Alluvial Chronology of the Tesuque Valley, New Mexico

Two Recent alluvial terraces are well developed along Rio Tesuque downstream from the limits of the Sangre de Cristo Range. The high terrace, which stands 18-20 feet above the present stream, is a prominent surface ¼-½ mile wide. The low terrace, which stands 8-10 feet above the stream, occupies a narrow strip adjacent to the channel. Charcoal from a depth of 13 feet in the high-terrace alluvium yielded a radiocarbon date of 2,230 ± 250 years. Deposition of high-terrace alluvium had ceased by A.D. 1200-1250, as indicated by the presence of datable pottery in the upper portion of the alluvium and by the dates of Pueblo sites built on the high terrace. Computations based on this chronologic information suggest that rates of sediment production during the period of high-terrace deposition were similar in magnitude to modern rates in this area.