Archeological Site Locations within the Rio Puerco Drainage Basin
Curt Larsen and Martha Herzog
U.S. Geological Survey
Reston, VA 20192
Archeological site locations can aid in the understanding of population dynamics, settlement pattern analyses, as well as provide clues to landscape and environmental changes. In New Mexico, a composite record of site locations is maintained by the Laboratory of Anthropology in Santa Fe. In the Rio Puerco drainage basin, a total of 10,905 known sites are recorded. These sites range in age from paleoindian (9,500 to 9,000 BC) to 19th and 20th century historic settlements. The types of sites in the database range from lithic scatters to masonry and adobe structures. Collecting bias notwithstanding, clear concentrations of sites are present within the upper and middle Rio San Jose sub basin, and the upper and middle Rio Puerco valley. The greatest numbers of sites are less than 2000 years old and fall within a puebloan cultural grouping commonly referred to as Anasazi. Using the Pecos chronological framework for discussion, there is a gradual increase in site number throughout the Archaic phase (5500-200 BC). Subsequently, site numbers increase at an apparent exponential rate from the introduction of early agriculture in the Late Archaic and Basketmaker II phases (1800 BC - 500 AD) and reach a peak during the Pueblo II phase (900-1100 AD), which corresponds with the maximum expansion and development at Chaco Canyon to the west. Site numbers fall off rapidly after this peak such that by the Pueblo IV phase (1300-1600 AD) the number of sites recalls the site density of the prior Basketmaker II phase (0-500 AD). Navajo sites make their first appearance in the basin with an apparent depopulation of the area during Pueblo IV. These sites tend to cluster in the northern portion of the Puerco basin in the Torreon sub drainage basin. By the time of Spanish contact in the 16th and 17th centuries, site density increased, but had shifted concentration to the upper Rio San Jose sub basin in the area of the present Acoma and Laguna Pueblos as well as the Jemez Pueblo area of the upper Rio Puerco valley. Although there are few sites in the data base for this period, 18th and early 19th century settlement continued in approximately the same areas as did subsequent Anglo-american and Hispanic occupation during the U.S. Territorial period and the first half of the 20th century.
In terms of landscape and water, Archaic sites are noted in the upper reaches of tributaries in the sub basins as well as the main Rio Puerco valley. Throughout the Archaic there is an apparent eastward shift resulting in site clusters in the middle Rio Puerco valley in the area of Guadalupe. Concentrated occupation continues in the Guadalupe area from Basketmaker II (0-500 AD) through Pueblo III (1100-1300 AD) with peak site density along the alluvial valley of the Rio Puerco immediately downstream from the confluence of the Arroyo Chico with the Rio Puerco and southward to Canons Tapia and Salado near Guadalupe during Pueblo II. Pueblo I and Pueblo II phases also show site concentrations west of Mount Taylor in the upper Rio San Jose valley suggesting physical continuity with the cultural center at Chaco Canyon.
It is significant to note that specific sub basins consistently lack archeological evidence. Most notable is the Arroyo Chico sub basin which is underlain by Mancos Shale and is the chief source of sediment carried by the present Rio Puerco. This suggests long term unsuitability for or desire for permanent settlement in this area. In contrast is the adjacent Torrejon sub basin to the north which shows little occupation until Navajo enter the area in the 16th and 17th centuries. This portion of the drainage basin consists of interbedded sandstones and subordinate shale. The Anasazi sites of the middle Rio Puerco valley are well sited for dependable water resources. The Pueblo I through III settlement downstream of the Arroyo Chico are sited to receive water throughout the growing season. Runoff supplied by the Arroyo Chico possibly delivered suitable sediment and water to alluvial floodplains while the upper Rio Puerco, with its headwaters in the Nacimiento Mountains to the north, could be depended upon for sustained water furnished by precipitation in higher elevations and possible snowmelt. Similar conditions exist further downstream in the Guadalupe area where runoff from Mount Taylor supplied water to the western flank of the valley to augment flow from either the Arroyo Chico or the upper Rio Puerco. The latter area also contains abundant springs along the slopes of the Mount Taylor complex.
When viewed through a paleoclimate filter, in this case Grissino-Mayer's tree ring reconstructions from El Malpais National Monument for the past 2000 years, the first concentrated spread of occupation to the middle Rio Puerco valley took place during a suggested higher rainfall period centered about 600 AD. The greatest number of sites, Pueblo II, correspond with a subsequent moist phase between 1000 and 1100 AD and represent the height of development at Chaco Canyon. The subsequent collapse at Chaco Canyon corresponds with drier period centered about 1150 AD. The general abandonment of the area during Pueblo IV (1300 - 1600 AD) also seems synchronous with a two-century shift to drier conditions as well as the entrance of Navajo and the Spanish to the area. The Spanish colonial period, which continued until Mexican independence in the early 19th century, appears to have corresponded with dominantly drier conditions. Rainfall apparently increased during the 19th and 20th centuries during the U.S. Territorial era, with clearly more arid conditions in the mid 1900's and greater moisture frequency over the past half century.
Note:
The uniqueness and sophistication of the New Mexico Laboratory of Anthropology makes it one of a kind. Its important data bases provide insights into the patterns of past human/environment interactions and can be effectively used to view dynamic changes in the ecological setting. Its ARMS database is digitized and available for use by qualified researchers. Although the sites contained in the files are not random (they result from both academic and private industry sources), they show distinctive clustering with regard to landforms, river systems, and in some cases, underlying geological conditions. Conversely, since archeological site survey is required for Federally initiated or funded construction projects, site patterns can also follow pipelines, transmission lines, and highways, hence linear arrangements of sites are not necessarily "roads to Chaco Canyon".
U.S. Department of the Interior
U.S. Geological Survey
This page is
http://esp.cr.usgs.gov/rio_puerco/archeo/index.html
Maintained by Richard Pelltier
Last modified:
14:42:15 on 15-Mar-2006