Refinement of the Chronology of La Quemada, Zacatecas, Mexico, Using Ceramic Seriation

During the Epiclassic period (AD 600–900), the northern frontier of Mesoamerica consisted of a regional network of polities focused on large, hilltop centers, including the site of La Quemada in the Malpaso Valley of Zacatecas, Mexico. Although extensive archaeological research has been conducted at the site, the refinement of its chronology is essential for two reasons: (1) to establish the chronological control necessary to characterize social processes diachronically and (2) to ensure that the occupational history of La Quemada is accurately integrated into the regional chronology of the northern frontier. A combination of frequency seriation, correspondence analysis, and discriminant function analysis results in the recognition of three occupational phases across the areas excavated by the La Quemada-Malpaso Valley Archaeological Project (LQ-MVAP). Our three-phase chronology independently confirms both the intra-context ordering of analytic units and the previously proposed growth trajectory of the site: beginning in the monumental core, expanding into the western flank, and later retracting back into the core. The separation of the LQ-MVAP material record into chronological phases means it is now possible to track changes in the social processes that may have contributed to the formation, maintenance, and decline of La Quemada and other northern frontier polities.

APPLICATIONS OF DENDROCHRONOLOGY IN NORTHWESTERN MEXICO

Although dendrochronological methods have the potential to provide precise calendar dates, they are virtually absent in Mesoamerican archaeological research. This absence is due to several long-standing, but erroneous, assumptions: that tree rings in this region do not reflect annual growth and environmental variability, that an adequate number of samples do not exist, and that tree-ring measurements cannot be useful without modern trees to link prehispanic chronologies. In this article we present data from the sites of La Quemada and Los Pilarillos, located in the Malpaso Valley, Zacatecas, to demonstrate that suitable archaeologically derived samples of dendrochronologically useful species do exist, that the samples from these sites are measurable and cross-datable, and that the tree rings can yield precise calendar dates using a method that “wiggle-matches” radiocarbon dates on tree-ring sequences. The work demonstrates the potential of these methods to address chronological, and, in the future, climatic questions, which have so far eluded archaeological work in the region.

Climate, agriculture, and cycles of human occupation over the last 4000 yr in southern Zacatecas, Mexico

Scholars attribute the growth and decline of Classic period (AD 200–900) settlements in the semi-arid northern frontier zone of Mesoamerica to rainfall cycles that controlled the extent of arable land. However, there is little empirical evidence to support this claim. We present phytolith, organic carbon, and magnetic susceptibility analyses of a 4000-yr alluvial record of climate and human land use from the Malpaso Valley, the site of one such Classic frontier community. The earliest farming occupation is detected around 500 BC and appears related to a slight increase of aridity, similar to the level of the modern day valley. By AD 500, the valley's Classic period Mesoamerican settlements were founded under these same dry conditions, which continued into the Postclassic period. This indicates that the La Quemada occupation did not develop during a period of increased rainfall, but rather an arid phase. The most dramatic changes detected in the valley resulted from the erosion associated with Spanish Colonial grazing and deforestation that began in the 16th century. The landscape of the modern Malpaso Valley is thus primarily the product of a series of intense and rapid transformations that were concentrated within the last 400 yr.

A Population Estimate for the Epiclassic Middle Malpaso Valley (La Quemada), Zacatecas, Mexico

Long-term excavations at two large La Quemada hinterland habitation sites provide data for developing population estimates based on ethnographic studies. Calculations based in part on ratio constants of roofed floor area to excavated space are applied to 183 habitation sites in the valley measured in 1974. These data reveal not only the range of population in the immediate valley, but also in major population aggregates around La Quemada during the period of major occupation (ca. A.D. 700). The mean population within the La Quemada core area is estimated as 6,867 (between 4,578 and 9,155) individuals, with an average population density of 38 persons per km2. Population density within three of the largest nearby settlement aggregates ranges around a mean of 209, 136, and 117 individuals respectively per square kilometer.

Pottery Production and Microcosmic Organization: The Residential Structure of la Quemada, Zacatecas

Incised-engraved pottery and clays from the Malpaso Valley region of northwest Mexico are chemically characterized to investigate the nature of residential organization of the capital settlement, La Quemada, during the Epiclassic period, ca. A.D. 600-900. Scanning-electron microprobe analysis of 115 pottery and 10 clay samples from settlements in the valley, and from middens associated with the civic-ceremonial core of La Quemada and flanking residential terraces, identifies locations of pottery production and indicates patterns of pottery circulation. The distribution of pottery at La Quemada, manufactured in specific outlying settlements, suggests that the social composition of the polity was reproduced in microcosm at the site, and that activities in civic-ceremonial zones involved a greater degree of separation among social groups than those in flanking residential areas.