PREFACE

Built-in age is a problem because wood decays slowly in arid or semi-arid environments, so wood that isseveral centuries old might have been used as fuel or incorporated into a structure. A radiocarbon datefrom that old wood will overestimate the age of the targeted cultural event. This source of error is notsignificant in terms of cultural chronologies for the Archaic period, but it is an important consideration inassessing the contemporaneity of sites or of features within a site. It also is an obvious source of error forsites dating to the Ceramic and Protohistoric periods, because the cultural chronologies for these periodsare more fine-grained. The radiocarbon date from a piece of wood also will be the average of the annualrings in that sample and not an estimate of the date when the tree died. Thus, if a timber containing 500annual rings were dated, the resulting radiocarbon date would predate the age of the outer ring by about250 years. This is cross-section effect. These potential sources of error can be avoid or minimized bydating annuals or short-lived perennials whenever possible. Small twigs or branches are better than largerfragments, since cross-section effect is less of a problem and they are less likely to have significant builtinage. If larger fragments must be used, the outer 10 or 20 rings can be stripped off and submitted fordating.Thermoluminescence (TL) dating also has some potential applications in the region. The standard errorfor TL dates incorporates most of the major potential sources of error, which makes them more directlyamenable to statistical analysis than radiocarbon dates. The other major advantage of this technique isthat sherds can be dated directly, so there is little question that the date can be linked to the targetedcultural event. The resolution of what are termed survey TL dates is ±20% which, for the general age ofoccupations in the southeastern New Mexico, is generally lower than that of radiocarbon dates. Theresolution can be improved to ±5-10%, though, if multiple samples of approximately the same age aredated and, if the soil dose rate can be measured by inserting TL probes at representative sites within thestudy area.PaleoindianThe Paleoindian period in southeastern New Mexico is roughly dated between 11,500 and 8000 BP.Chronological divisions of this period are based on a series of complexes defined primarily by variationsin projectile point form. The date ranges attributed to these complexes are supported to varying degreesby radiocarbon dates and stratigraphic associations, often from sites outside of the region. Because pointstyles are often the only basis for dating Paleoindian sites in southeastern New Mexico, issues ofchronology and typology are inextricably linked.In discussing the chronological problems associated with the Paleoindian period, Sebastian and Larralde(1989:23) echoed Cordell’s (1979:15) concern that too few radiocarbon dates were available forPaleoindian sites in the Plains and Southwest to build a reliable chronology. Since that overview waspublished, the number of radiocarbon dates associated with Paleoindian occupations in the Plains andSouthwest has almost tripled (Eighmy and LaBelle 1996;Table 1). These new dates have allowed somerefinement of the projectile point chronology, particularly for the fluted series points.There is currently no clear indication of a pre-Clovis occupation in southeastern New Mexico, so theClovis complex remains the earliest, definitive evidence for human occupation of the region.Radiocarbon dates from Blackwater Locality No.1, Miami, and Lubbock Lake bracket the Clovisoccupation on the Llano Estacado between 11,400 and 10,800 rcy BP (Holliday 1997:177). Based on theradiocarbon dates from Lehner and Murray Springs in southeastern Arizona, Haynes (1993:220) arguesthat the actual interval may be even shorter, possibly 11,200 to 10,900 rcy BP.4-3