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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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Spruce Tree House, Mesa Verde

This is a fascinating example of a serious attempt to design an urban cooperative community based on the concept of a canyon.  The term “urban canyon” is often used to describe the narrow streets surrounded by skyscrapers in many big cities, and I think there is actually more to that comparison than the people who make it often realize, but this project takes the idea in a very different direction.  Produced for a design competition in Dallas a couple of years ago where the goal was to come up with a totally sustainable urban block, “Co-op Canyon” is clearly influenced by Anasazi precedents, and the architects even used the term “cliff dwelling” in describing it (although they don’t mention the Anasazi specifically).  It goes well beyond just copying the outward forms of Anasazi architecture, as modern architects often do, and incorporates agriculture throughout the staggered terraces that make up the inward-facing development with an internal “canyon” at its center.  There’s also an innovative cooperative concept for the organization of the community, in which residents contribute work in the gardens or in other parts of the community to earn their keep, along the lines of Habitat for Humanity’s  “sweat equity,” in which residents help to build their own houses in order to purchase them.  This cooperative idea is probably influenced by popular ideas about Anasazi social organization as well, although for the Mesa Verde cliff dwellingsspecifically this may not be very accurate.  The design didn’t win, so it won’t actually be built in Dallas, but it’s a great example of architects really thinking through the possibilities and implications of precedents drawn from the archaeological record.

Cliff Palace and Sun Temple, Mesa Verde

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Houses with Yards, Colorado Springs, Colorado

Today is Blog Action Day, and the topic is water.  I did a post for this last year when the topic was climate change, so I figured I’d do it again.  Water is obviously a huge issue, especially in the arid Southwest, so there are a lot of directions I could go with this.  I did an earlier post on the importance of water at Chaco, which is certainly worth linking in this context.  For Blog Action Day, however, I thought a discussion of a rather different issue,  a bit far from my usual fare here, would be interesting.

One of the most noteworthy characteristics of urban sprawl is inefficient use of land, symbolized most obviously by the suburban development pattern of single-family houses on large lots.  Whatever space on these lots is not covered by the building footprint or a driveway is typically divided into yards.  Front and back yards are nearly universal in suburbia, and found at a smaller scale in some urban areas as well, and on particularly large lots side yards are found as well.  These yards are generally interpreted today as being for recreational use, and backyards in particular often have recreational amenities like swimming pools, but at least in my experience people don’t seem to use this space for recreational purposes to nearly the degree you might expect given the sheer amount of it.  Maintaining a yard is also a major effort in time and resources, especially if it is covered with a grass lawn which requires regular mowing and (at least in more arid regions) watering.  The amount of energy and water expended on these activities is huge, and for what?  A big empty space that isn’t generally used for much of anything.  This is not to disparage the choices of people who prefer to have large amounts of space on their property or like maintaining lawns, just to say that I really don’t understand the appeal, and judging by the popularity of apartment-style living where it is available it seems I’m not alone.  Plenty of people, it seems, find the amounts of open space provided by public parks and other public or semi-public areas to be perfectly adequate for their needs.  And yet, we still have all these yards.  In most suburban areas they are essentially mandated by setback requirements in zoning and subdivision codes.

So how did we get here?  Obviously it’s a complicated story, and I’m sure there are many different parts to the answer.  One important aspect of the story that doesn’t seem to get much attention is described by Jon Peterson in an article on the nineteenth-century sanitary reform movement and its influence on American urban planning.  As Peterson describes it, the origin of the yard is something of a byproduct of a series of important changes in urban sanitation and waste management in response to the rise of the industrial city.

Aragon Handyman Service Sign, Albuquerque, New Mexico

Up until about 1850, every house in America, rural or urban, had two things which were absolutely necessary for life: a well and a cesspool.  In rural areas, where most people were farmers, everyone had lots of land, so siting these so that contamination of the water supply was not a major issue would presumably have been pretty easy in most places.  Even in towns, lots were generally large enough to maintain a safe distance between the well and the cesspool.  In  preindustrial cities, lots were smaller than in typical towns, but there was still no public provision of water or sewerage, so people still had wells and outhouses on their small urban lots, and disease could be a problem.  As long as cities remained small, however, these problems were manageable.  Garbage, too, would generally be stored on-site until someone took it away, and waste kitchen and washing water would often be dumped right into the street.   There were sewers, but they were used exclusively for carrying away excess stormwater and preventing flooding (basically like storm sewers today), and dumping waste in them was illegal.

The problems with this system, such as it was, became most glaringly apparent once industrial growth led to massive increases in city size.  This happened first in Britain, where by the early nineteenth century the filthy conditions of fast-growing cities were atrocious, and the decision to deal with the problem by allowing waste to be dumped in sewers only made things worse.  Remember, these were storm sewers, and water only flowed through them when it rained.  The rest of the time, all sorts of waste accumulated and clogged them up.  By the 184os it was clear that the problem had reached crisis proportions, and the social reformer Edwin Chadwick came up with the idea of dealing with it by introducing a system by which water would be provided to houses and used to flush waste through a system of sewer pipes laid out so as to use gravity to carry the waste away.  This was known as “water-carriage sewerage,” and it was the principle upon which all subsequent sewer systems were based.  The full implementation of the idea in a slightly different form in London came in the 1860s under Joseph Bazalgette.

Water Tower, Hammonton, New Jersey

In the US, industrialization had not yet progressed very far at that point, but the nation’s few cities were growing, and other factors were making the waste problem worse.  Probably the most important was the introduction of public water supply in the 1840s.  Once people no longer had to depend on their own wells (which would become less productive as more people moved into the area with their own wells, lowering the water table) or cisterns, they began to use vastly more water, much more than the engineers who designed the water systems had anticipated, and the excess water overloaded the cesspools and created many of the same problems that British cities had been experiencing for a while.  US sanitary reforms were impressed with the sewerage ideas coming out of Britain and argued for sewer systems to be implemented in American cities.  Boston and New York, which had the biggest problems, accordingly put in extensive but largely uncoordinated sewer lines in the 1850s and 1860s.

In the 1870s, as industrialization began to take hold and American cities began to grow rapidly, the problems with the traditional water and waste disposal systems became apparent to more and more cities, and the use of sewers proliferated from then on.  This led to a considerable improvement in urban public health, although the other health problems resulting from the expansion of urban industry may have made this improvement less apparent at the time than it is from our perspective today.

Houses with Yards, Hammonton, New Jersey

So what does all this have to do with yards?  Peterson mentions briefly, near the end of his article, what he calls an “illustrative but little appreciated impact of sanitary reform upon urban land use,” namely, new uses for the space on urban lots formerly occupied by wells and cesspools.  Once urban households had running water and water-carriage sewerage, they no longer needed to devote space outside the house to these necessities of life, and they could use that space instead for recreation.  Thus, the yard was born.  In the biggest and fastest-growing cities, of course, rising land values in the late nineteenth century led most of these earlier lots to be bought up and used to build tenements, skyscrapers, and other high-density uses that maximized the amount of the lot used productively and destroyed both the houses and the yards that had been there before.  In smaller cities and towns, however, this didn’t happen to nearly the degree it did in places like New York and Chicago, and the yard remained.  Around the turn of the century civic improvement associations around the country associated with the City Beautiful movement encouraged the planting of grass, flowers, and other plants in these vacant parts of household lots to beautify them.  This is the origin of the lawn.  Later, this particular idea of beauty would be incorporated into the self-consciously suburban developments of the 1920s, and from there to the sprawl of today.  And so here we are, with big empty spaces filled with grass, the result of technological improvements in sanitation intersecting with emerging ideas of civic beauty.
ResearchBlogging.org
Peterson JA (1979). The impact of sanitary reform upon American urban planning, 1840-1890. Journal of social history, 13 (1), 83-103 PMID: 11632375

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Chaco Amphitheater

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

Secret Passage into Casa Rinconada

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

Pueblo Alto and New Alto from Tsin Kletzin

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

Canyon Wall from Pueblo del Arroyo

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

Huerfano Mesa from New Alto

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

Looking East from the Pueblo Alto Trail

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

Shell and Jet Display at Chaco Museum

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

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

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

Kiva A at Pueblo Bonito from Above

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

Intact Roof Beams in Room 6, Pueblo Bonito

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

Shell Display at Visitor Center Museum

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

Chaco Amphitheater in the Snow

So, given all that, it seems likely that if any conch-related ritual complex in the modern Pueblos is related to the conchs at Pueblo Bonito it’s the Zuni Big Shell, associated with warfare and witchcraft.  This is certainly intriguing, especially given the odd and ambiguous evidence about Chaco’s connections to warfare, although I think it’s ultimately inconclusive.  As Mills and Ferguson point out, it’s entirely possible that some of these prehistoric complexes have no modern equivalents at all.  Indeed, given the massive series of cultural changes and migrations separating Chaco from the modern Pueblos, it would hardly be surprising that the ritual traditions closely associated with Chaco specifically would have been lost or abandoned in favor of newer (or perhaps older) rituals considered more suited to the changing times.  It’s noteworthy that there don’t seem to be any modern (Pueblo) practices involving a combination of conch trumpets and cliff faces with special acoustic properties, given the strong circumstantial evidence that the two were connected at Chaco.  Whether or not any modern practices involving shell trumpets can be traced back to Chaco, however, the evidence for their importance at Chaco itself at its height is evocative and provides a hint of what Chaco may have been like for the Chacoans, even if what we hear today is only a faint echo of what they heard then.
ResearchBlogging.org
Mills, B., & Ferguson, T. (2008). Animate Objects: Shell Trumpets and Ritual Networks in the Greater Southwest Journal of Archaeological Method and Theory, 15 (4), 338-361 DOI: 10.1007/s10816-008-9057-5

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