Around a thousand years ago, an astonishing series of spur roads were built throughout the Four Corners area, focusing on the Chaco Canyon region. Here, Science Moab chats with archaeologist and anthropologist Rob Weiner, whose research focuses on these monumental trails built by the ancestors of the Pueblo and Diné peoples. Weiner studies at the University of Colorado Boulder.
Moab Science: How long has Chaco Canyon been inhabited?
Weiner: There have been people living in Chaco Canyon from at least the Archaic period to more recent times, 17-1800. But the main period that archaeologists usually focus on is from the 800s to around 1200, when people were building incredible monumental masonry architecture: large multi-story buildings aligned with the cosmos and grand roads. [Descendent Indigenous communities assert their presence on the Four Corners landscape has been since time immemorial. -Science Moab]
Science Moab: How have these roads been studied and photographed in modern times?
Weiner: For as long as archaeologists have been studying these roads, seeing them from above has always been the best way to see them. Especially in the early morning or evening when the light is sweeping across the roads, low angle sunlight really brings them out with intense shadow enhancement. The BLM used a lot of aerial photography and also aerial reconnaissance, where they flew in small planes to see the roads from above.
Moab Science: Is there some kind of pattern to these roads, some kind of symmetry around the Chaco area?
Weiner: I think it is very important that we distinguish at least two types of roads, one of which is regional roads. There is the North Trail, which runs 35 miles north of Chaco Canyon, the South Trail which runs about 40 miles southwest of Chaco Canyon, and the West Trail which runs about the same distance into the Chuska Mountains. At least three of these regional roads connect Chaco Canyon itself with the margins of the San Juan Basin. But most of the roads are actually these very short spoke-shaped segments in Chaco and the atypical places, where Chaco architecture was built outside the canyon in local communities. The regional roads, so the Camino del Norte, the Camino del Sur and the Camino del Oeste, definitely emanate from the Chaco, and that is a phenomenon of the southern San Juan basin. But the smaller paths that start at outliers and radiate out lie over a wide area.
Science Moab: Where do these roads lead?
Weiner: One of the things we consider with roads is that there are different types of roads that lead to different types of destinations probably for different purposes. One strong association is that roads lead to specific places in the landscape: many roads lead to springs or hills, or point to prominent mountain peaks. Sometimes the paths lead back to a building that had been depopulated hundreds of years before, so they will build a path to a site that is no longer used. We have examples where roads connect large houses. Another possible destination of the roads is actually the astronomical bodies, where the sun will rise or set on the summer solstice or on the winter solstice.
Science Moab: Are all these paths linear?
Weiner: One of the aspects of the Chaco roads that has caught people’s attention is how linear they are. You know, something is a Chaco road for two reasons. One, it’s extremely wide, they average 30 feet, which is 30 feet wide. So, when you look at an aerial photo, you know it’s a Chaco road because it has that incredible width and it has that straight linearity. Conversely, if you’re looking at a historic highway or wagon track, it meanders, comes to a topographical obstacle, and goes around it. The Chaco roads go directly up the cliffs. I was on South Road a couple of weeks ago where the road comes up to this little mound and goes right over it.
Moab Science: Can you ever find traces of roads on the ground, instead of airborne?
Weiner: Often nothing. Sometimes a linear depression can be seen. Sometimes you will see changes in the vegetation because the paths were created by being dug into the earth, and water would collect there. And so, sometimes a differential growth of the vegetation is obtained, either of different species or of different densities within the road bed. Because the roadbeds have been excavated and the excess piled to one side, linear scatterings of pebbles can sometimes be found with caliche, the naturally occurring calcium deposits in the undersides of the rocks. When you dig them up and toss them to the side, sometimes that can leak a layer, which shows up on top because you dug it underground and dumped it. So sometimes you find these lines of caliche rocks about 30 feet apart in linear lines, and that’s an example of an excavated road that’s since been filled in. One of the most intriguing signs of a path in the ground are linear ceramic paths. parts. What’s really fascinating is that these pieces don’t fit together again. They are from different ships.
Science Moab is a nonprofit organization dedicated to engaging community members and visitors with the science that happens in southeastern Utah and the Colorado Plateau. For more information and to listen to the rest of this interview, visit www.sciencemoab.org/radio.