PREFACE

Except for Brantley Reservoir, all of the sequences discussed above rely heavily on ceramic cross-datingin assigning temporal spans to specific phases. As those sequences were formulated 20–40 years ago,there is a clear need for a systematic review of the current date ranges assigned to the ceramic types, andfor revision of the dates assigned to the various phases. Additional absolute dates from local sites are alsoneeded to further refine the ceramic chronology.Radiocarbon and thermoluminescence dates can be used to refine the dates of some long-lived types, buthigher-resolution dendrochronological and archaeomagnetic dates will be necessary for the later paintedwares. Radiocarbon dates typically have 95% confidence limits of 200 years or more. Radiocarbon dateson wood charcoal are also potentially affected by the “old wood” problem and cross-section effect. Thebest that can be done to improve resolution is first to date annuals or small shrubs whenever possible, andsecond to run two or more dates from the same fragment of material and average the dates to reduce thestandard error. Thermoluminescence dating has a similar error range but there is no “old wood” problem,and it can be used to date sherds directly. On the other hand, collecting the samples is not asstraightforward as radiocarbon dating nor is its reliability fully proven. Dendrochronology has rarelybeen successful at sites in the region owing to the predominant aboriginal use of complacent species forconstruction timbers. Archaeomagnetic dating can also yield relatively precise dates, but its applicabilitymay be limited primarily to structural sites.The dating of Jornada Brown is particularly critical, as it relates directly to the question of when ceramicswere introduced into southeastern New Mexico. As the phase sequences indicate, dates for the initialappearance of ceramics in the region has been estimated at anywhere from AD 750 to 950. Based theradiocarbon dates from Deadman’s Shelter (Hughes and Willey 1978), however, Jornada Brown potterywas being produced by AD 200. Conversely, the absence of ceramics at Sunset Archaic sites, whichappears to have been repeatedly occupied between about AD 1 and AD 400, suggests that pottery was notin widespread use in the Sierra Blanca area until AD 400–500 (Wiseman 1996:187–188). Additionalabsolute dates are obviously needed from sites with plain brownwares to determine when pottery firstappeared in southeastern New Mexico and whether it was introduced at different times in different partsof the region. Nevertheless, the evidence currently available indicates that the ceramic period beganseveral centuries earlier than originally assumed, and the Ceramic Period chronologies should bemodified accordingly.There is a similar problem in dating the end of the Ceramic period in southeastern New Mexico. Whereasceramic dating of the initial occupation of a site is based on the ceramic types present, dating the end ofthe occupation is based in part on what ceramic types are absent. In southeastern New Mexico, the enddates for latest Ceramic period sites are typically based largely on the presence of Glaze A and absence oflater glazewares, suggesting that the sites were abandoned in the mid-to-late fourteenth century. In thesouthern Rio Grande valley, however, Marshall and Walt (1984:138) note that Glaze A appears to persistinto the fifteenth century. More recently, it has been suggested that Glaze A may date as late as the earlysixteenth century (Eckert 2006; Snow 1997).Another chronological issue is reconciling the local phase sequences to facilitate regional comparisons.In their overview for southeastern New Mexico, Katz and Katz (2001:37–40) address this problem bydividing the Ceramic period into seven regional phases: Formative 1(AD 500–750), Formative 2 (AD 750–950), Formative 3 (AD 950–1075), Formative 4 (AD 1075–1125), Formative 5 (AD 1125–1200),Formative 6 (AD 1200–1300), and Formative 7 (AD 1300–1375). To the extent that the date ranges for theregional phases are common to multiple local phases, it provides a provisional framework for regionalcomparisons.4-16