Bonito.

From then on, the dates are more or less continuous up to around AD 1200. The ranges are too wide to come to very firm conclusions on exactly where these later burials fall in the Chacoan sequence, but they do suggest that Room 33 continued to be used as a high-status burial chamber throughout the Chaco Era after beginning to serve that role early on.

This is all very interesting, and Plog and Heitman draw a number of tentative conclusions from it. They argue that this shows that social hierarchy arose earlier in the canyon than often assumed, well before the beginning of construction on a monumental scale, and suggest that the concept of “house society” may be a useful way to interpret Chacoan great houses, with symbolically important spaces like Room 33 serving to legitimize the position of elites through a connection to illustrious ancestors. They also argue that the preservation of the delicate placement of burials and artifacts, as demonstrated in Pepper’s notes, makes it very implausible that the scattering of remains he mentions could have resulted from water intruding as we suggested. Instead, they suggest that some of the scattering could have resulted from disturbance of earlier burials in the course of creating new ones in this small space over the centuries. Another possibility they suggest is that some of the burials are actually secondary, and were placed in Room 33 after having been left to decompose somewhere else for a while. This practice is not documented among the historic Pueblos, but then again lots of the other aspects of the Room 33 burials don’t have obvious modern parallels either.

The evidence for unexpectedly early import of macaws starting around AD 900 in the more recent paper reinforces the evidence in this one for an early development of complexity at Chaco. It’s still not clear exactly what was going on at Chaco in the ninth century, but it’s becoming increasingly clear that it was very important for the subsequent history of the canyon and of the Southwest as a whole.
Plog, S., & Heitman, C. (2010). Hierarchy and social inequality in the American Southwest, A.D. 800-1200 Proceedings of the National Academy of Sciences, 107 (46), 19619-19626 DOI: 10.1073/pnas.1014985107

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