STANDING ROCK

A spiritual site of the Anasazi, they built a large structure hear to observe the sunrise over the stone pillar.

The stone pillar known as Standing Rock

At first the archaeological site looks like a pile of dirt. But when you get closer you can make out some details.

Great House Reconstruction

Standing Rock Area Reconstrcted

MIAMO published a report on the site in 2005. Later ground surveys revealed something unusual. Standing Rock is probably not a great house but a great theatre. Standing on the platform and facing southeast people could watch the sun rise over the stone piller. This alignment can be extended further to the southeast and connects with another ancient structure call Section 8. It is probably not a great house either, but we really do not know why it was built.

Geomorphology, Geology, and Hydrology Of the Standing Rock Great House Community

 

ABSTRACT

Two relatively short linear swales previously inferred to be ancient roads are found in close proximity to the Standing Rock Great House. It is unlikely that these swales coincide with regional travel routes. Instead, they are remnants of structures that at least in part, controlled surface water flow. Geomorphic analysis of the terrain surrounding the great house indicates that the structures were placed in a well understood hydraulic environment. The ancient engineers accounted for the general condition of scarce water in the area and for those less common times when heavy rainfall would force them to deal with excess water. At Standing Rock, ancient engineers had more in mind than travel routes when they planned the construction of their community, and this raises the question, “When is a road more than a road?”

The identification of constructed roads associated with Chacoan great houses revolutionized archaeologists’ concepts of Chaco in the early 1980s. An extensive road system throughout the San Juan Basin and beyond indicated a degree of social complexity far beyond previous ideas about the nature of Chacoan culture. In the past two decades hundreds of miles of prehistoric roads have been “identified” using various techniques, including geomorphic analysis, aerial photographic analysis and excavation.

Numerous theories about the function of Chacoan roads have been proposed including (1) an economic redistribution network (Ebert and Hitchcock 1980), (2) a system for easily moving military personnel throughout the area (Wilcox 1993), (3) pilgrimage routes for regular (annual?) festivals in Chaco Canyon (Malville and Malville 2001), and (4) symbolic constructions that reaffirmed “Chacoan” identity (Marshall 1992; Sofaer et al. 1989).

But did all these identified roads and road segments really function to allow people and goods to move across the landscape quickly and easily? This research indicates that some small “road” segments may actually have functioned as surface water management systems. The extensive road system in the San Juan Basin suggests that ancient engineers were interested in creating an infrastructure that would provide for regional integration. There is evidence that the same engineers were also trying to integrate each community into its local hydrological environment. Both construction efforts suggest sophisticated organization and a systematic approach to community development.

Over the past century archaeologists have continued to expand the list of locations of Chacoan great houses and associated community structures (e.g. great kivas and village type pueblos) found within Chaco Canyon and throughout the San Juan Basin and beyond (Fowler and Stein 1992; Lekson 1999). In conjunction with these discoveries, numerous linear engineered structures have also been identified and described. These linear structures are typically classified into one of two categories as roads or components of surface water management systems (e.g. canals). In the past three decades, regional archaeological inventories have expanded more rapidly as new technologies like aerial photographic reconnaissance have been extensively used (Marshall et al. 1979; Obenauf, 1980; Powers et al. 1983; Nials et al. 1987). Such studies have identified hundreds of ancient structures outside Chaco Canyon referred to as “outliers.” These studies have also identified numerous linear structures and geomorphic alignments associated with outliers and suggest that a network of ancient roads might still be present crossing the San Juan Basin and connecting Chaco Canyon to regions far to the north, south, and west (Lekson et al. 1988). Site specific studies in Chaco Canyon confirm that ancient engineers operated with a sophisticated understanding of the local climate and water management principles. Archaeologists have therefore inferred that many linear structures, particularly along Chaco Wash, are canals or components of irrigation systems (Vivian 1971, 1974). But, in some cases investigators have changed their minds about features formally inferred to be canals and concluded that they are roads (Vivian 1983). Outside Chaco Canyon, some roads have been confirmed by ground inspections, but the formal evaluation of the numerous linear structures outside Chaco Canyon has not been conducted and the actual function of many linear engineered structures remains unknown.

PREVIOUS RESEARCH

Ancient roads in Chaco Canyon and in the surrounding San Juan Basin generally have been identified and mapped by one of two methods, ground surveys or aerial photographic interpretation. Many of the earliest roads identified were recognized on the ground near great houses and great kivas by the presence of linear features including swales, curbs, berms, grooves and walls (Fewkes 1917; Holsinger 1901; Judd 1954). As road studies continued, many new roads were identified using aerial photographs (Vivian 1972; Ebert and Hitchcock 1980; Obenauf 1980). Obenauf (1980) used aerial photographs taken in the 1930s by the United States Soil Conservation Service and in the 1950s and 1960s by the United States Geological Survey to identify possible linear structures on the ground that might indicate the presence of ancient roads. She notes (Obenauf 1980: 57) that ancient roads often appear as dark lines on photographs. Obenauf and other authors use various terms to refer to these dark lines including linears, linearities, lineations and lineaments. Vivian (1983, 1997a, 1997b) describes the methods and history of road discoveries based on both ground surveys and photographic interpretation. In conjunction with field surveys of the San Juan Basin for archaeological sites outside Chaco Canyon, an extensive list of possible roads has been assembled (Lekson et al. 1988; Roney 1992).

Four major regional studies (Marshall et al. 1979; Powers et al. 1983; Kincaid 1983; Nials et al. 1987) surveyed portions of the San Juan Basin outside Chaco Canyon for archaeological sites. These studies vastly expanded our database on the number and distribution of so called “outlier” communities and associated engineered structures, including roads. The Marshall et al. (1979) survey describes 33 communities including numerous great house and great kiva structures and associated smaller houses that occur throughout the San Juan Basin. Powers et al. (1983) conducted detailed studies of three outlier communities and reconnaissance descriptions of 33 other sites. Kincaid (1983) and Nials et al. (1987) document a phased reappraisal of prehistoric roads in the San Juan basin conducted largely by the Bureau of Land Management (BLM). While this work eliminated several photographic linears as road candidates, it further supported the inference that some ancient roads do exist in the San Juan Basin and provided extensive documentation on numerous structures found along these roads.

From these works and numerous other site-specific studies, Lekson (1999) estimates that more than 150 outlier communities are spread over 40,000 square miles in four states. Fowler and Stein (1992) produced a map and list of 177 great houses and/or great kiva locations through out the San Juan Basin and adjacent areas of the Four Corners. The map does not include all the linear engineered structures (e.g. roads and canals) and the numerous other smaller structures variously referred to as herraduras, zambullidas, avanzadas, Windes shrines, platforms, ramps and/or “unknown” structures that have been documented in the above regional surveys or in various other archaeological reports (Stein and McKenna 1988; Stein and Lekson 1992; Windes 1987). The function of most of these other structures is still unknown. With so many structures discovered but so few studied in any detail, it is difficult to have confidence in any hypothesis about their function. For purposes of inferring function, each structure needs to be placed in an environmental context that is defined by the presence and location of other structures and the surrounding natural features.

ROADS AND OTHER LINEAR ENGINEERED STRUCTURES

Early investigators of sites in Chaco Canyon were quick to note the presence of long linear swales which were interpreted to be canals or roads (Fewkes 1917). Other linear features described included dams, irrigation networks, hydraulic barrier walls, and other water control structures. Canals were confirmed near Pueblo Bonito in the early 1960s (Judd 1964). Extensive work in the 1960s by Gordon Vivian and R.Gwinn Vivian firmly established that many linear features in the landscape in and near Chaco Canyon are water control structures (Vivian, 1970, 1974). R. Gwinn Vivian was also instrumental in reevaluating many linear structures and reinterpreting them as roads (Vivian and Buettner 1971; Vivian 1983). The discovery of many new roads in the Chaco Canyon area inevitably led to searches in the greater San Juan basin. Vivian (1983) compiled a historical inventory of road discoveries and formal studies leading up to the more extensive BLM regional studies of Kincaid (1983) and Nials et al. (1987). The surging interest in ancient roads overshadowed any research into other linear features like canals, and little discussion has been forthcoming about the possibility that some linear structures may not be roads at all.

From the vast database on ancient roads assembled by the BLM and other research, several new models were developed that propose possible functions for the extensive Chacoan road system. Roney (1992) summarized these models which suggested that roads function as ceremonial (Judd 1954) and transport or communication conduits (Powers 1984), and as agents for regional social integration (Lekson et al. 1988). Some hypotheses also note that many roads emanate from Chaco Canyon and that the roads may have functioned as spokes of a Chacoan food redistribution center (Ebert and Hitchcock 1980).

Roney’s work on road mapping during Phase II of the BLM Chaco roads project (Nials et al. 1987), however, suggests yet another model. Roney (1992) notes that many “road postulated segments” are not ground confirmed. Ground confirmation typically involves the identification of one or more criteria coinciding with the location of a mapped photographic linear (Nials et al. 1987). Such criteria may include a surface swale, preserved border walls or berms, associated ruins and/or sherd scatters. Roney (1992) acknowledges that the North and South roads are regionally extensive and that several other long road segments can be identified near Chaco Canyon, but he also points out that numerous relatively short road segments (i.e. less than 5 kilometers) have been found that may not be part of a basin wide road system. In many cases, ground surveys indicate that these “roads” are closely associated with “Bonito-style” buildings. For Roney (1992:129), this fact suggests “a strong functional link”. He expands on this hypothesis by suggesting that “roads… may be seen as but one more embellishment of the local integrative structures…” Lekson (1999) however notes that the short road segments identified by Roney may serve to direct travelers to longer routes. Using an energy cost/benefit analysis of several roads, Kantner (1996) found that road postulated photographic linears did not correspond to the most efficient route between communities and suggests that most roads serve a localized religious, integrative, or political function.

These conflicting models in part seem to center on the well-preserved but short linear structures located in close proximity to Bonito-style buildings. Travel routes undoubtedly existed between the ancient communities of the San Juan Basin, but they may not have been constructed roads. As footpaths or even well traveled trails, many of these old routes may have been lost to natural erosion and alluviation. But structures receiving more attention during construction and subsequent regular maintenance are more likely to have survived. Although several linear structures are known to occur between archaeological sites and may be inferred to be ancient roads (e.g. North and South Roads), Roney (1992) has made the case that well-preserved linear structures are often relatively short and found within ancient communities. Many of these shorter structures do not appear to have specific destinations and do no exhibit characteristics that might support the inference that they were roads.  This does not preclude the possibility that they served some other function.

Many of the short roads listed by Roney (1992) and identified on maps by Nials et al. (1987) extend directly away from a great house and down slope, but many do not seem to be directed toward other communities. At the Haystack Great House (Nials et al. 1987: 129; map 48) three photographic linears extend away from the great house, but only a short portion of one is ground confirmed by the presence of an 8.5 meters wide swale. The swale extends approximately 250 meters to the northwest and ends at the first drainage channel. At the Kin Nizhoni community, five photographic linears have been mapped (Nials et al. 1987: 127; map 47). A portion of each extends to or across a key drainage area. Ground inspection found that only one is associated with a shallow swale that runs down slope and stops at the bottom of the drainage channel. At the San Mateo community (Nials et al. 1987: 100; map 34) there are fourteen mapped photographic linears of which five are in close proximity to the great house. Of these, only a portion of one was confirmed by ground inspection to be a prehistoric linear engineered structure (Nials et al. 1987). Described as an 8.5-meter wide shallow swale, it is bounded on both sides by a low stony berm. The swale descends a slope to the northwest and away from the great house and crosses a drainage channel where it climbs the opposite slope and stops on the crest of a ridge. This swale might be inferred to be two separate structures that somehow contribute to surface water drainage in the area of the same natural drainage channel. At the Andrews site Linear 190 (Nials et al. 1987: 133; map 50) is heavily eroded suggesting it is a preferential drainage path down from the great house to a natural drainage channel.  At the Standing Rock Great House there are two ground confirmed linears (Nials et al. 1987: 108; map 38) of particular interest. They are directed down-slope to the same small side valley to Standing Rock Wash and engineered only along part of the originally identified photographic linears.

These few examples suggest that some linear features may not be roads, but are engineered structures. Because they are directed down-slope to natural washes and channels, they may have had a local function to manage surface water drainage. In order to understand these short linear engineered structures, the local arrangement of other community structures (i.e. great houses, great kivas, and smaller buildings) and the local geomorphology should be mapped. To test the hypothesis that some of these short linear engineered structures may have functioned as something other than roads, I examined the structures and landscape in the Standing Rock community.

THE STANDING ROCK GREAT HOUSE AND ASSOCIATED LINEAR ENGINEERED STRUCTURES

The Standing Rock great house site is an estimated forty rooms surrounding a sub-rectangular plaza in a D shape (Powers et al. 1983 and Marshall et al. 1979). Marshall et al. (1979) identify it as having a Chacoan affinity and estimate an age of late Pueblo II to early Pueblo III. It is situated on the eastern edge of a broad north-south trending ridge (Figure 2).

A great kiva, described by Marshall et al. (1979) is located approximately 300 meters to the southwest (Figure 3).

Nials et al. (1987) report that several other “undocumented” structures occur in proximity to the great kiva and great house. I mapped a large mound south of the great house ruin and a short distance southeast of the great kiva. The mound is covered with sherds and rock slabs and may have been one or more single story structures; another “structure” mound is located west of the great kiva (Figure 3). Located to the north and east of the great house are several mounds described by Marshall et al. (1979) as “two midden formations containing an estimated 705 cubic meters of trash.” Powers et al.’s (1983: 212) map depicts four refuse mounds bounding a “possible prehistoric roadway” that wraps around the perimeter of the great house. Nials et al. (1987) also note a road-like feature that encircles the base of the site. To the west and southwest, the ground surface is generally flat and covered with sherds. Beyond the north mound is another flat area. (Figure 4).

Obenauf (1980) identified five photographic linears directly adjacent to the Standing Rock Great House that might be ancient roads. Nials et al. (1987: 108; Map 38) attempted to find evidence on the ground that would confirm that the linears were roads (Figure 2). I examined each of the features and the surrounding geomorphology with the intent to confirm their presence and find evidence that might explain the nature and/or origin of the photographic linears. Using the same numeric designations as Nials et al. (1987) each linear is discussed below.

Photographic Linear 147 trends directly west from the great house and toward Toyee Spring, located approximately 3 kilometers to the west (Figure 2). It can be inferred that this linear coincides with a portion of the Coyote Canyon Road connecting the Peach Springs community with the Standing Rock community (Kincaid 1983). It is referred to herein as the “Toyee Segment.” Powers et al. (1983) describe the Coyote Canyon Road as a major prehistoric road that passes through the Peach Springs community and east to Toyee Spring and the Standing Rock community. Based on aerial photographic interpretation (Obenauf 1980; Powers et al. 1983) an ancient road is inferred to extend from the Standing Rock community approximately 30 kilometers to the northeast. Nails et al. (1987:21) confirmed that the segment between the Peach Springs community and the Gray Ridge Compound to the west is “one of the best examples of constructed roadway known from the Chacoan road network.” The extension of the road from Peach Springs community east to Toyee Spring and the Standing Rock community is, however, still not confirmed.

Inspection of Toyee Spring revealed that it has been developed by local Navajo ranchers. In June 2004, several small ponds located near the spring were used for watering stock; the spring likely provides a local water source throughout the dry season. Climbing up a low rise east of the spring approximately 50 meters allows a direct line of sight to the Standing Rock Great House, the most prominent feature on the eastern horizon. Between the great house and the spring the terrain is a sandy grassland sloping to the west at a gradient of 0.02. It is likely that there was a travel route from the great house community to the spring, but no evidence of significant ground modification or engineering to define a “formalized road” was found. Nor is there evidence of significant historic activities or geologic processes that might have obscured the ancient road segment. There is, however, limited archaeological evidence of ancient activity along the postulated road segment in the form of sherd scatters and aligned structure mounds for approximately 0.5 miles west from the great house (Figure 3).

Photographic Linear 148 trends north 5 degrees east along the ridge crest (Figure 2). This portion of the ridge terrain is heavily disturbed by modern dirt roads and no photographic linear is visible on recent aerial photographs; nor was evidence found during my ground survey or by Nials et al. (1987) to indicate significant ground modification or engineering to define an ancient road. In addition, there is a topographic trend in the bedrock ridges in the area that coincides with the trend of Linear 148, suggesting that the underlying geologic conditions explain the photographic linear. To test this hypothesis, geologic mapping was conducted on bedrock outcrops south of the area along a similarly trending ridge (Figure2). Mapping in this area detected several extensive bedrock fractures trending north 5 degrees east along the ridge crest. It is possible, therefore, that the photographic linear designated 148, by Nials et al. (1987) is a product of local geologic structural trends.

There is a small unnumbered linear depicted on the Nials et al. (1987) map connecting the great house to Linear 148. No evidence was found during the ground survey to indicate significant ground modification or engineering to define a formalized ancient road along this linear.

Photographic Linear 149 and a portion of Linear150 are reported by Nials et al. (1987) to be clearly visible on aerial photography and on the ground. The eastern half of Linear 150, however, is not visible on the ground. This fact is significant because the pronounced character of the features on photographs seems to coincide with evidence on the ground of earth modification and actual presence of an ancient linear engineered structure (See below).

On the ground, Linears 149 and 150 can be generally characterized as broad swales running downslope from the great house in a relatively straight line toward Standing Rock Wash. Further examination of the terrain directly north and east of the great house and farther downslope to the northeast toward Standing Rock Wash identified several low mounds and linear berms associated with the engineered linear structures (Figures 3 and 4). There is an elongated mound on both sides of the swale that coincides with Linear 149 near the great house (i.e. Mounds A and B). These mounds are covered with sherds and border a linear gap that the swale follows downslope toward the wash. The swale coinciding with Linear 149 is approximately 10 meters wide and extends approximately 625 meters on a straight trend of approximately north 40 degrees east with a gradient of .05. Despite extensive disturbance by sand dune formation and two historic dirt roads, this swale is clearly visible along its entire length. Downslope from the great house, the northwestern edge of the swale is bounded by a linear berm and there are several sherd scatters within the swale. The engineered linear structure that coincides with Linear 150 passes between two mounds due east from the great house (i.e. mounds B and C; Figures 3 and 4). The shallow swale wrapping around the base of the great house described by Powers et al. (1983) and Nials et al. (1987) appears to connect the two linear structures (Figure 4). The swale coinciding with Linear 150 is approximately ten meters wide and trends in a straight line north 75 degrees east along a gradient of .03. As noted above, the swale visible on the ground does not occur along the entire length of the photographic linear (Figure 2), but stops approximately 230 meters downslope from the great house (Figure 3).

The swale associated with Linear 149 ends at a colluvium footslope adjacent to the edge of a flat-bottomed valley extending south from Standing Rock Wash (Figures 2 and 3). The valley is bounded on all sides by a low bedrock cliff except where the 149 swale ends. At this location, sediments have built up and formed a small deltaic deposit that is beginning to fill in the valley.  The bottom of the valley is flat and bounded on the north by the arroyo of the Standing Rock Wash. There is little evidence of a drainage channel within the valley that would direct surface water to the wash channel. At the extreme southern end of the valley, a drainage channel is marked by a narrow linear exposure of bedrock that extends approximately 160 meters farther south (Figure 3). The swale associated with Linear 150 ends at this bedrock channel. As noted above, no evidence was found during the ground survey to indicate that significant ground modification or engineering occurred on the 150 linear beyond this point.

DISCUSSION

The geomorphology of the terrain adjacent to the Standing Rock Great House suggests that ancient engineers integrated the great house and linear structures coinciding with Photographic Linears 149 and 150 (Figure 4) into a surface water control system.

Standing Rock Great House is located on the edge of a platform overlooking a broad slope that leads to Standing Rock Wash (Figure 3). Surface water can accumulate on the ridge platform and then drain east toward the great house and platform edge and then farther down the slope to the wash. Two small ephemeral water accumulations occurred on the platform after a short storm in July 2004. At a minimum, the great house engineers would have needed to divert water during heavy rains away from the great house and other structures. There is an estimated three acres of flat terrain adjacent to the great house that could serve to collect water. North from the great house, Mound A (Figure 4) would cause water to accumulate until it flowed over a small rise and into a short broad swale that intersects Linear 149 downslope. South from the great house there is a natural mound that would also act as a barrier to eastward surface water flow. A gap occurs at the platform edge between this mound and the southern edge of the great house. A broad swale/ramp occupies this gap that could direct surface water flow down slope to the east (Figure 4). After accumulating behind the great house or in other areas to the west, surface water could drain through the gap and into the swale at Linear 150 and then farther downslope to the natural creek drainage 230 meters away. Along this route water might be directed to downslope reservoirs or growing areas. The soil profile covering the slope east of the great house is thin, typically less than one meter and composed of easily removed loose sand. If the engineering of drainage channels at Linears 149 and 150 was conducted properly, these structures and associated mounds could function to control the direction of large amounts of water during heavy rains. Between Linears 149 and 150 there is a broad flat area that might have served as an irrigated terrace (Figures 3 and 4).

The dip of bedrock strata underlying the soil profile is generally east to northeast. Therefore, where exposed in the bottom of the swales, the bedrock surface slopes east and not north to the wash. Once exposed, it is possible that the engineers implemented some rock excavation to control the bedrock surface slope. But even if they did not, surface water would still generally follow the swales with some deposition on the east bank. The observation by Nials et al. (1987) that the eastern earthwork of Linear 149 has a much higher organic content suggests that water saturated this perimeter berm and allowed for more plant growth. Downslope where the 149 swale enters the valley, it might be expected that sediments would begin to fill in the valley and the presence of a small colluvial delta at the end of the swale would be expected.

Even if these linear features were built as roads, the coincidence of their orientation and the local topography would inevitably lead to their flooding during heavy rains. Linears 149 and 150 are engineered over a very short distance. They essentially start at the great house and lead to the same valley. They both follow the hydraulic gradient and the swale along the 150 linear leads over the shortest possible distance to a natural drainage channel. They easily could have been engineered to expose low permeability bedrock with minimal soil removal. Both would direct surface water runoff to a valley geomorphology that might be dammed to serve as a reservoir or used for farming.

The question then becomes, were these features constructed as roads for the purpose of transporting people or goods, or were they constructed for hydraulic management or both. The answer may be in the location of the various mounds adjacent to the great house. As surface water moves across the western platform to the great house it drains around the north and south perimeters and then directly down slope. The location of the downslope mounds, however, forces water flow to enter one of the two swales. Once in the swales, water flows along the shortest route to a discharge point in the valley for the swale coinciding with Linear 149 or to the natural bedrock channel in the case of swale coinciding with Linear 150 (Figure 3).

COMPARISONS

A preliminary geomorphic assessment of the area surrounding Pueblo Pintado reveals something very similar to the Standing Rock Great House site. Like the great house near Standing Rock Wash, Pueblo Pintado sits at the edge of a broad relatively flat mesa and upslope from a wash. Directly to the south is a flat area with a surface hydraulic gradient directed toward the great house and kivas. Heavy rains could have easily flooded the area around the great house and great kiva. What is most striking about the Pueblo Pintado site is that all the mounds at the site are located south and southeast of the structures. Between and adjacent to the mounds are several swales. This places the mounds and swales directly between the structures and the “up gradient” drainage area. I infer that the mounds and associated swales were designed to direct surface runoff away from the site and down slope to farming areas and the wash. Like Standing Rock Great House, Pueblo Pintado appears to have been designed to fit into the hydraulic environment.

But could the engineered drainage swales at Standing Rock Wash also have been designed to function as roads? Chacoan engineers typically designed their roads to follow very shallow gradients. The South Road follows a gradient of .01 or less for most of its length. Between Credibility Gap Herradura and sections farther north, the engineers made a dogleg to the north in the road at the Windes shrine on Mesita de la Junta (Nials et al. 1987). This allowed them to follow a .01 gradient rather than drop the road into Kin Klizhin Wash at the steeper slope of .026. Along the Coyote Canyon Road the gradient is also typically .01 or less. With the exception of the short section crossing Coyote Canyon, the road gradient is between .01 (Grey Ridge Compound to Coyote Canyon Community) and .014 (Little Ear Herradura section). The inferred route between the Peach Springs community and Toyee Spring would be .01 and follow the 6100-foot contour over it entire length. From Toyee Spring to the Standing Rock community the most direct route would follow a topographic gradient of .02. In contrast, the linear engineered structures coinciding with Linears 149 and 150 just east from the Standing Rock Great House have gradients of .05 and .034 respectively. Alternative routes to Standing Rock Wash from the north or southeast could follow gradients of 0.02 or less. The argument might be made that these steeper segments (i.e. 149 and 150) are only part of longer routes with shallower overall gradients. But as noted above, these sections do not appear to be directed toward anything but Standing Rock Wash. A north route would lead to the wash and could dogleg toward the northeast and hypothetical routes to Chaco Canyon proposed by Marshall et al. (1979). No confirmation evidence of this route has yet been found.

The Standing Rock Community was not alone. Approximately 30 kilometers to the southeast the Dalton Pass and Muddy Water Great Houses and the Kin Ya’a community occur near the South Road leading to Chaco Canyon (Figure 1). Communication and travel routes between these sites and the Standing Rock community are very likely, but formalized roads particularly to the southeast have not been identified. Investigation of the terrain southeast from Standing Rock Great House to Kin Ya’a and the South Road may provide evidence of a southeast extension of the Coyote Canyon Road.

Comparison of the Linears 149 and 150 to the linear associated with the “Toyee segment” of the Coyote Canyon Road highlights the relative engineering that went into these structures. The Toyee segment does not appear to be engineered at all despite the likelihood that it was a key route to a year-round water source. By comparison, the swales coinciding with Linears 149 and 150 are still present and the bordering mounds are also preserved despite being on relatively steep slopes. The degree of earthwork and excavation conducted on these two segments has rendered them clearly visible on aerial photographs and on the ground. Their preservation suggests that they were carefully constructed and maintained.

CONCLUSIONS

Photographic linear analysis has suggested that four ancient roads may converge on Standing Rock Great House (Obenauf 1980). Ground based investigations have confirmed that at least two of these linears show signs of significant engineering. Marshall et al. (1979) have inferred that a northeast route to Chaco Canyon may exist from the Standing Rock Great House and that the swales coinciding with these linears are formalized starting points. But local geomorphology suggests that these linear engineered structures are not roads. They are both relatively short and lead to the same side drainage and valley connecting to Standing Rock Wash. There is no evidence that either structure crosses Standing Rock Wash.   They are “articulated” to the Great House by a carefully arranged group of mounds and swales that direct surface water around the great house from the west and downslope to the heads of these linear swales. Extending away from the Standing Rock Great House and to a valley that seems perfect for farming and/or storing water, the structures cross a slope at gradients of 0.50 and 0.34 which are far steeper than formalized segments of either the Coyote Canyon Road or the South Road.  The shallow soil profile suggests that even if these were roads, they would flood during heavy rains and function as surface water drains. It is likely that this is exactly what the ancient engineers at the Standing Rock community had in mind. The location of the great house at the edge of a flat ridge crest and overlooking a relatively steep slope, and the position of the mounds and linear swales strongly suggests that this community was engineered with the local hydraulic environment in mind.

Water supplies are scarce in the dry season in the San Juan Basin, but heavy rains associated with short duration summer storms are not. Water control systems are common at sites in Chaco Canyon and should be present at other Chacoan engineered communities. At the Standing Rock community, capturing rain from intermittent summer storms and conveying it to a reservoir down slope certainly would provide the community with a more convenient and relatively reliable water supply. But more significantly, these ancient engineers also solved the problem of too much water at the same time. Heavy rains could have easily flooded the area around the great house and great kiva. Minimal slope control directed most surface water toward the edge of the ridge and away from the great house. A more ambitious engineering exercise was required to direct water more precisely around the great house and down slope to growing areas near the wash. With this surface water drainage system in place, flooding throughout the community was also controlled.

Acknowledgments. The maps of Fred Nials, John Stein, and John Roney were instrumental in my development of this hypothesis. John Roney was also helpful in my understanding of the quality of photographic evidence supporting the idea that linear structures are present near the Standing Rock Great House. Eric Force and Ronald Towner made several suggestions that greatly improved the manuscript. I am also grateful to Judi Arviso and Ron Maldonado of the Navajo Nation Historic Preservation Department for their help in my acquiring permission to examine the terrain in and around the site.

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1979    Anasazi Communities of the San Juan Basin, Public Service Company of New Mexico, Albuquerque and New Mexico State Historic Preservation Bureau, Santa Fe.

Nials, Fred, John R. Stein, and John R. Roney

1987        Chacoan Roads in the Southern Periphery: Results of Phase II of the BLM Chaco Roads Project. Cultural Resources Series 1, Bureau of Land Management, Albuquerque.

Obenauf, Margaret S.

1980        The Chacoan Road System. Unpublished Master’s Thesis, Department of Anthropology, University of New Mexico, Albuquerque.

Powers, Robert P., William B. Gillespie, and Stephen H. Lekson

1983        The Outlier Survey: A Regional View of Settlement in the San Juan Basin. Reports of the Chaco Center 3, National Park Service, Santa Fe.

Roney John R.

1992    Prehistoric Roads and regional Integration in the Chacoan System. In Anasazi Regional Organization and the Chaco System, edited by David Doyel pp. 123–131. Anthropological Papers No.5. Maxwell Museum of Anthropology, University of New Mexico, Albuquerque.

Soefaer, Anna, Michael P. Marshall, and Rolf M. Sinclair

1988        The Great North Road: A Cosmographic Expression of Chaco Culture of New Mexico. In World Archaeoastronomy, edited by Anthony F. Aveni, pp. 365-376. Cambridge University Press, Cambridge.

Stein John R., and Stephen H. Lekson

1992    Anasazi Ritual Landscapes. In Anasazi Regional Organization and the Chaco System, edited by David Doyel pp. 87 – 100. Anthropological Papers No.5. Maxwell Museum of Anthropology, University of New Mexico, Albuquerque.

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1988    An Archaeological Reconnaissance of a Late Bonito Phase Occupation near Aztec Ruins National Monument, New Mexico. Southwest Cultural Resources Center, National Park Service, Santa Fe.

Vivian, R. Gwinn

1970        An Inquiry into Prehistoric Social Organization in Chaco Canyon, New Mexico. In Reconstructing Pueblo Societies, edited by William A. Longacre, pp. 59-83. School of American Research, Santa Fe.

1971        Prehistoric Water Conservation in Chaco Canyon. Final technical letter report for National Science Foundation Grant No. GS-3100. on file Albuquerque District Office, Bureau of Land Management.

1974        Conservation and Diversion: Water Control Systems in the Anasazi Southwest In Irrigation’s Impact on Society, edited by Theodore E. Downing and McGuire Gibson, pp. 95-112. Anthropological Papers of the University of Arizona, No. 25. Tucson.

1983    Identifying and Interpreting Chacoan Roads: An Historical Perspective In Chaco Roads Project Phase I, a Reappraisal of prehistoric roads in the San Juan Basin, edited by Chris Kincaid, pp. A1-A33. Bureau of Land Management, Albuquerque.

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Vivian, R. Gwinn, and Robert C. Buettner

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Windes, Thomas C.

1987    Investigation at Pueblo Alto Complex, Chaco Canyon, New Mexico, 1975-1979 Volume I, Summary of Tests and Excavations at the Pueblo Alto Community. Chaco Canyon Studies, Publications in Archaeology 18F. U.S. Department of the Interior, National Park Service, Santa Fe.

Wilcox, David R.

1993    The Evolution of the Chacoan Polity. In The Chimney Rock Archaeological Symposium, edited by J. McKim Malville and Gary Matlock, pp 76-90. General Technical Report No. RM-227. U.S.D.A. Forest Service, Fort Collins, Colorado.

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