Back to the Square Rooms

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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Salmon Ruins and Chacoan Residence Patterns

Salmon Ruins Sign

One of the largest and most important of the “outliers” associated with the system centered on Chaco Canyon in the late eleventh century AD is Salmon Ruin on the San Juan River near Bloomfield, New Mexico.  Salmon is about 45 miles due north of Chaco, and its location in a fertile river valley makes it a much less surprising (though still impressive) site than Chaco, with its stark, desolate setting.  Salmon was partly excavated in the 1970s by Cynthia Irwin-Williams of Eastern New Mexico University, and the Center for Desert Archaeology has recently been working on an extended project to collect, reevaluate, and publish data from those excavations as well as new analyses taking into account more recent discoveries and interpretations relating to the Chaco system in general.  One result of this was the publication of a comprehensive three-volume site report in 2006, and another was the publication of a shorter, more synthetic volume in 2008.  I read the report a while ago and am currently about halfway through the newer book.  It’s definitely more accessible than the report, but it doesn’t really stand alone.  A lot of basic information about the site and the excavations seems to be assumed, presumably because it’s discussed in the site report.  The report doesn’t stand alone either, and in general there’s a surprising lack of overlap between the two publications.  You might think that the synthetic volume would be a more accessible book aimed at a general audience, since it’s published by a university press rather than by CDA and the Salmon Ruins Museum, but while the new book goes well beyond Salmon itself in discussing the archaeology of the “Middle San Juan” or “Totah” region in general it really seems to be aimed at specialists with substantial background who have either already read the site report or are willing and able to find and read it if they want to follow up on the numerous references to chapters in it.  Both books are very expensive, which is another factor standing in the way of a general audience for them.

This is all rather unfortunate, because there’s a lot of important and fascinating information in these two publications.  In the context of my recent discussion of kivas at Chaco and the debate over their function, one of the chapters in the synthetic volume is particularly relevant.  Here Paul Reed, the head of the CDA project at Salmon, makes a strong case for a largely residential function for Salmon during the Chacoan period.  This is interesting in itself due to the longstanding debate over the function of great houses like Salmon in general, with some arguing that they served as primarily non-residential ceremonial structures while others see them more as elite residences.  Reed doesn’t discount the importance of ritual functions at Salmon, nor does he try to argue that all great houses were primarily residential, but he shows from the evidence collected by the excavations in the 1970s that there is abundant evidence for residential use of many of the rooms at Salmon during its brief Chacoan occupation as well as during its longer subsequent occupation, which he sees as being by local people after the Chacoan residents left and went to Aztec.

Excavated Rooms at Salmon Ruin

One of the most important pieces of evidence Reed points to to support a residential function at Salmon is the very obvious presence of room suites throughout the site.  Salmon has a very formal, “planned” layout typical of later great houses, which makes sense since it seems to have been founded around 1090, toward the end of the Chacoan era (which lasted from about 1030 to 1130).  Indeed, it looks virtually identical in layout to Hungo Pavi, an unexcavated great house in Chaco Canyon about which little is known.  Salmon, like Hungo Pavi, is an “E-shaped” great house, with a central room block on the north side and wings extending to the south at the east and west ends.  The whole thing seems to have been constructed as a single unit within a few years around 1090, which makes it by far the largest single building episode known in the Chaco system and has interesting implications for understanding why it might have been built.  There has long been a dispute over whether the outliers in the Chaco “system” represent direct colonization by people from Chaco, local emulation of Chacoan forms by emerging elites, or something else.  Reed supports a colonization model, but he sees the Chacoans who came up to Salmon and built the great house as having also brought local residents in to live there with them, and perhaps to work on building the thing too.  The local area seems to have lacked a substantial pre-Chacoan population, so it’s not entirely clear where these locals would have actually come from, but it does make sense that colonists from Chaco would have selected a relatively uninhabited location for their new settlement.

Anyway, back to the room suites.  Most of the site seems to have originally been laid out as a series of suites, each of which involved a large square room facing the plaza connected to three smaller rooms behind it.  The large square rooms seem to have been single-story, but the smaller rooms mostly had two or three stories.  The large square rooms especially tended to have many residential features such as hearths, and the smaller rooms often had features such as milling bins that also suggest domestic use.  There were also a few rooms that had very large milling bins, larger than would have been necessary for individual households, which suggests that site residents might have been grinding corn on a large scale.  This, combined with Salmon’s location in a fertile valley, in turn suggests that the site may have been founded partly or even primarily as an agricultural colony that would have exported corn and/or cornmeal to Chaco and perhaps other areas with poorer agricultural potential.  There is evidence from studies of corn at Chaco that much of it was imported from the Totah, which meshes nicely with this idea.

Backfilled Rooms at Salmon Ruin

The key thing here, though, is that it’s the large square rooms that seem to have been the primary living rooms.  This is similar to the case at some early room suites at Chacoan great houses, such those in the western wing of Pueblo Bonito.  Later great houses at Chaco seem to have largely either lost the room suite pattern or modified it beyond recognition, but at Salmon it stands out clear as day.

There’s something missing here, though.  Salmon (in the Chacoan period) was composed almost entirely of room suites made up of large square and small rectangular rooms.  But what about kivas?  These round rooms are often considered one of the hallmarks of pueblo architecture, and while their function is disputed their presence is often thought of as near-universal.  Salmon complicates this picture considerably.

Great Kiva, Salmon Ruins

There were two round rooms in the Chacoan-period construction at Salmon (note these caveats; they’re important).  One was the great kiva in the plaza, a standard Chacoan form that presumably had ritual functions, and another was and elevated, blocked-in kiva at the center of the main roomblock that Salmon specialists refer to as the “Tower Kiva,” although it actually isn’t a tower kiva in the sense in which Chaco specialists use the term.  Both of these seem to have had important community-wide functions and they were probably not residential (though I’m less sure of this in the case of the Tower Kiva than in the case of the great kiva).  What Chacoan-period Salmon lacked, however, were the smaller kivas that are ubiquitous at Pueblo Bonito, Chetro Ketl, and other great houses at Chaco.  These are the kivas that Steve Lekson thinks were residential rather than ceremonial, although others disagree.  In any case, they don’t seem to have been part of the original plan for Salmon.

So what gives?  Well, if we buy Lekson’s theory, which I basically do, what seems to be going on here is that the residential functions filled by kivas elsewhere were filled by the large square rooms at Salmon.  As I noted in the previous post, the fact that some great houses have room suites with big square rooms while others have different types of suites with associated kivas suggests that there were two different residential patterns in the Chacoan system that might correspond to some important dimension of social complexity.  Salmon seems to support this idea, in that it apparently was designed (and occupied?) by one of these groups rather than the other, whereas at Pueblo Bonito, at least, both seem to have been present.

Kiva 121A, Salmon Ruin

If you’ve been to Salmon, this may seem a bit confusing, because one of the most obvious things you can see there is that there are plenty of kivas!  They’re built into the square roomblocks, just like at Chaco!  And, indeed, they are.  Excavation showed, however, that these kivas are not original to the building.  Instead, they were built into the large Chacoan rooms in the post-Chacoan period.  The Chacoan period at Salmon seems to have ended around 1125 or 1130, coincident with the end of major construction at Chaco and extensive evidence of major changes in the Chaco system that may or may not have constituted the “collapse” of that system.  The original idea the excavators had was that this involved the total abandonment of Salmon for a few decades, after which it was reoccupied by a new group with ties to the Mesa Verde region to the north which remained there until the site was abandoned completely in the 1280s or 1290s along with the whole region.  It later became clear that there was at least a small “Intermediate” occupation between the “Primary” (Chacoan) and “Secondary” (Mesa Verdean) occupations, and the CDA project has redefined these occupations to emphasize continuity between the last two, seeing them as “early” and “late” periods of a continuous local “San Juan” occupation as opposed to a migration from the north.

In any case, it was the “Secondary,” “Mesa Verdean,” or “San Juan” occupants, not the Chacoans, who built kivas into the Chacoan rooms.  Note that architecturally, these are not Chacoan kivas, which have a very standardized set of features, but instead more closely resemble Mesa Verde kivas and may reflect local architectural traditions such as the use of river cobbles rather than sandstone blocks in some contexts.  They were mostly built into the large square living rooms, although some were in the smaller rooms, which were also often subdivided with adobe walls to create spaces more typical of small sites in the area than the large rooms typical of Chacoan great houses.

Kiva at Salmon Ruin Showing Use of Cobble Masonry

The fact that these kivas were mostly built into the Chacoan living rooms is another point in favor of Lekson’s arguments that kivas were residential, especially since there’s some evidence from the Salmon excavation data that there was more continuity between the “Chacoan” and “San Juan” occupations than the excavators thought.  One interpretation for the construction of the kivas is that whoever was living at Salmon in the 1200s knew how the room suites had been used in the Chacoan era and wanted to continue to use them the same way but in a way that was consistent with local traditions and practices.  These people may or may not have been descended from the original inhabitants of the site.

The upshot of this is that we have strong evidence here that there was a practice in at least one Chacoan great house in the late 1000s and early 1100s of residential use of room suites focused on large square rooms facing the plaza.  It’s hard to tell if this pattern holds for any of the sites at Chaco itself (Hungo Pavi?), since the most extensively excavated ones were excavated long before the techniques that allowed the Salmon excavators to carefully differentiate between occupations were developed.  There is some evidence from the less extensive excavations at Pueblo Alto, however, which were done by the Chaco Project around the same time Salmon was being dug, that there was a similar pattern there of kivas being added to an original plan lacking them.  The kivas in the southeast corner of the Chetro Ketl plaza also seem to be very late, and the other parts of that site have relatively few kivas, most of them in elevated contexts similar to the “Tower Kiva” at Salmon.  Something similar may be true for the blocked-in kivas in the central roomblock at Pueblo del Arroyo.

Chacoan Masonry at Salmon Ruin

That leaves Pueblo Bonito.  The enormous complexity and early excavation of this site make teasing apart the different stages of construction enormously difficult, but one possibility is that at least some of the kivas there have a similar history to the ones at Salmon.  This may be particularly the case in the southwest corner, which has several kivas that may have been added into older square rooms and is also the area with the well-defined early room suites with large square rooms taking the place of kivas.  It’s also likely that many of the plaza kivas were very late additions like the ones at Chetro Ketl.  The blocked-in kivas in the southeast corner are trickier to interpret, and I’m not sure at this point if they represent something like the Salmon pattern or a different phenomenon entirely.

The excavations at Salmon resulted in a vast amount of information that is only now beginning to be incorporated into the study of the Chacoan system overall.  This evidence for residential use is just one example, but an important one, of how this data can lead to important insights not just about Salmon itself but about other parts of the Chaco world as well.

Central Roomblock at Salmon Ruin

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More on Food Imports to Chaco

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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