Archive for the ‘Totah’ Category

Old Bonito from Above

Old Bonito from Above

Having introduced the basics of archaeological use of DNA evidence, and discussed some other applications of DNA studies in archaeology, let’s take a look at the data relevant to the Southwest specifically. For modern populations in North America overall, there are some broad trends that have been identified in mitochondrial haplogroup distribution by region, as first elucidated by Joseph Lorenz and David Glenn Smith of UC Davis in 1996. They only looked at haplogroups A, B, C, and D, since haplogroup X had not yet been identified as a founding haplogroup at that time. Their results showed that there are definite patterns in haplogroup distributions by region. For the Southwest specifically, they found most groups showed very high levels of B and low levels of A, despite the fact that A was the most common haplogroup in their sample overall. The main Southwestern groups that showed high levels of A were the Athabascan-speaking tribes (Navajo and Apache), which is unsurprising since northern Athabascan groups, along with most other groups in the Arctic and Subarctic, are almost exclusively A, and it’s well established that the southern Athabascans immigrated into the Southwest from the north relatively recently. Some other Southwestern groups show some representation of A as well, which Lorenz and Smith attribute to intermixing with the Athabascans (although as I’ll discuss below this doesn’t seem to be the whole story). Similarly, the Navajos and Apaches showed substantial representation of B and C, unlike their northern cousins, and this is probably due to intermixing with the Pueblos and other Southwestern populations.

A subsequent study by Smith, Lorenz, and some of their students at Davis looked specifically at haplogroup X, which had been identified in both modern and ancient Native American samples by then and was established as a founding haplogroup. They found it widely distributed among modern populations speaking a variety of languages but particularly among speakers of Algonquian and Kiowa-Tanoan languages. The Kiowa-Tanoan connection is of particular interest for Southwestern purposes, of course, as this is one of the main language families spoken by the eastern Pueblos in New Mexico. In this case, haplogroup X was found in the Kiowa and Jemez samples. This is very interesting since the Jemez are Pueblo and the Kiowa are not, and the relationship between the Kiowa and the Tanoan-speaking Pueblos is a longstanding mystery. It’s hard to know how to interpret the haplogroup X data in this connection. Since X is so rare overall the fact that it is so concentrated in certain groups seems meaningful somehow, but since it’s still pretty rare in those groups and little follow-up research on this has since been done it remains quite mysterious.

Turning to the ancient evidence, the first work in the Southwest was associated mostly with the University of Utah. In 1996 Ryan Parr, Shawn Carlyle, and Dennis O’Rourke published a paper reporting on aDNA research on the remains of 47 Fremont individuals from the Great Salt Lake area, 30 of which could be assigned to a haplogroup. The Fremont have always been something of a mystery, with many Southwestern cultural features but living on the northern fringes of the Southwest and having some notable differences from Pueblo cultures to the south. What the Utah researchers found, however, seemed to show the Fremont patterning genetically with the Pueblos rather than with other groups in the Great Basin or Plains. Haplogroup A was completely missing from their sample, while B was by far the most common haplogroup and C and D were also present in small numbers. This seems to clearly rule out one theory about the Fremont, which is that they were composed in part of Athabascans on their way south from the Subarctic, and also casts in serious doubt other theories linking them to later cultures on the Plains (where haplogroup A is also very common). It’s true that there is internal cultural variation within the construct “Fremont” and it’s quite possible there was genetic variation as well, but the Great Salt Lake Fremont were the furthest north of the identified subdivisions and the closest to the Plains, so if even they show more genetic similarities to the Southwest that is strong evidence against theories associating them with areas to the north and east.

It’s also noteworthy that the Fremont distribution is in contrast to what Lorenz and Smith found among modern Numic peoples who now occupy the Fremont’s Great Basin home. The Numic Paiute/Shoshone sample that Lorenz and Smith looked at lacked haplogroup A, but it showed a very high proportion of haplogroup D (the highest in their whole study, in fact) and a low proportion of B and C. This doesn’t totally rule out some Fremont contribution to Numic ancestry, but it makes it seem unlikely that there was substantial genetic continuity between Fremont and Numic populations, which supports the “Numic Expansion” hypothesis for the late prehistory of the Great Basin. Smith and his student Frederika Kaestle later published a paper making this exact argument, using not only the Fremont data but additional ancient remains from the western Great Basin to argue that the differences in haplogroup frequencies supported a replacement of the earlier Basin inhabitants by the Numa.

Following up on this research, a subsequent paper by the same Utah researchers added in data from the Anasazi. They successfully assigned 27 Anasazi samples to haplogroups. Of these, 12 were from southeastern Utah, 9 were from Canyon del Muerto, 4 were from Canyon de Chelly, and 2 were from Chaco Canyon. Of the Chaco remains, one came from the debris in Room 56 at Pueblo Bonito, a part of the north burial cluster in Old Bonito which was very crudely worked over by Warren K. Moorehead in the 1890s. The other I can’t seem to find any specific information on. All of the Anasazi remains analyzed in this study were from the collections of the American Museum of Natural History, which makes me surprised that only two Chaco samples were involved. It’s possible that more were analyzed but only these two produced enough DNA to work with. In any case, if in fact there are more Chaco remains at the AMNH that have not yet been analyzed for DNA it would be very helpful to analyze them.

The results of this analysis were consistent with the standard archaeological understanding that the modern Pueblos are the descendants of the Anasazi. B was the most common haplogroup, with smaller levels of A and C. D wasn’t present at all, and two of the specimens didn’t fall into any of the four haplogroups, implying that they might have belonged to X. (The two Chaco samples belonged to haplogroups B and C; the sample from Room 56 belonged to haplogroup B.) Note that A is present here in populations dating well before any likely admixture with Athabascans, which is evidence against Lorenz and Smith’s contention that the presence of A in modern Pueblos can be attributed entirely to mixture with Athabascans.

Based on the dominance of B and low levels of other haplogroups, these researchers concluded that the Anasazi remains they analyzed were not significantly different from the Fremont remains they had analyzed earlier, adding further support to their contention that the Fremont pattern with the Pueblos. Note, however, that the Fremont hadn’t shown haplogroup A at all, while the Anasazi had it at a low but still respectable level (22%). Also, the Fremont showed a low level of haplogroup D, which the Anasazi didn’t have at all. These differences don’t necessarily mean the Fremont and Anasazi weren’t related, of course, but they do show how much that similarity is a judgment call supported by questionable statistics. In this case one big problem with the statistical analysis was treating the haplogroup frequencies as ratio-level data, which implies that they are meaningfully representative of the underlying populations despite the very small and non-random samples. This is highly implausible. This problem means that the authors’ conclusions about whether differences between samples were “significant” or not in a statistical sense is not really meaningful since it can’t reasonably be expected to generalize to the populations, which are what we really care about.

In addition, as Connie Mulligan pointed out in the general paper on aDNA that I discussed previously, the differences that the Davis researchers found between the haplogroup frequencies of the Fremont and Numic samples, which they used as evidence of a lack of population continuity, were actually quite similar statistically to the differences the Utah researchers found between the Fremont and Anasazi, which they interpreted as not being significant! This disconnect goes to show that there’s actually quite a bit of subjective judgment in interpreting results like this, despite the superficial impression of “objective” statistical data.

One way to overcome this confusion would be to increase the number of samples analyzed and try to make them as close to representative of the underlying populations as possible. That would certainly help, but the fundamental problem of defining the ancient population of interest, and the apparent impossibility of analyzing a sample from it that could be assumed to be truly representative, are daunting challenges. A more productive approach, which subsequent research has in fact been following, is to do more in-depth analysis of available samples, so that more detailed data than crude haplogroup assignments are possible.

One way to do more in-depth analysis would be to move away from relying exclusively on haplogroup assignments and look instead at the nuclear genome. Sequencing the whole nuclear genome provides vastly more, and more statistically robust, information than mitochondrial haplogroup assignment, as commenter ohwilleke pointed out in response to my initial DNA post. Most of the studies mentioned in my previous post in other parts of the world have used this methodology, with very informative results. This type of analysis has, however, not been done on ancient remains from the American Southwest to my knowledge. I’m not sure why exactly, but there are various reasons including cost and level of preservation of remains that could account for this lacuna.

Instead, Southwestern researchers have mostly doubled down on mitochondrial haplotype analysis and extended its reach by looking at further mutations within the defined haplogroups to identify sub-haplogroups that can further narrow down genetic relationships. This has been a productive line of investigation, as exemplified by a very interesting paper from 2010 dealing with Chaco-era sites in the area of Farmington, New Mexico.

B-Square Ranch, Farmington, New Mexico

B-Square Ranch, Farmington, New Mexico

The paper, by Meradeth Snow and David Glenn Smith of Davis and Kathy Durand of Eastern New Mexico University, analyzed human remains from two sites on the B-Square Ranch, a large ranch that includes most of the land south of the San Juan River in Farmington. The ranch is owned by the Bolack family, which has long been prominent in local and statewide affairs. Its patriarch for many years was Tom Bolack, who was governor of New Mexico for a brief period in the 1960s and was also well known for his elaborate produce displays at the State Fair. His son Tommy Bolack, who took over management of the ranch when Tom died, has long had an interest in archaeology and did his own excavations in various of the many archaeological sites on the ranch. In recent years rather than continuing his own excavations he has worked with Linda Wheelbarger, a professional archaeologist who teaches at San Juan College in Farmington, to conduct field schools in the summers for SJC students as well as analyses of artifacts and human remains from both these recent excavations and his own earlier amateur work.

Among these analyses was the aDNA analysis of remains that Bolack excavated from the Tommy and Mine Canyon sites, two small-house sites on the ranch dating to the Chaco era. The Tommy site is slightly earlier, dating to approximately AD 800 to 1100, while the Mine Canyon site dates to approximately AD 1100 to 1300. Since the Tommy site seems to have been abandoned at approximately the same time the Mine Canyon site was founded, one obvious interpretation is that the Mine Canyon site was founded by the same people who had previously lived at the Tommy site. The DNA evidence, however, challenges this interpretation and suggests a more complicated story.

For this study, 73 samples were sent to Davis for aDNA analysis. This included a mix of tooth and bone samples. Of these samples, 48 (65.7%) could be assigned to a mitochondrial haplogroup. Of these, 26 were from the Tommy site and 12 from the Mine Canyon site.

The successfully analyzed samples from the Tommy site showed a typical distribution of haplogroups for a Southwestern population: 3% A, 69% B, 14% C, and 14% D. (This study didn’t look for haplogroup X, and all successfully analyzed samples fell into one of the other founding haplogroups.) The Mine Canyon sample, however, showed a very unusual distribution: 58% A, 33% B, 8% C, and 0% D. This is an exceptionally high proportion of haplogroup A, which is generally fairly rare in the Southwest except in Athabascan groups which are generally thought to have arrived in the region well after these sites were abandoned. Haplogroup A is also very common in Mesoamerica, which makes its dominance in a Chaco-associated site particularly intriguing given the evidence for contact with Mexico seen at Chaco Canyon itself and some outlying Chacoan sites.

The authors are careful to note that these are very small sample sizes, which makes sampling bias a very real possibility to account for this sort of striking result. They compare these distributions to several other ancient and modern Southwestern and Mesoamerican populations using Fisher’s exact test and find, unsurprisingly, that the Tommy site sample isn’t significantly different from other ancient Southwestern populations but is significantly different from all the modern populations as well as the ancient Mesoamerican ones. The Mine Canyon sample, on the other hand, was found to be significantly different from all the ancient Southwestern samples as well as all the modern Southwestern ones except the Athabascan Navajo and Apache, while it wasn’t significantly different from any of the ancient or modern Mesoamerican samples. This result is clearly driven primarily by the unusually high proportion of haplogroup A at Mine Canyon, which means it doesn’t really add much to the paper. Although Fisher’s exact test does take into account the small sample sizes, it doesn’t address the more fundamental problem with this sort of use of statistics on this type of data which can’t really be trusted to be representative of the underlying population of interest. This is the sort of thing I was talking about in the earlier post under the somewhat tongue-in-cheek label of “elaborate statistical techniques” on data that don’t necessarily fit the necessary requirements for their use. This sort of technique is not actually very elaborate compared to more sophisticated statistical analyses used for studies of whole genomes, where the number of data points is immense and they can actually be assumed to be representative of the analyzed individual’s full ancestry. Calculating P-values for differences between two samples based on four data points for each, when neither sample is necessarily representative of its underlying population of interest, is not very useful, but very common in mtDNA studies at least in the Southwest. To their credit, the authors of this paper are well aware of the weaknesses of this part of it and are careful to downplay the significance of the statistical analysis.

With these intriguing preliminary results, the researchers attempted further sequencing to identify more specific mutations that might define sub-haplogroups and clarify relationships on a more granular scale. Of the 48 samples that could be assigned to haplogroups, 23 were successfully sequenced for mutations in a region of the mitochondrial genome known to be highly variable. (Note how small the sample gets with subsequent levels of analysis.) Poor preservation was a major problem at this point, and there wasn’t enough genetic material remaining to construct the sort of network diagram that is often included in papers like this, showing specific mutations and the relationships they imply between specific ancient and modern samples.

The most interesting results from this further sequencing were with haplogroup A. Of the 8 samples initially identified as belonging to this haplogroup, 6 samples from the Mine Canyon site showed two distinctive mutations that are otherwise known only from 3 modern Zuni samples, along with one Tohono O’odham and one Chumash sample. Importantly, this set of mutations is unknown from both Mesoamerican and Athabascan groups. This is strong evidence that the dominance of haplogroup A at the Mine Canyon site does not indicate either migration from Mesoamerica or an early Athabascan presence in the Southwest; instead, it seems that this site just happens to have had an unusually high proportion of a rare but natively Southwestern lineage which survived into modern times at Zuni (and may have had some connections further west). The samples belonging to haplogroup B similarly showed the dominance of a sub-haplogroup distinctive to the Southwest and unknown in Mesoamerica.

The differences between the Tommy site and the Mine Canyon site in haplogroup frequencies, while they may well be a function in part of the small sample sizes, may also provide evidence for complex population movements within the late prehistoric Southwest. The exact parameters of these movements can’t be defined until more evidence is available from other areas, however, especially Chaco Canyon and the Mesa Verde region.

Overall, despite the poor preservation of the samples involved, this study provides important support for a finding that has come out consistently across all lines of evidence relating ancient to modern Pueblo people: there is a lot of evidence for continuity over time on a regional scale with complex movements within the Southwest, but little to no evidence of significant population movement into or out of the Southwest in recent centuries. (There is a whole other debate about the extent of population movement into the Southwest much earlier, at the time when agriculture was first introduced, which I haven’t discussed much in these posts and which isn’t of much importance for the specific issue I’m addressing here.) I think there is a lot of potential for more detailed reconstruction of movement within the Southwest based on a combination of lines of evidence, but we’re certainly not there yet.

I’ve gotten some questions about how the DNA evidence relates to the issue of hierarchy at Chaco. I’ll have a more extensive post on the evidence for social hierarchy, which I think is extensive, but the short answer is that DNA doesn’t really provide any evidence one way or the other on this point. Since all evidence points to a general pattern of population continuity in the Southwest at least since the introduction of agriculture, the genetic patterns of any elites that arose wouldn’t be likely to differ in any noticeable way from those of the commoners they rose from. Indeed, the one sample to be analyzed for mitochondrial DNA that is very likely to come from an elite Chacoan context, the sample from Room 56 at Pueblo Bonito, belonged to haplogroup B, the most common in both ancient and modern Southwestern populations. It’s theoretically possible to imagine an elite group immigrating into the Southwest from Mesoamerica, and theories have been proposed along these lines, but the DNA evidence doesn’t particularly support this, and it’s much more likely based on all lines of evidence that the rise of an elite at Chaco was a primarily indigenous development involving some indirect influence from Mexico but little to no permanent population movement over that distance.

This is the last substantive post in my series about “tracing the connections” between the ancient and modern Southwest, although I will probably do a follow-up post linking to all the others for the convenience of readers. Overall, I think these posts have shown that we have substantial evidence from various perspectives that the modern Pueblos are the descendants of the ancient Anasazi (and other prehistoric Southwestern groups), but the evidence we have so far is not sufficient to connect any specific ancient sites with any specific modern pueblos. I am hopeful, however, that that may change as more evidence comes in and we are able to tie together new data with the evidence we already have to make some more specific connections.
Carlyle SW, Parr RL, Hayes MG, & O’Rourke DH (2000). Context of maternal lineages in the Greater Southwest. American journal of physical anthropology, 113 (1), 85-101 PMID: 10954622

Kaestle FA, & Smith DG (2001). Ancient mitochondrial DNA evidence for prehistoric population movement: the Numic expansion. American journal of physical anthropology, 115 (1), 1-12 PMID: 11309745

Lorenz JG, & Smith DG (1996). Distribution of four founding mtDNA haplogroups among Native North Americans. American journal of physical anthropology, 101 (3), 307-23 PMID: 8922178

Smith DG, Malhi RS, Eshleman J, Lorenz JG, & Kaestle FA (1999). Distribution of mtDNA haplogroup X among Native North Americans. American journal of physical anthropology, 110 (3), 271-84 PMID: 10516561

Snow, M., Durand, K., & Smith, D. (2010). Ancestral Puebloan mtDNA in context of the greater southwest Journal of Archaeological Science, 37 (7), 1635-1645 DOI: 10.1016/j.jas.2010.01.024

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Aztec West Great House, Aztec Ruins National Monument

In the spring of 1892, an expedition headed by Warren K. Moorehead traveled through northwestern New Mexico to collect archaeological specimens for the Chicago World’s Fair to be held the next year.  Moorehead was a young man from Ohio who had already conducted considerable excavations there that had drawn the attention of Frederic Ward Putnam of the Harvard Peabody Museum.  Putnam hired Moorehead to collect artifacts in Ohio and elsewhere for the World’s Fair.  Moorehead’s Ohio work was important to the definition of the Hopewell Culture and the acquisition of the Fort Ancient site by the Ohio Historical Society, and by the time of his death in 1939 Moorehead was considered one of the preeminent American archaeologists.  He wrote up some of his observations from the 1892 New Mexico expedition in an article published in 1908 which contains some important early information about the archaeological remains along the Animas and La Plata Rivers before those areas were extensively developed.

Moorehead’s party surveyed the major ruins at Aztec, but John Koontz, who owned the site at the time, would not let them excavate there.  (This is an issue that would recur in Moorehead’s Southwestern adventures.)  The 1908 article contains a decent description and plan of the West Ruin at Aztec, including the observation of an obvious road leading to a nearby quarry site that was the apparent source of building stone.  The more important part of the article, however, deals with the La Plata, where the group spent more time and were apparently given permission to excavate several sites.  Moorehead noted very extensive irrigation systems along the valley bottom, which he suggested accounted for the numerous prehistoric sites and the apparently very large population they indicated.  Since the La Plata Valley has been extensively developed for modern agriculture since Moorehead’s time, these observations are very useful for understanding the perennially understudied archaeology of that area.  It’s not totally clear how many sites the group excavated, but Moorehead describes one burial with numerous associated pots and mentions a large, three-story site surrounded by many smaller sites.  This is probably the community now known as the “Holmes Group,” after William Henry Holmes, another early archaeologist who studied them.  Moorehead estimated about two hundred rooms in the community, half of them in the great house.

The Moorehead party excavated many graves and collected the pottery left with them, but Moorehead says that the bones themselves “were in such a state of decay that it was not possible to preserve them.”  The group also found an interesting vertical masonry shaft, fourteen inches square and eight feet, five inches deep.  The bottom of the shaft was paved with slabs and connected to a horizontal passage leading north, which Moorehead’s group excavated for about four feet before they “were compelled, unfortunately, to abandon the work; and thus were prevented from gaining sufficient evidence to determine the purpose of the structure.”  Moorehead doesn’t explain what compelled this stop to the digging.  He does speculate about the possible purpose of this shaft:

It could not have been a chimney, for neither the stones nor the logs showed signs of smoke or heat, although fragments of charcoal were found occasionally during the excavation; nor is it likely that the shaft was used as an air flue for the purpose of ventilation, both on account of the narrowness of the perpendicular portion (fourteen inches), and the apparent disregard manifested by the ancient Southwestern villagers of everything that might tend to promote hygienic conditions.

Zing!  In fact, this shaft almost certainly was a ventilation shaft associated with a kiva, similar to those documented by Jesse Walter Fewkes at Mesa Verde.  The fact that it led north is a clear indication, and Moorehead’s objection on the basis of size doesn’t make a whole lot of sense.  His snide comment about hygiene is odd, though perhaps indicative of the gentlemanly racism common among early anthropologists, and it would perhaps be unfair to tar Moorehead too much with it, as he actually was quite concerned with the fair treatment of Indians and worked hard throughout his life to advocate for their interests in a rather paternalistic way, which was not a common thing for archaeologists to do.  Still, he was a man of his times, and he was apparently unimpressed with the sanitary conditions of the modern Pueblos.

Opening of Vent Shaft to Kiva L, Pueblo Bonito

Moorehead’s attitudes may have been slightly more progressive than those of his archaeological contemporaries, but his methods weren’t.  His style of archaeology was very heavily based on recovering artifacts for his various patrons, first Putnam and later Robert Peabody, who made him head of the Robert S. Peabody Museum of Anthropology at Phillips Andover.  As shown by his 1908 article, he did do some documentation of the sites he investigated, but the focus was always on the artifacts rather than the sites.  The Ohio History Society’s short biography of him notes, rather defensively, that this was not uncommon at the time:

Moorehead sometimes is remembered unkindly for his supposedly crude excavation methods and for his involvement in the buying and selling of artifacts. Both criticisms are unfair. In the light of today’s standards his field methods certainly would be considered deficient, but for their time they were not all that unusual. The practice of buying and selling artifacts, particularly specimens considered to be duplicates, also was not unprecedented at the time.

This is true, but it’s not so much a defensive of Moorehead as an indictment of archaeology as a discipline at the time.  The contrast with Richard Wetherill and George Pepper’s excavations at Chaco in the 1890s is instructive.  Their methods are often defended along the same lines, but in fact compared to the likes of Moorehead they did a very good job of documenting their work.  Pepper’s site report on Pueblo Bonito, though based on his sometimes sketchy field notes and quite inadequate by modern standards, is a wonder of careful documentation of artifact contexts and room features compared to Moorehead’s typical work.  Furthermore, Wetherill was a skilled amateur photographer at a time when that was rare, and there are numerous photographs of the excavations at Bonito.  I don’t know of any other excavation projects in the 1890s that were photographed as systematically as those at Bonito.  Moorehead never took any pictures of his work as far as I know.

South Wall of Room 53, Pueblo Bonito

Indeed, we can compare Wetherill and Pepper’s methods directly with Moorehead’s, because Moorehead excavated at Pueblo Bonito too.  In 1897, Moorehead made another collecting expedition to the Southwest, this time on behalf of Peabody, and one of the stops he made was at Chaco Canyon.  Wetherill and Pepper had begun excavations at Pueblo Bonito in 1896, sponsored by none other than Frederic Ward Putnam, who was at this point affiliated with the American Museum of Natural History, and word of their spectacular finds such as the burials in Room 33 had probably gotten out.  In any case, Moorehead showed up at Chaco in the winter, the offseason for the AMNH party, and proceeded to tear the hell out of two rooms just north of Room 33.  These rooms, which Pepper would later designate Rooms 53 and 56, were apparently part of the same burial complex as Room 33, and they contained numerous burials and grave goods.  The grave assemblages were apparently not as elaborate as those in Room 33, however, and Moorehead was not particularly impressed with what he found (which is perhaps why he didn’t continue to excavate).  He did find one complete skeleton, wrapped in a feather robe, which he thought was of a young woman.  Nancy Akins, who reexamined the remains from Pueblo Bonito for the Chaco Project, concluded that this burial was actually of a man aged 40 to 44.  She also noted four skulls, now in the Field Museum, which were also probably from these rooms.  The Moorehead group didn’t fully excavate the rooms, and when Wetherill and Pepper returned in the summer they excavated what was left and sorted through the mess left by Moorehead, who had apparently thrown the fill from the rooms around haphazardly.  They found a few more artifacts and burials, but couldn’t say much about the original state of the rooms beyond noting two subfloor graves in Room 56 that Moorehead had opened.

Here’s what Akins had to say about Moorehead’s work in Rooms 53 and 56:

It is unfortunate that Moorehead plundered these two rooms. There are indications that a fair number of persons were buried in them. It is unlikely that they contained the amount of ornamentation found in Room 33, as none is mentioned by Moorehead in his report, little is listed in the Phillips-Andover catalog, and Moorehead stated that no remarkable
discoveries were made.

Moorehead did write an account of this expedition, which was published by Phillips Andover and is not easy to find.  I haven’t been able to read it, but judging from his 1908 article on the other expedition and Akins’s comments I don’t expect that it contained much detailed information on his work at Pueblo Bonito.

South Wall of Room 53 from Room 56, Pueblo Bonito

Also on this trip, Moorehead stopped by Salmon Ruin, where the landowner, George Salmon, only allowed him to dig for three days.  This frustrated Moorehead, and it indicates that Salmon, like John Koontz, was concerned with preserving his ruin and not letting archaeologists like Moorehead tear it apart wholesale looking for artifacts.  Obviously Salmon was a bit more accommodating than Koontz, who apparently didn’t let Moorehead dig at all at Aztec.

In the context of Chaco, and especially in comparison to Wetherill and Pepper, Moorehead looks pretty bad, but it’s worth emphasizing that he really wasn’t that unusual at the time.  The line between pothunter and archaeologist was really quite thin, and many archaeologists of Moorehead’s generation started out digging haphazardly for artifacts and later transitioned to more carefully documented digging for information.  Earl Morris is a good example of a pothunter who successfully turned himself into a serious archaeologist, and Richard Wetherill is an example of a sort of semi-pothunter who tried to make that transition but failed.  Moorehead’s background was similar, and he was more successful in ingratiating himself with the emerging academic archaeological establishment than Wetherill but probably less successful than Morris.  Part of the issue was just the change in archaeological practice over time; Wetherill died in 1910 (101 years ago today), whereas Moorehead lived until 1939 and Morris, who was of a younger generation, lived until 1956.

Interpretive Plaque at Wetherill Cemetery

Wetherill often gets cast as a villain in the story of Southwestern archaeology.  This is largely the doing of Edgar Hewett, who was an inveterate opponent of what Wetherill and Pepper were doing at Pueblo Bonito, which he characterized as large-scale looting.  Hewett’s line was eagerly adopted by the Santa Fe press, and it has become entrenched in popular understanding and even implicitly adopted by many archaeologists today.  It’s important to note, however, what Hewett was actually objecting to.  The biggest problem as he saw it was not that artifacts were being taken out of Pueblo Bonito but that they were being taken to New York, to sit in the AMNH (where most of them remain to this day).  Hewett wanted artifacts from Chaco not to stay at Chaco, but instead to be brought to Santa Fe and kept at his own institution, the Museum of New Mexico.  His characterizations of Wetherill and Pepper’s activities tended to carefully omit the involvement of the AMNH, which helped to drum up support for his cause among locals outraged by outsiders coming in and taking away artifacts.  Hewett eventually got his wish, and in the 1930s and 1940s he dominated archaeology at Chaco and throughout New Mexico.

Hewett’s success in tarring Wetherill as a pothunter shouldn’t blind us to the realities of the context Wetherill and Pepper were working in.  Their methods were crude compared to today’s, but within the range of variation in methods at the time they really were quite good, and much better than Moorehead’s crude methods.  Indeed, in some respects they were significantly better than the methods employed in Hewett’s own excavations at Chaco thirty years later.  The dispute between Hewett and Wetherill wasn’t about methods, and it wasn’t about “professional archaeologists” versus “amateur pothunters.”  Rather, it was a dispute between two groups of professional archaeologists and their institutional sponsors over who should be excavating at one of the most important archaeological sites in the region and which museum should get the artifacts they found.

Moorehead’s bit part in this drama really just serves as context, I think.  Despite the title of this post, I don’t think it’s really reasonable to cast him rather than Wetherill as the villain of the story.  Instead, Moorehead just illustrates that there was more to archaeology in the 1890s than Wetherill and Hewett, and that it is best to interpret the history of research at Chaco within that broader context.
Moorehead, W. (1908). Ruins at Aztec and on the Rio La Plata, New Mexico American Anthropologist, 10 (2), 255-263 DOI: 10.1525/aa.1908.10.2.02a00080

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Fajada Butte from Pueblo Alto

Happy solstice, everyone.  To mark the occasion I figured I’d say a bit about archaeoastronomy, which is an important topic at Chaco that I don’t discuss very often.  The various alignments identified at the great houses in the canyon have become quite famous through the work of the Solstice Project to document them, and while I don’t think all of their proposed alignments are necessarily real, there is enough evidence by now to suggest that at least some of them are.  Cardinal direction alignments are the most obvious, and the least likely to be coincidental (in my view), and these are found at a few of the sites at Chaco, particularly Pueblo Bonito, Pueblo Alto, and Tsin Kletzin.  Interestingly, these three are all in the center of the canyon (“Downtown Chaco”), and the line running due north-south from Pueblo Alto to Tsin Kletzin runs between Pueblo Bonito and Chetro Ketl through the “Chaco Amphitheater.”  This all suggests some pretty extensive planning, but it’s interesting that the other parts of the canyon don’t seem to have been part of it.  I find the Solstice Project’s proposed alignments at many of the other sites in the canyon a lot more dubious, especially since so many of them are allegedly to the minor lunar standstill.  It seems more plausible that there would be solstice alignments in the canyon, and there do indeed seem to be some “viewing points” from which solstice sunrises are marked by prominent features on the horizon, but the only solstice-aligned building proposed by the Solstice Project is Aztec West, which isn’t even at Chaco, although it’s clearly Chacoan in style.

Steve Lekson has proposed that one possible reason for the variety of alignments in Chacoan great houses is conflict between factions within Chacoan society.  The way he sees it, solstice alignments were the regional tradition, and cardinal alignments were a new idea at Chaco, perhaps threatening to the old order in the way that many new developments at Chaco were.  Indeed, alignment to the southeast was a common architectural practice in pre-Chaco communities, and this may well have had something to do with the solstices, although as far as I know none of these buildings have been demonstrated to have precise solstitial alignments.  I’m not so sure that cardinal direction alignments were not present in the region before Chaco, however, and I’m also unsure of whether differences in building orientation really represent ideology the way Lekson proposes.  I’m more inclined to wonder if they may instead reflect different ethnic or regional origins for different groups.  In either case, though, the factionalism idea is interesting, and quite compatible with what we know of later Pueblo societies.  In Lekson’s version, the solstice alignment of Aztec reflects the founding of that center by the solstitial faction at Chaco, while the cardinal faction went elsewhere, maybe to Paquimé, which has a strong cardinal alignment.  I’m not sure how much of that I buy, but it’s worth thinking about.

Pueblo Alto and New Alto from Tsin Kletzin

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Whiteware Sherd at Una Vida

Pottery is the most important type of artifact for archaeology in the Southwest.  This is because the agricultural societies of the prehistoric Southwest made huge numbers of pots and often decorated them in distinctive ways that differed both from place to place and over time, often within quite short periods.  With the precision available from tree-ring dating, certain pottery types can be dated to remarkably short periods, in some cases consisting of less than 100 years, and those types in turn can be used to date unexcavated sites with no tree-ring dates of their own.  Differences in decoration over time are more obvious than differences among places for most periods, which is an interesting fact that probably deserves more attention than it has gotten.  Ceramic design styles changed at roughly the same times over amazingly large areas that in some cases don’t show any other evidence of substantial contact.  During the Chaco era, from about AD 1030 to 1130, the dominant design style throughout the northern Southwest used a lot of hachure, for example.  The specific types have different names, assigned to them by archaeologists working in different regions, and despite the general similarity in design these can be distinguished by distinctive aspects of their manufacture.  These include the type of clay used for the vessel (known as the “paste”), the presence and nature of an additional type of clay (the “slip”) put on top of the paste especially for painted types, the type of paint used, and the material used to temper the clay.  Tempering is the addition of some material to the paste to make it easier to work.  Almost all Southwestern pottery types are tempered, and the type of tempering material is one major way different regional wares are distinguished.

To make this more concrete, let’s look at the Cibola pottery tradition, to which Chaco’s pottery belongs.  There are two “wares” within this tradition: Cibola white ware and Cibola gray ware.  The gray ware is the “utility ware” used for cooking pots and other mundane vessels.  It is never painted, and when it has any type of decoration this typically consists of some sort of corrugation.  Types of corrugation vary over time.  During the height of the Chaco era, the dominant type was corrugation all over the vessel, whereas in earlier times only the neck would be corrugated.  Corrugated sherds are very common at Chacoan sites, because these vessels were made in large numbers, broke frequently from heavy use, and were mostly large jars that broke into many pieces.  Vessels forms are almost entirely jars rather than bowls.  Temper is typically either sand (in some cases probably from ground-up sandstone) or ground-up sherds.

Black-on-white Sherd at Pueblo Alto

Cibola white ware is more complicated.  This is the main “decorated” ware made at Chaco and in the area to the south of it.  These vessels have the same sand- or sherd-tempered gray paste as the gray wares, but the decorated surface also has a white slip that gives vessel a white appearance from the exterior.  The slips are thin and often applied in a sort of “washy” manner, and in some cases the gray paste can be seen beneath them.  Designs are painted on with mineral-based paint (usually made with iron oxide), at least until about AD 1100.  Forms are both jars and bowls.  Jars are decorated on the exterior, while bowls are usually decorated on the interior.

Similar gray and white wares are present for most other regions during the same period.  San Juan gray and white wares were made north of the San Juan River and are distinguished primarily by the use of crushed volcanic rock rather than sand or sherds as temper.  The white slips on the white ware are also thicker and often highly polished.  To the west, in the Kayenta area, white wares were generally painted with organic (carbon-based) paints, and over time this practice spread eastward, until after 1100 it was common in the Cibola and San Juan areas as well.

Chuska Mountains from Peñasco Blanco

A particularly important ceramic area for understanding the Chaco system is the Chuska Mountain area to the west, along the Arizona-New Mexico border.  In regional ceramic terms this area basically separates the Cibola and Kayenta traditions, and in some ways it was transitional between the two.  Chuskan potters adopted carbon paint earlier than those in the Cibola and San Juan areas, so imported white wares from the Chuskas to Chaco are typically carbon-painted although the designs on them are generally the same as local types.  The thing that really distinguishes Chuska pottery, though, is temper.  Chuskan ceramics are nearly universally tempered with trachyte, a rare and very obvious type of volcanic rock that outcrops only in a small area in the Chuskas.  Trachyte-tempered pottery is therefore virtually guaranteed to have been imported from the Chuskas.

Why is this?  Because potters are generally thought to have used local materials for temper (and for clay, but pinpointing clay sources is much more difficult).  Designs might be similar over a wide area, but if the temper in a vessel is a material only found in a very restricted area, it’s virtually certain that the vessel was made near there.  Unfortunately, most of the materials used for temper in the Southwest are very widespread; there’s sand everywhere, sherds would be present wherever anyone had broken pottery (so, again, everywhere), and the types of volcanic rock used in the San Juan region were quite widespread.  Luckily, however, trachyte-tempered Chuska pottery is an exception to this, which makes it very easy to identify imports from the Chuska area at Chaco and elsewhere.

Corrugated Grayware Sherd at Wijiji

There are other ways to determine the source areas for pottery.  X-ray fluorescence (XRF) and instrumental neutron activation analysis (INAA) are two widely-used methods of determining clay sources by the concentrations of trace elements in sherds, but they are very expensive and the results can be difficult to interpret.  Some studies using these techniques have been done in the Southwest, and a database of element concentrations for different source areas is beginning to develop.  At Chaco, however, analysis of pottery sources has so far depended primarily on the more traditional techniques of looking at paint, slip, and especially temper.  The biggest study was that done in connection with the Chaco Project, the results of which were presented in a 1997 publication by Wolky Toll and Peter McKenna (available on the Chaco Archive website).  Some of the data from this study was also used by Toll in his 2001 article that I have discussed before.

In brief, what Toll and McKenna found was that the Chacoans imported a lot of pottery.  The amounts of imports and their sources varied over time, however.  Imports were relatively rare before AD 800, making up 16.6% of the sample, but they came from a variety of sources, including the Chuskas, the San Juan region, and the Mogollon region to the south, which has very distinctive brownwares that are obvious imports when they appear.  Trachyte temper is only present in 3.6% of the total sample.  The period from 800 to 920 has a rather small sample from the Chaco Project excavations, but an increase in imported ceramics is apparent, with 28.1% imports and 9.7% trachyte-tempered.  The most common non-local temper, however, was chalcedonic sandstone, thought to come from the area to the south of Chaco, which comprised 13.2% of the ceramics from this period.  This is consistent with other evidence for intense contact with the area to the south at this time.

Pots from Early Periods at Chaco Museum

From 920 to 1040, overall imports drop slightly to 25.1%.  Chalcedonic sandstone drops to 7.9%, while trachyte rises to 12.3%, the highest percentage for any specific type of import.  This trend continues in the following period, from 1040 to 1100, which corresponds to the height of the Chaco system and the construction of most of the great houses in the canyon.  The overall percentage of imports rises to 39.8%, with almost all of that (30.7%) being trachyte-tempered.  It’s well-known that many other goods were being imported from the Chuskas at this time, especially wood, so it’s not surprising that Chuskan pottery would also have been popular.  There were a lot of Chacoan great houses and communities in the Chuska area, which seems to have been closely integrated into the overall Chacoan system, perhaps to a greater degree than other “outlying” areas.  The shift from south to west in the focus of the system seen in the pottery data is echoed in other types of evidence from this period.

The trend toward higher imports reaches a peak in the 1100 to 1200 period, which includes the end of Chaco’s regional dominance (but perhaps also its peak).  Imports constitute an astonishing 50.4% of all the ceramics from this period, and trachyte-tempered pots comprised 31.3%, a gain in overall percentage from the previous period but a loss relative to other imported types.  Chalcedonic sandstone continued to decline, while Kayenta wares increased to 4.8% after never having exceeded 1% before.  It’s important to note, however, that the sample from this period is much smaller than that for the previous period and it may not be totally representative.  The last period, from 1200 on, has a very small sample but continues to show a high percentage of overall imports (45.7%).  Trachyte drops to 21.6%, and San Juan wares skyrocket to 16.4% after never having exceeded 5% before.  This shift to the north for ceramic sources surely has to do with the relative decline of Chaco in this period and the rise of centers to the north, especially Aztec, which probably succeeded Chaco as the center of whatever Chaco had been the center of.  This is also the period during which Mesa Verde became a major population center, but despite the fact that the main decorated white ware type is known as “Mesa Verde Black-on-white” it’s unlikely that many of the San Juan wares found at Chaco came from Mesa Verde itself.  It’s much more likely that they came from Aztec or elsewhere in the Totah area, which had much closer ties to Chaco than Mesa Verde proper ever had.

Pots from Later Periods at Chaco Museum

So basically, the pattern that emerges from the ceramic data is of a shift in imports from the south to the west as the Chaco system really got going, followed by a shift to the north as it faltered or changed.  This is paralleled in other types of artifacts, as well as in settlement patterns.  The outlying communities to the south in the Red Mesa Valley were being abandoned in the late eleventh century even as new outliers like Salmon were being built to the north.  There are enough lines of evidence pointing in this direction to suggest that it corresponds to something real, but it’s hard to say what exactly was going on and why.

It’s also important to note the weaknesses in this analysis.  Remember, this is Chaco Project data.  It doesn’t include any of the pottery excavated from Pueblo Bonito, Chetro Ketl, Pueblo del Arroyo, or any other sites excavated prior to the 1970s.  It also has a heavy bias toward data from Pueblo Alto, which as I’ve mentioned before can be problematic in overall interpretations of Chaco.  However, at least the heavy importation of Chuska wares does seem to be supported by data from Pueblo Bonito.  Anna Shepard, the ceramic analyst who pioneered many of the techniques that are now standard in the Southwest, analyzed the sherds from Neil Judd’s excavations at Bonito in the 1920s and concluded that many of them were imported from the Chuskas based on the presence of trachyte temper.  Judd, who was heavily devoted to the currently prevailing notion that Pueblos were self-sufficient for utilitarian goods like pottery, was so skeptical of this finding that he actually wrote a rebuttal to Shepard’s analysis and published both in his report.  As it turns out, however, Shepard was right, and ahead of her time, in seeing substantial importation of pottery to Chaco.

Corrugated Grayware Sherds at Kin Ya'a

Of course, this leaves open the question of why the Chacoans would have imported so much pottery.  Was it due to a shortage of materials?  Surely there was no shortage of clay or sand; Chaco may be lacking in most resources, but it has virtually inexhaustible supplies of clay and sand.  Wolky Toll is inclined to think that a shortage of fuel for firing may have been a factor, and that the heavily forested Chuskas may have been a better place to find fuel and thus to make pots.  Certainly local wood resources in the sparsely wooded area around Chaco would have run out quite quickly what with all the monumental construction, but I don’t really buy this.  Wood isn’t the only type of fuel you can use to make fires.  There is plenty of evidence that the Chacoans burned corncobs and other material in their domestic hearths, and Toll and McKenna refer in their report to an apparent pottery production location in the Chuskas, dating to Basketmaker III times, that was not near wood sources but did have “complex hearths with substantial fuel waste build up (primarily corn stalks).”

So if not for lack of fuel, why all the imports?  One clue may come from the types of vessels imported.  The Chuska imports were primarily gray ware utility vessels, which were used for cooking.  It has been proposed that trachyte provides better resilience to thermal shock from repeated heating and cooling than other tempers, and Chuska vessels may thus have been higher-quality cooking pots than other local or imported vessels.  (Similar arguments have been made for the superiority of corrugated pots as compared to plainwares.)  This is certainly possible, but in light of the numerous other Chuskan imports it’s not really clear to me that functional considerations were primary determinants of Chacoan trade patterns.  Maybe the Chacoans just had particularly close social and political ties to Chuskan communities, and that led to closer economic ties.  A lot of this depends on the nature of the Chaco system, which of course we don’t know much about.

In any case, the large-scale importation of pottery is one of the most striking examples of how Chaco was very much at the center of a regional system.  We may not know what that system was, exactly, or how it functioned, but we can see that it existed.  The evidence is right there in all those potsherds that litter the ground around the sites in the canyon.
Toll, H. (2001). Making and Breaking Pots in the Chaco World American Antiquity, 66 (1) DOI: 10.2307/2694318

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Metate Incorporated into Wall Capping, Pueblo Bonito

I’ve written a bit about the recent research, spearheaded by Larry Benson of the USGS, into the sources of the corn found at Chaco.  These studies continue to refine the techniques used to identify source areas, but so far they have shown that corn was almost certainly being imported to Chaco both during and after the florescence of the Chaco system between AD 1030 and 1130.  As they begin to test more potential field areas, of course, the number of matches for the strontium isotope ratios in the corn at Chaco has increased.  While early studies indicated that much of it likely came from the Chuska Valley, it now looks much more likely that it instead came from the area along the Chaco River between there and the canyon.  This is an area with numerous outlying great houses, and it was probably the main route for the many commodities from the Chuska area that were brought to the canyon, and it’s also generally a better area for agriculture than the canyon itself, so this all makes sense.  There has also been some evidence that at least some corn was also coming from the Totah area to the north, again a more productive agricultural area with many Chacoan outliers.

Based on the proveniences of the corncobs from Pueblo Bonito that were tested early on, one tentative suggestion emerging from this research was that the main sources of imported corn changed over time.  The cobs that came from the lower Chaco River were from Rooms 3 and 92 in the northern part of Old Bonito, one of the earliest parts of the building to be built, while the one cob of possible Totah origin came instead from Room 170, in the southeast corner, one of the newest parts of the site.  Since there does seem on other grounds to have been a shift in the emphasis of the Chaco system from south to west to north over time, it would make sense that the early rooms contained early cobs from the west while a later room contained a later cob from the north.

Talus Unit with Snow

A paper published in 2008 by a group of big names in Chacoan studies sought to look at this directly by radiocarbon dating the cobs.  This is an interesting paper which goes beyond that narrow topic to also look at the characteristics of the corn found at the various great houses and other sites.  One of the co-authors is Mollie Toll, a specialist in archaeobotany who has done a lot of research on Chacoan corn.  As part of that research, she had long noted that the corn at Pueblo Bonito generally had bigger ears with more rows of kernels than most other corn known from the prehistoric Southwest.    It was bigger than earlier and later corn, for one thing, but it was also bigger than most other corn from the same period.  Corn from the Chacoan occupation of Salmon Ruin was also unusually large, as was corn from the Talus Unit behind Chetro Ketl, but corn from Pueblo Alto and Pueblo del Arroyo, other contemporary great houses at Chaco, was smaller and more in line with that from earlier and later sites.

Toll came up with three possible explanations for the difference.  Pueblo Bonito corn could be a different variety or “landrace” from the others, which is plausible but not directly testable with current technology.  It could also have been grown outside of the canyon where conditions were better for agriculture, while the corn from other great houses was grown in the canyon where conditions were poorer.  Finally, and problematically, the corn at Bonito might not have been Chacoan at all!  Since modern corn is generally bigger than ancient corn, Toll (when she was first looking at this in the 1980s) couldn’t exclude the possibility that the corn found at Pueblo Bonito had actually been put there by Navajos in the nineteenth century.  Much of it was from George Pepper‘s excavations in the 1890s, so it couldn’t be newer than that, but there was no way for Toll to tell how much older it was.

Room 3a/92/97, Pueblo Bonito

We still can’t tell different ancient landraces apart (although the recent sequencing of the maize genome may make this more feasible in the future), but the strontium isotope testing is giving us a sense of where the corn was grown, and accelerator mass spectrometry now makes directly dating the corn relatively easy.  Seven cobs from Pueblo Bonito that had been used in the strontium studies were dated for this paper.  One was the cob from Room 170 that possibly came from the Totah, one was from Room 92, and the rest were from Room 3.

The results were illuminating, but also challenging.  All the cobs clearly dated to ancient times, so the possibility that the size of Pueblo Bonito’s corncobs represents recent deposition is effectively quashed.  Three of the Room 3 cobs had closely clustered dates with intercepts around AD 1000, which offered some partial support for the idea that the corn in the early rooms was relatively early, but the other two were widely spaced, one at 870 and at 1170.  This is problematic for the idea that the date of corn in a room can be predicted from the date of that room’s construction, but it makes sense that the deposits in a room may date to well after its construction.  Since Room 3 dates very early, probably to the 900s, it’s likely that the deposits there resulted from much later trash dumping once it was no longer used for its original purpose.  Room 3 has a firepit, so it was probably originally a residential room, and it is likely one of those “big square rooms” that I have argued began to take the place of kivas in Chacoan room suites of the tenth century.  Room 92 is part of the maze of confusing rooms next to Room 3.  It had a well-preserved floor with corn and bean bushes on it (it’s not clear from Pepper’s description if this was the second or third floor), which suggests that it was used as a storeroom at the end of the period of occupation in this part of the building.  The cob from this room had the latest date of any in the study, with an intercept of AD 1220, which is consistent with the idea that this room was in use as a storeroom at the end of occupation.

Room 170, Pueblo Bonito

The biggest surprise, however, was the cob from Room 170, which dated to AD 1010.  This is particularly odd, since Room 170 was probably built around 1080 or even later.  Looking at the probability curve for this date, there is some chance that the actual date was around 1100, but the curve as a whole has a much more prominent peak around the intercept at 1010 than any of the other reported dates, which suggests that the probability is quite high that the intercept does in fact represent the true date or close to it.  The authors give various possibilities for why the cob might have been placed in this room long after it was grown, including the idea that it was put there as some sort of ritual offering of continuity with the occupation of earlier parts of the building.  I prefer another explanation they also suggest, which is that it was part of an earlier trash deposit that was redeposited in Room 170 for some reason.  There is very little information on what the deposits in this room were actually like, but many of the rooms in this part of the building were full of trash when excavated, and I think it’s most likely that this one was too.  The trash could have been put there for any number of reasons; if it was redeposited from somewhere else, it may have served as structural fill to support an upper story.  In any case, this puts a damper on the idea that the overall sources of corn changed over time.  Indeed, the sources seem to have been pretty constant through time for cobs left in different areas of the site, which suggests that the real story is much more complicated.

One nice thing about this paper is that the authors do a very good job of properly reporting their radiocarbon dates, particularly in giving point estimates as intercepts, which are meaningful, rather than midpoints, which are not.  Many papers make this mistake, including some of Benson’s reporting these and other dates on corn.  This paper also shows the probability curves for the dates, which give even more information.  This seems to be pretty common these days among Mesoamerican archaeologists, but it’s still quite rare in the Southwest, where radiocarbon dating has only recently become a major focus.  The availability of tree-ring dates, which are much more precise, has generally led Southwestern archaeologists to neglect radiocarbon, but it’s becoming increasingly obvious from studies like this one that the ability to date things other than trees is very useful in interpreting sites.

Obviously this paper just reports a handful of dates, and the authors take pains to point out the tentative nature of any conclusions they draw, but it’s an important contribution to the issue of where the Chaco system, whatever its nature, was getting its means of support.  As is often the case with new avenues of research, at this point papers like this pose more questions than they answer, but there are plenty of corncobs out there to date and analyze in other ways, just as there are plenty of potsherds to test for theobromine.  Once we get a bigger database of dates and strontium (and other) ratios, we’ll start to get a clearer picture of the behavior behind these remains.

Metate Fragment at Pueblo Alto

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Kiva E, Aztec West

In July 1914 Earl Morris, the pioneering Southwestern archaeologist who would later become famous for his excavations at Aztec and other sites in the region, happened to visit one Eudoro Córdoba, who owned a farm on the Animas River a short distance upstream of the major ruins at Aztec.  On his mantelpiece were various artifacts which immediately attracted Morris’s attention, and when Morris asked about them Córdoba told him that he had collected them in the course of plowing over a series of small ruins that were obstructing the cultivation of his fields.  He was at the time working on the last of these sites, and gave Morris permission to excavate the remaining portion of it in a more rigorous manner.  There wasn’t a whole lot left, but Morris did manage to excavate six rooms and a small area to the east of the roomblock which contained several burials.  He published a short article describing the excavation and artifacts the next year.  This was one of the earliest examples of what would later become known as “salvage archaeology.”

There are several interesting statements in Morris’s article on the site.  For one thing, while this was the last of the “seven or eight small ruins which had obstructed [Córdoba’s] fields,” Morris noted that there had been many more sites in the area:

Roughly three quarters of a mile east of the great pueblos the river swings obliquely across its narrow valley from northeast to southwest. The broad bench thus left north and west of the river was till recently dotted upon all sides of the large ruins with the remains of many cobblestone and adobe structures. Within the last few years a number of these lesser sites have been destroyed in order that the owners of the land might increase the tillable area of their fields.

Córdoba was one of these landowners, of course.  It appears from Morris’s statement that a large number of what we would now call “small houses” existed in close proximity to the great houses at Aztec, much like at Chaco.  This is particularly relevant to the question of the extent to which the Totah was densely inhabited before the Chacoan immigration that many have posited as being behind the founding of Aztec and Salmon.  People have generally agreed that Salmon, which is on the San Juan rather than the Animas, was founded in a previously uninhabited or sparsely inhabited area, and some people claim the same for Aztec.  Since we don’t know when the sites Morris mentions near Aztec were inhabited, his statement doesn’t provide direct evidence either way, but it does point out the dangers of making judgments about prehistoric habitation based on currently visible site distributions.  The San Juan valley has been just as heavily developed in modern times as the Animas valley, and the larger size of the San Juan also implies that more sites are likely to be buried under sediment there.  I remain skeptical about claims that the Salmon area was uninhabited before 1090.

South Wing of Aztec West, Looking East

The site Morris excavated, however, seems to have clearly been contemporaneous with the Aztec complex rather than predating it.  There was no way for Morris to know this in 1915, of course, which was before he even started excavating at Aztec West, but it’s clear from the artifacts he shows in his article that the site was inhabited in the 1200s, and perhaps a bit earlier.  Most of the illustrated ceramics seem to be Mesa Verde Black-on-white, which is typical of this period.  The site itself was made of adobe with occasional cobbles, which is standard local architecture, and it was apparently two stories high in places.  This is unusual among small houses (though standard for great houses), and it suggests that this site may be a residence of local inhabitants of some distinction or, perhaps, a somewhat larger aggregated site comparable to those known from the Mesa Verde region to the north during this period.  The site was mostly gone before Morris got to it, so he couldn’t tell how large it had been originally.  We know so little about sites in this region other than Salmon and Aztec that it’s hard to say what this site may have originally been like, but the sites excavated on the Bolack Ranch on the south side of the San Juan by the Totah Archaeological Project may provide a useful point of comparison.

As was apparently the case for some of the Bolack Ranch sites, the Córdoba site contained many burials.  In addition to five adults and two infants buried a short distance to the east of the roomblock, nineteen people were buried in three of the six rooms Morris excavated.  Morris suggested that “calamitous circumstances such as siege, pestilence, or famine overtook the inhabitants and caused great mortality among them,” leading to the unusually high number of burials in so few rooms and the oddities of the way some of them were buried.  The site appeared to Morris to have been burned, which might indicate warfare in the region during the late 1200s.  This would not be surprising, as there is abundant evidence for warfare in many other nearby regions at this time.

South Wing of Aztec West, Looking West

Another interesting thing about this site was the burial of a badger just north of the human burials east of the roomblock.  According to Morris “the animal had been put away with all the care ordinarily bestowed upon a human being.”  Animal burials like this are pretty common at Pueblo sites.  They are most often of dogs or turkeys, but occasionally of other animals.  As far as I know no one has looked at the spatial and temporal patterns in which animals are buried where, but that might be one way of getting some evidence for possible migrations of specific groups that might have had particular attachments to different animals.

Overall, this is an interesting paper, with quite a bit of interesting information despite its short length and emphasis (typical for the time) on artifact description rather than discussion of larger issues.  It doesn’t seem to get cited very much, which is unfortunate because it provides a useful point of comparison for more recent excavations in the region.
Morris, E. (1915). The Excavation of a Ruin near Aztec, San Juan County, new Mexico American Anthropologist, 17 (4), 666-684 DOI: 10.1525/aa.1915.17.4.02a00040

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Peñasco Blanco

Returning to my theory that the large square rooms with hearths and other residential features found at some great houses in Chaco and elsewhere were in some sense replacements for earlier kivas, I think the best evidence for this at Chaco itself (as opposed to at outlying great houses like Salmon) comes not from Pueblo Bonito, which is just too complicated a palimpsest to make something like this easy to see, but from the other early great houses: Una Vida and Peñasco Blanco.  These at least seem to have simpler layouts than Bonito, though the extent to which this is just an effect of their being (mostly) unexcavated is unclear.  Nevertheless, at least some parts of these two great houses do seem to show basically the pattern that I’m proposing for the development of residential room suites at great houses.

To recap the idea: The very earliest great houses, those built in the AD 800s, seem to show a pattern of suites similar to that seen at small houses or unit pueblos, with each suite consisting of one rectangular room backed by two smaller rooms.  In front of each roomblock there are subterranean kivas, usually with slightly fewer than would be expected if each suite had its own kiva.  This suggests to me that the suites housed individual nuclear families, but that they were grouped into larger units, perhaps extended families, which shared kivas.  Whatever rituals these residential units would have conducted would probably have been in the kivas, but for the most part these were still residential structures, similar to the pithouses occupied in earlier centuries but with some of their functions transferred to the rectangular front rooms of the roomblocks.  The smaller rooms in the back would have been used for storage.  A typical great house would contain a few of these suites, with a kiva for every two or three.  It’s unclear what the relationships among different kiva-units within a great house would have been, but they could have either been separate extended families within the same real or fictitious “clan” or “lineage,” or they could have been separate lineages that were politically or ceremonially allied.  Importantly, all of these buildings are still residential at this point, although the residents may well host rituals or feasts open to the whole community either to solidify their political authority or because generosity is expected of them in exchange for community acceptance of their greater wealth or political/religious authority.  The main difference between great houses and small houses is just that great houses are bigger, with multiple stories in some instances and generally bigger rooms, as well as more extensive use of masonry rather than adobe or jacal construction.

Room 330, Pueblo Bonito

Then, at some point in the 900s, a change takes place in some (all?) great houses.  Use of the kivas is discontinued, and instead the activities that had been conducted in them are transferred to square surface rooms added onto the existing roomblocks.  This definitely seems to be what happens at Una Vida and Peñasco Blanco, although the extent to which there were earlier kivas is unclear given the lack of excavation.  In great houses newly begun during this time (it’s unclear how many of these there were in Chaco itself, but Kin Nahasbas may be an example), room suites were built without any kivas but with large, square rooms in front and smaller rectangular rooms varying in number behind them for storage.  This pattern continues well into the 1000s, at least at some great houses, and it’s associated with the very formal, symmetrical, rectilinear layout seen at sites such as Hungo Pavi, Chetro Ketl, and Pueblo Alto.  Some outlying great houses, such as Kin Bineola and (especially) Salmon, show this pattern as well.  Salmon seems to show that new great houses with (almost?) exclusively square rather than round living rooms were still being built as late as 1090, and if the early construction at Aztec is in the same pattern, which seems to be a matter of some dispute, it would still be going on well into the early 1100s.  This is probably also what we see at Pueblo Bonito too, with the possible addition of square rooms like 329 and 330 to the older suites at the west end of Old Bonito and the later addition of linear suites to the south of these rooms at the southwest corner of the site.

At some point in the late 1000s, however, a different type of room suite begins to arise at some Chaco great houses.  This is still a linear suite, sort of, but it consists of a round kiva built aboveground into a first-story square room, with one or two rows of two- or three-story rectangular rooms extending back from it.  These are the “blocked-in” kivas that are probably the most famous innovation of Chacoan architecture.  I see them as still residential spaces, in combination with the rooms behind them.  Their appearance at most outlying great houses indicates residential use of those sites, perhaps by local elites.  It’s not clear what the relationship is between these plaza-facing blocked-in kiva suites and the “elevated” kivas surrounded by rectangular rooms that start to appear at the centers of the rectilinear great houses with the square living rooms around this same time.  If those rooms are still residential, they’re pretty damn fancy residences.  They’re also quite unlike the other residential rooms at these sites, which are still square.  The “Tower Kiva” at Salmon is one example, as are the corresponding kiva at Hungo Pavi and the numerous examples at Chetro Ketl.  The central placement and unusual elaboration of these structures has led many to assume that they were ceremonial rather than residential in function, but I’m not so sure.  These sites do generally have great kivas, which pretty much everyone agrees were community-scale ceremonial/integrative structures, and they look quite different from elevated kivas (although it’s not clear to what extent the unique features of great kivas are due to structural requirements following from their size).

Kivas in the Southeast Part of Pueblo Bonito

In any case, the best examples of the plaza-facing blocked-in kiva suites are at Pueblo Bonito in the southeast and southwest wings.  These appear to have been built over earlier construction, so it’s not totally clear what was going on with these multiple, quite rapid changes in site layout during this period.  Again, though, they’re also obvious at Una Vida and Peñasco Blanco, where some (but not all!) of the earlier square living rooms are replaced by blocked-in kivas.  This also appears to have happened in the west wing of Chetro Ketl, but it’s unexcavated so it’s hard to say for sure.  There definitely are two blocked-in kivas there, though, and they appear to have rooms behind them like at Pueblo Bonito.

Then, at some point toward the very end of the eleventh century or very early in the twelfth, a totally new type of room suite begins to appear at Chaco great houses.  This is the famous “McElmo unit,” with a central blocked-in kiva surrounded on three or four sides by rectangular rooms, most of them significantly higher (three or four stories), creating a sort of “patio” over the kiva.  These rarely have ground-floor exterior walls, and they are remarkably uniform and modular in form.  The most famous of these structures are the freestanding ones, including New Alto, Casa Chiquita, and Kin Kletso (which comprises two adjacent units), but clearly analogous forms can be seen within certain great houses, including the north and south wings of Pueblo del Arroyo and the Kiva B complex at Pueblo Bonito.  Similar units that are just outside of existing great houses can be seen at Chetro Ketl and Peñasco Blanco.  The masonry of most of these is very different from that used at earlier great houses, being composed of blocky yellow sandstone rather than fine, hard, dark sandstone, and this has been used to argue that they represent influence from the north.  The masonry may indeed reflect northern influence (though in a different way from what the original proposers of this idea thought), but the form predates the shift in masonry and probably developed locally in Chaco.

Kiva E, Kin Kletso

There has been a lot of debate over the function of McElmo units.  Some see them as warehouses, while others see them as ritual (or possibly astronomical) special-use sites.  I’m increasingly thinking that all this speculation is based on an overemphasis on their differences from earlier great houses, and that they were probably residential and represent the final version of the Chacoan room suite.  More on this later.

McElmo units may represent the final development of Chacoan architecture in terms of form, but the great houses continued to be occupied for quite some time after the construction of these roomblocks in the early 1100s.  What we see at this point is an increased emphasis on the blocked-in kiva concept, with new kivas, often of “non-Chacoan” form, being built into earlier square or rectangular rooms.  Some call these “intra-mural” rather than “blocked-in” kivas, to emphasize that they were built into earlier rooms rather than having square rooms built around them, and I think this is a helpful distinction.  These really proliferate at Pueblo Bonito late in the occupation period, and this also happens at Aztec and Salmon during their “post-Chacoan” (also called “secondary” or “Mesa Verdean”) occupations.  At the same time, many great houses also see the construction of new subterranean kivas in the plazas, often with accompanying small blocks of square rooms.  These aren’t usually datable directly, but they appear to be very late.   Pueblo Bonito has particularly many of these, and there are a few in the southeast corner of Chetro Ketl too.  These appear to represent the construction of typical small-house or unit-pueblo style residential units within earlier great houses, and they may or may not represent an occupational discontinuity of some sort.

So basically, what we see is a sequence of underground kiva to above-ground square room to above-ground kiva.  There are plenty of variations and complications, but that’s the general sequence.  The later use of intra-mural kivas, especially at Pueblo Bonito, has tended to obscure the middle stage here, but it really seems to represent something meaningful at least as a chronological marker in Chacoan architecture.  Does it mean anything else culturally?  That part I’m still looking into, but it may.

Fajada Butte from Una Vida

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