Foreshadow: Chaco

Visitor Center and Fajada Butte from Una Vida

Chapter five of Crucible of Pueblos brings us to Chaco Canyon and the surrounding area. This is an area of particular interest for me, and I presume for most readers of this blog as well. While the rise of Chaco in the tenth and early eleventh centuries AD was clearly a development rooted in earlier events, there has long been less information available for the area of Chaco itself than for the areas to the north that have seen extensive relatively recent excavations of sites dating to the Pueblo I period. The Pueblo I occupations of those areas, the subjects of the earlier chapters in this book, are now fairly well understood, although there of course remain a lot of questions and gaps to fill. Further south the picture is still much murkier.

This chapter is written by prominent Chaco specialists Tom Windes and Ruth Van Dyke, and is particularly important and useful because it includes the first published synthesis of the work Windes has been doing for many years to identify sites in and around Chaco dating to the Pueblo I period. This work was written up as part of the series of reports on the work of the Chaco Project, but that report, dated 2006, remains unpublished. I presume that this is a deliberate decision on the part of the National Park Service to keep sensitive information on site locations from becoming public (although I don’t actually know for sure). This chapter, then, appears to serve as the published record of this important work, which significantly alters the conventional interpretation of Pueblo I in Chaco.

The authors define their geographic scope as what they call the “Chaco Basin,” which is essentially equivalent to what is commonly know in the Chaco literature as the “San Juan Basin.” I think this is a useful change to the terminology, since “San Juan Basin” in the hydrographic sense refers to a much larger area than it is used for in this context, and while some use terms like “San Juan Physiographic Basin” to clarify this, it’s more straightforward to redefine the area and use a new term. “Chaco Basin” is a good term to use because the area more or less corresponds to the drainage basin of the Chaco River, including its tributaries, although it extends a bit beyond to the east and south into the Puerco Valley and Red Mesa Valley respectively. However it’s labeled, this region is roughly bounded by the San Juan River to the north, the Chuska Mountains to the west, the Zuni Mountains to the south, and the Jemez Mountains to the east.

Temporally, the authors restrict their attention in this chapter to the period from AD 700 to 925, unlike some other authors in this volume who also address the preceding Basketmaker III period. This is understandable but in some ways unfortunate, since there was an important Basketmaker III occupation of Chaco Canyon that was likely important in setting the context for Pueblo I developments, just as those developments were important in setting the context for Pueblo II. Confusingly, they use the term “Pueblo I” for sites dating from AD 700 to 875 and “late Pueblo I” for sites dating from AD 875 to 925. As we’ll see below, the distinction between these two periods is important in this region, as population and settlement patterns changed significantly at around AD 875. The specific terms they use still seem odd and liable to cause confusion, however.

Part of the reason the authors argue that the Pueblo I occupation in this region is poorly understood is that the ceramic chronology is different from that of the better-known sites to the north, and using the same types to identify time periods for sites in both regions leads to problems. They carefully define the types they use to identify sites to time period, and also use architectural criteria (which are however difficult to apply to unexcavated sites).

Most of this chapter is a summary of what is known about Pueblo I settlement in each subregion of the Chaco Basin, based in large part on hitherto unpublished fieldwork. As a result, I will structure this post according to the same subregions in the same order and summarize the information on each.

Northern and Northeastern Areas

The heading for this section says “Northwestern” rather than “Northeastern,” but it’s clear from the text that this in error. These areas, north and northeast of the Chaco River but still within the drainage of the San Juan, were sparsely populated throughout the Pueblo period. Windes and Van Dyke note that the Largo and Gobernador canyons, to the northeast of Chaco, may have served as conduits for populations migrating south from the Mesa Verde region into the Chaco Basin in late Pueblo I. A recently discovered village at the confluence of Largo and Blanco Washes included a great kiva and at least 22 habitation sites, with tree-ring dates from the great kiva pointing to construction at about AD 828. This area is roughly due south of the Cedar Hill and Ridges Basin areas of the Animas Valley, considered part of the Eastern Mesa Verde region in this volume, which had extensive but short-lived populations early in Pueblo I. The tree-ring dates from the Largo-Blanco village suggest that it may have been associated with the initial migration out of the Ridges Basin/Durango area in the early 800s rather than the larger migration in the late 800s. The Chaco River may have been another conduit for migrants from the north, as Windes and Van Dyke note that surveys have found a major increase in sites dating to the late 800s along the east side of the Chaco, compared to a virtual absense of sites for earlier in Pueblo I. This will be a recurring pattern in the region.

Chaco Canyon Proper and Environs

The initial survey work of the Chaco Project in the 1970s identified a fairly extensive Pueblo I occupation in and around the canyon, and publications from that time posited a gradual increase in population over the course of Pueblo I leading up to the florescence of Chaco as a regional center in Pueblo II. Based on his more recent work with ceramic classification and dating, however, Windes disputes this account. He argues that the number of sites assigned to Pueblo I in those surveys is vastly inflated, and that for most of the Pueblo I period the Chaco area had a small population which increased dramatically, presumably due largely to immigration, in the late Pueblo I period. In this chapter Windes and Van Dyke (though clearly this part is mostly Windes) summarize the results of Windes’s reevaluations of the Pueblo I occupation in and around the canyon, moving from east to west.

Pueblo Pintado Great House at Sunset

At the east end of Chaco Canyon, the Pueblo Pintado area was apparently unoccupied until about AD 875, when it was colonized by two groups who had markedly different material culture and appear to have come to the canyon from different directions. They formed separate site clusters about 3 km apart, north and west of the later great house of Pueblo Pintado.

The first cluster, located just north of the great house, includes one exceptionally large roomblock more than 50 meters long, accompanied by a trash midden that is also unusually large. Based on the temper of early ceramics in this cluster, the people appear to have come from the Mesa Verde region to the north, presumably as part of the mass exodus following the collapse of the Dolores villages in the late ninth century.

The second cluster, 3 km west of the first one, appears to have also been founded around AD 875 but continued in use well into the Pueblo II period. The ceramics are quite unusual in manufacture for the Chaco area and indicate origins to the south in the Mt. Taylor area. Interestingly, the roomblocks in this cluster were aligned along the road connecting the Pueblo Pintado community to the core area of Chaco Canyon, implying that this road may date to the late Pueblo I period.

Moving west, the next major cluster of Pueblo I sites is what is known as the Chaco East community, which also featured a later great house. This area also appears to have been unoccupied until about AD 875, when it was colonized by a group occupying small residential sites, possibly only seasonally. In the 900s the community grew considerably, and initial construction of the great house may date to this period, although it’s impossible to tell for sure without excavation.

Third-Story Walls with Type I Masonry at Una Vida

Fajada Gap, at the eastern end of the main concentration of sites in Chaco during Pueblo II, is one of the areas where early surveys indicated a dense Pueblo I occupation which Windes disputes based on current understandings of the ceramic chronology. In fact, while there was unquestionably a small occupation of the area throughout Pueblo I involving scattered hamlets, this appears to be yet another part of the canyon where there was an influx of people in the late 800s who established the basis for the community that developed subsequently. There are two great houses in this community, Una Vida and Kin Nahasbas, both of which were constructed beginning in the late ninth century.

The largest Pueblo I (pre-875) settlement in the Chaco area is actually outside the canyon, along the South Fork of the Fajada Wash. This community contained 26 sites in an arc along the west side of the South Fork; no contemporary sites are present on the east side. The community is loosely clustered around a complex of four roomblocks which were connected by a short road to a great kiva, and it likely included about 230 people overall. Its main occupation was around AD 800, making it contemporary with the earlier villages in the Mesa Verde region, but the layout of the community is more like later villages such as those at Cedar Hill and in the Largo drainage. (The description of the community in this chapter is very confusing and it’s hard to tell in what respects it’s being described as similar to or different from villages in other regions.)

Many of the potsherds from the South Fork community were tempered with chalcedonic sandstone, which is typical of sites to the south near the modern community of Thoreau. There is also an unusually high abundance of yellow-spotted chert among the chipped stone assemblage, again indicating connections to the south. This type of chert occurs in the Zuni Mountains near Thoreau and is common in sites in that area.

Although this was the largest Pueblo I community in the Chaco area, it appears to have been very short-lived, with little trash accumulation. This suggests that the Pueblo I period was a dynamic time of extensive population movements in this area just as it was in the better-understood areas to the north. The subsequent Pueblo II occupation of the South Fork was much more extensive than the Pueblo I occupation and quite different, with sites dispersed up and down the valley rather than clustered in one area. A similar though somewhat smaller cluster of sites dating to the Pueblo I period was also present in the upper reaches of Kin Klizhin Wash to the west of Fajada Wash.

Old Bonito

Returning to the main canyon, there were a few scattered Pueblo I hamlets between Fajada Gap and South Gap, but the occupation doesn’t seem to have been extensive. Even in South Gap itself, an area of considerable density during Pueblo II and the location of the cluster of great houses known as “Downtown Chaco,” Pueblo I occupation was sparse, with a few scattered sites in the gap. Apparently the only Pueblo I site known in this part of the canyon proper is Pueblo Bonito, where the earliest construction of the great house, known as “Old Bonito,” dates to the mid-800s (or possibly even earlier) and there is also an earlier pit structure excavated by Neil Judd in the 1920s. Judd thought the pit structure reflected an earlier occupation unrelated to the great house, but with improved dating showing that the great house was begun earlier than had been thought the idea of continuity is beginning to seem more likely.

There is no evidence for Pueblo I occupation between South Gap and the mouth of the canyon, possibly on account of flooding creating an intermittent lake on the canyon floor. At the mouth of the canyon itself, the Peñasco Blanco great house, begun in the late 800s, sits atop West Mesa, and right next to it is the important Basketmaker III village of 29SJ423. The period between these two important occupations, however, appears to have involved only minor settlement, although there are a few scattered Pueblo I sites. Just west of the mouth of the canyon, however, is Padilla Wash, which had a substantial Pueblo I occupation (possibly even more extensive than current records indicate, since many Pueblo I sites may have been misclassified as Basketmaker III in earlier surveys), another example of the main centers of Pueblo I population in the Chaco core being outside the canyon proper. Windes and Van Dyke note that Peñasco Blanco may have been an important focal point for migration into the canyon from the west and north during late Pueblo I, and that it was likely more important than Pueblo Bonito at this time.

The Chaco River

As noted above, the Chaco River (formed by the confluence of the Chaco and Escavada Washes at the mouth of Chaco Canyon) was likely one of the main conduits for migrants from the north, but it was much more than that. Pueblo I communities existed all along the Chaco and its tributaries, and some of these communities included early great houses that would have been influential in the development of the great house phenomenon that found its greatest expression in Chaco Canyon in the eleventh century. Windes and Van Dyke discuss a number of these communities, based on field research by Windes to reevaluate areas identified by early surveys as Chacoan outlier communities and to look for evidence of Pueblo I settlement and early great houses.

Just west of Padilla Wash is Kin Klizhin Wash, which was the site of extensive Pueblo II occupation but only has a few Pueblo I sites aside from the cluster at its upper reaches mentioned above. There is a late Pueblo I great kiva known as Casa Patricio in the upper part of the drainage, accompanied by a number of late Pueblo I residential sites; it’s not clear from the writeup here what relationship this site cluster has to the earlier Pueblo I cluster.

Just downstream from the mouth of Kin Klizhin Wash is the very important early site known as Casa del Rio. While this was initially labeled a large Chacoan great house, reexamination indicated that it is actually a composite of two building stages, both relatively early, with much of the bulk of the structure provided by a Pueblo I roomblock measuring 112 meters in length, with a later masonry great house built over the central portion beginning in the late ninth century. The early roomblock is by far the largest in the Chaco Canyon region, more than twice the length of the earliest construction stage at Pueblo Bonito, and it is estimated to have housed about 16 households or 88 residents. Windes and Van Dyke describe it as “reminiscent of those north of the San Juan River,” although again it is not clear what specific characteristics this refers to. A large number of food preparation tools were found in the area, although other residential sites are scarce. This was clearly an important site during the Pueblo I period which may have played a key role in attracting migrants to the area.

Looking North from Kin Bineola

One of the most important tributary drainages of the Chaco River is Kim-me-ni-oli Wash, which extends from the Dutton Plateau north past the current site of Crownpoint. The drainage of this wash includes several great houses and extensive Pueblo settlement, and it likely served as an important conduit between Chaco Canyon and areas to the south and southwest. The extent of Pueblo I occupation, however, seems to be unclear. Windes and Van Dyke mention large circular structures near the Bee Burrow great house that resemble Pueblo I great kivas, as well as small Pueblo I roomblocks in the same general area. The area around the Kin Ya’a great house at the upper end of the drainage appears to not have any Pueblo I occupation based on existing survey data, although there is a large Basketmaker III-Pueblo I site just west of Crownpoint and one arc-shaped roomblock near Kin Ya’a recorded as dating to Basketmaker III looks a lot more like a Pueblo I site. At Kin Bineola, site of a major great house dating to the early 900s or possibly slightlier earlier, there is a very small Pueblo I occupation that increased substantially after AD 875 as in many other parts of the region.

At the mouth of the Kim-me-ni-oli Wash near the current Lake Valley Mission there is a small cluster of Pueblo I sites “architecturally identical” to the South Fork cluster, with very sparse refuse indicating a very short occupation. A later occupation in the late 800s was more substantial, with three masonry roomblocks “sometimes portrayed as small great houses” and “enormous amounts of refuse” that Windes and Van Dyke describe as “excessive for normal domestic activities.”

Further down the Chaco drainage, the Willow Canyon area is unusual in showing evidence of both middle and late Pueblo I occupation in close proximity. The middle Pueblo I community consists of eight sites that show the typical “scattered hamlet” settlement pattern, while the eleven late Pueblo I sites are tightly clustered and associated with a large amount of refuse, leading the authors to interpret this as “a large group” that immigrated into the valley together. These sites show unusual amounts of Type I masonry, associated with later great house construction, although the authors declare that there is no “obvious” great house. It’s not clear what definition of “great house” they are using here, as one site in particular (known as the “House of the Weaver”) shows not only Type I masonry but a prominent mesa-top location with a broad view of the surrounding area, another common characteristic of later great houses. Another community south of Willow Canyon near the later Whirlwind great house also shows a similar pattern but has less information available. The Great Bend area, where the Chaco River turns from flowing west to flowing north toward the San Juan, also shows this pattern. The possible use of the river as a corridor for populations migrating from the north after the collapse of the Dolores villages makes this potentially an important area for understanding regional prehistory.

Chuska Mountains and Chaco River from Peñasco Blanco

The eastern flanks of the Chuska Mountains, which parallel the north-flowing segment of the Chaco River and form the western side of its drainage basin, are also important for understanding Pueblo I settlement but are poorly known. The general pattern seems to be the same as elsewhere in the Chaco Basin, with a scattered occupation in early and middle Pueblo I that sees a huge increase, presumably from immigration, in late Pueblo I after AD 875, but due to depositional factors it’s likely that the earlier Pueblo I occupation has been underestimated. A few sites dating to this period have been excavated through salvage projects. Late Pueblo I sites are more common and seem to provide more evidence for the use of the river as a corridor from the north. The largest concentrations are in the Skunk Springs and Newcomb areas, both of which would become major Chacoan outlier communities in Pueblo II. At Newcomb, at least, there seems to be some evidence of a preexisting Pueblo I occupation. It’s not clear if there is any similar evidence at Skunk Springs, where the earliest stage of construction on the great house seems to date to late Pueblo I. Given the importance of Chuskan imports to Chaco at its peak, more research on the background of these communities would be helpful in understanding Chaco’s origins.

The Red Mesa Valley

The Red Mesa Valley is the area between the Dutton Plateau on the north and the Zuni Mountains on the south. It is topographically rather than hydrologically defined, and straddles the Continental Divide, with the western part drained by the Rio Puerco of the West and the eastern part drained by the Rio San Jose. This means it falls outside of the “Chaco Basin” as hydrologically defined, of course, but its culture history means that it makes sense to include it with areas to the north for purposes of this chapter. This valley was presumably an important travel corridor prehistorically, as it certainly was historically with the railroad and Route 66 running through it and remains today with Interstate 40.

Casamero Pueblo

This area has been the main focus of Van Dyke’s research, and it is clear that she rather than Windes is responsible for most of this section of the chapter. The same issues of ceramic identification as in the Chaco Basin make understanding the Pueblo I sequence here difficult, but the same basic pattern appears to apply as further north. Early in Pueblo I there was a small, scattered occupation, exemplified by a site on the mesa above the later Chacoan outlier community of Casamero. This site consists of at least two arcs of surface rooms fronted by five to seven pit structures, and resembles White Mound Village further west along the Puerco, which was excavated by Harold Gladwin in the 1940s and dates to the late 700s and early 800s. Another site like this from the same period was excavated near Manuelito during the construction of I-40 in 1961.

This sparse population expanded immensely in late Pueblo, when many of the later Chacoan great house communities were founded. Some of the earliest great house construction in the region took place in these communities, which Van Dyke has elsewhere used to argue that great houses were not initially associated particularly with Chaco Canyon specifically. The huge increase in population at this time seems to indicate immigration, but this chapter doesn’t address the issue of where the people in this area might have come from. Given the similarities to the communities to the north in the Chaco Basin, that seems like an obvious point of origin (with earlier origins probably further north in the Mesa Verde region), but developments to the south are poorly understood and can’t be ruled out as important factors. As noted above, some of the immigrants to Chaco Canyon and its surrounding area appear to have come from the south rather than the north, and southern origins would presumably be even more likely for the Red Mesa Valley populations given their location. The fact that the influx here appears to happen at the same time as the northern one is an interesting complication, however.

The Eastern Chaco Basin

This area, stretching from the area south of Chaco Canyon across the Continental Divide to the Rio Puerco Valley of the East, shows very little evidence for Pueblo I occupation. Today this is a very sparsely populated area used mainly for cattle ranching, primarily on private land, so there has been little archaeological survey, but what survey has been done shows very little prehistoric occupation at all. Only two exceptions are noted by Windes and Van Dyke. One is a recently discovered Pueblo I community southeast of Mt. Taylor, about which little is known. Detailed information from the survey that identified this community is apparently not going to be released. It’s not clear from the brief writeup if this has anything to do with the fact that the survey was for proposed uranium mining.

The other exception is the Puerco Valley of the East, around the later Chacoan outlier of Guadalupe. Here, survey by Eastern New Mexico University in the 1970s identified a “modest but scattered” Pueblo I occupation, which increased substantially in late Pueblo I and Pueblo II, culminating in the Guadalupe community with its apparently close connections to Chaco Canyon. Windes and Van Dyke note that the Puerco may have served as an important conduit connecting the Chaco Basin to areas further east, although it remains poorly understood. The eastern associations of Chaco are poorly understood in general, and this appears to be the case as much for Pueblo I as for Pueblo II.

Storm in the Distance through Fajada Gap

After going through the detailed geographical summaries, the authors briefly address some region-wide issues important for understanding the patterns they describe. They acknowledge environmental factors as probably important in understanding population shifts, pointing in particular to an apparent “spike” in rainfall in the immediate area of Chaco Canyon between AD 885 and 905 that might have served as a “pull” factor bringing people in from other areas. Conditions in the Chuskas and Red Mesa Valley appear to have been generally unfavorable during this period in which they, too, saw significant immigration, so clearly rainfall totals weren’t the only factor.

They also discuss violence, noting that there is very little evidence for it in this region, particularly in the central Chaco Basin, during Pueblo I, especially compared to areas further north where burned structures are common. There are more burned structures in the Chuskas and near Mount Taylor, on the edges of this region, however, and it is possible that the lack of them in the central basin relates more to the lack of construction wood than to any lack of violence. The authors suggest that, given the known evidence for strife and community abandonment in the Mesa Verde region, one attraction of the Chaco Basin might have been its relative emptiness, which may have drawn people into this much harsher and less fertile region. There’s a general tendency for settlement to cluster around drainages and particularly at  confluences of drainages, likely because these locations offered the best agricultural potential in a very dry area even by Southwestern standards. Regardless of what it was that initially drew people into this area, it’s becoming increasingly clear that this influx of population was a key factor in the later rise of Chaco.

Peñasco Blanco Framing Huerfano Mesa

The authors also discuss visibility and sacred geography, which has been a key concern of Van Dyke’s in her previous work. Many of the prominent community buildings in late Pueblo I sites in this region, whether or not they can be considered “great houses,” are situated in locations where important regional landmarks can easily be seen. This indicates that the concern with visibility associated with later Chacoan great houses likely had its roots in this period.

Finally, the authors summarize community settlement patterns in the region. One interesting pattern they note is that in late Pueblo I communities great houses and great kivas don’t tend to occur together, with great houses being more common in the Chaco Basin and great kivas in the Red Mesa Valley. This suggests that two different community integration systems may have been in place in the region during this time. The great house pattern at more northerly sites is interesting in the context of the “proto-great-houses” apparently present at some Dolores area communities further north, especially McPhee Village, and it’s quite likely that there is a direct connection between the two. Great kivas are also common further south, and while they were present at some Mesa Verde Pueblo I sites they weren’t very common. This suggests that at least some of the Red Mesa Valley late Pueblo I communities were in fact settled by immigrants from the south rather than from the Chaco Basin. Some of the earliest communities showing both features were in Chaco Canyon, and it may well be that one factor in the rise of Chaco was the ability of emerging elites there to combine the two traditions into a new social and ideological system, one that would spread far and wide, remaking the course of Southwestern prehistory.

Great Kivas A and Q, Pueblo Bonito

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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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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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Holy Wars in Holy Lands

Chuska Mountains from New Mexico Highway 371

In the year AD 1098 a spruce tree was chopped down in the Chuska Mountains, which run roughly along what is now the border between Arizona and New Mexico.  We don’t know who cut it down, exactly, since the people living in the area at the time had no system of writing and have therefore not left us any explanation of their actions.  We do know why it was cut down, however, and what became of it, and that gives us some clue to who might have wielded the axe.  It was likely either the local inhabitants of the Chuskas or the inhabitants of Chaco Canyon, 45 miles to the east, who had close connections to the Chuskas and may have traveled there regularly to do things like cut down trees.

After the bark and branches of the tree were carefully stripped from the trunk, and its ends laboriously ground flat, it was probably left to dry out for a couple of years.  At the end of that period, a group of men carried it carefully, by hand, the 45 miles to Chaco, where it was used in the construction of Kiva G at Chetro Ketl, the prominent elevated round room that can still be seen prominently at the site today.  This room was built over the remains of earlier round rooms, and the architectural history of this part of Chetro Ketl is very complicated and hard to unravel.  This particular beam, now known as CK-168, was used as a “tie beam” in the northeast corner of the square room into which Kiva G was built.  I take this to mean that it was used to span the interstitial space roughly tangent to the outside of the circle of Kiva G as part of the elaborate support structure of beams that was necessary to support the “blocked-in” kivas like this one that are so typical of Chacoan great house architecture.  The stage of construction involving Kiva G, and therefore beam CK-168, was one of the latest at Chetro Ketl, and Kiva G is noteworthy for displaying the “McElmo” style of masonry, which is a relatively late style at Chaco that echoes the style of masonry found to the north at sites such as Aztec Ruins.

Elevated Kiva G at Chetro Ketl from the North

We know when and where beam CK-168 was cut down because of two types of analysis that have been done on this and many other pieces of wood from Chaco and other prehistoric archaeological sites in the American Southwest.  The first is tree-ring dating, which allows the determination of the date a given tree was cut down with amazing precision, potentially to the calendar year.  Not every beam that is analyzed produces what is called a “cutting date,” indicating the exact year in which it was cut, but CK-168 did, and this is how we know it was cut down in 1098.  The other technique, which was developed much more recently, is strontium isotope ratio analysis, which at its current level of development allows the determination of the general area in which a tree (or a person) lived.  Many fewer pieces of wood have undergone this type of analysis than have been tree-ring dated, but CK-168 is one that has, and it is from this testing that we know it came from the Chuskas.  We don’t know exactly where in the Chuskas it came from, but we can be reasonably sure it was somewhere in the range.  These techniques are more or less the state of the art in wringing information from the archaeological remains of the prehistoric Southwest, and the amount of information available from them in this arid region with good preservation of materials like wood is quite remarkable by the standards of prehistoric archaeology in general.

At the same time the tree that became beam CK-168 was being cut down and left to dry out, on the other side of the world a group of heavily armed men was rampaging through a country that was not yet under their control but soon would be.  These were the Crusaders, a group of pious Christian knights and others, mostly from the various lands that are now part of France, who had heeded Pope Urban II’s call in 1095 to aid the Byzantine emperor in fending of the Turks who were threatening his lands and who at some point added the goal of conquering the holy city of Jerusalem from the Turks as well.  This expedition is now known as the First Crusade, and by 1098 it had reached the Holy Land and begun to conquer parts of it.  In June of that year they captured the important coastal city of Antioch (now in Turkey) after an eight-month siege and began to move on toward Jerusalem.  One group, under the command of Count Raymond of Saint-Gilles, arrived at the nearby city of Ma’arra (now in Syria) on November 28 and began to lay siege to it.  This siege, in striking contrast to the long, miserable one at Antioch, lasted only two weeks, and on December 12 the Crusaders entered the city after having destroyed its defenses.  They then remained at Ma’arra for another month as Raymond and the other commanders who had assisted him in the siege argued over how to divide up the spoils of their conquests.  On January 13, 1099 the ordinary soldiers, who were impatient to get to Jerusalem, finally prevailed on Raymond to move on and the army left Ma’arra.  They reached Jerusalem in early June and, assisted by a group of Genoese sailors who landed at Jaffa on June 17 and disassembled their ships to make siege engines, seized the city on July 15.  They then massacred the majority of the inhabitants.

Villages in Syria from the Golan Heights

In the grand scheme of the Crusade, and compared to the brutality that marked the Crusaders’ actions at Antioch and Jerusalem, the siege of Ma’arra may seem like a minor chapter.  There was something distinctive about Ma’arra, however, and it remained a painful memory for both sides quite out of proportion to the short duration of the siege.  The Arab historians recorded that the massacre of the people of Ma’arra after the siege was even worse in total number killed than that at Jerusalem, and some reported that the Crusaders had promised the people of the city safety before treacherously killing them.  According to the chroniclers who accompanied the Crusaders, however, what happened at Ma’arra was even worse than that.  With clear discomfort but remarkable consistency, almost all of the chroniclers recorded that some of the Crusaders had engaged in an activity much less respectable in European eyes than killing Muslims: eating them.

The cannibalism at Ma’arra has long been a difficult issue for historians of the Crusades to understand.  Beginning with the contemporary chroniclers, some of whom were at Ma’arra and apparently witnessed the events personally, they have offered various explanations for the behavior.  In a recent article Jay Rubenstein took a close look at the accounts the chroniclers offered of Ma’arra, and found some interesting patterns.  For one thing, although almost all of the contemporary chroniclers mention the cannibalism, the specifics of their accounts vary considerably.  Some placed it during the siege, while others put it afterward, during the month when the Crusaders were hanging around the city as their leaders argued.  Some attributed it to famine and starvation among the soldiers, who were said to have eaten flesh from dead bodies furtively.  One eyewitness account says that when the leaders of the Crusade found out about this they piled the bodies in a mound and set fire to them to put an end to it.  Others, however, said that the Crusaders ate the flesh of the dead Muslim enemies avidly and publicly, and one even said that some of the Crusaders were so disgusted by the sight that they deserted, blaming the leaders of the Crusade for not providing sufficient supplies and letting things deteriorate to this point.  Some of the chroniclers blamed the cannibalism on an apparently fictitious group of poor Crusaders called “Tafurs.”

Church of the Holy Sepulchre, Jerusalem

Rubenstein makes some interesting connections between all this and various other medieval references to cannibalism, including various episodes of starvation cannibalism during famines in Europe and references to “theatrical” mock-cannibalism involving the ostentatious preparation of dead enemies as if to eat them in view of living enemies, including one instance allegedly during the siege of Antioch and one earlier, in Spain.  He also mentions Biblical references to cannibalism as a punishment for disobeying God, with the context often being siege warfare quite similar to that conducted by the Crusaders, as well as some suggestive references to the possibility that some Crusaders might have resorted to eating each other (or at least come close) during the long, hard months at Antioch.  This is all rather speculative, however, and most of it has one crucial difference with the reports of what happened at Ma’arra, which Rubenstein does acknowledge: in these cases people were generally eating members of their own group, while at Ma’arra all the chronicles are quite clear in saying that the Crusaders only ate the flesh of the Muslim enemy.  This alone suggests that more than simple survival cannibalism is involved here, since there would surely have been plenty of dead Crusaders around to eat and the contempt the Crusaders had for “infidels” makes it odd that they would choose to defile themselves by eating them.  Rubenstein notes this and comes up with an admittedly speculative reconstruction of what happened at Ma’arra in which he proposes that there had been scattered instances of survival cannibalism at Antioch and perhaps earlier but that at Ma’arra, during the siege, some of the starving Crusaders decided to make a virtue of a necessity by ostentatiously eating dead Muslims in full view of the defenders of the city as a form of psychological warfare.  This would presumably have struck fear in the hearts of the Muslims and perhaps led to an easier conquest of the city than had been the case at Antioch.  Upon learning about this, however, the chroniclers, highly uncomfortable with this celebratory cannibalism, finessed their accounts to put the cannibalism after the siege, attribute it to starvation, and make it furtive and discouraged rather than open and aggressive.  Rubenstein puts the celebratory cannibalism in the context of “holy war” and the idea that the Crusaders thought of themselves as tools of God sent to punish the Muslims, which justified anything they did in the course of achieving that aim, regardless of how perverse and taboo it might be under normal circumstances.

This is an interesting interpretation, and it is similar in some ways to the model I have proposed for the outbreak of cannibalism in the Southwest around AD 1150 (about fifty years after the Ma’arra incident) in which I argued that the attackers, whoever they were, may have been motivated by both hunger and the desire to terrify their adversaries.  I ultimately don’t buy it, though.  A careful look at how Rubenstein supports his argument shows that the sources he relies on are not the most likely to be reliable.  The chronicles that put the cannibalism at Ma’arra during the siege rather than after it, as well as those that mention the possibility of earlier cannibalism and various other aspects of Rubenstein’s theory, were mostly written well after the events in question by people who did not witness them.  Most of them did apparently speak to eyewitnesses in preparing their accounts, and in some cases these eyewitnesses may have included some of the cannibals themselves, a fact that Rubenstein leans on heavily in arguing for their validity as sources, but this is a thin reed on which to hang such an elaborate argument.  Looking just at the chronicles written by writers who actually accompanied the Crusade, some of whom were at Ma’arra personally, they generally seem to agree that the cannibalism took place after the siege, when the Crusaders were hanging around Ma’arra and probably still hungry from the months of deprivation and disease at Antioch.  These chroniclers do disagree on some other aspects of the cannibalism, but in general their disagreements are more minor than those between them and some of the later accounts by writers who were not there and relied on secondhand testimony.  The fact that only Muslims were eaten does still require some explanation beyond simple starvation, but a desire to humiliate the enemy, perhaps combined with an aversion to eating people they had known personally in life, could explain it at least as well as an attempt at psychological warfare, which as Rubenstein notes really requires that the cannibalism took place during rather than after the siege.  It may be a better explanation, in fact, in light of the fact that the Arab historians do not mention the cannibalism although they do note the brutality of the siege and massacre.  This suggests either that the Crusaders were unsuccessful in trying to terrorize the Muslims through ostentatious cannibalism or that the cannibalism took place after there were no living Muslims left in Ma’arra to see it.  It could also suggest that the cannibalism was successful in intimidating the defenders, who were then massacred, leaving no one left to tell other Muslims about it, but the fact that the eyewitness chroniclers were in general agreement that the cannibalism took place after the siege makes me think that it’s more likely that there just weren’t any Muslims around.

Sunset at St. Peter's Church, Jaffa

Note the difference here between Rubenstein’s interpretation of the cannibalism at Ma’arra and mine.  This is a context where we have abundant written documentation of the events in question, and yet we have a variety of possible interpretations of what really happened and no way to tell for sure which is closer to the truth.  We must just rely on which fits the evidence best and is the most plausible, a somewhat subjective matter at all times.  This is in contrast to the more “objective” evidence we have of what happened in some contexts in the prehistoric Southwest, such as the time and place that beam CK-168 was cut down.  Note, however, that the information we have about CK-168 is extremely limited compared to what we know about Ma’arra, despite the many conflicting accounts in the chronicles.  These just aren’t comparable levels of knowledge, and this points out the difference between history and archaeology.  Both can tell us stories about the past, but the stories are very different.  Without the written documents about Ma’arra we would likely never know that cannibalism occurred there; unlike in the alleged instance of cannibalism in the prehistoric Southwest, which are based largely (though not entirely) on extensive “processing” of human bones.  The type of cannibalism alleged at Ma’arra consisted largely of the cutting of strips of meat from the fleshy parts of the body, which would likely not have left any marks on the bones and thus no physical evidence visible in the archaeological record.  But because we do have written records we do know about it.  If we had written records of what happened at Cowboy Wash we would presumably understand it better than we do, but the example of Ma’arra shows that we would not necessarily understand exactly what had happened even then.

Archaeology has its advantages, however.  Judging from what people typically write down when they have access to writing, it’s very unlikely that anyone in the Chuskas or at Chaco would have bothered to write down exactly when and where beam CK-168 was cut down even if they could.  Hundreds of thousands of beams were imported to Chaco during its florescence, and it’s unlikely that the specific origin of each of them would have been important enough to anyone to record.  Nevertheless, the analytical techniques available to modern archaeology does allow us to know in some cases when and where individual beams were harvested.  The story of CK-168 and the story of Ma’arra may be very different types of story, known to us in very different ways, but they are both known to us, and knowing both of them enriches our understanding of the past despite the still unanswered and perhaps unanswerable questions the stories raise.  And remember that these two stories happened at the same time; they were literally simultaneous.  Many things were going on in the world in the year 1098, and the stories of most of them are lost forever.  The stories of these two events, however, are not, and we can still tell them today.

Rubenstein, J. (2008). Cannibals and Crusaders French Historical Studies, 31 (4), 525-552 DOI: 10.1215/00161071-2008-005

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More on Food Imports to Chaco

Pueblo Bonito from Peñasco Blanco

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

Peñasco Blanco from Pueblo Bonito

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

Aztec West Great House, Aztec Ruins National Monument

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

Pueblo Bonito from Above

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

Interior T-Shaped Doorway, Pueblo Bonito

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

Old Bonito

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

Type I and Type II Masonry Abutting at Peñasco Blanco

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

Side Wash by Chetro Ketl

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

High Walls at Kin Bineola

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

Sign at Kin Bineola

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

Kin Bineola from a Distance

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

Early Masonry at Kin Bineola

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

Room 3, Pueblo Bonito

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

Room 170, Pueblo Bonito

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

Metate Fragment at Pueblo Bonito

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

Sealed Vent, Pueblo Bonito

Like all good papers about Chaco, this one answers some questions but opens up others, and it definitely provides plenty of (imported) food for thought.  There’s still a lot we don’t know about the Chacoans, even such basic things as where they  got their food, but the process of finding these things out is quite a ride and full of surprises.

BENSON, L., STEIN, J., & TAYLOR, H. (2009). Possible sources of archaeological maize found in Chaco Canyon and Aztec Ruin, New Mexico Journal of Archaeological Science, 36 (2), 387-407 DOI: 10.1016/j.jas.2008.09.023

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Pecos 2009: Day Two

Forest Fire from McPhee Campground, Site of 2009 Pecos Conference

Today was the second (and final) day of the 2009 Pecos Conference.  Like the first day, it involved many short papers, and there was quite a bit of interesting stuff.  Several of the presenters specifically mentioned Craig Childs’s advice from the night before about how to tell their stories, and it did seem like the average quality of presentation was better in today’s presentations than in yesterday’s.  The morning was mostly taken up with a symposium on heritage preservation, which I only saw part of.  The part I did see was pretty interesting, with reflections on the role of private cultural resource management firms and museums in preserving heritage and disseminating information (the presenters were much less enamored of how CRM does this than of the potential role museums can play).  There were then a series of miscellaneous talks, none of which was about Chaco Canyon specifically, but several of which discussed Chacoan outliers and aspects of the Chaco system.  These included a talk about recent research on the Great North Road, one on the recent work at Chimney Rock, another on the San Juan College field school work on the Bolack Ranch in Farmington, and one on Carhart Ruin, the northernmost known Chacoan outlier.  One speaker giving a talk on an understudied Chacoan community in the Chuska Valley rather pointedly refused to name the community, saying that he felt we were just a little too close to Blanding for his comfort, and that while there was a rather noticeable forest fire visible in that direction, it probably hadn’t taken out Blanding yet.  There were various other interesting papers not as closely related to Chaco as well, including one on the enigmatic towers of the Mesa Verde region pointing out that they occur at sites of all sizes and in all sorts of topographical contexts, making arguments for their function based on a single use improbable.  Overall, it was an interesting conference to attend, and I’m glad I did.

Tower at Mule Canyon, Utah

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Floating Beams?

Doorway at Far View House, Mesa Verde

M. J. Hinton very kindly links to my post on Chacoan timber sources, and mentions another theory that I didn’t talk about in the post:

I’m certain it is not for lack of knowledge that he doesn’t mention that some think Chimney Rock was an outpost for gathering wood that might have been floated as far as Chaco. I don’t know if there is any merit to this idea. However, waterways may explain why wood would come from some areas and not others. In particular, Jemez may not be upstream from Chaco.

Kiva Pilaster at Escalante Pueblo

I am indeed aware of this idea, and I don’t buy it.  I see a variety of possible objections,  some more reasonable than others.

1. Chimney Rock is about twice as far from Chaco as any of the established sources for timber.  I don’t think this is really the strongest objection, since arguments that the Chacoans are unlikely to have done something because it was impractical or inefficient tend to founder on the considerable evidence that the Chacoans did all sorts of things that were impractical and inefficient.  They really seem to have had access to virtually unlimited amounts of labor, and they used it in all sorts of ways that don’t seem to make much logical sense.
2. There’s no clear evidence that any of the wood at Chaco came from Colorado.  While the spruce/fir study I mostly focused on in the last post didn’t look at the La Platas or San Juans as possible sources of timber, the subsequent ponderosa study did, with ambiguous results.  The strontium isotope ratios they found for the Colorado mountains overlapped with those for both the Chuskas and the Hosta Butte/Lobo Mesa area to the south of Chaco (which wasn’t included in the earlier study because it’s too low for spruce or fir).  While they did find some wood with isotope ratios in this range, with the data they had it was impossible to tell if it came from Colorado or from the other areas with similar ratios.
3. There is considerable evidence that at least some of the large primary beams were left to dry for a few years after being harvested, presumably to reduce their weight.  Floating them down a river after this would waterlog them and totally undo any effect of the curing.  This is particularly important since even after being floated the beams would still have to be carried the thirty miles or so from the San Juan River to Chaco.  While I’m generally skeptical about arguments based on practicality, for reasons mentioned above, the evidence for curing makes this one more plausible than most.
4. If the beams were in fact floated, they would presumably end up with a lot of scratches and scuff marks from hitting things in the river.  Floating logs down a river, especially with the technology the Chacoans had available, is not the easiest method of transportation to control.  And yet, the beams found at Chaco are remarkably pristine.  There’s barely a scratch on any beam in the whole canyon.  There aren’t even any axe marks from debarking, which is in striking contrast to beams at other sites such as Mesa Verde.  This suggests an amazing degree of care taken in the transportation of the beams, which is very hard to imagine if they were ever floated down a river.  I think this is probably the most devastating piece of evidence against the flotation theory.

Animas River, Farmington, New Mexico

In addition to the objections above to the specific idea of beams being floated down from Colorado, there are a lot of problems with the more general idea of timber sources being determined by waterways:

1. This idea isn’t actually consistent with beams being floated down from Colorado, since they could only be floated as far as the San Juan River and would then have to be carried the remaining 30 miles to Chaco.  It’s hard to see how an emphasis on waterways as routes for timber transportation could have led to a decision to do this.  Since there is no real evidence that any of the timber did come from Colorado, however, this isn’t necessarily a major problem for the general idea.
2. Most of the drainages in the southern San Juan Basin are intermittent and only flow at certain times of the year, which would have made transportation of beams a matter of careful timing.  Again, the Chacoans certainly had the ability to time things like this well enough, so this isn’t the most devastating objection.
3. Perhaps more importantly, the known sources of timber (established in the strontium isotope studies) are not upstream from Chaco.  The eastern slope of the Chuskas does drain into the Chaco River via a series of eastward-flowing washes, but these washes enter the Chaco a considerable distance downstream from the canyon.  Trees from the Chuskas, therefore, which seems to have been the primary source of timber for the canyon, could not have been floated and would have to have been carried.  The other major source area that has been identified, around Mt. Taylor, is on the other side of the Continental Divide from Chaco and drains in the opposite direction.
4. Furthermore, the Jemez, which doesn’t seem to have been a significant source of timber for the canyon, is upstream from Chaco.  More precisely, while the Jemez Mountains themselves are on the other side of the Continental Divide, they are just barely so, and the Chaco Wash originates right along the Divide near Star Lake, about 20 miles from Cuba.  Since the Chacoans were clearly carrying beams 50 miles from the Chuskas and Mt. Taylor, they could easily have carried them 20 miles from the Jemez to the wash and floated them in the late summer when it flowed high from the monsoon rains.  The fact that they didn’t seems to clearly indicate that waterways were not a factor in the decision-making process related to timber procurement.

Sign in Cuba Pointing to Chaco

I’m not sure where this idea came from originally, but it’s certainly out there and I’ve heard it several times.  It may have started as a way to explain the anomalous location of Chimney Rock, which really is odd in a number of ways, including its combination of considerable distance from Chaco with extensive Chacoan influence.  I think the evidence for an astronomical basis for the foundation of Chimney Rock is a lot more plausible than the idea that it was a lumber camp.  The idea of logs being floated from Chimney Rock to Chaco really doesn’t make much sense, and until any evidence for it surfaces (which I think is pretty unlikely) I’m not inclined to give it much credence.

Sign for Chaco Wash Laundromat (Formerly Pueblo Alto Trading Post)

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Where They Got the Wood

Chaco Wash and Escavada Wash Near Their Confluence

One of the most striking things about the environment of Chaco Canyon today is its vegetation, which is dominated by greasewood and saltbush and features an almost total lack of larger trees on the canyon floor.  There are some cottonwoods and tamarisks in the arroyo of the wash, which were mostly planted in the 1930s by the Civilian Conservation Corps, and on top of the mesas there are quite a few junipers and some piñon pines, but for the most part it’s a shrubby, treeless landscape.

Juniper Trees on the South Mesa Trail

The Chacoan style of architecture, however, features an enormous amount of wood, mostly in the ceilings of rooms but also in the lintels of doorways and vents and in some cases as intramural beams inside the walls.  It has been estimated that about 200,000 beams were used in construction in the canyon.  Because of the arid climate and the strength of the construction, a considerable amount of this wood has survived quite well and can be seen by visitors today.  One of the questions those visitors ask most frequently is where all this wood came from.  It’s a very reasonable question, and one that has resulted in a considerable amount of research that, unusually for Chaco research, has actually come up with some answers.

Intact Roof at Pueblo Bonito

Early excavators, like many modern visitors, generally assumed that the wood must have been local, and that the climate therefore must have been significantly different in Chacoan times from how it is now.  This view persisted as late as the 1960s, when most experts agreed that there had been a substantial forest in the canyon that had since retreated as a result of both human-induced deforestation and natural climate change.  Considerable research since then, however, has demonstrated quite clearly that this is not the case and that the climate in the canyon has been more or less the same for at least the past 5000 years.  Although there have been fluctuations from year to year and decade to decade in rainfall amounts and other climatic variables, the range of variation seen over the past 1000 years is basically the same as that seen in historical records over the past 100 years.  That is, rainfall can vary by a couple of inches or so pretty regularly, but there hasn’t been the sort of rainfall that would support a large forest during any time that would be relevant to the study of the great houses.

Tributary Drainage in Chaco Canyon

It’s likely that there were a few isolated stands of ponderosa pine in the canyon before construction really got going in the 800s, and the famous tree found in the excavations of the west plaza of Pueblo Bonito was presumably a remnant of one of these, but once construction began in earnest these would have been depleted very quickly.  After they were gone, it would have just been the juniper and cottonwood seen today.  These are found frequently as charcoal in hearths, indicating that they were likely widely used as firewood, but structural wood is mostly ponderosa, douglas fir, spruce, fir, aspen, and other large, straight, high-elevation species.

Roof Beams at Pueblo Bonito Showing Core Samples Taken for Dating

Over the past twenty years the Park Service has been conducting a series of studies, collectively known as the Chaco Wood Project, to sample every piece of exposed wood in the canyon and try to use the samples to come up with answers to a variety of questions.  The main purpose has been to create a very accurate and precise chronology using tree-ring dating, which has resulted so far in a substantial reinterpretation of the early history of Pueblo Bonito, but the samples have been used for other sorts of research as well.  Among these is the use of isotope ratios to determine the sources of structural wood.

Partial Roof at Pueblo del Arroyo

The main isotope ratio used in this sort of study is that of Strontium-86 to Strontium-87.  Strontium is a trace element found in all sorts of living things, and it has the useful property of being absorbed while the living thing in question is living but being unaffected by any biological processes after it is absorbed.  As a result, the amount of the various isotopes of strontium in a given organism is determined by the environment in which it grows and then remains constant throughout its lifetime and beyond.

Original Lintels at Chetro Ketl

Since the amounts of both Strontium-86 and Strontium-87 in an organism result from the environment in which it originated but don’t change after that, even if it is moved elsewhere after its death, measuring the ratio of the two in surviving samples of tissue and comparing it to the ratios found in various places where the organism might have originated can potentially reveal with considerable precision the area of origin.  This technique has been applied to samples of structural wood from Chaco with considerable success.

Viga Stubs at Peñasco Blanco

The most successful study of this type looked at spruce and fir (which are generally indistinguishable in this context) from sites in the canyon.  Although nowhere near as common as ponderosa in Chacoan construction, these species are from higher elevations and thus occur in fewer places in the region, which greatly simplifies this type of study since it reduces the number of possible areas of origin that need to be tested.  The study measured the ratios in the samples and compared them to those found at the three nearest areas where these species grow.  These are the Jemez Mountains to the east, the Mt. Taylor area to the southeast, and the Chuska Mountains to the west.  Each of these areas is about 50 miles from Chaco Canyon.

Jemez Electric Pole in Chimayo, New Mexico

The results of the study showed that both the Chuskas and Mt. Taylor were major sources of timber found in Chaco, but that the Jemez was not, despite being just as close.  There is no obvious ecological or economic reason for this, but it is noteworthy that outlying communities showing extensive Chacoan influence are very numerous in the foothills of the Chuskas and Mt. Taylor but totally absent in the Jemez.  Indeed, the east is the direction in which there is the least evidence for any Chacoan influence, and the evidence for any contact at all between Chaco and the areas east of the Rio Puerco is very scanty.  This suggests that the sourcing of timber destined for Chaco was affected more by social factors than by geographic or ecological ones.

Mt. Taylor from the Volcanoes Just West of Albuquerque, New Mexico

A subsequent study using the same methodology looked at possible sources for ponderosa, which is much more abundant in Chacoan construction than spruce and fir but much harder to investigate in this way because of its much more widespread distribution in the region, which is probably the reason for its greater abundance in construction.  Since it grows at lower elevations than spruce or fir, ponderosa is all over the place, and it is very difficult to test a sufficiently wide range of possible sources to come up with definitive results.  The results of this second study, therefore, while consistent with those of the first in indicating the Chuskas and Mt. Taylor, were more tentative than those of the first, and it’s quite possible that there were sources of ponderosa that were not tested in the study.  Still, the basic congruence of the results in the two studies indicates pretty clearly that, whatever additional sources there may have been, the primary sources for structural wood at Chaco were the Chuskas and Mt. Taylor.

Chuska Mountains from Tsin Kletzin

These two areas, but especially the Chuskas, in addition to having numerous outliers and considerable evidence of Chacoan influence, appear to have provided other goods to Chaco, such as pottery and chipping stone, in significant quantities as well.  All of these lines of evidence, therefore, point to a very close connection between Chaco and the Chuskas, and probably to a similarly close connection to the Mt. Taylor area as well.

Intact Roof Beams in Room 6, Pueblo Bonito

There are few questions about Chaco for which there are clear and relatively straightforward answers, but thanks to the application of modern geochemical techniques to archaeological questions this is one for which there are such answers.  In the future, this type of research is likely to become more and more widespread, and so other questions may soon be added to the “answerable” list.  In the meantime, however, the wood question stands as a beacon of hope in a sea of mystery.

Chuska Mountains from Peñasco Blanco

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