Chipped Stone

Stone Tools at Chaco Visitor Center Museum

When it comes to stone tools, archaeologists make a basic distinction between “chipped-stone” and “ground-stone” tools.  Chipped-stone tools are generally those that need to be sharp, such as projectile points, knives, scrapers, and drills, and are typically made of hard stone that keeps an edge.  Some ground-stone tools, such as axes, are also sharp, but for the most part ground-stone tools rely on other qualities of stone for purposes like hammering and grinding.  In the Southwest, ground-stone tools are usually made of sandstone, basalt, or other types of stone that are plentiful in the area immediately around a site.  These tools are heavy, and it generally wouldn’t have made any sense to import special types of stone to make them when, as is the case throughout the Southwest, there were plenty of rocks around.  The types of stone used for ground-stone tools are also generally those used for masonry in areas where masonry construction was typical, including at Chaco, where sandstone was the usual material.

Chipped-stone tools are a different story.  They are usually small and highly portable, and the best materials to make them are often scattered and not convenient for every habitation site.  Thus, widespread trade in chipping stone has very early origins.  Hunter-gatherers need very good stone for their projectile points, and also tend to be very mobile, so their chipped-stone tools tend to be very well-made and to be made of high-quality material from a wide variety of sources.  Settled agriculturalists such as the Chacoans don’t rely so heavily on chipped-stone tools for their subsistence needs (ground-stone tools like metates are much more important), and they typically put much less effort into both procuring stone for chipped-stone tools and making the tools themselves.

Flake of Narbona Pass Chert at Pueblo Alto

When it comes to Chaco specifically, chipped-stone shows a much more muted form of the pattern of massive imports of other goods such as pottery, wood, turquoise, and even food.  Cathy Cameron summarizes the patterns revealed by the chipped-stone assemblages from Chaco Project excavations in the 1970s in an article from 2001.  The basic pattern is that most chipped stone was from local sources throughout the occupation of Chaco, although “local” really refers to a wider area here than the canyon itself.  Good chipping stone is not plentiful in the canyon itself, but abundant sources of good chert and petrified wood occur a few miles to the north and would have been easily accessible to canyon residents in the course of their daily lives (i.e., special trips to gather stone would probably not have been necessary).  These local sources always dominate assemblages from Chaco.  Imported stone types do increase during the Chaco era from AD 1030 to 1130, especially at great houses such as Pueblo Alto.  The most abundant import at this time is Narbona Pass chert, a distinctive pinkish type of stone that comes from a very restricted area in the Chuska Mountains to the west.  The Chuskas are also the source of many other imports to Chaco, including huge amounts of pottery and wood, but the relative proportions of Narbona Pass chert in the overall chipped-stone assemblages are much more modest.  It comprises 21.1% of the total Chaco Project sample for AD 1020 to 1120 and 18.9% of the sample for AD 1120 to 1220.  This is much higher than any other type of imported stone ever reaches, and even higher than any single type of local stone for these periods (though much lower than the total proportion of local stone).

Other imported materials found in notable numbers include Brushy Basin chert from the Four Corners area, a type of yellow-brown spotted chert and a special type of petrified wood, both from the Zuni area, and obsidian.  Brushy Basin chert (along with other materials from the same formation) and Zuni petrified wood reach relatively high proportions of the overall assemblage at the same time that Narbona Pass chert does, and Zuni chert does too but at a much lower level.  The pattern of obsidian is different, and hard to understand.  It’s the most common exotic type of stone before AD 920, rising to as high as 7.6% of the assemblage in the seventh century.  Sourcing studies seem to show that most of the obsidian coming it at this point came from the area around Grants, New Mexico, near Mount Taylor, during this period.  Once the Chaco system really gets going, though, the proportion of obsidian plummets to less than 1%.  From 1120 on, however, it rises again, comprising 7.3% from 1120 to 1220 and 2% after 1220, still less than Narbona Pass chert but respectable.  This obsidian seems to come mostly or entirely from sources in the Jemez Mountains to the east of Chaco.

Log of Petrified Wood at Chaco

So what were the Chacoans doing with this imported stone?  Not much, as it turns out.  One of the oddest things about the amount of Narbona Pass chert, particularly, is that it doesn’t appear to have been used for anything special.  Like all other types of stone, both local and imported, it was used primarily for expedient, informal tools.  The Chaco Project found 2,991 pieces of Narbona Pass chert, and only 18 of these were formal tools.  This pattern is typical for most material types, though obsidian seems to have been more often used for formal tools, many of which were probably imported as finished tools rather than made in the canyon.  Of the formal tools the Chaco Project did find, of all materials, about half were projectile points, and the rest were various types of knives, scrapers, and drills.

So what’s going on here?  Hard to say.  Cameron evaluates the chipped-stone data in the context of the models for the organization of production proposed by other participants in the conference from which this paper originated, and she decides that Colin Renfrew’s pilgrimage model fits best, with some adjustments.  This conclusion is driven largely by the fact that so much of the Narbona Pass chert came from the Pueblo Alto trash mound and the idea that this indicates that it was deposited there as part of communal rituals.  I find claims like this dubious, and I think it’s more likely that people in Chaco were just importing this type of stone either because it is so visually striking or because of their strong social connections to Chuskan communities (or both).

Chuska Mountains from Tsin Kletzin

The thing I find most puzzling is the obsidian.  Obsidian was hugely important in Mesoamerica, and in view of the appropriation and importation of many aspects of Mesoamerican culture by the Chacoans, most recently dramatized with evidence for chocolate consumption, it seems very odd that the rise of the Chacoan system would coincide with a steep decline in the amount of obsidian imported.  This is particularly odd since the Grants area was very much a part of the Chaco world, and there were numerous outlying great houses and communities near Mt. Taylor.  If the Chacoans had wanted obsidian, they could easily have gotten it.  And yet, it seems they didn’t.

Or did they?  Keep in mind that this data is based mostly on Chaco Project excavations, although Cameron does incorporate some insights from a study of formal chipped-stone tools done by Steve Lekson that incorporated other data as well.  Lekson’s study noted that Pueblo Bonito in particular had an astonishing number of projectile points relative to most other sites, and I can’t help but wonder if part of the lack of obsidian at other sites was a result of more of it flowing to Bonito.  The excavations at Bonito were done a long time ago without the careful techniques of the Chaco Project, so the data isn’t totally comparable, but I’m going to look at the artifact records from Bonito (conveniently made available at the Chaco Archive) to see how common obsidian was there.

Arrowheads at Chaco Visitor Center Museum

Speaking of projectile points, another thing Cameron mentions is that many of them seem to have been imported to Chaco, some of them apparently embedded in meat.  Others were particularly finely made and left in burials and caches, suggesting that they may have been specially made for votive purposes.  That’s probably the case for many of the points Lekson identified as being particularly numerous at Bonito, but what I want to know is why arrowheads were such common grave goods and offerings there.  Was there a particular association between Chaco and hunting?  The great house residents do seem to have eaten a lot more meat than other people in the canyon and elsewhere.

On the other hand, arrows weren’t only used for hunting.  Cameron notes that one projectile point found by Neil Judd at Pueblo Bonito was embedded in a human vertebra, and the Chaco Project also found a woman at the small site 29SJ1360 near Fajada Butte who had two points inside her.  We often talk about how peaceful Chaco was and how little evidence there is for warfare during the Chacoan era, but I’m starting to wonder about that.  It’s certainly true that Chaco itself and most other sites occupied during its florescence show less obvious evidence for violence than sites afterward do, but there are still some signs that things may not have been totally peaceful throughout the Southwest in Chacoan times.  Arrowheads in vertebrae don’t get there on their own, after all.  Who shot those arrows?

Cameron, C. (2001). Pink Chert, Projectile Points, and the Chacoan Regional System American Antiquity, 66 (1) DOI: 10.2307/2694319

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On This Solstice Day

Fajada Butte from Pueblo Alto

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

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

Pueblo Alto and New Alto from Tsin Kletzin

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Where They Got the Pots

Whiteware Sherd at Una Vida

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

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

Black-on-white Sherd at Pueblo Alto

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

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

Chuska Mountains from Peñasco Blanco

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

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

Corrugated Grayware Sherd at Wijiji

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

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

Pots from Early Periods at Chaco Museum

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

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

Pots from Later Periods at Chaco Museum

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

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

Corrugated Grayware Sherds at Kin Ya'a

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

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

In any case, the large-scale importation of pottery is one of the most striking examples of how Chaco was very much at the center of a regional system.  We may not know what that system was, exactly, or how it functioned, but we can see that it existed.  The evidence is right there in all those potsherds that litter the ground around the sites in the canyon.

Toll, H. (2001). Making and Breaking Pots in the Chaco World American Antiquity, 66 (1) DOI: 10.2307/2694318

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Unusual Animals at Pueblo Bonito

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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The Complications of Corn

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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On the Purported Evidence for Feasting at Pueblo Alto

Trash Mound from Pueblo Alto

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

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

Niche at Pueblo Alto

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

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

Flake of Narbona Pass Chert with Ant at Pueblo Alto

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

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

Shell Bead at Pueblo Alto

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

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

Plaza at Pueblo Alto

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

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

Rim Sherd at Pueblo Alto

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

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

Toll, H. (2001). Making and Breaking Pots in the Chaco World American Antiquity, 66 (1) DOI: 10.2307/2694318

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

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Colin Renfrew Has a Hammer

Pueblo Alto Trash Mound

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

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

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

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

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

Corrugated Potsherd at Pueblo Alto

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

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

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

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

Hachured Potsherd at Pueblo Alto

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

Renfrew, C. (2001). Production and Consumption in a Sacred Economy: The Material Correlates of High Devotional Expression at Chaco Canyon American Antiquity, 66 (1) DOI: 10.2307/2694314

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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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Echoes of the Past

Chaco Amphitheater

There’s a spot near the west end of the Pueblo Bonito parking lot, close to the spot where guided tours begin, where you can yell something in the direction of the canyon wall and hear a very clear echo back.  Some of the tour guides at Chaco regularly demonstrate this impressive effect when beginning their tours, and it’s certainly an interesting way to capture people’s attention.  I never did it myself; I’m generally averse to this sort of thing because I’m never confident that I’ll get it quite right, and it would be very awkward if I tried it and it didn’t work.  (There’s a similar effect in Statuary Hall in the US Capitol which I never demonstrated when I gave tours there either.)  This is kind of silly, though, and says more about me than about the echo.  In general I think highlighting this kind of acoustic effect is a good way to show just how special Chaco is, and while this particular echo is in a very accessible location there are many other places in the canyon with similar characteristics.  There are several places in and around Pueblo Bonito where you can hear with crystal-clear precision everything people say up on the Threatening Rock overlook, and there are some spots where you can even hear things clear across the canyon.

Secret Passage into Casa Rinconada

These effects have been known to the park’s interpretive staff for a long time, but until recently they’ve received very little attention from scholars.  In the past few years, however, the growing field of archaeoacoustics has begun to look rigorously at echoes and other acoustic phenomena in the canyon with an eye to understanding what role they may have played in Chaco’s past.  Rich Loose, a former archaeologist and old Chaco hand, has been at the forefront of this research, in collaboration with our old friends John Stein and Taft Blackhorse.  Rich recently sent me a couple of articles of his that have recently been published on this issue, along with a paper by John and Taft that I don’t think has been published anywhere.  The most important of these articles, I think, is one in which Rich describes in detail the research the team has done at the so-called “Chaco amphitheater” between Pueblo Bonito and Chetro Ketl.  Using sophisticated recording equipment and acoustic analysis software, they made a series of recordings of different sounds produced in various locations in and around the amphitheater and determined many of its important acoustic properties.  They also examined the cliff face in this area and concluded that there was considerable evidence that it had been deliberately sculpted, perhaps to improve its acoustic properties or for other purposes related to its use as a performance venue.  There is some evidence that there may have been a masonry wall along at least part of the sculpted area which could have created a “backstage” for performers, which Rich compares to the “secret passage” at Casa Rinconada.  There are also three large holes in the cliff face which appear to be natural but may have been enhanced as well.  One of these is large enough to fit a person and leads to a small cave that can apparently fit multiple people (though presumably in very close quarters).  Again, this has interesting implications for possible stagecraft.

Pueblo Alto and New Alto from Tsin Kletzin

One of the most interesting discoveries in Rich’s paper involves a small hill on the other side of the canyon, near Casa Rinconada, which he concludes was almost certainly deliberately constructed artificially for some purpose related to the amphitheater.  This hill, which is quite prominent and which I have often wondered about, apparently doesn’t show any sign of covering up a small-house site like the ones surrounding it, but neither does it appear to be natural.  It is, however, located almost exactly on the line along which sound from the amphitheater focuses, which also seems to coincide almost exactly with the north-south line between Tsin Kletzin and Pueblo Alto.  Sounds played from the hill could be clearly heard in the amphitheater, although their source could not easily be ascertained from there, and even speech from the hill could be heard in a somewhat garbled manner.

Canyon Wall from Pueblo del Arroyo

As with archaeoastronomy, archaeoacoustics suffers from the persistent problem that there’s no way to know for sure if the patterns it discovers are real or due simply to coincidence.  Rich is quite open in acknowledging this shortcoming in his articles.  In the absence of any means to verify results completely, a compelling combination of separate types of evidence is the best way to support an argument that the acoustic properties of a place are not accidental but reflect conscious decisions on the part of ancient people.  In the case of the Chaco amphitheater, I think Rich’s results clearly meet this standard.  Again as with archaeoastronomy, it’s hard to say what the specific implications of all this are for understanding prehistoric behavior, but in this case the acoustic evidence seems to shed at least some tentative light on several mysteries about Chaco.

Huerfano Mesa from New Alto

One of these is the nagging question of why Chaco was chosen in the first place as the location for such a grandiose center, given that it has no apparent natural resources and is in a particularly harsh and inhospitable location even by local standards.  The acoustic properties of the canyon walls, however, which as I noted above are not limited to the phenomena at the amphitheater specifically, provide one possible answer.  The main way in which Chaco does differ from the surrounding San Juan Basin is that it is, of course, a canyon, and has a long stretch of exposed sandstone cliffs with acoustic effects that can’t be found in many other places nearby.  This doesn’t necessarily explain its advantages in a larger geographic context, of course, and there are many other places just a bit further away with similar sorts of cliffs, but it does potentially shed some light on the question of what leverage the Chacoans would have had over other people in the area that they could use to gain their important position in the region.  People often gesture vaguely to “spiritual authority” or something similar in trying to explain this, but the acoustics provide an explanation for how a reputation for spiritual power could arise in the first place.  The position of the amphitheater at the center of the canyon, at the intersection of many alignments between buildings, certainly suggests that it was an important focal point for the area, and the acoustic characteristics are very suggestive.

Looking East from the Pueblo Alto Trail

Since this research involves John Stein and Taft Blackhorse, of course, Navajo oral traditions also enter into the story.  Specifically, the unpublished paper by John and Taft talks about a connection between the amphitheater and a ritual involving the use of the hallucinogenic datura plant, as well as a connection to the Great Gambler (specifically that the Gambler came to Chaco to take advantage of the powers associated with the amphitheater).  Indeed, they even say that the amphitheater is still used by “Navajo ceremonial practitioners,” which Rich incorporates into his articles as a key piece of evidence backing up his acoustic studies.  I’m a little dubious about a lot of this, and I intend to look into it further, but I do think oral traditions are an important place to look for an independent line of evidence to serve as a check on conclusions derived from archaeoacoustic (and archaeoastronomical) research.

Shell and Jet Display at Chaco Museum

Another issue this acoustic research sheds light on is the remarkable number of musical instruments, many quite elaborate, found in excavations at Chaco.  Almost all of these were found at Pueblo Bonito; the flutes in Room 33 are probably the best known, but I want to focus here on the conch shells apparently used as trumpets, which were also quite numerous and found in many rooms at Bonito.  Rich mentions these in his articles as well, although he doesn’t go into great detail about them.  He does, however, note that a conch shell trumpet was one of the sound sources he used in his archaeoacoustic research, and adds this interesting statement:

I found the shell trumpets to be one of the easiest ways to produce a loud stimulus for an echo. They are simple, easily portable, don’t require batteries, and are nearly foolproof once you master the technique of blowing one.

As luck would have it, Barbara Mills and T. J. Ferguson have recently published an important article on shell trumpets in the prehistoric Southwest in which they record all the places they have been found and try to see what conclusions about prehistoric ritual and ideology can be drawn from the distribution of trumpets through time and space.  They conclude that there are at least two separate ideological systems associated with shell trumpets: one having to do with the plumed serpent and associated with rain and agricultural fertility, and another having to do with warfare and healing (these might be two separate traditions, in which case there would be a total of three traditions).  Temporally, they find that the plumed serpent tradition, which is quite strong at Hopi and Zuni today, appears rather suddenly in the early fourteenth century, a time of considerable population movement and cultural change, and may have something to do with influence from the major center at Casas Grandes in Chihuahua as well as with migration of large numbers of people from the southern Southwest into the Pueblo region.  During this period conch shells are found primarily at Casas Grandes and in a large area of east-central Arizona along the Mogollon Rim, as well as in the Hohokam region of southern Arizona and as far east as Pecos.

Kiva A at Pueblo Bonito from Above

There is basically no evidence for plumed serpent iconography earlier than AD 1300, although there are conch shells.  Their distribution is much more limited, however, being confined essentially to the Hohokam region and Chaco, although there is one isolated example from the Mimbres area of southwestern New Mexico.  The geographic isolation of Chaco is striking on their map of sites where conchs have been found; there don’t seem to be any examples from any other sites on the Colorado Plateau during this period, despite the large population of this area and the presence of many strongly Chacoan-oriented or -influenced regional centers.  Apparently there were no shell trumpets even at Aztec, which is in general pretty similar to Chaco in the numbers and types of valuable artifacts found.  There were a bunch of them at Chaco, however, at least 17 overall, and all except two of them came from Pueblo Bonito specifically.  Within Bonito they were generally found in significant locations such as rooms containing other rare artifacts and a wall niche in Kiva R, rather than in trash deposits, which suggests that they were particularly important items.  One was found in Room 33, and four were found in Room 38, which also contained many rare items of apparent ritual significance as well as macaws.  Others were found in Kiva A (the great kiva in the east plaza) and Room 6 (one of the earliest rooms in Old Bonito).  Clearly, then, conch trumpets seem to have been associated very closely not just with the Chacoan system or Chaco Canyon in general but with Pueblo Bonito specifically.  And Pueblo Bonito, of course, is right next to the amphitheater.  The combination of the impressive acoustics of the amphitheater with the exotic sound of the conch shell would likely have been pretty powerful, perhaps in more ways than one.

Intact Roof Beams in Room 6, Pueblo Bonito

So what light does this combination shed on the Chacoan system overall?  Well,  it’s hard to say for sure.  Mills and Ferguson make a strong case that the Chaco and early Hohokam conchs are associated with the warfare/healing complex rather than the plumed serpent one.  Evidence for this complex comes mainly from Zuni, where there are many stories about the use of a “Big Shell” that was used to magically defeat the enemies of the Zunis.  There is also an association between this shell and witchcraft, both in fighting it and in possibly causing it.

Shell Display at Visitor Center Museum

The (non-witchcraft-related) healing part of the complex comes from one of the medicine societies, best known at Zuni but apparently also present at Hopi and Zia, and historically at Laguna.  This society is apparently named for a “spiral shell,” and its rituals include shells, but otherwise it’s not clear how much it has to do with conch shells or trumpets specifically as opposed to shells more generally.  The songs of the society at Zuni are said to be in the O’odham language of southern Arizona, and its origin story mentions a series of long migrations.  To me this combination suggests a Hohokam origin about as clearly as is conceivable, and it’s possible that at least some of the Hohokam conchs, particularly the small ones that may have been used as standards on staffs rather than as trumpets, may have been associated with a precursor of this society.  As I said, though, I’m not totally convinced that conchs specifically have anything to do with this society.  Shells of all kinds were a very big deal among the Hohokam.

Chaco Amphitheater in the Snow

So, given all that, it seems likely that if any conch-related ritual complex in the modern Pueblos is related to the conchs at Pueblo Bonito it’s the Zuni Big Shell, associated with warfare and witchcraft.  This is certainly intriguing, especially given the odd and ambiguous evidence about Chaco’s connections to warfare, although I think it’s ultimately inconclusive.  As Mills and Ferguson point out, it’s entirely possible that some of these prehistoric complexes have no modern equivalents at all.  Indeed, given the massive series of cultural changes and migrations separating Chaco from the modern Pueblos, it would hardly be surprising that the ritual traditions closely associated with Chaco specifically would have been lost or abandoned in favor of newer (or perhaps older) rituals considered more suited to the changing times.  It’s noteworthy that there don’t seem to be any modern (Pueblo) practices involving a combination of conch trumpets and cliff faces with special acoustic properties, given the strong circumstantial evidence that the two were connected at Chaco.  Whether or not any modern practices involving shell trumpets can be traced back to Chaco, however, the evidence for their importance at Chaco itself at its height is evocative and provides a hint of what Chaco may have been like for the Chacoans, even if what we hear today is only a faint echo of what they heard then.

Mills, B., & Ferguson, T. (2008). Animate Objects: Shell Trumpets and Ritual Networks in the Greater Southwest Journal of Archaeological Method and Theory, 15 (4), 338-361 DOI: 10.1007/s10816-008-9057-5

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