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Watching the Skywatchers

"Supernova" Pictograph

“Supernova” Pictograph

I recently finished reading Living the Sky: The Cosmos of the American Indian by Ray Williamson. This is a classic work on the archaeoastronomy of North America, and it’s the best introduction to the subject I’ve found. (Granted, there aren’t many out there.) Although it was written in the 1980s, the research it discusses is still quite relevant, and Williamson does a good job of giving a pretty comprehensive overview of research in most parts of the US. The 1970s and 1980s were kind of the heyday of archaeoastronomy in the US, and while there has been continuing research since then, it’s striking how few major discoveries have been made since Williamson’s book was published. Virtually all of the major discoveries I knew about before reading the book are included, plus many others I didn’t know about.

Williamson did quite a bit of research himself on astronomical phenomena at Chaco, which gets lots of coverage in the book. There is some discussion of the Sun Dagger on Fajada Butte, as well as of alignments at Pueblo Bonito and Casa Rinconada and the alleged “supernova petroglyph” near Peñasco Blanco. Williamson gives the latter a lot more credence than others, and actually has a whole chapter on alleged representations of the 1054 supernova in rock art, including several other sites I had not heard about. I’m pretty skeptical about the supernova stuff, but it’s interesting to hear about these other sites.

Reconstructed "Woodhenge" at Cahokia

Reconstructed “Woodhenge” at Cahokia

While the Chaco stuff is interesting, I already knew most of it and Williamson’s account doesn’t add a whole lot to anyone who is reasonably well-versed in it. Where this book really stands out for me is in its discussion of archaeoastronomy in other areas that get less attention, especially the Plains and California, which have a lot of archaeoastronomical phenomena despite their lack of impressive well-preserved architectural sites like those in the Southwest. The chapter on the East is also interesting, with discussion of the famous “Woodhenge” at Cahokia and the “SunWatch” site in Dayton, Ohio as well as other lesser-known sites. Even within the Southwest, Williamson devotes space to research at more obscure places like Hovenweep (which turns out to have a lot of interesting potential alignments) as well as major centers like Chaco.

Williamson also does a good job of connecting the archaeological data to ethnographic reports about astronomical practices among modern groups. There has historically been a tendency for archaeoastronomers, many of whom are astronomers or surveyors by training, to focus on identifying alignments without giving much consideration to the cultural context in which they may have existed. Williamson avoids this pitfall by giving extensive attention to ethnographic practices and their potential connections to the evidence from ancestral sites. He does a particularly good job with respect to the Pueblos, for which both the ethnographic and archaeological data are extensive, but he also includes extensive discussion of the Navajo, Pawnee, and Chumash, and some attention to various other groups. His interpretations of the ethnography at times show a tendency toward oversimplification, and some of his general comments about Native American societies are, well, overly general and imply more widespread commonalities among very different societies than is really reasonable, but he’s not an anthropologist and as such I think these flaws are quite forgivable given all the interesting data he presents in accessible form.

Hovenweep Castle, Utah

Hovenweep Castle, Utah

I also read a 2003 review article on archaeoastronomy in the Americas, written by prominent archaeoastronomer Anthony Aveni, to get a sense of research since the 1980s, but it didn’t add much. For one thing, as mentioned above, the pace of archaeoastronomy seems to have leveled off a lot since then, and it’s striking how many of the references in Aveni’s article are to publications from the 1970s and 1980s. Also, while the article does cover North America as one of its three main sections, it spends much more space on the other two sections, Mesoamerica and South America. This is unsurprising, since the major civilizations in these areas have written records (mostly from the contact period but in the case of the Maya precontact as well) to which archaeological data can be compared. In addition, they have just received more attention in general from archaeoastronomers than cultures further north. Aveni himself studies Mesoamerica, so he has a lot to say about research there.

That said, however, Aveni’s account of North American archaeoastronomy is also surprisingly sloppy and riddled with obvious errors. He refers to Cahokia as “part of the Adena-Hopewell culture,” which is just laughably wrong; Cahokia is the preeminent site of the Mississippian culture, which arose centuries after the decline of Hopewell. He also attributes the Poverty Point site in Louisiana to the Adena, whereas it is actually significantly earlier. His discussion of the Southwest doesn’t contain any obvious errors of that magnitude, but it is very brief and superficial, as is the whole North American section of the paper.

Fajada Butte with Green Vegetation

Fajada Butte with Green Vegetation

Overall, then, I guess I would say that Williamson’s book is a much better introduction to North American archaeoastronomy than Aveni’s article, but that is kind of a trivial conclusion since it’s also much easier to find for the general reader. Even academics who have access to the Aveni paper, though, probably won’t get much out of it on this topic.
ResearchBlogging.org
Aveni AF (2003). Archaeoastronomy in the Ancient Americas Journal of Archaeological Research, 11 (2), 149-191 DOI: 10.1023/A:1022971730558

Utah Welcome Sign

Utah Welcome Sign

The initial discovery of chemical markers for chocolate on potsherds from Chaco Canyon in 2009 was a hugely significant development in understanding Chaco. The evidence for the presence of chocolate, a Mesoamerican product that couldn’t possibly have been locally grown and is very unlikely to have been gradually traded northward through a series of intermediaries, gave a huge boost to the “Mexicanist” school of thought about Chaco, which holds that many of the unusual aspects of the Chaco system are due to influence from Mesoamerica.

The initial study only involved a few sherds, though, and understanding the exact role of chocolate at Chaco and its implications for Mexican contact needs a much deeper understanding of where and when cacao was present in the ancient Southwest. Thus, soon after the initial discovery further research by a different set of researchers (using somewhat different methods) began to test other pots from Chaco and elsewhere. They did find further evidence that at least some of the famous cylinder jars from Chaco were used in the consumption of chocolate, but they also found traces of cacao in vessels of similar form from the later Classic Hohokam period in southern Arizona, and, most surprisingly, also in vessels from the “small-house sites” at Chaco and elsewhere that are thought to have housed the lower classes of Chacoan society. The previous evidence for chocolate came from distinctive vessels at the “great houses” that are the hallmark of the Chaco system and seem to have been used by elites (though exactly what they used them for remains unclear and controversial). This is exactly the kind of setting where it would be unsurprising to find unusual, exotic things, and indeed the great houses clearly contained many such things in addition to the chocolate. Finding this sort of exotic foodstuff in more mundane pots at the small houses implies that it may have been more widely accessible than previously thought, which has important implications for understanding the nature of the Chaco system.

Well, now things have become even more complicated. The same researchers who did that follow-up study have done another, this time looking at a much earlier period and a different part of the Southwest. They used their same techniques to test for the presence of chocolate in pottery at Alkali Ridge Site 13 in southeastern Utah, a very important early village site dating to the eighth century AD. Site 13 was one of the earliest large villages established in the northern Southwest during the Pueblo I period, and its architecture shows some striking parallels to later Pueblo I villages such as McPhee Village in the Dolores, Colorado area, as well as to some of the early great houses at Chaco and elsewhere that developed even later. The early Pueblo I period in southern Utah is also associated with the introduction of a new type of pottery, San Juan Red Ware, which was widely traded from an apparently rather restricted production area and probably used for ceremonial purposes of some sort. In addition to being a different color from the more common gray and white pottery of the area, San Juan Red Ware also featured a distinctive design system in its decoration, one without obvious local antecedents. Combined with the distinctive architecture, this has led some archaeologists to posit that there was a migration into southern Utah during early Pueblo I from somewhere to the south, bringing these distinctive traits.

In that context, looking for cacao makes sense, as that would be a clear sign of ties to the south and cultural distinctiveness. Dorothy Washburn, who was the lead author on both this and the previous study,  has actually written mainly on design style in ceramics and other handicrafts, focusing on symmetry patterns. Based on the changes she has found in these patterns, she has argued for a very strong Mexicanist interpretation of Chaco, involving actual migration of people from far to the south bringing a distinctive pottery decoration style. She seems to have a similar view about Alkali Ridge, for similar reasons.

In any case, the study found that there was in fact evidence for cacao on several of the vessels found at Site 13, including some (but not all) of the redware ones. The conclusions, understandably, focus on the association between the new ceramic design system and the use of chocolate, but in fact the redware vessels don’t seem to be much more likely to have evidence of chocolate use than the other ones that were tested. It’s quite possible that San Juan Red Ware was associated with consumption of chocolate specifically, but it seems that other types of pottery were also used for chocolate-related purposes.

This is all very interesting, but it’s also confusing and hard to interpret, in a way that the authors of this paper don’t really address. Back when it seemed like chocolate was limited to cylinder vessels at Chaco great houses, that was easy to interpret: chocolate, like many other exotic goods found at these sites, was part of an extensive trading systems for elite goods, probably used for ritual purposes, which the elites of Chaco participated in (and perhaps dominated and directed). Finding it in the Hohokam vessels implied a similar system operating among elites at Classic Hohokam sites, which is consistent with some interpretations of Classic Hohokam society, plus the Hohokam in general show lots of evidence of contact with Mesoamerica in general so the presence of chocolate is much less surprising there than it was at Chaco. Finding it in the small houses at Chaco complicated the story somewhat and implied that the chocolate imported to Chaco wasn’t as restricted as had been thought, but since it was already known to be present at the great houses it’s not too surprising that the contemporaneous small houses had it too.

Alkali Ridge, though, is much earlier and much further north than any of these other sites. Getting chocolate there in significant quantities would have required a pretty elaborate and robust supply chain over a very long distance, much of which was inhabited by societies that are not generally considered to have been capable of this kind of long-distance coordination. Checking some of those intermediate areas (especially the Hohokam region) to see if they too had chocolate this early is necessary to understand the logistics of this.

There’s also the question of time. We now have evidence of chocolate from Utah in the eighth century, New Mexico (and to a lesser extent Colorado and Arizona) in the eleventh, and Arizona in the fourteenth. There are some big gaps there that need to be filled in to determine if these are three snapshots of a long-term and continuous tradition of chocolate consumption in the Southwest (which would have important implications about trade networks and relations with Mexico) or three separate episodes of chocolate being introduced from the south, possibly through population movement (which would have important implications for regional culture history in general). I think the most important place to look for evidence of continuity between Alkali Ridge and Chaco is in the large late Pueblo I villages in southwestern Colorado, especially the Dolores-area ones like McPhee Village. These sites have apparent connections to both earlier villages like Site 13 and later developments at Chaco. If they also reveal evidence for chocolate use, that would be a strong indication of continuity. The most important places to check for continuity between Chaco and the Classic Hohokam would probably be the Pueblo III communities in east-central Arizona, which again show connections in both directions. Both of these sets of sites are among the best-studied in the Southwest and there should be plenty of pots available for these analyses.

Finally, there is a methodological issue here. It’s possible that these tests aren’t actually detecting chocolate at all, but something else. The authors of the recent paper noted this possibility and looked into whether there are any plants native to the Southwest that might have chemical profiles similar to cacao that would throw off the analysis. They didn’t find any, but they note that many plants have not been analyzed in this way and it’s possible there is a different plant that is showing up in these analyses instead. Another possibility is that there is something about their method itself that is leading to false positives. It’s noteworthy that they have been finding much more extensive evidence of chocolate than the team, led by Patricia Crown and Jeffrey Hurst, that did the initial Chaco study found. That team hasn’t published any more about chocolate at Chaco since then, but I hear Crown was able to do some re-excavation in Room 28 at Pueblo Bonito this summer so there may be more from her on this in the future. Ideally I’d like to see a test of both methods on the same vessels to see how they match up.

The ultimate message here is that even important discoveries, like chocolate at Chaco, require many further studies and refinements to interpret properly. We’re nowhere near a full understanding of the true role of chocolate at Chaco or any other site in the prehistoric Southwest, but every study gets us closer.
ResearchBlogging.org
Washburn DK, Washburn WN, & Shipkova PA (2013). Cacao consumption during the 8th century at Alkali Ridge, southeastern Utah Journal of Archaeological Science, 40, 2007-2013 DOI: 10.1016/j.jas.2012.12.017

Black-on-white Sherd at Pueblo Alto

Black-on-white Sherd at Pueblo Alto

In keeping with what seems to be the recent pattern around here, my previous post led to some interesting discussion in the comments. Frequent commenter marcaeolog provided a link to a pdf version of Anna Shepard’s Ceramics for the Archaeologist, a classic work that challenges some of Florence Hawley’s theories that I discussed in the post. Andy Ward, who has done extensive experimental work attempting to recreate prehistoric pottery-making techniques, then chimed in with some information on his own efforts, focusing specifically on the question of what keeps carbon-based pigments from burning off during firing. Here’s part of his comment:

I have been doing research in just this area by collecting clays and firing them in open mesquite fires. While it is easier to keep carbon based paint on a pot in a reducing atmosphere this doesn’t account for polychromes. To make polychrome with a carbon based paint, like the ubiquitous Gila Polychrome, requires an oxidizing atmosphere. Certain kinds of clays have the ability to hold these carbon paints through a firing, bentonite clay in particular. Modern pueblo potters have used a slip called Cochiti slip which has these properties, ancient potters in cultures such as the Salado had access to similar slips.

As it turns out, Shepard had the same theory, based on her own experiments, which also provided solid evidence against Hawley’s theory, based on experiments with hydrofluoric acid, that it was compounds in the ash of the organic material that reacted with silica in the clay to protect the pigment from burning away. She acknowledged that this was a reasonable conclusion based on the information available to Hawley at the time, but Shepard’s own experiments comparing organic material with and without this sort of ash showed no substantial difference. Instead the biggest factor was clay type:

The most striking fact brought out by these tests is the effect of the type of clay on the permanence of the carbon. Bentonitic and other highly adsorptive clays retained a good black under firing conditions that completely oxidized the carbon on unnadsorptive, sedimentary clays. All of the clays that held the paint well required a high percentage of wafer to bring them to the plastic state and they had high shrinkage. These clays take up much more of the paint solution than the less adsorptive clays, and on drying, the clay plates are drawn tightly together, protecting the film of paint that surrounds them. The effectiveness of hydrofluoric acid in facilitating oxidation of carbon paints is explained by the fact that it attacks the clay, opening the surface and loosening the bond and thus exposing the carbon to air.

The upshot of this in cultural terms is that, contrary to what I said in an earlier post, it seems like the difference between mineral- and carbon-based black pigments is actually technological rather than cultural. Here’s Shepard again:

The relation of the type of clay to the depth of color of carbon paint from a plant extract is not a matter of merely theoretic interest to the technologist. It has a bearing on the distribution of this class of paint because it could not be produced in regions lacking adsorptive clays unless such clays could be obtained in trade. The use of plant extracts is not open to free choice or established merely by custom; it is limited by ceramic resources.

This is particularly interesting given the well-documented expansion of carbon-based pigments at the expense of mineral ones over the course of the late prehistoric period. If special clays were required to make this work, and those clays had restricted distributions, what accounts for the change? In areas that switched from mineral to carbon paint, such as Chaco, was this the result of a change in clay sources? The discovery, perhaps due to increased contact with other areas that had long used carbon, of which local clay sources worked for this? Importation of clay? Importation of finished pots? This raises a lot of questions, which to my knowledge have not received much attention in the archaeology of these areas, despite the fact that it’s now been several decades since Shepard’s research.

Black-on-white Potsherd at Kin Bineola

Black-on-white Potsherd at Kin Bineola

“Never read the comments” is generally sage advice, so it’s likely that many of my readers have missed the interesting comment thread in response to my previous post. I won’t try to summarize it all here, but the gist is that a potter showed up and took issue with my use of the word “paint” to describe the pigments applied to prehistoric Pueblo pottery. Apparently, while archaeologists routinely refer to these pigments as paints, that’s not actually an accurate characterization and they are instead best described as types of “slip,” a term that archaeologists usually use only for the underlying layer of thin clay that the “paints” are often applied to. There’s a long history of archaeologists appropriating and misusing terminology from other fields, so it’s not surprising that they would have done this in this case too, but I’m not sure how best to proceed with the terminology, as it is pretty useful in practice to be able to distinguish the underlying “slip” from the “painted” designs on top of it. For now I’ll try using the (hopefully) more neutral term “pigment” for the “paint” and continue to use “slip” for the underlying clay.

Another issue that came up in the discussion, however, is separate from the terminology. This is the question of how the carbon-based pigments that are so well known from many parts of the Southwest could have adhered to pots after firing at all. After all, at the temperatures necessary to create usable ceramics any purely carbon pigment would burn right off. As I started to think about it, I realized that this was indeed a puzzle, and I went looking back into the literature to see if it had been addressed anywhere.

As it turned out, it had, and in the very first research on this subject, that of Florence Hawley in the 1920s. Hawley was an important figure in Southwestern archaeology throughout much of the twentieth century, and her early chemical studies of pottery pigments were fundamental in establishing the classification system by which they have been interpreted ever since. The most important aspect of this system was the division between “carbon-based” and “mineral-based” black pigments, although looking back at her initial publication on this topic from 1929, it’s clear that the dichotomy is more subtle than the terms imply. In fact both types of pigment contain both carbon and mineral elements, the difference being the relative proportions and the specific minerals involved. Both involve the boiling of certain plants, usually Tansy mustard or Rocky Mountain beeweed, to create a thick, black substance that can be applied to an unfired pot with a brush. The carbon type consists only of this substance, while the mineral type involves a subsequent step of adding ground iron oxide before applying it to the pot. Hawley also identifies a third type using manganese, which she speculates was used for certain types of pottery made of clay to which the usual carbon pigment wouldn’t adhere properly. (She also identifies a fourth type, so-called “smudged” pottery, that resulted from adding organic material after firing and letting it sink into the clay. This type is generally associated with the Mogollon culture in the highlands of east-central Arizona and west-central New Mexico and is quite different from the others in appearance.)

The chemical tests Hawley suggests to distinguish among these types of pigment are complicated and involve the use of dangerous acids, so they have not caught on as routine methods for archaeological analysis in more recent years. The tests appear to have been worked out and conducted mainly by Hawley’s father Fred Hawley, who was a chemist at a smelter in one of the mining areas of Arizona. Instead of these tests, archaeologists have generally tried to learn to distinguish the more common types by sight. As one of the papers I discussed earlier found in a test of this method, it works pretty well except in more marginal cases that are difficult to interpret using the standard visual criteria. The methods that have been proposed more recently using modern imaging technology have also not yet become very popular. In general the visual criteria seem to work fine.

As I noted in the previous post, the fact that both organic and mineral pigments seem to work to create black designs, but the mineral type is basically the same as the carbon one, raises the question of why there were two types at all. I suggested that cultural tradition rather than technological considerations probably was the main factor. Hawley doesn’t address the question in those terms, but she does argue that the different pigment types correspond to different cultural traditions, and the second half of the paper consists of her conclusions about cultural provinces and their spheres of influence based on pigment types through time. Her basic scheme of carbon pigments predominating in western areas and mineral pigments further east has generally held up, but otherwise her interpretations show how little was known at the time about Southwestern prehistory. She was clearly writing before tree-ring dating had established a firm foundation for the absolute chronology of cultural developments and pottery types, and the assumptions she makes about which sites were contemporary are strikingly wrong in light of that chronology. This makes her conclusions about changing patterns of cultural influence through time basically useless.

All that said, what about the question I mentioned earlier? How does the carbon pigment survive firing? Hawley’s answer, backed up by the chemical tests, was that it actually contains some mineral inclusions in addition to the carbon, especially silica and carbonates that melt in the process of firing and form a very thin film over the carbon that protects it from burning away. She considers this layer too thin to be considered a glaze, but it appears to serve the same basic function. It only works, however, when firing is in a reducing atmosphere, i.e., with oxygen prevented from reaching the surface of the pot. It’s not totally clear from her explanation where these mineral compounds come from, but the implication seems to be that some are from the plants from which the pigment is made and others are perhaps from the clay of the underlying pot. In the case of the mineral pigments, these potential sources are complemented by the trace silica in the iron oxide. As the more recent papers note, this interpretation has been questioned by others, most significantly Anna Shepard (another pioneering ceramic analyst at the same time as Hawley). It seems clear, however, that getting these pigments to survive firing requires some sort of chemical reaction along these lines, involving compounds in the pigment and/or the clay, along with a reducing atmosphere during the firing process itself.

It turns out pottery is pretty complicated! Archaeologists usually use pottery types primarily as a means to date sites and establish trade relationships, but studying potsherds intently with an eye to technological issues can reveal a lot of additional and potentially useful information.
ResearchBlogging.org
Hawley, FM (1929). Prehistoric Pottery Pigments in the Southwest American Anthropologist, 31 (4), 731-754 DOI: 10.1525/aa.1929.31.4.02a00110

The Paint on the Pots

Hachured Potsherds at Casamero Pueblo

Hachured Potsherds at Casamero Pueblo

When I was working at Chaco, people would ask me a lot of questions. I usually knew the answers, but when I didn’t I was quite upfront about saying so. I would often try to find out the answers to questions that had stumped me, but I didn’t always succeed, and many of those questions are the ones that I remember best, even now.

One of those questions had to do with the black-on-white pottery that is a hallmark of Chaco. A guy once asked me what they had used as a fixative to get the paint to adhere to the pottery, and I didn’t know. I didn’t really make much of an effort to find out then, as I didn’t really have any idea where to look. Recently, though, I’ve read two papers that shed interesting light on this question. Understanding them, though, requires some background on Pueblo pottery in general.

Hachured Potsherd at Pueblo Alto

Hachured Potsherd at Pueblo Alto

Basically, there are three main types of paint that were used in the prehistoric Pueblo Southwest. Two of these were in use during the period when Chaco was occupied: mineral and carbon. (The third, lead glaze, wasn’t used until later.) Both were used to produce a black color. Other colors were occasionally produced by a variety of means, but for this period black was the overwhelmingly dominant color of painted ceramics. It’s generally possible for experienced archaeologists to tell mineral and carbon paint apart by sight. Although they both tend to look black on a well-fired pot, there are various subtle differences between the two.

Carbon paint is basically just plant material, usually Rocky Mountain beeweed or tansy mustard, boiled down into an extract and applied to the pot. Mineral paint is made of ground iron-rich minerals, usually hematite, mixed with either water or an organic extract similar to those used alone as carbon paint, and sometimes with clay as well. Both types have been used both in prehistory and among the modern Pueblos. However, there were some marked patterns to usage of the different types of paint both geographically and temporally. Overall, the trend was of increasing use of carbon rather than mineral paint over time, spreading from west to east. Chaco ceramics at the height of the Chaco phenomenon in the eleventh century AD were overwhelmingly mineral-painted, while Chuska and Mesa Verde ceramics, while very similar in decoration and imported to Chaco in large numbers, were generally carbon-painted. Around AD 1100 there was a marked shift, and even Chaco pottery began to be primarily carbon-painted. By the 1200s use of mineral paint only continued in areas on the eastern and southern fringes of the Pueblo world. Distinguishing between carbon and mineral paint is thus quite useful for making inferences about culture history during this period. (In subsequent periods things became much more complicated with extensive long-distance migration and the introduction of glaze paints.)

Sherd with Checkered Pattern, Kin Klizhin

Sherd with Checkered Pattern, Kin Klizhin

Both of the papers I mentioned above are about using more formal means than visual criteria to tell mineral and carbon paint apart. One, by Joe Stewart and Karen Adams, used a scanning electron microscope-energy dispersive X-ray spectrometer (SEM-EDS) system to differentiate the two based on the amount of iron detected in the pigment. The other, by Robert Speakman and Hector Neff, used laser ablaction-inductively coupled plasma-mass spectrometry (LA-ICP-MS), a simpler and potentially less expensive method to distinguish between the two types of paint based on the concentrations of various elements. Both found that the methods they used came up with similar results to traditional visual methods, and were superior for certain sherds with unusual mixes of characteristics that made them visually ambiguous. Speakman and Neff also found a surprising amount of variety in elemental composition even within the “carbon” and “mineral” groups, suggesting that there were multiple “recipes” used to mix paint in prehistory, not just the two broad categories. This isn’t all that surprising given that this is clearly the case in modern times based on ethnographic data, but it’s still interesting.

That’s all well and good, but one thing that occurred to me in reading these papers was that it’s not at all clear why there would be multiple paint recipes, since they all ended up with pretty much the same result and some were definitely more complicated than others. This is particularly the case when considering mineral paint, since in many cases it appears that it was actually mixed with the plant concoctions that were in other places used independently as carbon paint. If boiling down beeweed produced a perfectly suitable black paint, why bother adding hematite? This might well explain why the trend over time was from mineral to carbon paint, but it’s still unclear why mineral paint originated in the first place. It does not appear to have predated carbon paint overall, at least at Chaco, where both carbon and mineral types are present as early as Basketmaker III.

Hachured Potsherds at Kin Ya'a

Hachured Potsherds at Kin Ya’a

The lack of obvious functional reasons for preferring mineral to carbon paint suggests that the choice may have been more a matter of cultural tradition, which is interesting and implies that some sort of cultural differentiation may have been present quite early in the prehistory of the northern Southwest. This isn’t really surprising, as there is plenty of other evidence for this, but teasing out the implications of all these different lines of evidence pointing to differentiation in material culture is a task that archaeologists have only recently begun to take on. It should be interesting to see what more we have to learn from these differences.
ResearchBlogging.org
Speakman, RJ, & Neff, H (2002). Evaluation of Painted Pottery from the Mesa Verde Region Using Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) American Antiquity, 67, 137-144 DOI: 10.2307/2694882

Stewart, JD, & Adams, KR (1999). Evaluating Visual Criteria for Identifying Carbon- and Iron-Based Pottery Paints from the Four Corners Region Using SEM-EDS American Antiquity, 64, 675-696 DOI: 10.2307/2694212

Lessons from Bolivia

Visitor Center and Fajada Butte from Una Vida

Visitor Center and Fajada Butte from Una Vida

I often read articles on the archaeology of other parts of the world to gain a better understanding of the context for Chaco. The areas I focus on for this are primarily those that had interesting things going on contemporaneous with the Chacoan era, but I also look to some extent on archaeological phenomena in other places that are comparable to the Chaco Phenomenon itself to see if there are any lessons for understanding Chaco to be drawn from them.

Recently I’ve been reading a bit about the archaeology of Tiwanaku, Bolivia, which falls into both categories. The period of Tiwanaku’s florescence overlaps with Chaco’s to some extent, although it falls most earlier, but more importantly the history of research there has some intriguing parallels to the history of Chacoan studies and may hold some useful lessons. My account of Tiwanaku here is drawn mainly from John Janusek’s 2004 review article, as well as some other papers by Janusek and others who seem to share his general perspective.

Tiwanaku itself is a major site located on the Bolivian altiplano near Lake Titicaca. It is in a very stark and desolate-seeming location, which makes its monumental architecture seem incongruous (sound familiar?). Early explorers noted that the site pre-dated the Inka empire, and some considered it the oldest site in the whole Andean region. Archaeological investigations in the early twentieth century showed that the latter characterization was definitely not accurate, but they also found little evidence of domestic occupation, and the idea arose that Tiwanaku was a vacant ceremonial center and pilgrimage destination, which some interpreted as the center for a religious movement that was spread by the expansionary state centered at the site of Wari further north in Peru.

Starting in the 1950s, however, a new archaeological program sponsored by the nationalist government of Bolivia and led by Carlos Ponce Sanginés conducted extensive excavations at the site and concluded instead that Tiwanaku was the urban capital of an expansionist state, which rivaled Wari and eventually even conquered it. By the 1980s researchers from the US were invited to work in the area as well, and their research has generally supported this reconstruction of Tiwanaku rather than the “vacant ceremonial center” hypothesis, although the idea that Tiwanaku actually conquered Wari didn’t hold up. Janusek is part of this research tradition, which is why the fact that my information on the site comes mainly from him is important. There are apparently still other archaeologists who still hold to the older interpretation, but there don’t seem to be many.

Anyone who is familiar with the history of research at Chaco should see the similarities here. One important difference, of course, is that the early research at Chaco assumed that it was a residential rather than a ceremonial center. It was not until the work of the Chaco Project in the 1970s that it began to seem like the great houses in the canyon were something other than “pueblos” in the traditional sense. While the idea of Chaco as a vacant ceremonial center was never universal, and it arose rather recently in the history of Chacoan research, it has been quite influential in recent years. Recent research, such as that of Chip Wills, Steve Plog, and Steve Lekson, has been moving away from this idea, however, and back to the idea of a substantial population in the canyon. In parallel with Tiwanaku, however, many of these recent interpretations have seen Chaco as more of a complex, hierarchical society than a set of autonomous, egalitarian villages. This makes the monumental architecture that is a hallmark of the Chaco Phenomenon seem like more of an expression of hierarchical than spiritual ideals.

One important lesson of Tiwanaku, however, is that these are not necessarily mutually exclusive. The monumental architecture and art at the main site and other sites considered to be regional centers of the same polity (“outliers” in Chacoan terminology?) is generally interpreted as reflecting a religious ideology that supported the hierarchical structure of the Tiwanaku state. This is hardly unusual in early states, of course, but the fact that Tiwanaku was not originally considered to be such a state makes it more relevant to the case of Chaco, which is in the same situation.

Another important similarity between the two systems is in the presence of astronomical alignments in the monumental buildings, and the resultant implication that astronomical observation and the maintenance of a calendar were important elements in the societal system. Tiwanaku was apparently the first society in the region to show this astronomical focus, and Janusek, in a paper on Tiwanaku religion, links this explicitly to its success as a state. In that paper he argues that the changes in monumental construction at Tiwanaku proper were linked to changes in the religious ideology of the site, which over time came to incorporate diverse regional traditions as well as cosmic cycles into a complex, syncretic religion that supported and justified the spiritual and material power of the Tiwanaku elites. As Janusek concludes:

Tiwanaku’s long rise to power in the Andean altiplano was predicated on the integration of diverse local ritual cults and various symbolic dimensions of the natural environment into a reasonably coherent, supremely elegant and powerfully predictive religion. The shifting physicality of Tiwanaku’s religious monuments attests the construction and ongoing transformation of an urban landscape that not only visually expressed the altiplano’s ‘natural’ forces and cycles, but, via recurring construction and ritual, simultaneously shaped new social practices and Tiwanaku’s ever-increasing political influence and productive coordination, intensification and expansion. Tiwanaku was an imperfect and potentially volatile integration of religious cults, productive enterprises and societies. The material objectification of a seductive religious ideology that infused the monumental centre with numinous natural forces and simultaneously projected those forces across distant Andean realms helped drive Tiwanaku’s very worldly imperial mission.

I haven’t seen this same argument applied explicitly to Chaco, but I think it may apply there as well. The part about incorporating diverse cultural traditions seems to match pretty closely with the well-known diversity of material culture at Chaco, with different sites within the canyon, and even different parts of some of the larger sites, showing ties to different parts of the region. I don’t know of any pre-Chacoan sites in the Southwest that show obvious astronomical alignments the way Chaco does, so it seems probable that the Chacoans were the first to figure out these alignments, and they may have also been the first to develop the rigorous calendrical knowledge that such mastery of astronomy implies. I hadn’t really thought about that as a source of Chacoan power before reading about Tiwanaku, but it certainly makes sense. This is a good example of the way reading about these far-flung places has practical advantages for understanding Chaco.
ResearchBlogging.org
Janusek, John W. (2004). Tiwanaku and Its Precursors: Recent Research and Emerging Perspectives Journal of Archaeological Research, 12 (2), 121-183 DOI: 10.1023/B:JARE.0000023711.96664.1b

Janusek, John W. (2006). The Changing ‘nature’ of Tiwanaku Religion and the Rise of an Andean State World Archaeology, 38 (3), 469-492 DOI: 10.1080/00438240600813541

University of New Mexico Observatory, Albuquerque, New Mexico

University of New Mexico Observatory, Albuquerque, New Mexico

I’m currently in Albuquerque visiting my mom and helping her out with some things. I usually try to mark the solstices on this blog, but in this case I’ve been too busy to put together a real post. (The solstice was technically yesterday in this time zone anyway.) I know the blog has been pretty quiet lately; I’ve been busy with various things, but I have been getting back into reading stuff about the Southwest and will have some substantive posts soon. Anyway, happy solstice and so forth.

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