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Animas-La Plata Project Advances the Archaeological Record of the West Construction project yields unexpected results in prehistory

A seven year archaeological project in support of the Animas – La Plata Project (ALP) outside of Durango, Colorado has resulted in a rewriting of the prehistory of the Four Corners Region.

The ALP Archaeological Project occurs in the locale of Ridges Basin Dam and Lake Nighthorse. Since 2002, Reclamation has conducted data recovery to address impacts from construction and reservoir development. More than 74 sites have been investigated in accordance with a rigid scientific sampling strategy. The work in the project area concentrates on pit house villages dating to the early Pueblo I time period (750 to 850 A.D.) of the Ancient Pueblo (Anasazi) occupation. These sites are much earlier, and precursor to, the famous cliff dwellings found at nearby Mesa Verde (which date to the 1200s). The Ridges Basin people were among the earliest farmers in the northern Southwest, and among the first to settle in villages.

Investigators, led by Dr. James Potter of SWCA Environmental Consultants employ a multistage process utilizing cutting-edge techniques to address the various questions posed by the project’s findings. The process involves:

• Fieldwork: Excavation of pit houses, surface rooms, and midden (trash) areas using horizontal and vertical control using electronic data storage (Total Station and GPS) instrumentation. Recovery included collection and field conservation of artifacts and other materials.
  
  
• Analysis of materials: basic and specialized analyses, including chronometry (dating), ceramics, stone tools, faunal (animal) remains, human remains, geomorphology, and plant and soil samples.

Specific, remarkable, findings include the earliest cultural feature, a fire pit, ever discovered in the Durango area (12,000 years old). A second was the discovery that this is not the first time an impoundment existed at the site of Lake Nighthorse. During the Pueblo I occupation, a natural lake or marsh existed in the same area. A third is the discovery of the foundation of a tower structure on Sacred Ridge, in the center of Ridges Basin. This is the earliest evidence of a tower structure in the Southwest.

What is probably the most remarkable is the brief but intense occupation of Ridges Basin. Ridges Basin, at its peak at about 800 A.D. was home to hundreds of people living in pit house villages. However, more precise analysis indicates the area was occupied for less than 100 years. This provides an ideal case study for examining how and why communities form and eventually disintegrate. As such, the ALP Archaeological Project plays not only a significant role in the development of the cultural history of the region, but of the understanding of early village formation and decline from a global perspective.

For more information visit: www.usbr.gov/uc/progact/animas/

Last updated: Fall/Winter 2008