Archive for the ‘Chaco Halo’ Category

Chaco Preservation Crew Repairing Masonry at the Fort Site

Today’s Albuquerque Journal has an article, originally published in the Gallup Independent, about the Chaco preservation crew and their work maintaining the various sites in the park.  The article focuses specifically on recent work they’ve done at Pueblo Pintado.  I don’t have a whole lot to add, but it’s an interesting account that addresses some of the complications of doing this sort of work for traditional Navajos, who have a strong taboo against even visiting Anasazi sites.  The article says that the crew deals with this in part by conducting prophylactic ceremonies before starting work on the sites, which I hadn’t known.  These ceremonies are apparently led by Harold Suina, a member of the crew who is from Cochiti Pueblo and is not Navajo (although I believe his wife is, and they live near Chaco in an area inhabited almost entirely by Navajos).  The article doesn’t say this, but I suspect that Harold’s role is particularly important since Pueblos like Cochiti have different attitudes toward the sites at Chaco than Navajos do, so he may not feel as uncomfortable dealing with them as the other members of the crew, all of whom are Navajo, do.  Not all of the Navajo members of the crew are traditional, however; some are Christian, as are many Navajos in the Chaco area, and they may not have the same qualms about their work that their more traditional colleagues have.

Anyway, it’s an interesting article, and it’s nice to see the preservation crew getting some media attention.  They do crucial work for the park, but it rarely gets noticed by either visitors or the many people who have written books and articles about Chaco over the years.  When I was doing tours I would usually do a fairly detailed description of the preservation work early on in the tour, both because people often want to know how much of what they see at the sites is reconstructed (at Chaco, very little, unlike at many other parks) and because I wanted them to appreciate how much work it is to maintain the sites and why it is therefore important for them as visitors to treat them respectfully and minimize the amount of damage they cause.  Hopefully this article will serve a similar function for a wider audience.

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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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Old Bonito from Above

In discussing a recent paper using stable-isotope techniques to evaluate subsistence in the Southwest during the Basketmaker period, I mentioned that one of the control samples used for contextual comparisons of the Basketmaker results came from Chaco Canyon great house burials.  I don’t know how on earth the Utah-based researchers managed to get permission to test these burials, as this is a highly sensitive political issue in Southwestern archaeology in general, but somehow it seems they did, and the information they got is enormously useful in understanding some aspects of the Chaco system.  It appears to only be reported in this Basketmaker paper so far, and only as comparative data, although there is a reference to a manuscript in preparation by the same authors focused on the Chaco data specifically.  This doesn’t appear to have been published anywhere in the three years since the Basketmaker paper was published, as far as I can tell.

This type of analysis of Chaco burials is remarkable enough, but even more remarkable is that these aren’t just any Chaco burials.  Two of them are the two most remarkable burials found anywhere at Chaco and arguably in the whole Southwest: Skeletons 13 and 14 from Room 33, which had the largest and most elaborate grave assemblages known in the region.  Also included were two burials from the adjacent Room 56 and one from Kin Bineola, a nearby outlying great house which is generally described as “unexcavated” but which did see some largely undocumented digging by the Hyde Expedition in the 1890s resulting in a few specimens now in the collections of the American Museum of Natural History.

Kin Bineola from Plaza

These remains were all tested for carbon and nitrogen isotope ratios, like the Basketmaker specimens and some other comparative samples from Pueblo period sites in the Kayenta area and Canyon de Chelly.  All the samples showed carbon isotope ratios in the same general range, indicating a heavily maize-based diet.  The nitrogen ratios, however, which are used to determine the amount of meat in the diet, varied considerably, with the non-Chacoan Pueblo remains patterning with the Basketmaker examples in showing a diet with little meat but the Chacoan ones showing evidence of much more consumption of meat.  This supports what had already been suspected based on the generally healthier appearance of great house burials compared to those found in other Pueblo sites, even small-houses within Chaco Canyon, namely that the people, whoever they were, who were being buried in the great houses were not only given much more elaborate and numerous grave goods in death but were also considerably healthier in life.  This in turn provides strong support for interpretations of Chacoan society that see it as having had a strong hierarchical component, with the great house burials coming from the higher ranks of society.

That’s all well and good, and it provides important information bearing on some major questions in Chacoan archaeology, but what I find more impressive about this data is that most of the Chacoan burials (all except one of the two from Room 56) were also radiocarbon dated.  The advent of the Accelerator Mass Spectrometry (AMS) technique, which requires much smaller amounts of organic material than traditional radiocarbon dating, has made it feasible to do direct dating both on small amounts of material (e.g., pollen) and on important specimens like human remains that are too valuable both politically and scientifically to sacrifice large quantities of bone for dating.  Like similar dates that have been taken on corn cobs, these direct dates provide important chronological anchors in understanding the development of Chaco and its system.

Wall Niche, Pueblo Bonito

Unfortunately, while the paper does report calibrated 95% date ranges in addition to raw dates, it reports midpoints of those ranges (which are not very meaningful) rather than intercepts, so it isn’t really possible to get a sense of probable dates more precise than the 95% ranges.  (Also, the reported midpoints don’t appear to actually be the midpoints of the reported 2σ ranges; maybe they’re from the unreported 1σ ranges?)  Still, that’s something, and there are some interesting implications.

The one specimen from Room 56 that was dated had a range of AD 1023 to 1208, which probably puts it sometime during the height of the Chacoan era (AD 1030 to 1130) or perhaps a little later.  This is significantly later than the initial construction of this room, which took place during the earliest period of construction in the ninth and early tenth centuries, but from the ceramic types associated with the burials in this cluster of rooms it seems it was used for burials throughout the period of major occupation, so this is a very plausible date.  These bones apparently came from Room 56, and are listed in a specimen list as coming from the debris in that room, but the description of them in that list reads “Human Bones with #53 the dark ones,” and the undated specimen from the same room on that list has a note reading “Some were found in R. 53, thrown from R. 56.”  The first description is cryptic and I can’t make any sense of it, but the second seems to imply that these bones all originally came from Room 56 but some were thrown into Room 53, probably by Warren K. Moorehead during his rather crude excavations in this part of the site.  Regardless of the specifics, it seems there is little contextual information for these remains, so not much more can be said about them.

Lintels Sampled for Tree-Ring Dating, Kin Bineola

The Kin Bineola specimen has a date range that overlaps considerably with the Room 56 one but has a generally earlier range: AD 891 to 1147.  Much of the construction of Kin Bineola apparently dates to the tenth century, judging from both masonry style and the few tree-ring samples, and some seems to date to the early twelfth century, so either end of this range is quite plausible, although the bulk of evidence suggesting the importance of this site in the tenth century, a period of relative quiet for construction at Chaco itself, makes me inclined to think an earlier date is more likely.

The most interesting dates are from the Room 33 specimens.  Since these are such important burials for understanding Chaco, knowing when they were interred is very desirable.  They were the two lowest burials in the rooms and the only ones that were completely intact when excavated; the twelve burials above them were substantially jumbled, although they still had plenty of grave goods associated with them.  This implies that they were the earliest people to be buried in the room, and the pottery associated with them was relatively early but can’t be dated very precisely beyond that.  It is not clear from any of this how early they were buried, expecially whether it was before or after the major expansion of Pueblo Bonito beginning in the 1040s that may have involved substantial changes in the function of the building, perhaps including a change in the function of some rooms in the older part of the building into burial chambers.

Northwest Part of Pueblo Bonito Showing Expansion of Outer Wall

The date ranges reported here are AD 690 to 944 for Burial 13 and AD 690 to 940 for Burial 14.  Statistically these are virtually identical, and they strongly imply that the two were buried at the same time, which makes sense given their relative position and similar grave assemblages.  This is also really early, with the early part of the range extending long before the earliest known construction dates for Pueblo Bonito.  Since these clearly seem to be primary rather than secondary burials, this probably just means that the true age doesn’t lie at the early end of the 95% range.  That puts the most likely time of burial at between AD 850 and 940 or so, or between the earliest construction dates and the end of the date range.  This is still well before the expansion of the building, and it doesn’t extend much after the latest dates for the initial construction stage.

The upshot of all this is that these two burials appear to be significantly earlier than has generally been assumed.  They seem to date to a very early period in the history of Pueblo Bonito, and it’s even possible that Room 33 was initially constructed as a burial chamber for them.  George Pepper, who excavated it, thought the room had not originally been intended as a burial chamber, but he didn’t explain what led him to that conclusion.  Whatever the original function of Room 33, it seems clear from this evidence that it became a burial room very early on, and that these two enormously elaborate burials were part of Pueblo Bonito for at least the vast majority of its period of occupation.  I think this may have some important implications for understanding the construction sequence of the building and possible changes in its use over time, and perhaps even in understanding the rise and nature of the Chaco system as a whole.  Piecing together what exactly those implications are, however, will require considerably more thought and study.
Coltrain, J., Janetski, J., & Carlyle, S. (2007). The Stable- and Radio-Isotope Chemistry of Western Basketmaker Burials: Implications for Early Puebloan Diets and Origins American Antiquity, 72 (2) DOI: 10.2307/40035815

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Pueblo Bonito from Peñasco Blanco

The paper I discussed earlier about evidence that corn was imported to Chaco was interesting, but while it provided important information about the poorly understood “Mesa Verdean” period after the fall of the Chaco system it didn’t address the question of food imports during the operation of that system.  This has been a topic of considerable debate, and the extent to which corn was being imported to Chaco from outlying areas versus being grown in the canyon itself has major ramifications for which theories about the nature of the system seem most plausible.  Luckily, however, that paper was just one in a long series reporting on research done by Larry Benson and others on this topic, and a slightly earlier one by Benson, H. E. Taylor, and our old friend John Stein addresses the question of earlier (and later) periods.

Peñasco Blanco from Pueblo Bonito

This paper uses the same basic methodology of the other one, based on strontium isotope ratios, and it also attempts to use concentrations of other trace elements to further narrow down source areas for corn cobs from archaeological sites.  Unfortunately, however, most of the trace elements the researchers looked at had their concentrations heavily skewed by post-depositional contamination, which made them useless for determining sources.  The only elements that seemed to be mostly unaffected by this problem were potassium and rubidium, so the paper uses the ratio of these two elements as an additional marker for places where the cobs may have been grown, although it cautions that it’s not yet totally clear that this ratio is actually as meaningful as the analysis implies.

Aztec West Great House, Aztec Ruins National Monument

This study looks at more cobs than the other one.  These are from both Chaco and Aztec, and the Chaco ones come from a variety of sources.  The most numerous are from Gallo Cliff Dwelling and are part of the large group with nearly identical radiocarbon dates in the late 12th century that was analyzed in the more recent paper.  This paper conducts a similar analysis and comes to similar conclusions about the wide range of possible sources for these cobs.  This group also includes a few cobs from Pueblo Bonito, Chetro Ketl, and Kin Kletso, although the authors caution that the late dates on these cobs don’t necessarily imply that these great houses were still occupied at this late date; the cobs could also result from people living in small sites like the Gallo Cliff Dwelling dumping their trash in the abandoned buildings.  While most of the Chaco cobs come from this narrow time period, and the Aztec cobs (which have not been carbon-dated) likely date from a roughly comparable time as well, some Chaco cobs are dated to both earlier and later times.  The later ones, some of which date to the nineteenth century, are presumed to reflect the later Navajo occupation of the area.  It’s the earlier ones that are of interest for the light they can shed on the operation of the Chaco system in its heyday.

Pueblo Bonito from Above

There are six cobs with carbon dates earlier than the major drought of the mid-12th-century.  Five of these come from Pueblo Bonito, and one comes from the Gallo Cliff Dwelling.  The Gallo one is puzzling, since all the other Gallo cobs date to much later and cluster tightly together, and the site itself was probably not occupied early enough to account for the early cob.  It’s possible that this date is due to something odd going on with the radiocarbon dating, and in any case it seems hard to generalize from, so I’m not going to discuss it further here and will instead focus on the five cobs from Pueblo Bonito.

Interior T-Shaped Doorway, Pueblo Bonito

Four of these come from Room 3; the other one comes from Room 170.  These are both interesting rooms in their own right, but first let’s talk about the cobs.  Although the authors of the paper classify them only as “pre-AD-1130″ (i.e., before the drought that is thought to have coincided with the fall of Chaco), they actually all date considerably earlier than that.  The earliest, which unfortunately seems to have been contaminated and thus unusable for the strontium analysis, is from Room 3 and has a calibrated radiocarbon date range of AD 765 to AD 902 with 95% confidence (2σ).  The other four are somewhat later and cluster tightly together, with 95% confidence intervals of AD 944–1052 (this is the one from Room 170), AD 892–1034, AD 893–1026, and AD 889–1021.  This means that these cobs all date to a period before the Chaco system reached its full florescence, which is generally dated to the late eleventh century.  They also seem to date earlier than the expansion of Pueblo Bonito in the 1040s.  The 95% confidence interval for the cob from Room 170 does make it possible that it dates to the period of the expansion, but at a lower level of confidence (1σ) it has a tighter range of AD 974 to AD 1040, which means it too probably predates the expansion.

Old Bonito

Thus, all these corn cobs seem to have been grown and eaten during the period when Pueblo Bonito consisted only of the original arc of rooms, constructed with early, Type I masonry, that we now call Old Bonito.  This makes their geographical origin even more interesting to investigate.  During this period, consisting of the ninth, tenth, and early eleventh centuries, Chaco Canyon seems to have been growing in regional importance, as evidenced by the construction of the early great houses, but it doesn’t seem to have yet attained the preeminent position and centrality it would achieve in the late eleventh and early twelfth centuries before its collapse.  The earliest cob, which probably dates to the ninth century, which is when the early great houses were first being constructed, would be of particular interest in determining where the people in Chaco were getting their food at that time.  It’s very unfortunate, then, that its origin can’t be determined from strontium analysis because of its apparent contamination.  The other three cobs, however, which probably date to the late tenth or early eleventh century, were included in the strontium analysis, so it’s worth looking closely at what the results of that analysis can tell us.

Type I and Type II Masonry Abutting at Peñasco Blanco

These cobs date to a period when there seems to have been little or no construction at Pueblo Bonito, Una Vida, and Peñasco Blanco, the three earliest great houses in the canyon.  All three saw extensive construction in the late ninth and early tenth century, and major expansion starting in the middle of the eleventh.  The time of the cobs, then, seems to have been a relatively quiet period in the canyon, although the early stages of construction at some of the other great houses, such as Chetro Ketl and Hungo Pavi, may date to this period.  There doesn’t seem to have been a whole lot of great-house construction outside of the canyon, either; there were already quite a few great houses out there, especially to the south in the Red Mesa Valley and to the west along the Chuska Slope, but most had already been built, and the biggest of the outliers, especially to the north, wouldn’t be built until considerably later.

Side Wash by Chetro Ketl

So, if the strontium evidence were to suggest that the cobs from this period were grown in the canyon, that would suggest that local agricultural production was important at Chaco, and it would support theories that attribute Chaco’s rise to regional dominance as having to do at least in part with agricultural surplus during favorable climatic conditions.  If, on the other hand, the strontium evidence were to suggest that the cobs were grown outside of the canyon, that would be evidence in favor of other theories that see the rise of Chaco as due not to local production but to the Chacoans’ ability to somehow acquire food from other areas with better growing conditions.  This would be particularly the case if the cobs came from areas that had early outliers.  It would also be interesting if the cobs came from areas that aren’t known to have had outliers this early but did have them later (e.g., the Totah).  These theories propose a variety of answers for how the Chacoans could have done this, of course, ranging from coercive political domination to inspirational spiritual power.

High Walls at Kin Bineola

So, with that in mind, what does the strontium (and potassium/rubidium) evidence say?  In brief, it supports the latter option.  The strontium ratios in the cobs are close to the values at a few of the sampled sites in and around the canyon, but when the potassium/rubidium ratios are added in, they narrow the potential sources down considerably, and none of the local Chaco sources makes the cut.  So, to the extent that the potassium/rubidium evidence is useful (which, remember, is still not totally clear), it seems that the Chacoans were importing corn at least as early as the early eleventh century, and possibly a century earlier.  This seems to support the theories that hold that local agricultural production was not the main driver of Chaco’s rise, although this is of course a very small sample and it would be foolish to draw too many firm conclusions from it.

Sign at Kin Bineola

So if the corn wasn’t being grown at Chaco, where was it grown?  Unlike with the later cobs, and again likely owing at least in part to the small sample size, the number of potential source areas identified here is pretty small.  A couple are in the Totah near Aztec, but all the rest are in the area surrounding Chaco often called the “Chaco Halo” and consisting of the parts of the Chaco Wash drainage both upstream and downstream from the canyon, including the South Chaco Slope area on the north side of Lobo Mesa.  The specific sampling sites with matching ratios were near a number of important Chacoan outliers, including Kin Ya’a, Kin Klizhin, Kin Bineola, and Pueblo Pintado.  Interestingly, of these four only Kin Bineola is known to have been built at this time, and the others were not built until considerably later, at least in their current form.  The fact that Kin Bineola is one potential source area, as are a few smaller early great houses that were present at this time, suggests that the later outliers may have been built on top of earlier versions, or at least that the communities surrounding them may have been incorporated into the Chaco system earlier than the dates of their great houses would imply.  Of course, it’s also possible that all of these cobs came from one or a few of the areas with known early great houses; the fact that a large number of areas could have grown these cobs doesn’t mean that they all did, and in fact given the small number of cobs it would be impossible for all the areas identified to have contributed to growing them.

Kin Bineola from a Distance

It’s not necessarily surprising to find that nearby areas known to have been in close contact with Chaco would have been supplying it with corn.  Indeed, many of these areas are considerably better for agriculture than the canyon, and there has long been speculation that at least some of the outliers were founded specifically in order to supply the canyon with food.  What is somewhat surprising here, however, is the early date at which this appears to have already been happening.  The great houses at Chaco would not necessarily have been any more impressive than those in many other local communities at this point, and given the lack of construction activity in the canyon it would be quite reasonable to suppose that Chaco was not yet considered exceptional within the region.  This evidence, however, suggests that there was already something unusual going on in the canyon, and that something was getting people around it to supply it with at least some food.

Early Masonry at Kin Bineola

One more thing to consider about these cobs is where they were found.  Since Pueblo Bonito was definitely around at the time they were grown, imported, eaten, and presumably thrown away, and since they were found at Pueblo Bonito, it seems logical to conclude that the rooms where they were excavated were the same rooms where they had originally been tossed.  This is almost certainly not true, however.  Rooms 3 and 170, where they were found, had not yet been built in the early eleventh century.

Room 3, Pueblo Bonito

Room 3 is part of an arc of rooms fronting on the western section of Old Bonito.  Unlike the rooms behind it, however, it is built out of late core-and-veneer masonry, and it was likely built considerably later than those rooms, which are built with early masonry.  The difference is quite noticeable.  The spaces later enclosed by it and the other plaza-facing rooms in this arc was probably originally enclosed by a ramada or awning, or perhaps a wattle-and-daub (or “jacal”) wall, which was later replaced with masonry.  The sequence of construction in this part of the site is hard to untangle, and Room 3 produced no tree-ring dates, but it is pretty clear that it must have been constructed at some point after AD 1040, just judging from the masonry, and the presence of the cobs in it likely dates to a time long after its initial construction when it was used for dumping trash.  One of the other cobs found in this room was part of the late-12th-century date cluster, so that may be when this trash deposit originated.

Room 170, Pueblo Bonito

Similarly, Room 170 is part of the southernmost block of rooms, which was one of the last parts of the site to be built.  It seems to have been built as part of the construction of the southeast corner of the site, one of the largest single building projects in Chaco’s history, which probably took place around AD 1080.  Room 170 has an odd set of internal features; its first story was at some point divided by an east-west wall, and the part of the room north of the wall was filled in, with a space left, however, to allow access to the second floor of both it and the room north of it.  There is also a small opening just south of the dividing wall leading into the next room west, and a step below it.  Again, this room was likely not originally used for trash dumping, and the trash deposits in it likely date to a later period.

Metate Fragment at Pueblo Bonito

Since neither of these rooms was used for dumping trash until quite late, perhaps even after the fall of Chaco as a regional center, why did they contain corn cobs from centuries earlier?  Probably because the trash being dumped in them was being moved from wherever it had originally been dumped.  Where that would have been, who would have been doing this, when, and why are all very difficult questions to answer, but I don’t see any other explanation to reconcile the dates of the corn cobs with their locations.  This also means that, while these cobs were found at Pueblo Bonito, they weren’t necessarily originally brought there.  They may have been, of course, and I’d even go so far as to say that they probably were, but it’s also possible that the trash deposit in which they were originally placed was somewhere else in the canyon, perhaps even associated with another site.

Sealed Vent, Pueblo Bonito

Like all good papers about Chaco, this one answers some questions but opens up others, and it definitely provides plenty of (imported) food for thought.  There’s still a lot we don’t know about the Chacoans, even such basic things as where they  got their food, but the process of finding these things out is quite a ride and full of surprises.
BENSON, L., STEIN, J., & TAYLOR, H. (2009). Possible sources of archaeological maize found in Chaco Canyon and Aztec Ruin, New Mexico Journal of Archaeological Science, 36 (2), 387-407 DOI: 10.1016/j.jas.2008.09.023

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Exterior of Reconstructed Great Kiva, Aztec Ruins National Monument

One of the most interesting and potentially productive lines of research in Southwestern archaeology these days involves the use of chemical analyses of various archaeological materials to extract more information about the societies that used them than is apparent just from looking at them.  The oldest and most established type of research like this is radiocarbon dating, which has historically been used less in the Southwest than elsewhere because it’s both expensive and less precise than tree-ring dating, which was invented in the Southwest and has been extremely important in the study of its prehistory.  Lately, however, archaeologists in the Southwest have been using radiocarbon more and more, since it can be used on anything organic (useful for sites which produce no datable wood but plenty of other organic material) and it’s been around for so long that the dates are considered very reliable.  They’ve also begun to use some other techniques that are newer but have enormous potential, which is already starting to be realized, to illuminate aspects of the past that have been the cause of much debate.

Intact Roof at Aztec Ruins National Monument

The most important of these is strontium isotope analysis, which we’ve seen before in the analysis of the wood brought to Chaco for architectural use.  Like radiocarbon dating, strontium analysis is based on looking at the ratio of two isotopes of an element, one of which is stable and the other of which is produced by the radioactive decay of another element and therefore varies.  Unlike radiocarbon, however, strontium cannot be used for dating on archaeological timeframes, since the half-life of the radioactive decay process involved (the conversion of rubidium-87 to strontium-87) is 48.8 billion years.  It can, however, be used to identify locations, since the amounts of strontium and rubidium in different areas vary a lot and strontium is absorbed unchanged by organisms from their environment.  Thus, in theory, one could test an organic artifact for its strontium ratio, then compare that to the strontium ratios of the water or soil in various places where the artifact may have originated and figure out where it came from.  This would then allow all sorts of archaeological conclusions.

Intact Roof at Pueblo Bonito

Of course, it’s never quite that simple, as the case of the wood shows.  It was relatively easy to use this analysis for the high-elevation types of wood that occur in relatively few places in the Southwest, but when the technique was extended to the very common ponderosa pine beams the number of possible origins increased so much that few definite conclusions could be reached.  There is also the problem of making sure that the strontium ratios found in the archaeological material actually resulted from growth processes rather than contamination by later mineral deposits.  Since this technique is relatively new, the methodology for it is not yet totally worked out, and not every attempt to use it ends up working.

Row of Metates, Aztec Ruins National Monument

Both the promise and the pitfalls of strontium analysis are shown clearly by a new paper by Larry Benson of the United States Geological Survey.  Benson has made something of a name for himself as the main player in the increasingly important analysis of corncobs found in Southwestern archaeological sites.  Corn is a useful plant to use for this sort of thing for a number of reasons:

  • It’s pretty common, especially in sites like cliff dwellings and Chacoan great houses with especially good preservation of organic material.  The Anasazi depended heavily on corn for their diet, so there are corncobs all over the place.
  • It grows quickly.  This is not important from the perspective of strontium analysis, but it means that radiocarbon dating can provide a very accurate range of dates within which the corn was grown and eaten.  This is in contrast to slow-growing plants, such as trees, which have the problem that the part tested may happen to be much older than the date of use.  The combination of accurate dating with strontium-based source determination makes corn a very powerful source of information.
  • It bears directly on a variety of important cultural questions.  Since corn was the main source of food for the Anasazi, finding out if they were growing it themselves or importing it from elsewhere has major implications for models of cultural systems and their means of support.  This is a longstanding issue in the study of Chaco specifically.

This particular paper addresses several issues, both substantive and methodological.  Substantively, Benson analyzes a set of corncobs excavated from the Gallo dwelling in the Chaco campground in the 1950s and adds the data derived from them to the data from earlier studies of cobs from this site as well as from Pueblo Bonito and Chetro Ketl.  He also reports on strontium isotope ratios from several agriculturally productive areas of the Zuni Reservation and adds them to the previously reported data from other parts of the Colorado Plateau.  He then combines this new information with the previously reported data to draw some specific conclusions about the sources of some of the cobs.  Importantly, however, he does not come to any conclusions about the sources of the newly analyzed Gallo cobs.

Metate at Pueblo Bonito

The reason for this lies in the methodological side of the paper, which may be the most important in the context of overall research on this topic.  The cobs Benson reports for the first time here, unlike the previously analyzed cobs, were not burned, and part of the purpose of this research was to see if the procedures used to prepare and analyze the burned cobs could be used for unburned cobs as well.  As it turns out, they can’t, and the strontium ratios from the unburned cobs appear to come from post-depositional mineral contamination rather than growth conditions.  This seems to be because the act of burning effectively “seals in” the trace minerals in the cobs, protecting them from contamination.  While this result is somewhat disappointing, in that it means that the strontium data from the new cobs can’t be used to draw any conclusions, it is important in informing others that if they want to do this kind of research on unburned corn cobs they need to come up with new procedures.  In the course of doing this analysis Benson also uses some data on recent experimental growing of Pueblo varieties of corn in Farmington that provides valuable reference material on just how closely strontium ratios in corncobs can be expected to correspond to the ratios in the soil and water in the area.  The answer is closely, but not perfectly, which is also useful information for future researchers.

Keyhole-Shaped Kiva, Aztec Ruins National Monument

Despite those issues, however, this paper does include some important substantive conclusions.  Although the new cobs couldn’t be used for strontium analysis, they did produce radiocarbon dates, which correspond very closely to the dates on the earlier Gallo cobs as well as some of the ones from Pueblo Bonito and Chetro Ketl.  Interestingly, these dates all cluster tightly around the AD 1180s.  As Benson points out, this is after the major drought of the mid-twelfth-century, which is generally interpreted as marking the “collapse” of the Chaco system and the possible depopulation of Chaco Canyon.  It has long been known that the canyon was occupied later, from the late twelfth century until the total abandonment of the region during the “Great Drought” of AD 1276 to 1299, but it’s unclear if the population at that time consisted of a remnant from the earlier Chacoan occupation or a reoccupation by people from elsewhere who may or may not have been descended from the earlier Chacoans.  In any case, whoever the people were who lived in the canyon in the 1180s, these are their corn cobs.

Keyhole-Shaped Kiva at Pueblo Bonito

They didn’t grow them, though.  In what is probably the most interesting conclusion of Benson’s paper, and certainly the most surprising, he goes through a careful analysis of the strontium data, excluding the data from the unburned cobs, and finds that the values from the cobs do not overlap with any of the locations in the Chaco area, either in the canyon or around it, that have been tested.  It’s certainly possible that they come from somewhere nearby that hasn’t been tested, but at this point a lot of potential growing locations in and around the canyon have been analyzed, so there aren’t a whole lot of additional options.  It’s not a very promising area for agriculture, after all, and pretty much all of the obvious places have now been tested for strontium ratios.

Hubbard Tri-Wall Structure at Aztec Ruins National Monument

So if these cobs didn’t come from Chaco, where were they grown?  Benson compares their strontium ratios to data from several areas in and around the San Juan Basin: in addition to the newly reported Zuni sites, these include Lobo Mesa, the Red Mesa Valley, the Rio Puerco of the West, the Defiance Plateau, Chinle Wash, the Four Corners area, Mesa Verde, the Totah, and the Dinetah.  This covers almost the whole area once occupied by Chacoan outliers, and several places beyond.  The cob ratios turn out to overlap considerably with one of the Zuni areas, the Mesa Verde/McElmo Dome area, the Totah, the Defiance Plateau, Lobo Mesa, and the Rio Puerco valley.  For some reason Benson doesn’t mention the Puerco in the text of the article, but in the figure showing the boxplots of the values for the various regions it clearly overlaps a bit with the cob values.

Tri-Wall Structure at Pueblo del Arroyo

Unfortunately, the strontium analysis itself doesn’t provide any way to choose which of these areas is the most likely source of the corn.  Any of them is consistent with the evidence.  Benson therefore turns to other lines of evidence to narrow down the choice.  He eliminates Lobo Mesa and the Defiance Plateau because of evidence that they were not occupied during this period; he doesn’t go into a whole lot of detail on what this evidence is, which is unfortunate.  As I mentioned above, he doesn’t discuss the Puerco at all, which is also unfortunate.  This leaves Zuni, the Totah, and Mesa Verde as the remaining options.  These are all areas that had Chacoan outliers during the height of the Chaco system and probably experienced immigration of people from Chaco after the system’s collapse, and they were all home to significant populations during this relatively wet period, so they are all plausible sources of corn imported to Chaco.  Benson concludes that the Totah is the most likely source based on the fact that it is the closest of the three areas and the one that seems to have had the strongest connections to Chaco, and while he acknowledges that this is little more than a guess, it sounds plausible enough to me.  Certainly Aztec, which is often interpreted as a successor to Chaco in some sense, was a major center in the late twelfth century, as was Salmon, and the material culture of the people living in Chaco at the time shows considerable influence from areas to the north (although it’s not entirely clear how to interpret this).

Aztec West Great House, Aztec Ruins National Monument

This paper is part of a growing corpus of data, much of it contributed by Benson, showing that the inhabitants of Chaco at various times did in fact import corn to the canyon.  This seems to largely settle one of the longstanding disputes in Chacoan archaeology, and it further points out the pointlessness of trying to estimate the population of the canyon by first estimating its agricultural potential.  What remains puzzling is how this system would have worked, and why.  Beyond the obvious question of who was supplying the corn, which is partially addressed in this paper, the question of what leverage the canyon inhabitants would have had to get those people to supply them remains open.  This paper, in fact, seems to raise more questions than it answers in this respect.  While during the height of the Chacoan system it is relatively easy to come up with theories for how the canyon inhabitants could have acquired supplies from the surrounding area, in the post-collapse period, when the canyon population was tiny and regional importance had clearly shifted elsewhere, explaining how the few people left at Chaco managed to get others to grow food for them becomes a daunting task.  It’s this sort of challenge, however, that I think makes Chaco so fascinating and ensures that it will continue to be a place worth studying for a long time to come.
Benson, L. (2010). Who provided maize to Chaco Canyon after the mid-12th-century drought? Journal of Archaeological Science, 37 (3), 621-629 DOI: 10.1016/j.jas.2009.10.027

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Back Wall of Kin Klizhin

I mentioned that I have some criticisms of Keith Kloor’s article on Chaco, and I do, but before getting to the more substantive issues I’d like to just mention a minor error of fact.  This is a very common mistake, and it’s certainly not Keith’s fault for making it, but I think it’s important to point it out when I see it precisely because it’s so common.


Hosta Butte Framed by Kin Klizhin

The article begins at Kin Klizhin, which John Stein and Taft Blackhorse are showing to Keith and interpreting in their own inimitable way.  In an aside Keith says that the name of the site means “Black Charcoal” in Navajo, which it most certainly does not.  It means “Black House,” which is a rather generic name for an Anasazi ruin that has been applied to many different sites.  I even once heard a Navajo from the Chaco area use it for Pueblo Alto, which is interesting given that site’s more common name “Gambler’s House.”  While confusions of Navajo words are very common among Anglos who only know a little bit of Navajo, this is a very straightforward, obvious name.  Navajo kin means “house” (specifically a “square” Pueblo or Anglo house as opposed to a hogan), and łizhin means “black.”  These are both common words, and there’s nothing confusing about their combination here.  The voiceless lateral fricative at the beginning of łizhin is often rendered “kl” in English transliterations of Navajo words, since English doesn’t have this sound.


Sign at Kin Klizhin

Nevertheless, the translation of “Kin Klizhin” as “black charcoal” or something similar persists, even in the official park interpretive literature, which is probably where Keith got it.  (I can’t imagine John and Taft would have gotten this wrong; indeed, Taft is known for making fun of Anglos mispronouncing or misinterpreting Navajo words.)  The description of the site on the park website gets the translation right, because I wrote it, but the official site brochure linked as a (rather slow-loading) pdf from that site still translates it as “black wood.”


Tsin Kletzin Sign on South Mesa Trail

So where does all this mistranslation come from?  It seems to come from a confusion between Kin Klizhin and another site with a similar name: Tsin Kletzin, which is atop South Mesa in the main unit of the park.  There are a variety of versions of the Navajo name for Tsin Kletzin, but they all seem to mean “charcoal” or something similar.  The standard English name “Tsin Kletzin” seems to come from tsin, meaning “wood,” and łizhin, the same term for “black” found in “Kin Klizhin” (perhaps involving some confusion with the word łitso, meaning “yellow,” as in Kin Kletso, another site in the canyon), which makes the literal meaning “black wood,” i.e., charcoal.  There are other ways of describing charcoal, however, such as tsin nitł’iz, meaning “hard wood,” which is sometimes cited as the origin of “Tsin Kletzin” although it doesn’t make much sense phonetically.


Corner of Room Containing Blocked-In Kiva at Tsin Kletzin

As I say, this is a very minor point that doesn’t make much difference to anything, especially since the Navajo names for these sites are by no means fixed.  Since it is a very clear mistake, however, and especially since it’s in the very second sentence of Keith’s article, I figured it was worthwhile to point it out and correct it before getting bogged down in more important matters.


Fallen Walls at Tsin Kletzin

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Sign at Kin Klizhin

Sign at Kin Klizhin

Chaco Culture National Historical Park includes, in addition to the famous archaeological sites in Chaco Canyon itself, four “outlying” great houses located outside the canyon but in close proximity to it and showing considerable evidence of close contact with people there and integration into the system centered on the canyon.  One of these is Kin Klizhin (Navajo for “black house”), which lies just west of the main canyon on a small tributary of the Chaco River known as Kin Klizhin Wash.  The land surrounding Kin Klizhin was originally a detached unit of the park like the land surrounding the other in-park outliers, but over time the park boundaries have been expanded to connect it to the main unit.  This can be seen clearly on the official park map.  Also evident on the map, however, is that Kin Klizhin is not accessible directly from within the main park unit, and it is necessary to leave the park to get to the road that leads to it.

Sign on Road to Kin Klizhin

Sign on Road to Kin Klizhin

The road to Kin Klizhin is a small two-track dirt road that branches off from New Mexico 57, the south road out of the park heading toward Seven Lakes and Crownpoint.  There isn’t a sign right at the junction, but there is a small one a short distance afterward, and there aren’t a whole lot of other roads around there so it’s hard to miss.  The junction comes at the point where 57 curves from going east-west along the San Juan-McKinley county line to going south toward Seven Lakes.

Road to Kin Klizhin

Road to Kin Klizhin

The road to Kin Klizhin is considerably more basic than 57 (which is to say that if you think 57 is the worst road you’ve ever seen, you probably shouldn’t try to go to Kin Klizhin), but it’s generally passable with any sort of vehicle.  After the summer rains it may become washed out in places, so a high-clearance vehicle would be preferable.  Four-wheel drive isn’t really necessary except maybe if it’s actively raining, in which case you probably shouldn’t be trying to do this trip at all.  The road goes over some fairly hilly terrain for a few miles before reaching Kin Klizhin, which is right on the edge of the park boundary.

Kin Klizhin

Kin Klizhin

Kin Klizhin is completely unexcavated, and it isn’t very large as Chacoan great houses go, but it’s one of the better-preserved and more impressive ones.  This is due largely to its tower kiva, which is still in fairly good shape (although a look at the historic photographs at the Chaco Archive shows that it has deteriorated quite a bit in the past century).  Tower kivas are among the more mysterious aspects of the Chacoan system.  The term often gets thrown around a bit loosely, but it is generally used to refer to round rooms that have multiple levels with floors between them.  This is in contrast to the “elevated” or “blocked-in” kivas built into the roomblocks at many great houses both inside and outside the canyon; although those can in some instances be more than one story in height, they always have only one floor.

Interior of Tower Kiva at Kin Klizhin

Interior of Tower Kiva at Kin Klizhin

Tower kivas, which are found mostly at outlying great houses, usually  have two or three levels remaining.  Some have argued that they all originally had four levels, symbolizing the four worlds through which the people passed in some Pueblo origin legends, but this is a rather extreme jump to conclusions given that we don’t actually have any idea what these tower kivas were for.  There’s nothing like them in modern Pueblos.

Hosta Butte Framed by Kin Klizhin

Hosta Butte Framed by Kin Klizhin

Some have argued that the tower kivas were part of a signaling network using line-of-sight relationships between great houses.  A fair amount of data on the line-of-sight relationships has been assembled, but the role of the tower kivas in it is doubtful, and some research by John Kantner has recently suggested that at least in the southern San Juan Basin (where tower kivas are pretty common) they probably didn’t serve as part of a signaling network.  Whatever they were for, tower kivas are certainly impressive, and the one at Kin Klizhin is a good example.  It has collapsed enough that the main parts still standing are the corners, but they are still standing quite high, and from certain angles they look like football goalposts.

"Goalposts" at Kin Klizhin

"Goalposts" at Kin Klizhin

The function of the outliers in general, not just those with tower kivas, is a matter of intense debate and little consensus.  “Inner-ring” outliers like Kin Klizhin are particularly odd.  Were they examples of Chacoan colonization out from the canyon into the surrounding area?  If so, why were the Chacoans moving out?  If not, who was building them, and why?

Earthen Dam near Kin Klizhin

Earthen Dam near Kin Klizhin

These aren’t really answerable questions given current information, but a few possibilities have been suggested.  Kin Klizhin lies in a relatively promising area for floodwater agriculture, in a valley near the canyon with a wash that could be easily dammed to provide a reservoir for water storage.  There is in fact an earthen dam near the great house, although it’s impossible to tell if it’s actually ancient rather than a modern Navajo construction.  (It could also be both; Navajos have been known to use and modify Anasazi dams in many areas.)  One intriguing thing about the area around Kin Klizhin is that despite its agricultural potential it seems to have relatively few small-house sites compared to other outlier communities, which suggests a small population that could have easily produced an agricultural surplus for export to Chaco.

Rim Sherd at Kin Klizhin

Rim Sherd at Kin Klizhin

Like the other outliers, Kin Klizhin gets many fewer visitors than the main sites in the canyon.  This makes it a very peaceful, quiet place to visit.  There are a lot of potsherds and other artifacts lying around near the great house, since fewer people come around and steal them.  A visit to Kin Klizhin isn’t for everyone, and it’s particularly not for the many people who come into the Chaco visitor center furious about the lack of paved roads, but for the adventurous few who are willing to take the effort to get there it’s definitely worth a visit.

Heavily Reduced Walls at Kin Klizhin

Heavily Reduced Walls at Kin Klizhin

And, of course, there are some other interesting ideas out there about Kin Klizhin and its role in the Chaco system, but discussion of them will have to wait for another day.

Tower Kiva Bench at Kin Klizhin

Tower Kiva Bench at Kin Klizhin

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