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Archive for June, 2011

Whiteware Sherd at Una Vida

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

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

Black-on-white Sherd at Pueblo Alto

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

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

Chuska Mountains from Peñasco Blanco

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

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

Corrugated Grayware Sherd at Wijiji

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

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

Pots from Early Periods at Chaco Museum

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

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

Pots from Later Periods at Chaco Museum

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

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

Corrugated Grayware Sherds at Kin Ya'a

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

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

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

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Train Station, Dolores, Colorado

Southwestern archaeology, especially in the Chaco area, is structured chronologically primarily by the Pecos Classification.  This system was initially worked out at the first Pecos Conference in 1927, and it was originally interpreted as a series of stages in cultural development, with the assumption that sites with similar characteristics and material culture were roughly contemporaneous.  Once tree-ring dating became available, however, it became clear that this wasn’t quite true, and furthermore that different sub-regions of the Southwest went through the stages at different times.  There have been a variety of approaches developed in the decades since to either redefine the Pecos system or abandon it.  In the Four Corners, the main approach has been to just recast the Pecos stages as chronological markers without any inherent cultural content.  The exact dates used for each stage vary by specific area and specific researcher, but here’s a rough outline of how they are often defined:

  • Basketmaker II: 500 BC to AD 500
  • Basketmaker III: AD 500 to 750
  • Pueblo I: AD 750 to 950
  • Pueblo II: AD 950 to 1150
  • Pueblo III: AD 1150 to 1300
  • Pueblo IV: AD 1300 to 1540

There’s no Basketmaker I.  The Pecos Conference attendees were unsure what, if anything, came before Basketmaker II, and they provisionally included an earlier stage in case there did turn out to be earlier sites.  As it turned out, there were, but they were sufficiently different from Basketmaker sites that they ended up being considered part of the Archaic period of hunter-gatherer societies predating the introduction of agriculture.  (Recent discoveries have begun to muddle this picture, at least for certain areas, but while not everyone still uses the term “Archaic” for the period just before Basketmaker II no one has yet begun to call it “Basketmaker I.”)

Camping at McPhee Campground for 2009 Pecos Conference

Although the stages are generally interpreted as chronological rather than developmental these days, there is still a general sense of what sorts of sites are “typical” or expected for each stage, and this has driven a lot of the variation in specific date ranges.  Basketmaker II sites are generally associated with corn and squash agriculture, a scattered settlement pattern, lots of basketry but no pottery, and the use of the atlatl.  In Basketmaker III this pattern was adjusted by the introduction of the bow and arrow, pottery, and beans, and people began to cluster in some cases into pithouse villages, although there were still many isolated hamlets in some areas.  Pueblo I was something of a transition between Basketmaker III and Pueblo II, with the first construction of significant above-ground architecture in addition to pithouses.  Pueblo II was associated with masonry roomblocks and kivas, generally organized as “unit pueblos” of a few rooms with a kiva and trash mound in front and loosely grouped into “communities.”  The height of Chaco dates to this period, and within the area of Chacoan influence these communities typically had great houses in addition to the unit pueblos but separate from them.  In Pueblo III people began to aggregate into larger, denser communities more like the “pueblos” of historic times.  The cliff dwellings at Mesa Verde and elsewhere date to this period and are the best known of these aggregated sites, but there were many others in a variety of locations.  At the end of the Pueblo III period almost all of the Four Corners area was abandoned and people aggregated further into even larger pueblos in the Rio Grande Valley and the Zuni and Hopi areas to the west, in addition to a few other areas.  The Pueblo IV period is marked by the increasing concentration of population into ever-larger sites and the clustering of these sites in particular areas separated from other clusters by uninhabited “buffer zones.”  This period also saw the apparent introduction of the kachina cult and various other novel social phenomena, and it continued until the Spanish showed up and smashed everything.

That’s the picture in a nutshell, but some periods are better-known than others.  Pueblo II and III have been particularly well-researched in the Chaco and Mesa Verde areas, although there is still plenty that remains unknown about them.  In contrast, Pueblo I was very poorly understood until the Dolores Project in the 1980s totally revolutionized our knowledge of it.  This project was a massive cultural resource management (CRM) salvage project in advance of the damming of the Dolores River and the creation of McPhee Reservoir.  At the time it was the largest CRM project ever, and it might still have that distinction.  Numerous sites in the Dolores River Valley were excavated carefully and thoroughly documented.

McPhee Reservoir from McPhee Campground, Site of 2009 Pecos Conference

It’s impossible to overstate how much our current knowledge of the Pueblo I period is based on the discoveries made at Dolores.  What the project found was that the Dolores Valley, although sparsely occupied both before and after Pueblo I, during Pueblo I contained numerous large, dense villages, most of which only existed for a very short period of time during the AD 800s.  As research continued throughout southwestern Colorado, it became more apparent that these villages were just part of the story of the incredibly dynamic Pueblo I period.  People were moving all over the place, very rapidly, and forming and dissolving villages within the space of one or two generations.  Abundant evidence for drought and conflict at certain key points during the period provided some explanation for why, but the really important thing that came out of the Dolores Project specifically was the detailed study of some of the specific villages that allowed reconstruction of their short histories with remarkable precision.

On a larger scale, it appears that the Pueblo I period involved the movement of people into higher elevations than they had occupied during Basketmaker III, followed by movement back down after 900 and into Pueblo II.  While areas with Pueblo I villages typically didn’t have substantial earlier or later occupations, many other areas (including Chaco) had major Basketmaker III and Pueblo II occupations but little evidence of use during Pueblo I.  This probably had to do with climatic changes, but there were clearly also a lot of social processes going on as well.  Since the rise of Chaco as a regional center began right after all of this, Chacoan specialists have been realizing recently that the evidence from Dolores is very important as background for understanding Chaco.

McPhee Reservoir, Dolores, Colorado

Particularly influential in shaping understandings of Chaco has been one of the Dolores villages in particular, known as McPhee Village.  Like the other Dolores villages, McPhee was founded around 840 as people began to move out of earlier villages further south around Mesa Verde and Durango.  Not everyone from these earlier villages went to Dolores (an important point), but many did, and the Dolores villages grew rapidly, only to decline just as rapidly as people moved out starting in the 870s and continuing until around 900, at which point there was only a very small remnant population in some of the villages.

The remarkable thing about McPhee Village was the presence of some roomblocks there that bore an uncanny resemblance to the early “great houses” that would arise in the San Juan Basin to the south, including at Chaco, shortly afterward.  Not all of the roomblocks were like this; most were small, linear unit pueblos typical of those in most other villages.  Two roomblocks in particular, however, known as McPhee Pueblo and Pueblo de las Golondrinas, looked astonishingly like the early form of Pueblo Bonito.  They were arc-shaped rather than linear, with two arcs making up McPhee Pueblo and Pueblo de las Golondrinas consisting of one larger arc.  (Note that “McPhee Pueblo” refers to a specific roomblock within “McPhee Village.”  The terminology is confusing.)  Furthermore, these roomblocks were made up of room suites consisting of three rooms, with one large room facing the “plaza” within the arc backed by two smaller “storage” rooms.  The “plaza” area within each arc contained pit structures presumably associated with these suites.  Again, this is much like the layout of Pueblo Bonito and other early Chaco great houses.  These roomblocks were also made largely of masonry rather than adobe, in contrast to most earlier sites as well as many other Dolores villages, which again linked them to the later Chaco sites.

Dolores Medical Center, Dolores, Colorado

A variety of studies have been done of these sites, particularly focused on what differentiated them from other roomblocks at McPhee Village.  James Potter did a study of animal remains at McPhee Pueblo and Pueblo de las Golondrinas, looking for evidence that the residents of these sites might have hosted community-wide feasts and/or conducted special rituals, either of which could have been ways for them to gain social power within the community.  Both sites contain, in addition to the standard residential pitstructures common at all sites in the village, special “oversized” pitstructures with more formal, elaborate features that could have served as special locations for feasts or rituals.  He found that McPhee Pueblo did indeed have a much higher number of different types of animal remains present, including many “non-economic” species such as carnivores and certain birds that may have had important ritual uses.  Furthermore, it had a higher proportion of rabbits than most other roomblocks, which is significant because among the modern Pueblos rabbits are often hunted communally and eaten in ritual feasts.  Interestingly, Pueblo de las Golondrinas, despite its size and the presence of an oversized pitstructure, did not have these characteristics, suggesting that its inhabitants may not have been as successful as those at McPhee Pueblo at hosting communal rituals and increasing their power.

Another take on this question comes from an analysis of ritual architecture by Gregson Schachner.  Starting from the assumption that times of significant environmental and social change, such as those that surely accompanied the rapid founding and dissolution of the Dolores villages, offer opportunities for ambitious individuals or groups to gain power and influence by taking control of ritual practices or introducing new ones, he noted that unlike some other Dolores villages McPhee Village doesn’t have a great kiva, the standard community ritual structure both before and after the Pueblo I period.  Instead, roomblocks like McPhee Pueblo and Pueblo de las Golondrinas have the oversized pitstructures that might have been used for special ritual practices that the inhabitants of those sites may have tried to introduce to their communities. Schachner assumes that these pitstructures were primarily ritual rather than residential, which I think is dubious, but otherwise his arguments make sense.  He basically sees the process as having involved certain individuals or groups having tried to introduce new rituals that gave them increased status and power in the context of the convulsions of the Pueblo I period.  Those rituals might have been adopted because they offered a new way forward during the drought that coincided with the founding of the Dolores villages in the 840s, but they might have lost their appeal as a new drought in the 880s led people in the village to reject the innovations of these would-be leaders.  As the village dissolved, construction seems to have begun on a new great kiva over the oversized pitstructure at Pueblo de las Golondrinas.  This great kiva was not completed, however, and the whole village was soon abandoned.  Great kivas continued to be a key part of the new villages further to the south that appear to have absorbed many of the people leaving Dolores after 880, but the oversized pitstructure does not seem to have continued as a recognizable architectural form.

Mac's Plumbing, Dolores, Colorado

The great house form, however, which began to proliferate in the San Juan basin starting in the tenth century, seems to have some connection to the arc-shaped roomblocks at Dolores.  Recently, a model for the rise of Chaco incorporating the insights of the Dolores Project has begun to gain increasing acceptance.  Under this model, the frustrated would-be elites from the Dolores villages moved south into Chaco and other communities and began to build similar structures to those they had lived in at Dolores.  This time, however, circumstances were better, and they were able to gain more control over their communities.  These communities were spread throughout the basin, but those in Chaco Canyon specifically eventually gained ascendancy over the others, and the Chaco Phenomenon was born.

There is a certain logic to this, and parts of it are likely true, but it’s important to note that the timing isn’t quite right for frustrated elites from Dolores to have founded the first great houses at Chaco.  The earliest parts of Pueblo Bonito are now thought to have been built by 860 and perhaps considerably earlier, while the Dolores villages didn’t start to dissolve until the 870s.  It’s quite possible that later additions to the site in the 890s and early 900s involved immigration from Dolores, and indeed it is these room suites that are particularly similar to those at McPhee Pueblo.  It’s worth considering, however, the possibility that the early history of Chaco involved people moving in from the south as well as the north, and we don’t know nearly as much about the Pueblo I period in that area.  Were there large, unstable villages with ambitious families or individuals there too, or was something totally different going on that led people to head north at the same time people were heading south from Dolores?  We can only guess at this point, but it’s important not to let our greater knowledge of developments at Dolores lead us to focus too much on it to the exclusion of other important areas.  Dolores was very important, no question, but it wasn’t the only important place at the time.
ResearchBlogging.org
Potter, J. (1997). Communal Ritual and Faunal Remains: An Example from the Dolores Anasazi Journal of Field Archaeology, 24 (3) DOI: 10.2307/530690

Schachner, G (2001). Ritual Control and Transformation in Middle-Range Societies:
An Example from the American Southwest Journal of Anthropological Archaeology, 20, 168-194 DOI: 10.1006/jaar.2001.0379

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Room 38, Pueblo Bonito

Pueblo Bonito is the best-known and most-studied site at Chaco, but there’s still a lot we don’t know about it.  Because it was excavated early in the history of Southwestern archaeology, provenience information for the vast numbers of artifacts found at Bonito is not nearly as precise as would be expected today.  We do generally have information about what was in each excavated room, and often where in the room specific artifacts were, but the careful stratigraphic approaches used today were either totally unknown or in their infancy during the excavation of various parts of Bonito, so interpreting the field notes and site reports can be a challenge.  Partly for this reason, a lot of recent interpretations of Chaco have been based mainly on the more recent and better-documented excavations by the Chaco Project in the 1970s.  This makes Pueblo Alto in particular, the only great house extensively excavated by the Chaco Project, enormously influential in recent interpretations, not always in beneficial ways.  The Pueblo Bonito data has been incorporated into most theories to varying extents, but this often just takes the form of vague gesturing at the elaborate burials and huge quantities of high-value artifacts found there, and sometimes it basically amounts to discounting the importance of Bonito because it is so unlike the other sites.

Still, Bonito is important!  The problematic nature of the documentation notwithstanding, there’s still a ton of data available, and the Chaco Archive has been doing excellent work lately in making it more widely accessible.  Their cool interactive map of the site even allows you to click on a room and see a list of all the features, artifacts, tree-ring dates, and pictures associated with that room.  I’ve been playing around with it a lot lately, and there’s really a ton of interesting stuff in many of the rooms that we don’t hear so much about.

Room 309, Pueblo Bonito

Building on what I was saying earlier about a badger burial at a small site excavated by Earl Morris near Aztec, I decided to look for unusual animal burials or remains that might suggest some patterns in ritual practices or group identities at Bonito.  Many modern Pueblo clans are named after specific animals, and it seems reasonable that some Chacoan social groups (which may or may not be equivalent or ancestral to the modern clans) might have had similar identities that would lead them to leave animal remains in certain contexts that could indicate connections through time between different rooms or sites.  The Chaco Archive database allows you to search for specific types of artifacts, and it even has a special option for non-human burials.  The database doesn’t have all the sites included yet, but it does have all of Bonito, and it’s a powerful tool for finding information about the sites that are included.

Starting with the non-human burials, the ones at Bonito seem to all be of macaws and parrots.  The close connection between Bonito and macaws has long been noted, and Room 38 is particularly known for its large numbers of them, but one thing I hadn’t realized is that, like so much else at Bonito, the distribution of macaws is highly concentrated, not just in a few rooms, but specifically in a few rooms on the east side of the site.  The macaw burials, in addition to the two in Room 38, are in Rooms 71, 78, and 306, all of which are in the eastern part of Old Bonito.  Not all of these are actually formal burials, but they are all complete skeletons.  Extending the search to individual bones adds Rooms 249, 251, 309, and 312, as well as Kiva J and the east mound in front of the site.  Again, these are all on the east side of Bonito, although not just in Old Bonito this time.  Rooms 309 and 312 aren’t technically in Old Bonito, but they are among the rooms added right in front of it, and are very close to Rooms 306, 71, and 78, which also had macaws.  Rooms 249 and 251 are in the block of rooms added onto the southeast part of the site over an earlier extension that apparently built over part of the eastern end of Old Bonito (this part of the site is very complicated and its construction sequence is poorly understood).  Kiva J is one of the six blocked-in kivas between this block and the plaza.  And, of course, the east mound is the easternmost of the two mounds.

Kiva J, Pueblo Bonito

What does all this mean?  Many have suggested that the number of macaws at Bonito indicates the possible presence of a macaw clan like the one known today at Zuni.  If this is indeed the explanation for all the macaws, and it seems plausible given the restricted distribution of them to just a few sites at this time and the contexts in which they are found, it seems that this clan probably lived in or had claims on the eastern part of Pueblo Bonito, and that this association held not just in the earliest stages of the site but even after it was expanded.  Perhaps members of this clan were the initial residents of the eastern suites in Old Bonito, then when those rooms were converted to other uses as the site was expanded they moved into the new southeast wing.

One question that might be raised at this point is whether this distribution is actually specific to macaws.  Maybe all exotic birds and animals are concentrated in this part of the site, which would suggest that there might be something special about the eastern half of the site but not necessarily anything tied to a specific clan.  Some research into the layout of the rooms has shown that the southeast corner is unusual in not being divided into obvious room suites, whereas the southwest corner seems to be.  Maybe instead of the macaw clan living in the eastern half, everyone lived in the western half and they used the eastern half for macaw-related (and other) ritual.

Room 330, Pueblo Bonito

One way to test this would be to look at other unusual animals.  Finding animals of ritual importance beyond obvious exotics like macaws is tricky, because many animals were certainly used for mundane purposes and their remains are therefore all over.  Dogs and turkeys were kept domestically, so their remains probably wouldn’t indicate anything special about social groupings, and game animals such as rabbits and deer might have interesting implications for access to different kinds of meat but, again, not necessarily specific symbolic implications.  That basically leaves animals that don’t serve a clear subsistence or other utilitarian purpose but are nevertheless found in sufficient numbers to suggest something more than mere chance is behind their presence.  The best example I’ve found: bears.

You basically never hear about bears in discussions of Chaco.  They are not present in the area now and probably weren’t in antiquity either, and their remains are certainly rare at Chaco but not entirely absent.  At Pueblo Bonito, bear remains are mostly concentrated on the west side of the site, in stark contrast to the macaw remains on the east side.  There are some artifacts made of bear bone, including two apparent gaming pieces, one each from Rooms 267 and 290 (both on the east side), but there are also unworked bear bones, especially jaws and feet, particularly concentrated in Rooms 92, 102, and 109, which are part of the same suite of rooms in the west wing of Old Bonito.  Room 92 also had a bear hide and mass of hair that is probably also from a bear.  Another room in this part of the site, Room 330, had a grizzly bear jaw.  Another bear jaw was in Room 66 and a claw was in Room 10; both these rooms are on the east side of the site.  So not as clear-cut as the macaw evidence, but still a strong suggestion that people with some sort of connection to bears lived in the western part of the site.  The “bear-paw” motif is well-known in rock art, and George Pepper, who excavated these rooms, reported that Room 97 (the room under Room 92) had similar “bear paws” drawn on the smoke-blackened plaster.  Finally, Kiva Q, the great kiva in the west plaza, contained a (dedicatory?) cache of objects that included bear paws.  This is all very suggestive, though of course not totally dispositive.

Kiva Q and West Plaza, Pueblo Bonito

There may be other examples of these sorts of patterns that could give us a better sense of who exactly was living at Pueblo Bonito and what other people at which other sites they had particularly close ties to.  Despite the fact that this information has been available for a long time, it’s only now that it’s starting to become widely available in a useful form.  New analytical techniques are revolutionizing our understanding of Chaco in all sorts of ways, but one of the most important contributions technology can make is just to make existing information available so it can be assembled, analyzed, and compared to information from elsewhere.

Bear Paw at Three Rivers Petroglyph Site

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Metate Incorporated into Wall Capping, Pueblo Bonito

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

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

Talus Unit with Snow

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

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

Room 3a/92/97, Pueblo Bonito

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

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

Room 170, Pueblo Bonito

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

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

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

Metate Fragment at Pueblo Alto

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Display Case at Chaco Museum Showing Cylinder Jar and Canteens

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

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

Cylinder Jar at Chaco Museum from Above

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

Room 28 at Pueblo Bonito

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

Pitchers at Chaco Museum

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

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

Bc 51

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

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

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Chetro Ketl from Above

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

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

Una Vida from Petroglyph Area

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

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

Pueblo Bonito from Above

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

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

Kin Kletso

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

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

Pueblo del Arroyo from Above

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

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

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

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Trash Mound from Pueblo Alto

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

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

Niche at Pueblo Alto

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

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

Flake of Narbona Pass Chert with Ant at Pueblo Alto

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

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

Shell Bead at Pueblo Alto

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

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

Plaza at Pueblo Alto

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

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

Rim Sherd at Pueblo Alto

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

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

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

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