Many of the questions visitors ask again and again about Chaco are pretty obvious and, I think, pretty reasonable. Indeed, many of them have been the starting points for considerable amounts of archaeological research. The issue of the sources of the enormous amounts of wood used in the construction of the great houses in the canyon is one good example of a question of interest to casual visitors and scholarly specialists alike.
Some questions that visitors often ask I find rather puzzling, however. Since many of these are asked rather frequently, I get the sense that there is some common set of assumptions underlying them that I should probably be addressing both in person when they come up and here on the blog as a more general matter, but for the life of me I cannot figure out what those assumptions are. All I know is that I clearly don’t share them, since the questions, while easy enough to answer, don’t seem to me like topics worth thinking or discussing in much detail, but there they are, again and again, like so many flies to be swatted.
One of these, which seems to be coming up with particular regularity in the past few days, is the source of the admittedly immense amount of building stone used in the great houses. People seem very impressed, even astounded, with both the overall quantity of stone and the number of individual blocks (“all those little rocks!”), and to a lesser and more understandable extent with the amount of effort that seems to have gone into both acquiring and shaping them.
On the one hand, the fineness of the masonry at Chaco is one of best-known aspects of the Chacoan system, and it certainly does set the canyon apart from many other manifestations of Puebloan culture elsewhere in the southwest. Mesa Verde, for instance, for all the impressiveness of both its general setting and the locations of its individual sites, tends to feature fairly rudimentary stonework.
On the other hand, however, if there’s one thing present in enormous quantity at Chaco it’s stone. While the scale of construction in the canyon is impressive by any standard, especially given the relatively short time period in which the most extensive building events took place, and the fineness of the masonry is justly famous, there are plenty of other sites elsewhere featuring one or the other.
Further west, for instance, places like Wupatki have remarkably fine stonework, and the large pueblos of the late prehistoric period in many parts of the southwest certainly involved a lot of stone (although in other areas construction involved large amounts of adobe instead). Chaco’s distinctiveness lies largely in the combination of the enormous size of its great houses and the enormous amount of care and effort that clearly went into their construction. Making a building as big and well-built as Pueblo Bonito took a lot of work and skill, but the acquisition of stone took only a very small portion of the effort involved.
In any case, while the question of where the Chacoans got the stone for their buildings puzzles me by the fact that it is asked at all, it’s actually pretty easy to answer. Most of the major great-house sites are built largely of what’s known as “Bonito-style” masonry, which is distinguished by both its very strong, stable, and useful core-and-veneer wall-construction technique and its use of a particular type of sandstone.
This is not the soft, yellowish, massive sandstone seen at the base of the cliffs, but the next level of sandstone up, a hard, tabular, gray or brown type of stone that is thinly bedded and tends to break cleanly in straight lines and right angles, which makes it very easy to shape either by simply snapping it or by scoring it with a sharp stone and then hitting it with a hammerstone to form a very straight edge.
This tabular nature makes this type of stone, which outcrops on top of the mesas surrounding the canyon approximately a mile from the major great houses, particularly well suited for the elaborate coursing involved in the Bonito-style veneers. While the soft, yellowish stone from the lower level is used in some types of Bonito-style masonry, it is much less common than the hard, tabular stone, presumably since it doesn’t break cleanly and requires a considerable amount of effort to grind it to a reasonably straight edge. While it would certainly have been easier to acquire the yellow stone, which is lying around on the ground all over the canyon, it would take so much work to shape it that it probably didn’t end up saving any overall effort compared to the tabular stone, which was a little harder to get but a lot easier to use. It was likely broken off along natural horizontal planes in whatever sizes came most easily, then carried down in baskets to the construction sites in the canyon, where it was worked further, if necessary, along the vertical edges and then laid in the walls.
In the early 1100s, toward the end of the Chacoan era, a new style of core-and-veneer masonry using the soft, yellowish sandstone almost exclusively became popular in the canyon. This is known as “McElmo-style” masonry and was used mainly in the construction of extremely standardized, symmetrical, modular buildings that were much smaller than the Bonito-style great houses (although some additions to Bonito-style sites used it as well). These are known as McElmo-style great houses or McElmo units. They include Kin Kletso, New Alto, Casa Chiquita, and others.
The name “McElmo” comes from McElmo Creek, just north of Mesa Verde, and was originally applied to this style at Chaco because it seemed to some archaeologists to reflect influence or even population movement from the north at a relatively late time in the canyon’s occupation. While Steve Lekson, in his seminal study of great house architecture, has argued persuasively that the McElmo style is largely a local development that bears only a superficial resemblance to Mesa Verdean architectural styles, the name has stuck.
It’s not clear why the McElmo style used the soft, yellowish stone rather than the hard, tabular stone. The yellow stone is considerably harder to work, but it is obviously possible to work it to a fine condition, and the McElmo units show typically Chacoan care and elaboration in their masonry despite the material.
The use of the stone may indeed be a reference or homage to northern styles, either from Mesa Verde or from the Totah area along the San Juan River and its major tributaries. Aztec Ruins is built almost entirely in the McElmo style, and much of the most impressive building there was done around the same time that the McElmo units were being built at Chaco.
In any case, both the Bonito-style and the McElmo-style masonry used stone that was easily accessible nearby. Although there are few resources present in large quantities in and around Chaco, sandstone is one thing that is extremely easy to find. I don’t know why people keep asking about it, but the answer to the constant questions about where they got the stone is: right here.