CHACOAN AND POST-CHACO OCCUPATIONS IN THE MIDDLE SAN JUAN REGION: CHANGES IN SETTLEMENT AND POPULATION

Abstract

The Middle San Juan region occupies a critical location between Chaco Canyon to the south and Mesa Verde to the north. Site-settlement analysis and demographic reconstruction reveal continuous occupation across the Pueblo II–III transition and steady population growth for 200 years prior to regional depopulation in the late A.D. 1200s. These findings challenge previous research which postulated two distinct occupations: Chacoan domination during the Pueblo II period, followed by abandonment and subsequent immigration from Mesa Verde comprising reoccupation during the Pueblo III period. Our research indicates that late Pueblo II Chacoan colonization at Salmon Pueblo (along the San Juan River) and Aztec Ruins (on the Animas River) occurred abruptly in areas with little previous settlement. In contrast, much smaller Chacoan outliers were built within dense, extant communities in the La Plata Valley and lower San Juan River between A.D. 1075 and 1125. Instead of abandonment coinciding with the region-wide drought during the mid-1100s, we argue that demographic trends and other archaeological evidence indicate sustained population growth coinciding with changes in social identity during the post-Chaco era. Depopulation did not occur until the late thirteenth century when a similar process affected the entire Four Corners area.

La parte media de la región de San Juan tiene una ubicación crítica entre Chaco Canyon al sur y Mesa Verde al norte. El análisis de asentamiento de sitios así como reconstrucciones demográficas revelan ocupaciones continuas durante la transición Pueblo II-III, así como crecimiento poblacional constante por 200 años previo al despoblamiento regional en la parte tardía del siglo 13. Estos hallazgos desafían investigaciones previas que postulaban dos ocupaciones diferentes: una ocupación Chaco durante el periodo Pueblo II, seguido de abandono y subsecuente migración de Mesa Verde con una reocupación durante el periodo Pueblo III. Nuestra investigación indica que la colonización Chaco del periodo Pueblo II tardío en Salmon Pueblo (en el río San Juan) y en Aztec Ruins (en el rio Ánimas) sucedió de manera abrupta en áreas con escaso asentamiento previo. En contraste, muchos centros Chaco periféricos fueron construidos con densas comunidades restantes en el valle La Plata y la región baja del rio San Juan entre 1075 y 1225 D.C. En lugar de abandono coincidente con la sequía regional durante el siglo 12, sostenemos que tendencias demográficas y otra evidencia arqueológica indican un crecimiento poblacional constante que coincide con cambios en la identidad social durante la era post-Chaco. El despoblamiento no ocurrió sino hasta la parte tardía del siglo 13, cuando un proceso similar afectó toda el área de las Cuatro Esquinas.

ACKNOWLEDGMENTS

We appreciate the invitation by Ben Bellorado and Richard Wilshusen to participate in the symposium “East of Eden, North of Chaco.” Ben provided thoughtful discussion while the symposium was in the planning stage, as well as afterwards when he urged us to combine two conference papers into a single synthetic article and to widen our interregional comparisons. The symposium discussants, Ruth Van Dyke and Mark Varien, helped us develop our thoughts on the transition from the Chacoan to Post-Chaco eras in the Middle San Juan region. Mark also provided the latest demographic results of the Village Ecodynamics Project while we worked on the original symposium papers. Although other friends and colleagues who have contributed to our perspective and knowledge of the area are too numerous to list, we are grateful for insights they have shared with us. Development of the Middle San Juan site-settlement database has been assisted by a grant from the National Science Foundation (BCS-0520579).