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Rio Grande from Coronado State Monument, Bernalillo, New Mexico

Rio Grande from Kuaua Pueblo, Coronado State Monument, Bernalillo, New Mexico

Today is the winter solstice, which also makes it the fifth anniversary of this blog. I tend to like to post about archaeoastronomy on these occasions, and as I mentioned in the previous post I’m currently in Albuquerque and have been reading up on the archaeology of the Rio Grande Valley. Luckily, a recent article I read has a very interesting archaeoastronomical proposal specific to this region, which makes everything come together nicely. Getting to that point requires some explanation of the context first, however.

Today the northern Rio Grande Valley is one of the main centers of Pueblo population, and this was also true at the time the Spanish arrived in the sixteenth century. It’s been clear to archaeologists since the late nineteenth century that the modern eastern or Rio Grande Pueblos belong to the same overall cultural tradition as both the modern western Pueblos (Laguna, Acoma, Zuni, and Hopi) and the prehistoric Pueblo sites found all over the northern Southwest. Within this overall cultural tradition, however, there are noticeable differences in certain aspects of culture between the Rio Grande Pueblos and those further west, as well as between both groups and the prehistoric sites. The long and complicated history of interaction between the Rio Grande Pueblos and the Spanish has both led to cultural changes in this region and made the modern Pueblo residents very reluctant to reveal information about their cultures to anthropologists. Both of these phenomena make understanding the background of Pueblo diversity exceptionally difficult.

As a result, archaeological research in the northern Rio Grande area has proceeded along a somewhat different course from research further west. While extensive early research at well-preserved abandoned sites at places like Chaco Canyon and Mesa Verde led to the formulation of a robust and well-supported relative chronological scheme by the late 1920s that was soon anchored by the absolute dates provided by tree-ring dating, fitting the Rio Grande sites into this sequence proved to be a challenge. Alfred Vincent Kidder’s extensive excavations at Pecos provided clear evidence of continuity between prehistoric and historic Pueblo culture, which allowed the historic Pueblos to be easily placed at the end of the sequence, aligning earlier developments in the east and west proved to be a challenge. Pecos itself was founded quite late in prehistory, and very few other prehistoric sites had been excavated in the Rio Grande area. The so-called “Pecos System” of chronology and culture history was actually based primarily on western sites, and over time it became clear that it didn’t fit the emerging picture of Rio Grande prehistory pretty well. That picture, based primarily on survey and excavation work done by the Laboratory of Anthropology at the Museum of New Mexico starting in the 1930s, by the 1950s resulted in a new framework for eastern Pueblo prehistory.

The main architect of the new system was Fred Wendorf, an archaeologist at the Museum of New Mexico who had done a lot of the work of documenting sites in the region. He published a paper in American Anthropologist in 1954 describing his proposed system, which consisted of five periods:

  • Preceramic: Before AD 600
  • Developmental: AD 600 to 1200
  • Coalition: AD 1200 to 1325
  • Classic: AD 1325 to 1600
  • Historic: AD 1600 to present

Contrast this to the Pecos System, as presented by Joe Ben Wheat in a paper published in the same journal in the same year:

  • Basketmaker II: Before AD 400
  • Basketmaker III: AD 400 to 700
  • Pueblo I: AD 700 to 900
  • Pueblo II: AD 900 to 1100
  • Pueblo III: AD 1100 to 1300
  • Pueblo IV: AD 1300 to 1600

The most obvious difference between the two systems is that the Pecos System contains more periods. A more subtle difference is that in the Pecos System all of the periods are associated with agriculture, which appeared quite early in the Four Corners area. Exactly how early was not quite clear in 1954; Wheat says it was “about the time of Christ.” In the Rio Grande, on the other hand, the Developmental was the earliest agricultural period in Wendorf’s scheme as well as the first ceramic one, preceded by a Preceramic period that was totally undated at the time but that Wendorf suggested may have lasted quite late, even after the beginning of the Developmental.

This pattern of delayed appearance of typical “Anasazi” cultural phenomena in the Rio Grande persisted throughout Wendorf’s scheme. He defined the beginning of the Coalition period by the switch from mineral to organic pigment in pottery decoration, a trend which had been gradually diffusing east from Arizona over the past few hundred years. Similarly, the beginning of the Classic was defined by the appearance of glaze-decorated ceramics, which had appeared a few decades earlier in the Zuni area. The Historic period began with the onset of Spanish colonization. In general Wendorf’s period definitions depended heavily on trends in pottery decoration, in contrast to the Pecos periods which were defined by a broad suite of material culture changes, with architecture especially important. One reason for this was that architecture and other cultural traits were bewilderingly diverse within each of these periods, especially the Developmental, and this diversity was apparent even with the very small number of excavated sites at that time.

Palace of the Governors, Santa Fe, New Mexico

Palace of the Governors, Santa Fe, New Mexico

Wendorf’s scheme was in conflict on various points with a different scheme for Pueblo culture history as a whole developed by Erik Reed of the National Park Service. After Wendorf’s paper was published, discussions between the two led to an updated version of it published under both their names the next year in El Palacio. This paper has been extremely influential and the framework it established has been used by most archaeologists in the Rio Grande area since. The basic outlines of the framework are the same as those in Wendorf’s 1954 paper, with the changes involving the correction of the numerous typos in that paper, the addition of data from more recent excavations, and a somewhat different discussion of attempts to correlate archaeological phenomena with the complex distribution of modern linguistic groups. The latter was a particular interest of Reed, whose theories on it had been criticized by Wendorf in the earlier paper. I find it interesting as well, but I won’t get into it here.

Instead my focus here is on Wendorf and Reed’s Developmental period. Wendorf originally defined this period based on extremely limited information as a time of low population, diverse architectural styles and settlement patterns, and evidence of cultural influence from the San Juan Anasazi to the west. Population was extremely limited until about AD 900, when many more sites appear to have been inhabited and sites began to appear in the northern part of the region for the first time. This is the time of the rise of Chaco, and local Rio Grande ceramics show clear similarities to Chacoan types. Some archaeologists, including Reed, had argued that this rise in population came from an actual immigration of people from the Chaco area, but Wendorf doubted this, pointing out that other cultural traits showed considerable differences from Chacoan patterns. He suggested that while there could well have been some immigration from the west at this time, it was more likely from somewhere like the Mt. Taylor area that was part of the general Chacoan sphere of influence but closer to the Rio Grande, and that the number of people was likely small.

Architecture during the Developmental period was varied, with site sizes ranging from ten to 100 rooms and one to four kivas. The kivas were round and lacked most of the typical Chaco/San Juan features such as benches, pilasters, and wall recesses. They also usually faced east, in strong contrast to Chaco kivas, which usually faced south or southeast, even when they were associated with east-facing surface roomblocks (a common pattern for small houses at Chaco).

While the Wendorf and Reed system has remained in general use among Rio Grande archaeologists, the Developmental period in particular has seen much more data emerge from subsequent research, much of it associated with cultural resource management salvage projects. Cherie Scheick argued in a 2007 article that the period was much more diverse and complex than Wendorf and Reed had portrayed it as, illustrated by two nearby and contemporaneous sites in what is now Santa Fe that nevertheless had quite different ceramic assemblages which would place on in the Developmental period and the other in the Coalition period based on the Wendorf and Reed system. (This sort of thing is a major flaw with chronologies based mainly on ceramic styles, since time is by no means the only factor affecting differences in pottery.) Basically there seems to have been a long transitional period between the Developmental and Coalition in which communities with a variety of ceramic styles existed in close proximity. In particular, the introduction of carbon pigments seems to have been more variable than Wendorf and Reed realized, and they coexisted with mineral pigments for a substantial period. Scheick also points out that, contrary to what some earlier researchers had thought, there are no particular patterns over time in the architecture, such as larger villages developing later in the Developmental period.

Lurking in the background of all this research is the question of the abandonment of the Mesa Verde region and whether any of the apparent increases in population in the Rio Grande correspond to an influx of people from that area. Wendorf and Reed placed this migration in the middle of their Coalition period, with the appearance of a ceramic type, Galisteo Black-on-white, that is very similar to late Mesa Verde Black-on-white, and various other changes in material culture in the region that accompanied a population increase. However, recent research in the Mesa Verde region itself has suggested that the depopulation was a longer-term process beginning much earlier than previously thought, so some of the changes in the early Coalition period, could also be due to immigration. The basic problem is that while there are plenty of individual examples of similarity between San Juan/Mesa Verde culture and Rio Grande culture over a long period of time, there are no sites showing a complete package of San Juan cultural traits. There seems to be an emerging consensus that this is because the migration was primarily not of entire communities moving as units but of smaller units (families or lineages) that joined existing communities in the target region, perhaps ones that they had had earlier contact with through trade or other activities.

Round Kiva at Kuaua Pueblo, Coronado State Monument

Round Kiva at Kuaua Pueblo, Coronado State Monument, Bernalillo, New Mexico

An additional piece of evidence for this idea comes from the paper I mentioned at the beginning of this post, published by Steven Lakatos in 2007. Lakatos did an analysis of features in Rio Grande pit structures (kivas) during the Developmental period. He looked at size, orientation, and presence or absence of a hearth, an ash pit, a deflector, and a ventilator in a total of 131 excavated pit structures in the Rio Grande Valley dating to AD 600 to 1200. He looked at specific types of each of these features and came up with a wide variety of statistical comparisons. The sample sizes for most of the subsamples he looked at are so small, however, that I doubt many of these comparisons are meaningful. His overall conclusions, however, are probably reliable.

Lakatos found that there is a consistent pattern of features in pit structures throughout the Developmental period: hearth, ash pit, deflector, and ventilator, sometimes accompanied by sipapu and/or ash grinding stone, in a row aligned to the east-southeast (average azimuth from true north of 118 degrees for the Early Developmental period and 123 degrees for the late developmental). This is in strong contrast to the San Juan (Chaco/Mesa Verde) kiva pattern, where ash pits are rare, other features like benches and pilasters are common, and orientation is usually to the south or south-southeast. Lakatos notes that this Rio Grande kiva pattern continues into the Coalition period and later, as kivas become more formalized community-scale integrative structures, and while all the features in the complex potentially had originally mundane uses, the formalization of the pattern and its persistence over time suggest that at some point it acquired ritual significance. He notes the ritual importance of ash to modern Rio Grande Pueblos as a way of explaining the ash pit and ash-grinding stone as ritual features. The persistence of the pattern into the Coalition period and beyond suggests to Lakatos that immigrants to the Rio Grande from Mesa Verde and elsewhere not only joined existing communities, but largely assimilated to existing religious and cultural practices in an area that had developed a distinctive identity already. Thus, the reason it is so hard to pinpoint continuity between San Juan and Rio Grande archaeological sites is that the San Juan immigrants changed their culture to conform to Rio Grande practices.

I’m not sure I buy that there was quite as much continuity in the Rio Grande as Lakatos and other Rio Grande archaeologists tend to think. Looking at it from the outside, the ceramic evidence certainly seems to imply at least some continuity with Mesa Verde culture, and a close examination of what little ethnographic information is available on the Rio Grande Pueblos may reveal other traits of western or northern origin. Still, Lakatos’s evidence for continuity in kiva form looks convincing to me, and the patterns he identifies are certainly quite different from those of Chaco and Mesa Verde. The fact that his interpretation meshes well with other research suggesting migration by small groups into established communities is also encouraging.

So what does all this have to do with the winter solstice? Well, Lakatos also calculated the azimuth of winter solstice sunrise for the Albuquerque area in AD 1000, and it was 119 degrees east of north. This is strikingly similar to the average azimuths of the kiva alignments he analyzed, which have small standard deviations indicating strong clustering around the average values. The variation that does exist could easily correspond to local horizon variation in this rugged, mountainous region. Lakatos expresses surprise at this finding, but it makes perfect sense to me. The winter solstice is an enormously important event for the modern Pueblos, as Lakatos discusses, and pointing their kivas toward it would be a natural response to that importance. And with that in mind, I wish all my readers a happy solstice.

ResearchBlogging.org
Lakatos, SA (2007). Cultural Continuity and the Development of Integrative Architecture in the Northern Rio Grande Valley of New Mexico, A.D. 600-1200 Kiva, 73 (1), 31-66

Wendorf, F (1954). A Reconstruction of Northern Rio Grande Prehistory American Anthropologist, 56 (2), 200-227 DOI: 10.1525/aa.1954.56.2.02a00050

Wendorf, F, & Reed, EK (1955). An Alternative Reconstruction of Northern Rio Grande Prehistory El Palacio, 62 (5-6), 131-173

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Mercer Museum, Doylestown, Pennsylvania

Mercer Museum, Doylestown, Pennsylvania

I was in Philadelphia for Thanksgiving, and the next day I went with my family to the quaint nearby town of Doylestown, where we visited two local museums: the Michener Museum (named after, yes, that Michener, who grew up in Doylestown and spent most of his life in the area) and the Mercer Museum. The Michener is basically a local art museum, and we went there to see an exhibit about Grace Kelly, who is a big deal in the Philadelphia area. Not really my kind of thing, but it was fine.

The Mercer, on the other hand, is a really unusual sort of museum. It was established by Henry Mercer, a Doylestown native who had a variety of interests and a good deal of money with which to pursue them. He studied law but never practiced it, instead going into archaeology in the 1890s. I haven’t found much information about his specific contributions to American archaeology, which was in its infancy at that time, except that he apparently supported the authenticity of the obviously forged Lenape Stone that allegedly contains an image of a mammoth and is now part of the Mercer Museum collections (though not on display).

In the late 1890s, however, Mercer came to the realization that the advancement of industrialization meant that most aspects of traditional life in the US were likely to disappear forever, and he began to collect what were then considered mundane objects for the museum of the Bucks County Historical Society. He collected huge numbers of things from all aspects of pre-industrial life, over time branching out to the US as a whole and eventually other parts of the world as well. His collection got so big that he built a new building to house it, using an innovative design and construction approach using poured concrete. He organized the collection thematically by the sorts of societal needs that objects served, and put together display cases by category.

The museum is still much as he designed it, although there have been various changes over the years. It’s a fascinating place, idiosyncratic and full of extremely detailed information. What I found especially interesting, however, was the way the museum’s own self-descriptions explicitly tied Mercer’s collecting of what most people considered “junk” to his earlier interest in archaeology. That is, one way to see what Mercer was doing was taking an archaeological approach to studying and preserving the material culture of the present and recent past, to ensure it would be understood in the future. This approach was quite ahead of its time for both history and archaeology, and the museum that resulted is fascinating and well worth a visit.

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The Twin Mounds from Monks Mound, Cahokia

One of the major areas of interest for the “New Archaeologists” who came to dominate American archaeology in the late twentieth century was mortuary analysis. In keeping with the arguments of Lewis Binford and other leaders of the movement that archaeology as a discipline should be “problem-oriented” and focused on reconstruction prehistoric societies as fully as possible using archaeological evidence, the patterning evident in the way those societies disposed of their dead was held to reveal important information about social structure and the positions held by the deceased in life. Many important studied of mortuary behavior in various cultures were published in this period, including a 1984 article by George Milner on the burial patterns of Mississippian sites in the American Bottom of southwestern Illinois.

Milner’s article is a classic example of the New Archaeology as applied to mortuary patterns, hampered only slightly by the immense complexity of Mississippian mortuary behavior and the scanty evidence from the many burials excavated in the nineteenth century and poorly documented. Noting that most Mississippian burials in this area were placed in dedicated cemetery areas, he divides these cemeteries into three broad categories, reflecting two dimensions of variation in social structure. The categories are elite burials at major centers such as Cahokia, non-elite burials at those same centers, and non-elite burials at peripheral sites (which do not appear to contain elite burials).

By far the most and best information available to Milner was from the third category, and this is the one he focuses the most attention on. There is quite a bit of diversity even within this category of cemetery, but some general patterns do emerge. Cemetery sites are typically either on prominent bluffs above the Mississippi River floodplain or on low ridges within the floodplain, with a trend apparent over time of a shift from the former to the latter. The bluff-top cemeteries tend to be quite large, and they probably represent the dead of multiple rural communities in the general area. This inference is backed up by the diversity of mortuary treatments even within these cemeteries. Some burials are intact, articulated skeletons, often laid out in one or more rows, sometimes with the heads pointing toward a nearby mound center. Others are disarticulated jumbles or bones, often containing the remains of multiple individuals. There is considerable evidence of complicated mortuary treatment involving exposure of the bodies for some period after death, perhaps in the “charnel structures” that accompany some of the cemeteries, followed by secondary burial. Grave goods are rare and usually relatively mundane items such as pottery, although shell beads and certain exotic minerals are found in some cases.

Ironically, burials at the major mound sites are generally poorly documented compared to those in the rural hinterland. This is in part because the former were often excavated haphazardly in the nineteenth and early twentieth centuries, with little or no detailed documentation, while the latter have been largely excavated by systematic cultural resource management salvage projects more recently and extensively documented. Nevertheless, Milner combed through the available data on the mound center burials in the American Bottom, and he comes to a few tentative conclusions about them.

For one thing, there is definitely a big difference between the elite and non-elite burials. The non-elite burials are similar to the ones at outlying sites in many ways, including linear arrangements of graves and modest assemblages of grave goods, but there is also more substantial variation in mortuary treatment, which Milner plausibly attributes to greater diversity within the more populous mound communities, perhaps including more subtle gradations of status than are accounted for by his crude “elite”/”non-elite” dichotomy.

Sign Describing the Twin Mounds at Cahokia

The elite burials, however, are quite different. They are generally in mounds, specifically in conical mounds as opposed to the flat-topped ones that served as platforms for buildings. A common pattern seen at Cahokia and other sites, is for mounds to be paired, with a conical mound accompanying a platform mound. The Fox and Roundtop mounds (the so-called “Twin Mounds”), south of Monks Mound on the opposite side of the Grand Plaza, are the best-known of these paired mounds, but since they are largely unexcavated relatively little is known of their contents. Much of the Cahokia data Milner uses comes instead from Mound 72, which was excavated relatively recently and extensively documented. The very complicated mortuary deposits in this mound include two burials associated with numerous shell beads, as well as various other groups of both articulated and disarticulated remains. One group of articulated skeletons was missing skulls and hands, apparently indicating some sort of human sacrifice.

One of the most striking ways the elite burials differ from the non-elite ones is in the sorts of grave goods. Mundane items such as pottery are generally rare, while very elaborate, labor-intensive artifacts are numerous. The shell beads from Mound 72, also common in several of the other mounds Milner discusses, are one example. Mound 72 also contained various other items, including a cache of finely made chert projectile points, and other exotic materials including copper items were found in other mound burials.

Another interesting characteristic of the elite burials Milner describes is that they are quite communal in nature. Individual burials are not present, and even the most elaborate assemblages of grave goods seem to be associated with large groups of burials within the mounds. This may have important implications for the nature of political power in Mississippian society, although Milner doesn’t go into the implications in any detail in this paper.

Some of Milner’s conclusions in this paper have been superseded in part by newer discoveries and refinements to the chronology of the American Bottom since the time he wrote, but this is still an important paper, not least because of the way it draws on what information is available on the early excavations. The tentative nature of Milner’s conclusions is due in part to those data limitations, but also to the fact that what becomes glaringly obvious from this work is that Mississippian burial practices were extremely complicated and shaped by a wide variety of possible factors, not all of them easily discernible from this type of study.
ResearchBlogging.org
Milner, G. (1984). Social and Temporal Implications of Variation among American Bottom Mississippian Cemeteries American Antiquity, 49 (3) DOI: 10.2307/280355

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Reconstructed House, Spiro Mounds, Oklahoma

Mississippian societies are best known for their mound centers, with Cahokia in Illinois being the largest and most impressive but by no means the only one. These sites have drawn the interest of archaeologists since the very beginning of American archaeology as a field of study, but the focus on mounds meant that other aspects of Mississippian culture got relatively little attention until much later.

One of these aspects was domestic architecture. While Mississippian mounds, unlike those of many earlier societies in the Eastern Woodlands, often served at least in part as platforms for elite residences, the fact that both these and more humble dwellings were made of perishable materials and did not survive in the damp conditions of the region led their subtle remains to be largely ignored until well into the twentieth century. At this time archaeology as a discipline was rapidly professionalizing, and archaeologists began to shift their focus from acquiring impressive specimens for museum display to investigating the remains of ancient societies in an attempt to understand them as totalities, including the more humble parts.

Partially Reconstructed House, Angel Mounds, Evansville, Indiana

When it came to Mississippian residential architecture, what these newer, more careful excavations revealed was that Mississippian houses were relatively flimsy, at least as compared to the impressive stone architecture of the Southwest and Mexico. Indeed, masonry architecture was apparently totally unknown in the East throughout the prehistoric period, even in areas near outcrops of useful stone. The conception thus entered the archaeological literature that the Mississippians, for all their effort at building mounds, didn’t do much to build substantial houses.

This is kind of a misleading way to think about it, however, as John Bennett of the University of Chicago pointed out in a 1944 article. As he put it:

There can be no doubt that a dwelling or ceremonial structure built of such perishable materials as wood, canes, and grass thatch is hardly as durable or lasting as a stone building. From the standpoint of preservation such construction is “flimsy.” This interpretation unfortunately implies, however, that this architecture was flimsy in terms of its own cultural setting. That is, it represented a poor attempt at sheltering and housing the people.

Bennett goes on to argue that this is a mistaken conclusion to draw, basing his remarks on his institution’s recent excavations at the Kincaid site in southern Illinois, which had exceptionally well-preserved remains of burned houses. Basically, he argues that while the individual materials may have been flimsy, they were put together in an ingenious way that gave the result structures plenty of strength and durability for their intended purposes:

Walls were constructed by placing poles or saplings in a trench and bending these over at the top to produce a peaked or domed roof. Horizontal poles were lashed to the sides, to produce a lattice. Reeds were then lashed to the lattice. The next step was to plaster a thick layer of clay on both sides of this lattice, over the reeds, then to cover this clay with a matted layer of grass fibers. The final step was to cover this grass with cane mats—large and thick for the outside, thinner for the inside. The wall thus formed was nearly one foot thick, and obviously very rigid—hardly a “flimsy” structure.

There was actually quite a bit of variation within the Mississippian tradition in house construction; some areas had straight-walled houses with gabled thatch roofs, while others had houses with more of a curved shape. This basic pattern of wall trenches filled with upright poles which were then covered with some sort of wattle-and-daub was widespread, however, and in some areas the appearance of wall trenches is considered a sign of the beginning of the Mississippian period. It’s true that these houses didn’t last very long and had to be replaced frequently (which has been used in some cases to estimate occupation spans and population totals at certain sites), but any type of construction short of stone masonry would have this drawback in the rainy East. Given that these houses would have provided quite useful shelter with relatively little effort, they seem quite well suited to their context.

Kincaid Mounds, Massac County, Illinois

Speaking of stone, though, why didn’t they use it? Some sites in alluvial plains wouldn’t necessarily have had nearby sources of stone, but this isn’t the case for Kincaid and many other sites. As it turns out, Bennett has an answer to this too:

The proximity of Kincaid to stone outcrops in the hills might make us wonder why the Indians never utilized stone for building materials. The answer is twofold: (1) The southeastern cultural tradition did not include such a trait, and (2) the climate and frequent floods in the bottoms required just such a structure as described. The architecture can be considered as a nearly perfect adaptation to the environment.

It’s interesting to see here, given the early date of Bennett’s article, that he hits on both of the major categories of explanation that have dominated archaeology in recent decades: environmental determinism and cultural specificity. Neither is necessarily all that convincing on its own, but between the two of them they probably cover whatever the true answer was. It’s noteworthy that when Europeans began to settle eastern North America they mostly didn’t build with stone either, instead preferring wood until well into the nineteenth century when cities grew to such a size that local wood resources became scarce and fire became a major concern. This even though they, unlike the indigenous tribes, did have a cultural tradition of building in stone which reached quite a high degree of elaboration in the castles and cathedrals of medieval Europe.

Closeup of Kincaid Mounds Mural, Paducah, Kentucky

One way to interpret this information is to posit that building with stone is sufficiently difficult that people are only going to do it when they have few other options, as in arid regions with little wood and when local wood resources have been largely exhausted. In the forests of the Eastern Woodlands this was never really a problem during the prehistoric period (and well into the historic), so people just built with wood and other easily available materials. Even for monumental purposes, such as mound-building, they used dirt rather than bothering with stone. Ironically, this meant that everything they built except the mounds eventually rotted away in the wet climate, so their ingenuity in this regard wasn’t discovered until rather recently.
ResearchBlogging.org
Bennett, J. (1944). A Note on Middle Mississippi Architecture American Antiquity, 9 (3) DOI: 10.2307/275792

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View of Monks Mound from the East, Cahokia

Monks Mound is both the largest mound at Cahokia and the largest at any Mississippian site, by a huge margin. It’s 100 feet high and about 1,000 by 800 feet at the base, covering more than 18 acres. Its mass is five times that of the second-largest Mississippian mound (Mound A at the Etowah site in Georgia). The thing is just gigantic, and it has long been of intense interest to archaeologists. Back in the nineteenth century there was considerable debate over whether it was an artificial mound at all rather than some sort of unusual natural formation, and even into the early twentieth century there was some discussion of whether it might have been a natural rise of some sort that was built up artificially. Those debates had largely been settled by the 1960s, with increasing evidence that it was in fact an artificial construction like the smaller mounds surrounding and forming the core of the Cahokia site around the Grand Plaza. There still remained a dearth of detailed information on the composition of the mound, however, and after some excavation of various small parts of the mound in the early 1960s the archaeologists working at Cahokia came up with the idea of doing some core drilling to get a more general sense of its composition. They reported their results in a paper published in 1968.

After reviewing the techniques available to them, the researchers decided to go with the heaviest equipment they could find, a truck-mounted rig used to take soil samples for highway and building construction. This rig worked by ramming a three-inch diameter tube down at two-foot increments, after each of which the core sample would be extracted and a new tube attached to take the next two-foot sample. This worked pretty well, although some of the tubes broke loose, broke, or were otherwise lost in the course of drilling. The clay soils of the American Bottom are notoriously tough on equipment, so it’s probably a good thing they chose the most heavy-duty rig they could. They found that the core samples were somewhat compacted from the pressure of the drilling, but this didn’t end up being a major problem for interpreting them.

View of Monks Mound from the South, Cahokia

To check on the accuracy of interpretations derived from the core sampling, a small area adjacent to one of the sampling holes was excavated to get a better look at the stratigraphy. This digging generally confirmed the interpretation of the cores, especially the interpretation of thin bands of limonite, which often forms on exposed surfaces in this area, as indicating discrete construction stages of the mound. The coring and excavation also resulted in the submission of a few pieces of wood for radiocarbon dating to give a sense for the absolute chronology of mound construction. Since this was early in the history of radiocarbon dating, the standard deviations on the resulting dates are so large as to make the results of limited usefulness in delimiting substages within the Mississippian period, but they do show the general period when the mound was most likely under construction to be between AD 800 and 1300, which matches the dating of the Emergent Mississippian and Mississippian periods at Cahokia.

Probably the most important result of this research was the discovery that two of the major construction stages, including the earliest, consisted of massive deposits of black clay which likely came from topsoil deposits in various areas around the mound. The later paper I discussed earlier suggested that some of this clay may have come from the upper layers of the area to the south that would later be filled in to become the Grand Plaza, while the authors of the original paper suggested that some of it may have come from the area to the north along Cahokia Creek. It probably took a hell of a lot of clay to build these layers, so both could easily be right.

Closeup of Monks Mound Sign, Cahokia

Another interesting proposal from the authors of the coring paper is that the other mounds at Cahokia may have postdated Monks Mound. This is based on the fact that the handful of radiocarbon dates from excavations beneath other mounds that had been obtained as of that time were uniformly later (though not necessarily very much so) than the dates obtained from the coring and excavation at Monks Mound. This idea is supported by the fact that some of the other mounds are clearly aligned with Monks Mound. There has been a lot of excavation and reanalysis of older materials since the 1960s, of course, so I’m not sure if this pattern still holds up.

Monks Mound is both so huge and so important that this sort of broad-scale coring, like the conductivity survey done later in the Grand Plaza, is a reasonable way to quickly get a general sense of patterns that would take much longer to uncover via excavation, which might not even be possible to do on account of preservation concerns. This is therefore a pretty important paper. Even though it doesn’t reveal a whole lot of detail about the construction stages of Monks Mound, it’s unlikely that we’ll get much more detail than this without a seriously huge effort.
ResearchBlogging.org
Reed, N., Bennett, J., & Porter, J. (1968). Solid Core Drilling of Monks Mound: Technique and Findings American Antiquity, 33 (2) DOI: 10.2307/278515

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Sign Explaining the Grand Plaza at Cahokia

Mississippian societies are known for their mounds, but there’s more to them than that even if you just look at community layout at the largest centers. One of the most distinctive characteristics of Mississippian mound centers is that the mounds at the biggest centers are typically grouped very formally around a central plaza. Historic records of the Mississippian societies in the Southeast that survived into the sixteenth and seventeenth centuries give some sense of the uses of these plazas, which as you might expect seem to have centered on communal ritual, feasting, games, and other events that brought people together and solidified the authority of the elites who lived on the mounds and governed the commoners. Archaeologists have been slow to give plazas the same level of attention they’ve given mounds for a long time, however. There’s long been a tendency to view them as simply empty spaces devoid of interest compared to the impressive mounds that surround them.

That has started to change over the past twenty years or so, however. One of the early efforts in this direction was a field school at the biggest and most spectacular Mississippian site, Cahokia, in 1989. The results of this research were reported in an article published in 1993, and they reveal that there’s more to Cahokia’s Grand Plaza than meets the eye.

Grand Plaza from Monk's Mound, Cahokia

The American Bottom, where Cahokia is located, is characterized by a relatively flat but gently rolling terrain resulting from many years of the Mississippi River winding its way across the floodplain, creating a wide variety of sand ridges interspersed with lower swales filled with alluvial silt and clay. Given this context, the flatness of the Grand Plaza calls out for some sort of explanation. One possibility is that this is an area where natural deposition of sediment happens to have filled in the swales and covered over the ridges, creating a particularly flat area that the Cahokians took advantage of as a natural plaza site by building mounds around it. Other parts of the Cahokia site that have been excavated appear to have been built on similar natural flats. The other option is that the Cahokians themselves took an area that was dominated by the usual ridge and swale topography and flattened it out by cutting down the ridges and filling in the swales to create an artificially flat plaza. If this were the case it would obviously have important implications for the amount of labor that went into the building of Cahokia, which in turn would be an important factor in understanding the nature of the site and of its influence in other areas.

To investigate this question the researchers started with an electromagnetic conductivity survey of the western portion of the Grand Plaza. Since sand tends to have a lower conductivity than silts and clays, sand ridges should show up in a survey like this as areas of lower conductivity compared to swales. This sort of survey should also pick up underground borrow pits (where material was dug for use in mounds and other construction) that were later filled in, provided the later fill was different in conductivity from the surrounding soil. The survey was followed by core sampling to confirm the results, then by limited excavation of a few blocks in the plaza to get a closer look at the stratigraphy of areas that came up with interesting survey results.

The Grand Plaza and Monks Mound, Cahokia

The conductivity survey found that there was indeed a subterranean sand ridge under part of the plaza, with apparent swales on either side of it. Some apparent borrow pits also showed up. The coring confirmed these results, and five excavation blocks were dug: two on the ridge, two in an adjacent swale, and one in a possible borrow pit.

The excavation results showed pretty clearly that the final flat condition of the plaza was indeed the result of human action rather than natural deposition. There was a very sharp delineation between the underlying natural deposits of both the ridge and the swale and the overlying fill, which contained varying amounts of artifacts and did not look anything like natural alluviation. This was also the case for the borrow pit, where the fill was indeed quite different from the surrounding material and clearly secondary.

From the artifacts found in the fill, it appears that the leveling of the plaza occurred around the time of the transition from the Emergent Mississippian to the Mississippian period, which current dating places around AD 1050. Interestingly, it appears that the leveling was actually a secondary activity after the area had been pretty thoroughly dug over for fill, perhaps to build the early mounds at the site. This means that this may in fact have originally been a naturally flat area (although there’s really no way to be sure) but that the upper layers of soil were stripped away for mound construction early on, only to have the resulting pits and scars covered up later by fill that created the final plaza surface. The authors propose a tentative scenario in which early mound construction during the Emergent Mississippian period took fill from this area, which was at the time away from the main area of occupation along Cahokia Creek to the north, and it was only later, when Cahokia began to really hit its stride, that plans changed and this area was refilled to become the Grand Plaza. Whether this was the case or not, it’s very clear from this study that the history of the Grand Plaza is a lot more complicated than it looks at first site.
ResearchBlogging.org
Holley, G., Dalan, R., & Smith, P. (1993). Investigations in the Cahokia Site Grand Plaza American Antiquity, 58 (2) DOI: 10.2307/281972

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Monks Mound Sign at Cahokia Mounds

Regardless of exactly how many people lived at Cahokia, it’s clear from recent research that the population of the site and its immediately surrounding area grew immensely in a short period of time in the eleventh century AD. As Timothy Pauketat points out in the 2003 article that I was discussing earlier, the scale of this growth is much too great to be due to natural increase of a local population. Thus, even though there was a local population of some size in the American Bottom in the immediately preceding period that presumably contributed to the growth of the Cahokia site, it’s pretty clear that there must have been quite a bit of immigration in addition to account for the huge influx of people.

Who were these people, and where did they come from? It can be fiendishly difficult to untangle migrations in the archaeological record, even in conditions like this where it seems clear that there must have been some migrating going on. Archaeology depends mainly on the remains of material culture, which can change quite rapidly under conditions of change and stress such as those that often obtain during and immediately after migrations. Nevertheless, there do seem to be some clues to where at least some of the immigrants into the American Bottom may have originated. These clues mostly revolve around the type of material culture on which archaeologists most often rely to understand prehistoric societies: pottery.

Pots can’t automatically be equated with people, of course, but certain types of pottery are sufficiently distinctive and limited in distribution that they may serve as markers for population movements. In the case of Cahokia, Pauketat and others have pointed out that one of the many pottery types found in deposits dating to the period of population growth bears a striking resemblance to a type known as “Varney Red Filmed” found in northeast Arkansas and southeast Missouri around the same time. Importantly, these pots are often tempered with ground shell. Shell-tempering would later become one of the defining traits of Mississippian societies throughout the South and Midwest, but it appears particularly early in the area where Varney Red Filmed was made, starting around AD 800. According to another study reporting on evidence of Varney-like ceramics found at sites in Wisconsin, examples of Varney wares have been found in the American Bottom starting shortly before AD 1000. While these early finds are considered trade wares, by the time Cahokia emerges about 50 years later similar ceramics are apparently being made there, as shown by analysis of the clays in them, and some shell-tempered sherds that seem to be made from American Bottom clays were identified at the aforementioned Wisconsin sites, attributed to a short-lived influx of immigrants from the American Bottom, perhaps those who lost out in the struggles that led to the rise of Cahokia.

Cahokia Interpretive Center from Monks Mound

Returning to Pauketat’s 2003 article, he finds that not only are locally produced but clearly Varney-influenced pots being made at Cahokia itself in the mid-eleventh century, some of the sites in the rural Richland Complex to the east, which was settled rapidly around the same time, show the same high proportions of Varney sherds as some areas of Cahokia itself, implying that at least some of the people who established the Richland Complex came from the American Bottom. The relationship between these people and those at Cahokia remains difficult to entangle.

One of the hallmarks of the American Bottom in the period immediately preceding the rise of Cahokia is remarkable diversity in ceramic style. Varney is only one of the many local and “foreign” ceramic styles present in sites during this period, and it seems clear that people were coming to the area from all over. Nevertheless, the important similarities between Varney ceramics and those that soon begin to spread along with other attributes of Mississippian culture implies that northeast Arkansas and southeast Missouri may have played an important role in developing the complex of ideas that we today call “Mississippian” and that an increasing body of research suggests initially spread through the influence of Cahokia. Studying the archaeology of these areas during the period before and during the rise of Cahokia is therefore potentially important.

Ceramic sourcing using Instrumental Neutron Activation Analysis has been one line of evidence applied to sites in southeast Missouri during this period, not least because the University of Missouri happens to have a research reactor that has been widely used for sourcing of ceramics and other archaeological artifacts. One paper from this effort, published in 2000, showed that this technique can indeed distinguish among sherds made from clays from three major physiographic regions of southeastern Missouri: the Ozark Highlands and the Western and Eastern Lowlands in the Mississippi Valley. The results showed in addition that there was extensive movement of vessels, including shell-tempered Varney wares, between the Western Lowlands and the Ozark Highlands. It can’t be determined from this data if this reflects trade or migration, but it certainly shows interaction between the two. There is also some limited evidence, in the form of possibly transitional sherds tempered with a mix of shell and sand or limestone, that the shell-tempering technique may have developed here rather than being imported from elsewhere. Given the importance of shell tempering later on, the idea that it may have been an indigenous development among Varney potters may have important implications for lines of cultural influence.

This is all very suggestive of the idea that some of the people who immigrated to the American Bottom around AD 1050 came from the Varney area and brought with them some ideas that they had developed there or perhaps borrowed from other groups. People were certainly coming from other directions too, and their ideas may have been just as influential even if they were less visible archaeologically. In addition, there was a longstanding local population in the American Bottom that surely played a role as well. All of these people likely contributed to the unique flowering of the greatest cultural and political center north of Mexico that began soon afterward. Untangling exactly what contributions each group made, and figuring out in more detail who they were, are bigger challenges than simply tracing where they may have come from and what their pots looked like, of course.
ResearchBlogging.org
Lynott, M., Neff, H., Price, J., Cogswell, J., & Glascock, M. (2000). Inferences about Prehistoric Ceramics and People in Southeast Missouri: Results of Ceramic Compositional Analysis American Antiquity, 65 (1) DOI: 10.2307/2694810

Pauketat, T. (2003). Resettled Farmers and the Making of a Mississippian Polity American Antiquity, 68 (1) DOI: 10.2307/3557032

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