Durango Herald Online
Archaeologists excavating clues of Ridges Basin
By Dale Rodebaugh
Herald Staff Writer
Fresh data indicate that the ancient inhabitants of Ridges Basin southwest of Durango were there for a much shorter time than previously thought, the archaeologist in charge of excavation said.
A team from SWCA Environmental Consultants is wrapping up four years of investigations this summer because the Animas-La Plata Project, a settlement of American Indian water-right claims, will leave the study area under water within a few years.
“Tree-ring analysis shows there were two distinct periods of occupation,” Jim Potter said on Monday during a tour of the Sacred Ridge, the most significant settlement. “There was a late Basketmaker II period from 200 to 400. After a long hiatus, the area was occupied from 750 to 800 at which time there was a very abrupt abandonment.”
Tree-ring analysis of wood found in pit houses indicates no wood later than the year 803, with intense use of the area in the period 775 to 800, Potter said.
Previous estimates of second-period occupation, which didn’t have the benefit of tree-ring analysis, pegged use of the area from 650 to 850. The earliest tree-ring evidence dates from the 300s.
Narrowing the period of occupation indicates that the basin wasn’t inhabited by a few people moving around, but a lot of people during a relatively short time, Potter said.
“We think that multiple ethnic groups, composing 500 to 1,000 people, lived in the area during the late 700s,” Potter said. “When they left at about 800, they probably dispersed in different directions.”
The inhabitants were probably different to the level of language, Potter said. They were certainly socially diverse, as evidenced by their architecture and how they buried their dead. Modern Puebloans such as the Zia, Acoma, Jemez and Laguna have ties to varying degrees with the inhabitants of Ridges Basin.
Eighty sites, including 72 pit structures, will have been excavated by the time the archaeological field season ends Sept. 30, Potter said. The Sacred Ridge, which overlooked wetlands, was the most populated site, occupied right up to the departure of the ancestral Puebloans.
Three years of data analysis will follow the conclusion of field work, Potter said. Finally, all artifacts, photographs, maps and written records will be housed at the Anasazi Heritage Center in Dolores. All material will be available to researchers and the general public. The Southern Ute Indian Tribe and the Ute Mountain Ute Tribe are interested in the educational and archaeological aspects of the project.
Interpretation of findings is speculative at this point, Potter said, including the reasons the ancestral Puebloans abandoned the basin. Possibilities for their departure could have been environmental (a hard life at high elevation in a cool temperature) or social conflict (trauma evidenced in bones).
In addition to the chronology gleaned from analyzing tree rings, geological evidence indicates Ridges Basin was a very marshy environment, Potter said. Prehistorically, the basin contains a natural lake fed by what today is known as Basin Creek.
Obsidian artifacts from the Jemez Mountains in northern New Mexico and redware shards and vessels from today’s Utah were uncovered in Ridges Basin excavations. Their presence suggests trade connections with neighboring groups, Potter said.
Once excavation is done, archaeologists will have literally millions of artifacts (a single shard is an artifact) to analyze, Potter said. Projectile points, charred botanical matter (corn, wood, seeds and tobacco), bones and ceramics will be examined.
“We have the skeleton of what the Ridges Basin settlement looked like,” Potter said. “We’ll flesh it out in the next three years.”