Archive for June, 2011

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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Display Case at Chaco Museum Showing Cylinder Jar and Canteens

I mentioned earlier that there was a new paper out on chocolate at Chaco that I needed to read.  I read it today, and it’s quite interesting.  One of the most interesting things about it is that it’s by a different group of researchers than the first one and uses somewhat different methods.  As far as I can tell, all the study of chocolate residue in archaeological pottery until this paper has been done by Jeffrey Hurst at Hershey, in collaboration with a variety of archaeologists.  Except for the Chaco paper he did with Patricia Crown, all of Hurst’s work in this area has been on Mesoamerican pottery and in collaboration with Mesoamerican archaeologists.  This makes sense, since Mesoamerica is where chocolate is grown and was used most extensively in antiquity.  Hurst’s methods involve scraping residue from the interior of pots or grinding up potsherds to test them for the presence of theobromine, a chemical compound that serves as a biomarker for chocolate.  They aren’t hugely destructive methods, as analytical methods applied to artifacts go, but there is a certain amount of damage inherent in the scraping (and more in the grinding, of course).

This new paper pioneers a different method, which uses a wash of deionized water on whole vessel interiors (this could presumably be done with sherds too, but these authors used whole vessels) and subsequent analysis of the water with a very sensitive mass spectrometer.  The researchers are not affiliated with Hershey, but instead with Bristol-Myers Squibb, except for the lead author, Dorothy Washburn.  Washburn has for many years now been studying symmetry patterns on pottery and other artifacts and she has come up with a variety of interpretations of social structure and change from the patterns she sees.  The work she has done on Chaco has led her to posit that the “special” vessel forms associated with the Chaco Phenomenon, particularly cylinder jars but also pitchers and shallow bowls, show a very different type of symmetry from that prevailing on Pueblo pottery before and after Chaco.  In publications such as her chapter in the Salmon Ruins synthesis volume, she further contends that this sudden difference indicates an influx of people from elsewhere with a very different social structure, and she points to Mexico as the most likely source given the presence of both similar symmetries and similar vessel forms there.  This puts her in what I’ve called the “hard Mexicanist” camp, not a popular position among Chacoan scholars these days (although this chocolate stuff may start to change that).  I don’t really buy her arguments for physical migration of Mesoamericans to Chaco, and I think she generally goes a bit too far in inferring specific social structures from the abstract symmetries she studies, but her evidence for a big difference between Chacoan and other designs is solid and well-taken.

Cylinder Jar at Chaco Museum from Above

Given Washburn’s theories, it makes sense that she would jump at the chance to look for chocolate residue in Chacoan vessels.  The Crown and Hurst paper that started all this really came out of nowhere; no one in the Southwest was expecting it at all, and it’s likely to end up being one of the major turning points in interpretations of Chaco.  The paper itself, though, was short, and the research behind it was modest in scale.  Crown and Hurst only tested five sherds from the mounds in front of Pueblo Bonito, three of which seemed from their curvature to be from cylinder jars while one of the others was from a pitcher and the final one could have been from either a cylinder jar or a pitcher.  Testing revealed that the three definite cylinder jar sherds showed evidence of chocolate, while the other two didn’t.  This was remarkable, groundbreaking stuff, to be sure, but it was still only five sherds.  The really important thing about that paper was that it opened up the possibility of running tests like this on all sorts of sherds and vessels to determine the extent of chocolate use in the prehistoric Southwest, and it seems Washburn was inspired to take it a step further.

Room 28 at Pueblo Bonito

She and her coauthors, William Washburn, who I presume is her husband, and Petia Shipkova, both of whom work for Bristol-Myers Squibb’s Pharmaceutical Research Institute in Princeton, NJ, apparently developed this new technique for doing the theobromine testing and they applied it not to sherds but to whole vessels.  Not just any whole vessels, either; they went straight for the important ones: the cylinder jars from Room 28 at Pueblo Bonito, along with cylinder jars, pitchers, and shallow bowls from burial rooms elsewhere in Bonito (including Room 33).  They also tested three cylinder jars from Pueblo del Arroyo, at least two of which are of plain redware rather than the whiteware that characterizes all other known cylinder jars (there is some confusion over whether the other jar is red or white, in that the paper says all three are red but the National Museum of Natural History catalog seems to say that one is white).  In addition, they tested a variety of similar forms from the Hohokam site of Los Muertos.  This is interesting, because the Hohokam in southern Arizona showed a wide variety of Mesoamerican influences to a much greater degree than Chaco ever did, and one of the first things I wondered when I read the Crown and Hurst paper was whether a similar study of Hohokam vessels would also show chocolate use.  They picked Los Muertos specifically because it’s a Classic-period platform-mound complex with what appear to be elite burials.  The platform mounds of the Hohokam Classic are the only other phenomenon except for Chaco in the prehistoric Southwest that show clear evidence of social hierarchy, and the authors of this paper clearly chose this set of vessels to see if chocolate use corresponded to increased hierarchy.  In all they tested 57 vessels from Chaco great houses and 10 from Los Muertos, and as a control they also tested eight vessels from small sites at Chaco, on the Little Colorado River in Arizona, and in southwestern Colorado.

Pitchers at Chaco Museum

What they found was that most of the great-house and Hohokam vessels did indeed test positive for theobromine.  Specifically, 80% of the Los Muertos vessels tested positive, as did 65% of the Chaco cylinder jars, 41% of the Chaco pitchers, and 83% of the shallow bowls from Chaco.  The lower percentage for the pitchers may indicate that they were used for a variety of things, not just chocolate, which might in turn explain why Crown and Hurst’s pitcher sherd tested negative.  The very high number of positives for the shallow bowls is very interesting, and suggests that this class of vessels, largely overlooked because they resemble local forms more than the cylinder jars, may be more important than people have thought.  On the other hand, only 12 bowls were tested (versus 23 cylinder jars and 22 pitchers), so this could just be a fluke of sampling size.  These results seem to confirm the Crown and Hurst results and reinforce the idea that the presence of chocolate, a clear sign of ongoing trade and contact with Mesoamerica as well as acceptance of Mesoamerican ideas and practices, may correlate strongly with the evidence for social hierarchy at both Chaco and the Classic Hohokam platform mounds.

But wait, what about the small-house sites?  Here’s where things get really interesting, in an unexpected way.  All eight vessels from the small houses tested positive for theobromine.  This was totally unexpected, and the authors devote quite a bit of discussion to this result.  Apparently concerned that there might be a problem with the whole theobromine-testing enterprise, they went looking for native plants in the Southwest that might contain theobromine.  If there were any, of course, that would call all of these results into question.  They couldn’t find any, so it does seem (unless there’s something amiss with their experimental protocols) that the results for the small houses really do indicate that chocolate was not just confined to the great houses at Chaco and the platform mounds in Phoenix.  They suggest that commoners might have been paid in chocolate for their work for the great-house elites, a very interesting idea.  In Mesoamerica cacao beans were often used as currency, and if something similar was going on at Chaco that would be cause for some serious rethinking of how the Chacoan economy worked.

Bc 51

One issue that the authors don’t really address is that the small houses they picked are all within areas that could plausibly have been part of the Chaco system, so there isn’t really an independent check here on how widespread chocolate was in the region as a whole.  They preferentially selected vessels from early excavations because early excavators usually didn’t wash the vessels they found, which makes sense for this type of project but also means that provenience information for the small sites is not ideal.  Nevertheless, one of the small houses that produced these vessels was Bc 51 at Chaco, which is right across the canyon from Pueblo Bonito and would obviously have been closely incorporated into the Chaco system.  The others included a cluster of sites in the Montezuma Valley of southwestern Colorado, which is an area with several nearby Chacoan outliers, and a site on the Little Colorado River in eastern Arizona that is not located very precisely but could have been relatively close to the far western edge of the Chacoan system.  There are several major outliers along the Rio Puerco of the West, a major tributary of the Little Colorado, and some evidence for at least a small amount of Chacoan influence as far west as Winslow.

Further testing of vessels and sherds from a wide variety of sites and time periods should help to clarify this picture.  The great thing about this chocolate stuff is that it’s all about analyzing pottery, which is by far the most common type of artifact found at sites in the Southwest.  There are vast numbers of vessels in museums throughout the country that could easily be tested using these techniques, and even vaster numbers of sherds collected from sites throughout the region that could potentially produce an unbelievably huge and detailed database of information on the distribution of chocolate in the prehistoric Southwest.  There are a lot of questions still outstanding at this point, but there is also a huge opportunity to try to answer them.  Hopefully this question will keep a lot of archaeology grad students set for thesis and dissertation topics for years to come, and the rest of us will benefit from the information they find and the patterns they discover.
Washburn, D., Washburn, W., & Shipkova, P. (2011). The prehistoric drug trade: widespread consumption of cacao in Ancestral Pueblo and Hohokam communities in the American Southwest Journal of Archaeological Science, 38 (7), 1634-1640 DOI: 10.1016/j.jas.2011.02.029

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Chetro Ketl from Above

The great houses at Chaco are by any measure monumental in scale.  This has been in some ways the defining characteristic of the Chaco system in the eyes of many who have studied it, and the overriding question has been “why are these monumental buildings here, in such an unexpected place?”  Many, many answers have been proposed over the years.  Some have simply argued that the massive scale of the sites was a result of the number of people they housed.  This is the traditional approach, which was dominant up until the 1970s, in which archaeologists saw prehistoric sites like Pueblo Bonito, Chetro Ketl, and the rest as functionally equivalent to modern pueblos like Taos and Acoma, which is to say, as massive towns in the form of apartment buildings.  Some still hold to this idea, most notably Gwinn Vivian, but most have accepted the reinterpretation of the “scale of social action” at Chacoan great houses that sees much less evidence for residential use than would be expected if they were standard pueblos.  This reinterpretation is based in part on the (relative) lack of features indicating residential use, but also on the fact that the buildings are not only huge but very carefully built.  In this respect they differ dramatically from the late prehistoric sites, unquestionably pueblos in the modern sense and ancestral to the extant ones, that are in some cases even bigger in bulk but generally of much rougher, more expedient construction.  Sites like Hawikuh and Grasshopper Pueblo were clearly residential pueblos, and they’re really big, but they show nothing like the formal layout and fine masonry of the great houses at Chaco.

So if great houses weren’t pueblos, what were they?  Here’s where contemporary archaeologists tend to break into two main camps.  One sees them as elite residences, part of some sort of hierarchical system centered on the canyon or,  alternatively, of a decentralized system of “peer-polities” with local elites who emulated the central canyon elites in the biggest great houses.  In either case, note that the great houses are still presumed to have been primarily residential.  The difference from the traditional view is quantitative, rather than qualitative.  These researchers see the lack of evidence for residential use in most rooms, but they also see that there is still some evidence for residential use, and they emphasize that and interpret the other rooms as evidence of the power and wealth of the few people who lived in these huge buildings and were able to amass large food surpluses or trade goods (or whatever).  The specific models vary, but the core thing about them is that they see the great houses as houses, not for the community as a whole (most people lived in the surrounding “small  houses” both inside and outside of the canyon) but for a lucky few.  In this camp are Steve Lekson, Steve Plog, John Kantner, probably Ruth Van Dyke (although she doesn’t talk about the specific functions of great houses much), and others.

Una Vida from Petroglyph Area

On the other side are those who see the difference between pueblos and great houses as qualitative.  To these people, the great houses were not primarily residential in function, although they may have housed some people from time to time.  Most of these researchers see the primary function of the sites as being “ritual” in some sense, although what that means is not always clearly specified.  In many cases a focus on pilgrimage (based on questionable evidence) is posited.  This group tends to make a big deal out of the astronomical alignments and large-scale planning evident in the layouts and positions of the great houses within their communities.  They tend to see the few residents of the sites as caretakers, priests, or other individuals whose functions allowed them to reside in these buildings.  Importantly, they don’t see these sites as equivalent to other residences in any meaningful way.  They are instead public architecture, perhaps built by egalitarian communities as an act of religious devotion.  Examples of monumental architecture built by such societies are known throughout the world (Stonehenge is a famous example), and this view fits with the traditional interpretation of modern Pueblo ethnography, which sees the Pueblos as peaceful, egalitarian, communal villagers.  There is a long tradition of projecting this image back into the prehistoric past based on the obvious continuities in material culture, so while these scholars are in some ways breaking with tradition in not seeing great houses as residential, they are also staying true to tradition in other ways by interpreting them as a past manifestation of cultural tendencies still known in the descendant societies but expressed in different ways.  In this corner are such researchers as Wolky Toll, Dean Saitta, and maybe Tom Windes.  Not everyone who looks at Chaco fits into this neat dichotomy, of course, but it does express one of the major issues over which “the experts” are divided.

Another axis along which people are divided over Chaco concerns the source of the aspects of the Chaco system, whatever they were exactly, that set it apart from other manifestations of Pueblo culture.  The two camps here are the “Mexicanists” and the “Indigenists.”  The Mexicanists, who have been out of the mainstream for a while now but may be moving back toward the spotlight with the recent discovery of chocolate at Chaco (and elsewhere, as documented in a recent paper that I still need to read), see the sudden florescence of Chaco as the result of direct action by Mesoamerican societies, usually seen as an attempt to control the supply of turquoise.  The noteworthy association of Chaco with turquoise gives this a certain plausibility, as does the huge scale of the great houses and other aspects of the Chaco system compared to developments in the region earlier and later.  The most extreme version of Mexicanism sees actual Mesoamericans physically coming up and establishing Chaco, either as a merchant outpost or as a military center.  Few hold to this theory today, although it enjoyed some respectability in the 1970s and 1980s, but it adherents include Dorothy Washburn, Christy Turner, and a few others.  These scholars are all in the “more hierarchy” camp, of course, given the high levels of inequality in the Mesoamerican societies in the question, which generally also means they interpret great houses as elite residences, although some see them as more specialized facilities associated with whatever system they see being imposed on the hapless Southwesterners by the Mexican interlopers.  Another version, which might be called “soft” Mexicanism, sees Chaco as the result of influence by Mesoamerican centers on indigenous societies.  This view, which could just as easily be called soft Indigenism, is held by Lekson and Ben Nelson, and there may be other Indigenists who prefer this interpretation to the rejection of any meaningful Mexican influence by the “hard” Indigenists like Vivian.  Many Chacoan specialists just don’t talk much about the level of Mesoamerican influence they see as having been important to the development of Chaco, which makes them hard to classify using this typology but implies that they’re somewhere in the Indigenist camp by default.

Pueblo Bonito from Above

So, having laid out the schools of thought like that, which are best supported by the evidence?  Obviously each individual scholar would see the evidence as supporting their own view of Chaco, but there are a few lines of evidence that I think do clearly support some more than others.  On the question of great house function, those who see great houses as primarily non-residential tend to finesse the fact that there is actually rather a lot of evidence for residential use of many great houses, especially outliers like Salmon.  Pueblo Bonito also has plenty of evidence of residential use in many of its rooms, although that’s hard to interpret given how complicated a site it is.  A lot of these interpretations seeing little residential use rely heavily onto Pueblo Alto, but even there Chaco Project excavations found some evidence of residential use.  It’s not that people who support a primarily non-residential function ignore this data entirely, but they tend to pass over it too quickly.  An explanation for what a great house was that sees it as something other than a house needs to address the fact that there is evidence for residential use.  There are potentially ways to do this convincingly, but many explanations just get kind of hand-wavy.

Similarly, “hard” Mexicanists really need to explain the lack of most of the defining characteristics of Mesoamerican societies at Chaco if they want to posit Mesoamericans actually coming up and founding the sites there.  Where are the ballcourts?  Where are the pyramids?  (Some have, to their credit, tried to answer that one.  More on that later.)  Where are the incense burners, mirrors, and copals?  Where’s the obsidian?  (This one is particularly puzzling, as I’ll explain in a subsequent post.)  “Hard” Indigenists have a similarly tough road in front of them; they have to explain the chocolate, for one thing, as well as the macaws, copper bells, cylinder jars, and other signs of rather more substantial Mesoamerican influence than casual, down-the-line trade would be likely to produce.

Kin Kletso

Overall, I think great houses were most likely elite residences, occupied by elite families of local origin who selectively appropriated Mesoamerican objects and symbols to justify their power and perhaps to try to emulate the great cities of Mexico to the extent they could in the very different environment of Chaco.  Obviously they failed at this, if it is indeed what they were trying to do, but that doesn’t mean they didn’t try.  The fact that their descendants, the modern Pueblos, have a generally egalitarian ideology and often aggressively act to suppress personal aggrandizement and the accumulation of power doesn’t conflict at all with this model.  Indeed, that ideology may have developed specifically in reaction to the excesses of Chacoan elites.  This is Lekson’s basic model, and I agree with it at least up to this point.

My conclusions on both these questions really stem from the same source: the architecture of the great houses.  Basically, what strikes me about them is that they look overwhelmingly like extremely elaborate, formal versions of the ubiquitous small houses or unit pueblos that were the standard form of regional architecture during this period.  What makes them special and unusual is not any difference in overall form but, rather, their massive scale and fineness of construction.  This, to me, implies strongly that they were built to be houses, but special houses, and that they were built by local people, but special local people.  There’s nothing in Mexico that looks like Pueblo Bonito, but there’s plenty of stuff in the Southwest that resembles it to a greater or lesser degree.  Furthermore, the Chacoans already had a form of public architecture that they seem to have appropriated as their power grew: the great kiva, which is clearly non-residential and both predated and outlasted the great houses.  There was no need for a new form of public architecture in the local architectural system, and there’s no sign that the Chacoans tried to import one from Mexico or anywhere else.  No ballcourts, no pyramids.  Just houses.  Big, elaborate, formal houses, but houses nonetheless.  Houses full of Mesoamerican imports, but again, still houses.

Pueblo del Arroyo from Above

On the other big questions about Chaco, I’m still undecided.  I don’t have a clear answer for why Chaco developed where and when it did or why it declined when it did.  I don’t know exactly where the Chacoans came from or where they went; I’m confident enough to say that all these movements were within the Southwest, but the Southwest is a big area, and we’re increasingly learning that migrations were frequent and often quite long-distance.  I don’t know what went on in the great kivas (and frankly, I don’t particularly care).  I don’t know why great house form changed so much over time, but I do care about this one and am determine to figure out as much as I can about it.

I do know what’s so special about Chacoan architecture.  The great houses were big, bigger than anything the Southwest had seen before, and they were remarkably well built, so well that they’re still in pretty good shape after a thousand years.  But most importantly, the great houses were a recognizable part of the local architectural system that had been developing for hundreds of years when they first appeared and would continue to develop for hundreds of years after they were abandoned.

Chetro Ketl, the Talus Unit, and Pueblo Bonito from the Cliff Top

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Trash Mound from Pueblo Alto

Many recent interpretations of Chaco Canyon see it as a site of pilgrimage, and this is often specifically seen as taking the form of regular region-wide ritual events involving communal feasting, construction work on the massive buildings in the canyon, trade involving various mundane and exotic items, and ritual breakage of pottery and deposition of it in the mounds accompanying most great houses.  This idea, which has been incorporated into a wide range of models of Chacoan society both hierarchical and egalitarian (although it is especially important to egalitarian models), is heavily dependent on data gathered in the excavation of Pueblo Alto by the Chaco Project in the 1970s.  In addition to excavating about 10% of the great house itself, Project personnel excavated a trench and several stratigraphic columns in the large trash mound to the southeast.  What they found was a series of well-defined layers.  Some of these, toward the bottom, seemed to consist mostly of construction debris, and others, toward the top, consisted mostly of windblown sand and redeposited artifacts, but the ones in between seemed to show a pattern of large, well-defined deposits.  This was interpreted as being quite different from the expected pattern from the regular deposition of domestic trash from a residential site, and the theory developed, particularly by Wolky Toll, explained it as the result of occasional massive depositional events in which large amounts of pottery and other artifacts were deposited all at once.  Toll estimated that the number of layers approximately matched the number of years during which Pueblo Alto was occupied, and that they therefore accumulated as the result of annual events in which numerous people came from throughout the region to attend events at Pueblo Alto (and presumably at other great houses too).  As part of these events, pilgrims would probably have brought offerings of items from their home areas, thus explaining the huge amount of imported goods at Chaco as well as the lack of apparent exports.  These items would have included mundane items like wood, corn, and pottery, as well as more exotic things like turquoise and Narbona Pass chert.  People may have also worked on constructing the great houses as part of some sort of ritual offering of labor, which would explain the massive scale of these buildings despite the small permanent population of the canyon itself.  While there is a certain amount of evidence for residential use at Pueblo Alto and other great houses, it indicates a pretty small population relative to the size of the buildings, and Toll’s model interprets this as a small “caretaker” population of what were primarily non-residential, public structures with large plazas that could serve as the sites of ritual feasting and other activities during these festivals.

Furthermore, the composition of the artifact assemblage found during the excavations of the Pueblo Alto mound seemed to offer an interesting possibility for another ritual activity.  Basically, there was a huge amount of pottery in it, especially gray utility ware, much of it imported from the Chuska Mountains to the west.  Based on the number of rim sherds in the excavated portion and an estimate of the size of the whole mound, Toll calculated that 150,000 vessels were used during the 60-year period (AD 1040 to 1100) during which Gallup Black-on-white was the predominant decorated type, a period that roughly corresponds to the height of the Chaco system.  This works out to 2500 vessels a year, or 125 for each of the 20 households estimated to have lived at Pueblo Alto at any one time.  This is a huge number compared to ethnographically documented rates of pottery usage and breakage or ratios seen at small sites, and to Toll it suggested that the pottery deposited in the mound was probably not broken in the course of everyday life at Pueblo Alto but was instead broken deliberately in rituals associated with the annual pilgrimage fairs.  Ritual breakage and deposition of pottery is a known Pueblo practice, but this would be on a scale not seen at any other known site.  Nevertheless, this is the model of the formation of the Pueblo Alto mound that has been widely accepted and incorporated into a wide variety of interpretations of the Chaco system that differ wildly in many respects but all have some sort of pilgrimage function for the canyon as part of its regional role.  It’s important to note that this is the only direct evidence for a pilgrimage function known from excavations at Chaco.

Niche at Pueblo Alto

I think it’s pretty plausible that pilgrimage and communal feasting took place at Chaco, but I’ve increasingly come to think that the evidence from the Pueblo Alto mound is extremely weak.  There are a few different reasons I don’t buy it, and a couple of the most important ones are well illustrated by two articles published in American Antiquity in 2001.

One of these, by Toll himself, is part of the same special issue on the organization of production at Chaco that included Colin Renfrew‘s model of Chaco as a “Location of High Devotional Expression” or pilgrimage center.  Toll likes this idea, obviously, and his article, in addition to summarizing the known data on the production and use of pottery at Chaco, attempts to take a closer look at the Alto data to evaluate Renfrew’s model.  This basically involves looking at each of the “event layers” (as distinguished from the construction and post-occupational layers) and calculating the proportions of local and non-local ceramics and lithics (as well as the different types of pottery forms and wares) in each.  These were then compared to the proportions in the mound as a whole, other Chaco Project excavations dating from the same period, and excavations dating earlier and later.  If Renfrew’s theory works, the event layers should show higher proportions of imported ceramics and lithics, as well as possibly higher proportions of ceramic types likely to have been used in feasting, compared to these other data sets.

Flake of Narbona Pass Chert with Ant at Pueblo Alto

Toll does his best to spin the results to be consistent with Renfrew’s model, but looking at the actual numbers in his tables, there’s just nothing there.  The event layers are virtually identical to the whole mound, which isn’t really surprising given that they comprise a large portion of it, and both are very similar to contemporary non-mound contexts in most ways.  Earlier and later contexts are different in interesting ways, but that’s neither here nor there in terms of evaluating Renfrew’s model.  Chuska ceramics are a case in point: they comprise 33.4% of the event layers, 30.8% of the whole mound, and 33.1% of the contemporary non-mound contexts.  That doesn’t look like a meaningful difference to me.  In the cases where the mound layers do differ from other contemporary contexts, they generally have fewer exotic materials.  For example ceramics from the Red Mesa Valley comprise 3.3% of the event layers, 3.8% of the whole mound, and 4.6% of the contemporary non-mound contexts.  The presence of Narbona Pass chert is something of an exception, with the proportions for the event layers, the whole mound, and other contemporary contexts being 26.1%, 26.4%, and 19.5% respectively, but stone from the Zuni Mountains has proportions of 2.2%, 2.4%, and 10.9% (!) respectively, which suggests that there’s just no pattern here in which the event layers or the mound as a whole contain higher proportions of imported material.  Basically, Chaco was awash in all sorts of imported stuff during this period, and it was not particularly concentrated in the mound more than anywhere else.  The mound has lots of imports because there were lots of imports all over the place, not because it was formed as the result of annual pilgrimage feasts.

The biggest difference between the mound and other contemporary contexts comes with the forms of pottery.  Generally, the forms of pottery found at sites in this area at this time are whiteware bowls, whiteware jars, grayware jars, and redware and brownware bowls.  Red and brown bowls were long-distance imports and are found in small numbers at most sites.  The other wares were local, at least in a general sense, and while there was surely some variation, the standard idea about functions is that gray jars were used for cooking food, white bowls were used for serving food, and white jars were used for storage.  Thus, for feasting contexts an unusually high number of white bowls, and possibly gray jars, would be expected.  Since red and brown bowls are likely to have had symbolic or ritual importance, given the distances from which they were imported, they may occur in higher frequencies in feasting or ritual contexts too.

Shell Bead at Pueblo Alto

The pattern in the Pueblo Alto mound, while distinct from other contemporary sites, didn’t really match these expectations.  The most obvious difference was a much lower proportion of white bowls: 27.0% for the event layers versus 32.7% for the whole mound and 33.4% for other contexts.  This was balanced by a higher proportion of gray jars, which Toll interprets as still giving evidence for feasting, but this is mighty weak evidence for pilgrimage and feasting, even though the high proportion of grayware that came from the Chuskas during this period means that the high proportion of gray jars in the mound contributed to a higher level of Chuskan imports.  Red and brown bowls were also much rarer in the mound (both in the event layers and in the whole thing) than in other sites.

So, despite Toll’s efforts to show the data from the Pueblo Alto mound supporting his and Renfrew’s pilgrimage theories, I don’t buy it.  That’s not to say that there was no pilgrimage or feasting at Pueblo Alto, of course, just that this evidence doesn’t show that there was any.  And, remember, this is the only evidence out there for feasting and pilgrimage at Chaco.

Plaza at Pueblo Alto

But what about those unusually large, distinct layers in the mound?  Don’t those indicate unusual depositional events consistent with annual feasting and the deliberate breaking of huge numbers of pots?

Well, no.  To understand why not, we turn to the second paper published in 2001 on this topic, written by Chip Wills.  Wills is a Chaco Project alum who worked on the Pueblo Alto mound excavations, so he knows what he’s talking about here, and what he says is that the layers in the mound aren’t at all necessarily evidence for annual feasts.  Basically, what he says is that there’s nothing special about the layers in the mound.  They’re not really bigger or richer in artifacts than deposits found elsewhere.  He has a lot of specific criticisms of Toll’s interpretations and methodology, but that’s the gist of it.  He says that the unusually well-defined nature of the layers could well be the result of natural processes on layers deposited in various ways, so that it doesn’t necessarily indicate occasional large deposits rather than steady trash accumulation.  Most importantly, he finds that there isn’t actually a clear distinction between the “construction” and “event” layers, and that it’s quite plausible that the whole mound, or at least the vast majority of it, resulted from the deposition of construction debris from the various stages of construction and remodeling at Pueblo Alto.  There would have been other “depositional streams” as well, including the dismantling of earlier architecture below the present site (which is known to have been present from the excavations).  Wills doesn’t deny that ritual may have played a role in the creation of the mound, since the construction of the great house itself may well have been a ritual act, but he does deny that there is any sign that the actual contents of the mound indicate that it resulted from occasional ritual deposits rather than a combination of construction debris and regular trash dumping.

Rim Sherd at Pueblo Alto

Okay, but what about all those smashed vessels?  Basically, Wills doesn’t find Toll’s calculations convincing.  He says that Toll calculated the number of vessels based on the number of rim sherds found, then extrapolated that number to the whole mound based on the excavated portion.  The assumptions here are that each pot is represented in the mound by a single rim sherd, and that sherd density throughout the mound is constant.  Neither of these is really reasonable, although the “one rim sherd per vessel” one is particularly problematic.  It was apparently based on the fact that few rim sherds from the same vessel were found, but what are the odds that only one rim sherd from each pot made it into the mound?  Extrapolating the number of vessels is tricky, of course, and obviously the raw sherd counts can’t be a reliable way to do it (since vessels varied in size), but this rim sherd idea is questionable at best.  The idea of uniform density is really just an example of a reasonable assumption given an unknowable reality, but it’s still not necessarily right.  Wills mentions another estimate of 30,000 vessels for the whole mound, which he also attributes to Toll, and this produces much more reasonable per year and per household numbers suggesting that the observed sherd density could easily reflect regular domestic trash.  He also notes that it was the number of households, based on architectural data, that was held constant when this seemed to conflict with the number of vessels deposited, but he doesn’t elaborate on the implications of this beyond noting the privileged place architecture tends to hold in population estimates at Chacoan sites.

I originally read both of these articles a couple years ago when I was first starting to work at Chaco, and at the time I found Toll’s more convincing.  Rereading them now, though, I find Wills more convincing, and his arguments have never really been squarely addressed by Toll or anyone else associated with the pilgrimage/feasting theory (although they are occasionally mentioned in passing).  Chaco may well have been a pilgrimage site and the location of communal feasts, but it’s important to note that the Pueblo Alto trash mound doesn’t provide evidence for this idea, and neither does anything else.
Toll, H. (2001). Making and Breaking Pots in the Chaco World American Antiquity, 66 (1) DOI: 10.2307/2694318

Wills, W. (2001). Ritual and Mound Formation during the Bonito Phase in Chaco Canyon American Antiquity, 66 (3) DOI: 10.2307/2694243

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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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Pueblo Alto Trash Mound

Kristina Killgrove has an interesting post on the numerous broken Cycladic figurines on the Greek island of Keros that have been documented over the past few years by the prominent British archaeologist Colin Renfrew.  Renfrew’s interpretation seems to be that these figurines were deliberately broken in various Cycladic communities, then deliberately brought to Keros to be deposited.  This is based partly on the fact that the various pieces can’t be fit together, suggesting that they were not broken on Keros and that the remaining portions were disposed of in some other manner (perhaps dumped in the ocean).  Furthermore, as a Cambridge press release on the project explains, there is other evidence suggesting that Keros served as a ritual destination rather than a normal residential community:

Meanwhile, across the short stretch of water to Dhaskalio, a very different picture was emerging. From the outset, the islet showed evidence of having been a major Bronze Age stronghold with structures built on carefully prepared terraces circling a summit, on which a large hall was erected. The settlement dates from around the time of the Special Deposits, and then continued to operate before being abandoned around 2200 BC.

Examination of its geology showed that the beautifully regular walling of the settlement was imported marble rather than the flaky local limestone found on Keros. Remarkably, in the same era the pyramids were being built and Stonehenge erected, Cycladic islanders were shipping large quantities of building materials, probably by raft, over considerable distances to build Dhaskalio.

Here, too, there were puzzling finds: a stash of about 500 egg-shaped pebbles at the summit and stone discs found everywhere across the settlement. And, although there was evidence that the olive and vine were well-known to the inhabitants of Dhaskalio, the terrain there and on Keros could never have supported the large population the scale of the site implies, suggesting that food also was imported.

Readers who are familiar with Chaco will probably have realized by now why I’m talking about this, as it’s eerily similar to a lot of recent interpretations of Chaco Canyon as a destination for pilgrims who brought in vast amounts of pottery, wood, and other materials as part of some sort of ritual system focused on the canyon but also including the whole area throughout the San Juan Basin and beyond in which Chacoan “outliers” are found.  There is even evidence that food was being imported to Chaco.  The Chaco Project‘s excavations at Pueblo Alto uncovered evidence in the trash mound of repeated events in which huge numbers of pots were broken, which some have interpreted as evidence for ritual breakage of pottery (though not everyone agrees with this).  This sort of pilgrimage model is one way to explain the rather inexplicable findings of huge amounts of material being imported to Chaco but basically nothing coming out.  It also potentially offers a way to explain the apparently low permanent populations of both the canyon as a whole and the individual great houses, and one version (espoused by Wolky Toll) even posits that there may have been virtually no permanent population at all, with the small houses that comprise the bulk of the residential space in the canyon having only been occupied seasonally or for special gatherings by people who spent most of their time in the outlier communities.

Corrugated Potsherd at Pueblo Alto

What’s particularly interesting about this comparison is that Renfrew himself, in an article stemming from one of the Chaco Project capstone conferences, proposed a model like this for understanding Chaco as a “Location of High Devotional Expression” or “LHDE.”  The article is quite reasonable and measured in pointing out the characteristics of such a center and how Chaco seems to fit pretty well, although Renfrew really seems to go overboard with the use of the passive voice to a greater extent even than most other archaeologists.  He acknowledges that some known LHDEs are part of hierarchical societies or states and are often associated with political or economic authority, but he emphasizes that this is not necessarily the case and that many well-known examples such as Stonehenge seem to have clearly been built by egalitarian societies.  The implication is that Chaco may have been egalitarian as well, an idea near and dear to the heart of a certain type of Southwestern archaeologist and still quite deeply entrenched in both Southwestern archaeology and popular perception.  He does note that the rich burials in Room 33 at Pueblo Bonito are problematic for this interpretation, but like most people proposing egalitarian models for Chaco he doesn’t really pursue the implications of that.

At one point, Renfrew discusses where he’s coming from with all this:

My approach to Chaco is colored by my experience of several early societies that are by no means urban but which can nonetheless boast impressive monumental constructions and other presumably symbolic features. Prominent among these are the so-called “temples” of prehistoric Malta, the ahu of Easter Island, and in particular the henges and other prehistoric monuments of Orkney.

It would seem his approach to the Cyclades is similarly colored.  Thus the title of this post, although it is admittedly unfair, as Renfrew has a done a lot more in his long career than this LHDE stuff.  Still, I think it’s interesting to see the way archaeologists’ backgrounds can influence how they perceive novel sites and societies.  In many cases this can lead to important insights that people who have been myopically focused on that society for decades may have missed, and there is some interesting and useful stuff in Renfrew’s article along these lines, but his clearly (and admittedly) superficial knowledge of Chaco leads him to not seem to realize that many of his arguments for an egalitarian Chaco are basically old wine in new bottles.  As alternatives to his LHDE model he evaluates two other models, which basically correspond to the “Mexicanist” idea of Chaco as a trading center providing turquoise to Mesoamerica and the “indigenous complexity” model of Chaco as an “elite power base.”  These are indeed two of the models that have been frequently put forth to explain Chaco, but there are others, including some egalitarian ones quite similar to his own.  He acknowledges this to some degree, but he again doesn’t really go into the details.

Hachured Potsherd at Pueblo Alto

I don’t mean to criticize Renfrew too harshly here.  He’s clearly a very smart guy, and Chaco is well outside his areas of expertise, so he can be forgiven for not being totally aware of all the nuances of Chacoan research.  His article is probably the best summary out there of the evidence for Chaco as a pilgrimage center and what that might mean.  As I said above, this is a popular idea these days among a lot of archaeologists who otherwise disagree about the exact nature of Chaco.  I have expressed some fondness for it myself in the past, but I’m now starting to reconsider.  It’s an attractive way to explain a lot of things about Chaco, but it has the distinct disadvantage of not having any direct evidence supporting it.  Any pilgrimage model is therefore sort of inherently speculative about who these pilgrims were, where they were coming from, and why.  This isn’t to say that I think Chaco was definitely not a pilgrimage center, but I’m not really convinced that there’s any particular reason to believe it was, based on the evidence we have.  The strength of models involving pilgrimage will just have to depend on the strength of the evidence supporting the other aspects of the models, I think.
Renfrew, C. (2001). Production and Consumption in a Sacred Economy: The Material Correlates of High Devotional Expression at Chaco Canyon American Antiquity, 66 (1) DOI: 10.2307/2694314

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Western Burial Rooms in Old Bonito

There’s a persistent archaeological meme about there being a “lack of burials” at Chaco Canyon.  The idea is that not nearly enough burials have been found there to account for the size and magnificence of the architecture, so something odd is going on.  This has been interpreted in various ways and used as support for a variety of theories seeking to explain the Chaco Phenomenon.  As Nancy Akins pointed out 25 years ago, however, the idea of a “lack of burials” is not very well founded.  It’s true that the extensive excavations at Pueblo Bonito produced relatively few burials for such a large site, but excavations at small houses have found plenty of burials, and there are historical sources indicating that many more were looted, especially from small-house trash mounds, in the late nineteenth century.  Add to this the fact that preservation conditions at Chaco are often fairly poor for human bone, and the mystery becomes a lot less pronounced.

And, to reiterate, there were in fact quite a few burials at Pueblo Bonito.  Over a hundred individuals were found, almost all of them clustered in two small sets of rooms in the oldest part of the site.  One of these clusters, in the north-central part of the site, contained the richest collections of burial goods known from the prehistoric Southwest, especially in Room 33.  The other cluster, in the western part of the site, had less lavish burial assemblages but contained more individuals.  Both clusters contained many disturbed burials, which the excavators found hard to understand given the good preservation of the remains and the numerous grave goods.  Akins suggested that secondary burial might account for the disturbance, and this seems like a reasonable theory.  Secondary burial is not known to have been practiced by any Pueblos in historic times, but there’s a lot about Chaco that hasn’t been maintained by the modern Pueblos (perhaps deliberately).

Room 326, Pueblo Bonito

One of the disturbed burials from the western burial group is the subject of an interesting recent paper by Don Ortner and Kerriann Marden.  The individual in question is a woman who was between 35 and 45 years old at death and was buried in Room 326, which happens to be one of the more visible rooms at Pueblo Bonito today.  It’s probably best known among visitors and staff for its particularly well-preserved plaster on the south wall.  Room 326 contained at least 10 adults, but the burials were quite disturbed and the collections of bones cataloged in the National Museum of Natural History from the excavations don’t correspond to separate individuals.  This woman’s bones ended up being catalogued under four separate numbers, some of which also contained bones from other individuals.  One contribution Marden and Ortner make in this article is to show that this skeleton is actually mostly complete, once the matching bones from the various cataloged specimens are reassembled.  This jumbling of individuals is a common feature of burials excavated from Chaco, so seeing that distinguishable skeletons can be defined at least in some cases is a significant development.

Perhaps more significant, however, is that, when reassembled, the woman’s bones showed clear evidence that she had suffered from infection by the treponema bacteria.  This type of infection is known generically as “treponematosis,” a cover term for a variety of diseases caused by specific treponema species.  These diseases include pinta, yaws, bejel, and syphilis.  Pinta is a skin disease that doesn’t affect the skeleton, but the other three all leave similar lesions on certain bones that can make them visible in archaeological populations.  These include most importantly a certain type of depression on the exterior of the skull which is associated with peculiar “stellate grooves” and lesions on the tibia and, much less often, on other long bones on both sides of the body.

South Wall of Room 326, Pueblo Bonito

The skull of this woman from Pueblo Bonito has lesions that have been tentatively suggested by previous analysts as possible evidence for treponematosis, but this remained speculative as long as the skull was thought to be isolated without other associated bones.  It turned out that those bones were just classified under other catalog numbers, however, and Marden and Ortner show clearly that they all go together and that lesions on one tibia and a few other bones confirm the diagnosis of treponematosis.  Some of the lesions seem to have been active at the time of death, which is important in assessing the type of treponematosis involved.  Marden and Ortner carefully assess other possible explanations but conclude that none is as plausible as treponematosis in explaining the observed lesions.

But what type of treponematosis is this?  Surely not pinta, which wouldn’t leave any sign in the skeleton.  The other three leave similar lesions, and Marden and Ortner reject claims by some other physical anthropologists that it’s possible to distinguish them based on the physical evidence, so they instead look at environmental and demographic factors.

Chuska Mountains from Peñasco Blanco

Yaws is only found in hot, humid regions and is typically found in children, so it is very unlikely that it would afflict a grown woman in an arid location like Chaco.  Bejel is found in arid regions, but is again primarily a childhood disease, so it is unlikely that this woman had it.  It’s not impossible, however; while the active state of the lesions suggests that she did not contract this disease in childhood, she could possibly have contracted it in adulthood through travel to a place where it was endemic or contact with someone who came to Chaco from such a place.  Given the far-flung trading networks in which Chaco was involved, this is certainly possible, although not particularly likely.  Like pinta and yaws, bejel is not sexually transmitted.  It generally spreads through mouth-to-mouth contact or by sharing domestic utensils.  Marden and Ortner also suggest that it’s possible that the nature of bejel has changed over time and that it was once more common among adults than it is now or that the skeletal lesions developed after a longer incubation period, but in the absence of any other evidence for this (and they don’t cite any) I don’t see any reason to find this probable.  While bejel is a more plausible source for the observed lesions than pinta or yaws, it’s still not very likely given the circumstances.

That leaves syphilis.  Unlike the other types of treponematosis, syphilis infection would make sense in an adult woman, given its sexually transmitted nature.  Oddly, Marden and Ortner seem to downplay this conclusion.  Although they do argue that syphilis is the most likely explanation, they bend over backwards to accommodate other possible explanations, mostly focusing on ways this woman could have been infected with bejel as an adult.  It’s not really clear why they do this (perhaps a response to comments during the peer review process?), since a diagnosis of syphilis is plausible given the known epidemiology of that disease and the known characteristics of the other types of treponematosis.  It’s almost as if they are trying to sidestep the implications for this woman’s sexual history of a syphilis diagnosis, but that seems rather silly to me.  The woman’s been dead for a thousand years.  Who cares how slutty she was?

Pueblo del Arroyo from the Southwest Corner of Pueblo Bonito

Because I clearly can’t leave a pithy-enough quip alone, I hasten to add that “how slutty she was” is of course not at all the best way to think about this.  While a diagnosis of syphilis does imply sexual transmission, and thus that this woman was not a life-long virgin, it doesn’t even necessarily imply that she had more than one partner.  Even saying that, however, probably brings too much of our own modern, Western sexual mores into the matter.  Chacoan sexual mores were probably different, perhaps to a significant degree.  The Christian heritage of European societies has tended to leave them a legacy of attitudes toward sexuality that are quite unlike those of many other societies, and while we can never know exactly how the Chacoans felt about sex, there’s no reason to assume that they felt the same way we do.  There are few hints in the archaeological record of what Chacoan sexual attitudes actually were, and the ethnographic record of the modern Pueblos doesn’t contain a whole lot of detail on the matter either, probably due to a combination of Pueblo reticence and Victorian modesty.  One interesting clue, however, is the very detailed and accurate rendering of the female genitalia on an effigy vessel from Pueblo Bonito, especially in contrast to the equally obvious but much less detailed penises on other effigy vessels.  The implications of this for Chacoan social mores and sexual practices are unclear, but the contrast to, say, ancient Greek sculpture is interesting.

The Marden and Ortner paper is very interesting along numerous dimensions, and it’s an example of the kinds of information that can be obtained by careful study of human remains.  I’m still a bit dubious about the ethics of all this, but there’s no denying that important information can come out of it.
Marden, K., & Ortner, D. (2011). A case of treponematosis from pre-Columbian Chaco Canyon, New Mexico International Journal of Osteoarchaeology, 21 (1), 19-31 DOI: 10.1002/oa.1103

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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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Shannon Bluffs, South of Farmington, New Mexico

One reason for the relative lack of information available on the prehistory of the Totah is that the presence of all those big rivers leads many sites to be buried under alluvium and/or destroyed by flooding and changes in the courses of the rivers.  As a result, many sites are not visible at all on the surface, and this is particularly the case for small sites, especially since the local architecture for much of the Pueblo period relied heavily on adobe and cobble masonry, which is much less durable than the sandstone masonry typical of Chaco and Mesa Verde.  Thus, aside from really big sites like Salmon and Aztec, many Totah sites are only discovered with very deep excavation or erosion.

Linda Wheelbarger’s chapter in the Salmon synthesis volume, reporting on the findings of the Totah Archaeological Project on the Bolack Ranch just south of Farmington, emphasizes this in pointing out how many of the sites on the ranch were not visible in any way from the surface and were only discovered inadvertently, such as when breaches in irrigation ditches lead to swift erosion, revealing sites well below the ground surface.  The most obvious sites are on the terraces above the river, and these are also some of the largest sites (including some probable Chacoan great houses), but it’s not clear if they are actually the largest or if there are larger ones buried somewhere in the floodplain.   Most of the known floodplain sites are small houses, but they are quite numerous, and Wheelbarger is able to define five “communities” along the southern bank of the San Juan between the confluence of the Animas River to the west and the Gallegos Wash to the east.  These tend to be at the confluences of various side drainages (including the Animas and the Gallegos) with the San Juan, which is a pattern noted elsewhere in the San Juan Basin as well, including to some degree at Chaco itself.

Plaza at Salmon Ruin

This is something to keep in mind when evaluating the conventional wisdom that the area around Salmon Ruin was largely uninhabited when construction of the building began around 1090.  The basis for this very common assertion is an extensive site survey done in the area around Salmon by the San Juan Valley Archaeological Project in the 1970s in conjunction with excavations at Salmon.  This survey revealed only four small sites within 1 kilometer of the great house that might have been contemporary with it, and only 12 such sites within 6 km.  In his chapter on the function of Salmon in the synthesis volume, Paul Reed explains the survey and its limitations:

The survey did not entail 100 percent coverage because of the complexity of land ownership and lack of permission to survey some parcels.  Nevertheless, much of the territory in the 1 km area around Salmon was surveyed.  As a caveat, it is likely that flood deposits from the San Juan River, along with alternating cycles of erosion, may have concealed or removed other sites located on the floodplain below Salmon.  We have no way of knowing how many such sites may have been present.  With the data that are available, however, it is clear that Salmon was not the center of a large community of surrounding small pueblos; rather, Salmon largely comprised the entire community.

Reed is clearly aware that it is likely that any sites that may have existed on the floodplain are no longer visible, but he nevertheless concludes that “it is clear that Salmon was not the center of a large community of surrounding small pueblos.”  Well, no, it isn’t clear, even “with the data that are available,” unless you make the totally unwarranted assumption that the available data do in fact reflect the reality despite their obvious shortcomings.  It’s worthwhile to note that the handful of sites that were identified were mostly on the terraces, rather than the floodplain, which means that they don’t have much relevance to the issue of how many sites there were in the region overall.  It’s certainly possible that Salmon was founded in a vacant area, as Reed concludes, but it’s important to note (as he does) that this would make Salmon quite unusual among Chacoan great houses, which usually were built among contemporaneous small sites both in Chaco Canyon itself and at outlying communities.

West Wing of Aztec West and Terrace to the North

A somewhat comparable situation exists at Aztec, although there is evidence of a fairly substantial residential district on the terrace above the West and East great houses.  Very little is known about the extent of settlement on the floodplain around the main “downtown” district, and some have argued that Aztec, too, was founded in an area without substantial prior settlement (with the terrace-top houses presumed to postdate the initial construction of the great houses), whereas others have argued that there probably was some sort of existing settlement there that is no longer visible because of the river-side location.  In either case it is clear that Aztec was a larger and presumably more important community within the region than Salmon.

There isn’t any way to settle this issue without extensive testing and excavation, which is unlikely to happen any time soon, but I just want to flag it to emphasize that a lot of the ideas that get entrenched in the archaeological literature are not necessarily well founded, and it’s important to understand the evidence behind them and how strong it is.

Terrace North of Salmon Ruin with Salmon Museum at Top

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North Road to Chaco

In comments to the previous post, paddyo’ links to this very good article on the fraught issue of paving the road to Chaco.  The article notes a recent development and explains why it isn’t going forward any time soon:

Chaco Culture officials struck a tentative deal with the county and the Navajo Nation, which owns the last four miles of the road closest to Chaco Canyon, that would have allowed the park to maintain to its standards eight miles of the road outside park boundaries.

But when NPS regional officials met with the Navajo Nation and the county in May, that idea was tossed out.

“We would have had to seek special legislation to do that,” said NPS Denver regional spokesman Rick Frost, adding that for the park to maintain a road outside its boundaries would set a precedent for the entire National Park System.

“Yellowstone plows a stretch of road called the Beartooth Highway at a significant cost to the park,” he said. “We didn’t want to continue that at Chaco and send a signal that we’re willing to do that in a place where it isn’t already taking place.”

I had heard about this idea, and it makes a lot of sense.  I had also heard that it wasn’t going to happen, but I hadn’t realized what the specific roadblock (so to speak) was.  The reason this makes sense is that one of the issues with the road thing is that the county doesn’t do a very good job of maintaining it, especially for the last few miles heading into the park.  They have claimed that this is because that part of the road is on Navajo land and the county isn’t responsible for maintaining it, which sounds dubious to me; it still has a county road number rather than a Navajo one.

Be that as it may, however, the problem is that the last part of the road that visitors encounter before reaching the park is often the roughest part, so they’re often more upset about it on arriving at the visitor center than they would be if they had encountered a full thirteen miles of a consistent quality equivalent to the average quality of the actual road.  The park would have a strong incentive to maintain that part of the road well if it managed to get the authority to do it.  The actual grading, although it would certainly add a certain amount of additional operating costs to the park’s maintenance budget, would be easy and the park could easily manage it with existing equipment and manpower, whereas paving the whole road would necessitate a huge increase in staffing and a whole host of changes in management practices that would be much more expensive.  I can see why the NPS doesn’t want to set a precedent for maintaining roads outside of parks, but this seems like a special case (there area vanishingly few other park units that are not accessible by paved roads, which is one of the reasons people cite for paving this one), plus the precedent really already seems to have been set by the Yellowstone case.

In the long run, I think the road probably will eventually be paved.  The reason we’ve been hearing so much about this in the past few years, in addition to the big push for it by the San Juan County Commission (the reasons for which no one seems to quite understand), is that many of the local Navajos, especially younger people, are now in favor of paving.  For many years the Navajos were generally opposed to paving the road and to anything else that would lead to more tourists visiting the park, but now that paved roads have become pretty common in the Navajo country the younger generation is more willing to accept increased visitation by outsiders in exchange for better mobility for themselves.  I’m pretty sure that’s not what’s driving the Commission, which is dominated by white guys from Farmington and has not historically been very responsive to the concerns of the Navajos (although it does seem to now have one Navajo member).  In any case, I imagine local support for paving will only increase in the future, and eventually the Friends of Chaco will no longer be able to hold it back.

Cattleguard on North Road into Chaco

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