2009-08-24_REVISION - C1982056 (4)

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The Settled Period is reflected in the record at at a number of sites in the Yampa River basin, including two occupations of the Red Army Rockshelter (Pool 1997) and in dated features at 5RT139 (Tucker 1981). Basin houses appear, all the major Archaic Era styles of projectile points in the regional assemblage are present, and a cultural pattern that lasted until about 3400 BP was in place. The division between the Settled Period and the Transitional Period in the Northern Colorado sequence at 4450 BP occurs approximately at the beginning of the period of stability marked by the initial dates for the Spring Creek Paleosol (ca. 4700 BP). Transitional Period. The Transitional Period exhibits some continuity with the preceding period but with less evidence of sedentism, greater seasonality in the use of higher elevations, and greater variability in material culture (Reed and Metcalf 1999:79). Despite evidence for variability in material culture, however, a strong thread of continuity is also present. Use of pit features and basin house structures continues, there is little change in occupation intensity or in site function from the preceding period, and there is little to suggest a distinctive shift in subsistence. One date from the Red Army Rockshelter (Pool 1997) falls into this cultural period. At the height of the stable period between 4600 BP and 3400 BP, archaeological components assigned to the McKean Complex appear. The nature and meaning of McKean Complex occupation in the Wyoming Basin and Northern Colorado Plateau is not well understood despite the fact that projectile points assigned to the complex show up in numerous localities. The McKean Complex is solidly assigned to the Middle Plains Archaic on the northwestern Plains with a general age range of 5000 to 3000 BP (Frison 1991:91). Point types assigned to the McKean Complex include the McKean Lanceolate point, the Duncan-Hanna series, and the Mallory point. In the best dated of the Yampa valley contexts, McKean components date around 4200 to 3800 BP (Metcalf and McFaul 2006; O'Neil 1980:88). The dates for McKean manifestations are in the middle of the date range for the formation of a regionally expressed Spring Creek Paleosol (Metcalf and McFaul 2006) and probably correspond to a period of more favorable climatic conditions. Metcalf (1987) suggested that post- Altithermal expansion of bison ranges may have led McKean hunters into new territories where other Archaic peoples lived. While this supposition has not been conclusively demonstrated, the idea has gotten some support from data in Wyoming and from a slight increase in bison use in some Yampa valley sites (McNees 1999:3-65; McDonald 2000). Whatever the nature of McKean occupations, however, the influence of such occupations was not sufficient to displace the stable Archaic Era base. Perhaps climatic conditions were mesic enough to increase carrying capacity to a degree where both apparent adaptations worked. Terminal Period. The latest Archaic Era time period is defined as beginning about 2950 BP and ending about 1950 BP. The Terminal Period was apparently initiated by a time of stress in the subsistence systems and it witnessed experiments in use of the bow-and-arrow, early experiments in growing corn, an increase in the use of seed processing and other lower rate-of-return foods, and more apparent mobility in subsistence systems, as measured by a decrease in the use of basin houses (Reed and Metcalf 1999:79). Regionally, the number of dated components increases during this period, but in the Yampa valley, components of this time period are less frequent than for the earlier two Archaic periods. One date from the Red Army Rockshelter pertains to this period, however (Pool 1997). There is no clear demarcation that solidly ends the cultural period. 6