Excavations of a Pueblo site in the Four Corners region linked to the Chaco culture that once dominated the Southwest indicate the site was still occupied well after the collapse of the ancient empire about 1125.
Known as the Great Bluff House, the site harbors the remains of a two-story structure known as a "great house" as well as a great kiva and sections of prehistoric roads and berms near the town of Bluff, Utah. 1997 excavations of the berms -- long mounds of earth and trash about a meter high -- turned up corn cobs that were radiocarbon dated to about 1212, said University of Colorado at Boulder assistant anthropology Professor Catherine Cameron.
The Bluff site is being excavated by a CU-Boulder student field team in collaboration with the Southwest Heritage Foundation, a nonprofit group, and Abajo Archaeology, a local contract firm in Bluff. The archaeological project has been funded primarily by the National Geographic Society for the past two summers.
Architecturally similar to great houses in Chaco Canyon, N.M., the heart of the Chaco culture that was located about 125 miles to the southeast, the Bluff site is thought to have been one of the most distant Chacoan "outposts."
"It was an eye-opener, because it indicates the berms were built long after Chaco collapsed," she said. The Bluff people may have "experienced a religious revival," perhaps tied to the growing influence of the Aztec culture centered near present-day Aztec, N.M., roughly 100 miles to the southeast.
Cameron directs the student field school, now in its third year, with her husband, Steve Lekson, an assistant professor at the University of Colorado Museum. Fourteen students will be participating in the 1998 excavation, including nine from CU-Boulder and one 1998 graduate of Boulder High School. The field school will run from June 1 to July 2.
The berms may have served as bases for wooden defensive structures around the Bluff site, said Lekson. "There was a lot of violence in the region in the 1300s, and Chaco was not around anymore to keep a lid on it." The team will probe the berms further in June for signs of ancient postholes.
Although the Chaco influence stretched through 40,000 square miles of the Southwest during its zenith in the early 1100s -- an area about the size of Ohio -- the culture abruptly disappeared about 1125, most likely because of drought, warfare or internal political strife, archaeologists believe.
The CU team also found a series of antechambers around the exterior of Bluff's great kiva -- a large ceremonial structure about 30 yards from the great house -- in 1997. The antechambers may have served as storage areas or dressing rooms for priests that performed ceremonies there, said Cameron.
Artifacts from Bluff include locally made pottery shards that appear to copy typical Chaco pottery. Geochemical tests on several pieces of obsidian from Bluff show they came from a quarry near Jemez, N.M. Obsidian from the Jemez source was commonly found at sites in Chaco Canyon.
In addition, an ancient sash made from the feathers of macaws native to Mexico -- and which were regularly traded through Chaco Canyon -- was found in a cave north of Bluff several years ago. "I imagine this object passed through the Bluff site at some point," said Lekson.
Additional findings in 1997 included more evidence the great house was built in several episodes, Cameron said. While the western portion of the 115-foot-long house is one story with rooms built from sandstone slabs, a later addition constructed on the east side features two stories of thick "core-and-veneer" walls similar to the stout walls in Chaco Canyon great houses.
A typical Chacoan kiva also had been added onto the Bluff great house with a flat roof that may have served as a small plaza, she said. The great house may have been purely ceremonial or inhabited by a few elite families.
Animal bones in the middens, or trash pits, excavated by the students, indicated Bluff people were eating deer and small game, said Lekson. He estimated 20,000 to 40,000 people lived between the Bluff site and the Aztec site by the 1300s, depleting natural resources and likely accelerating conflict.
Lekson believes the Chaco Canyon people may have moved north to the Aztec site after the Chaco culture collapsed, establishing a new center of power in the Southwest and perhaps incorporating new religious beliefs.