Arizona Radiocarbon Dates Ix: Carbon Isotope Dating of Packrat Middens

Abstract
The carbon isotope analyses reported here include all radiocarbon dates run on packrat middens in the United States and Mexico by the Arizona radiocarbon laboratory through October 1977. All samples described below report dates by CO2 (0.5 or 2.0L) counting. Age calculations are based on a 14C half-life of 5568 years, using 0.949 NBS oxalic acid as the modern value. Errors, based on counting statistics, are quoted to ± 1δ; infinite ages quoted to — 2δ.