VOLUME 28 / NUMBER 1 / 1986 Published by THE AMERICAN JOURNAL OF SCIENCE Editor MINZE STUIVER Associate Editors To serve until January 1, 1989 STEPHEN C PORTER Seattle, Washington To serve until January 1, 1987 W G MOOK Groningen, The Netherlands HANS OESCHGER Bern, Switzerland To serve until January 1, 1987 RONALD B DAVIS Orono, Maine To serve until January 1, 1990 ANDREW MOORE I RENEE S KRA Kline Geology Laboratory Yale University New Haven, Connecticut 06511 ISSN: 0033-8222 NOTICE TO READERS AND CONTRIBUTORS Since its inception, the basic purpose of Radiocarbon has been the publication of com- pilations of 14C dates produced by various laboratories. These lists are extremely useful for the dissemination of basic 14C information. In recent years, Radiocarbon has also been publishing technical and interpretative arti- cles on all aspects of 14C. We would like to encourage this type of publication on a regular basis. In addition, we will be publishing compilations of published and unpublished dates along with interpretative text for these dates on a regional basis. Authors who would like to compose such an article for his/her area of interest should contact the Managing Editor for infor- mation. Another section is added to our regular issues, "Notes and Comments." Authors are invited to extend discussions or raise pertinent questions to the results of scientific inves- tigations that have appeared on our pages. The section includes short, technical notes to relay information concerning innovative sample preparation procedures. Laboratories may also seek assistance in technical aspects of radiocarbon dating. Book reviews will also be included for special editions. Manuscripts of radiocarbon papers should follow the recommendations in Suggestions to Authors* and RADIOCARBON Style Guide (R, 1984, v 26, p 152-158). Our deadline schedule for submitting manuscripts is: For Date Vol 29, No. 1, 1987 Sept 1, 1986 Vol 29, No. 2, 1987 Jan 1, 1987 Vol 29, No. 3, 1987 May 1, 1987 Half life of 14C. In accordance with the decision of the Fifth Radiocarbon Dating Conference, Cambridge, 1962, all dates published in this volume (as in previous volumes) are based on the Libby value, 5570 ± 30 yr, for the half life. This decision was reaffirmed at the 11th International Radiocarbon Conference in Seattle, Washington, 1982. Because of various uncertainties, when 14C, measurements are expressed as dates in years BP the accuracy of the dates is limited, and refinements that take some but not all uncertainties into account may be misleading. The mean of three recent determinations of the half life, 5730 ± 40 yr, (Nature, v 195, no. 4845, p 984, 1962), is regarded as the best value presently available. Published dates in years BP can be converted to this basis by multiplying them by 1.03. AD/BC Dates. In accordance with the decision of the Ninth International Radiocarbon Con- ference, Los Angeles and San Diego, 1976, the designation of AD/BC, obtained by sub- tracting AD 1950 from conventional BP determinations is discontinued in Radiocarbon. Authors or submitters may include calendar estimates as a comment, and report these esti- mates as cal AD/BC, citing the specific calibration curve used to obtain the estimate. Cal- ibrated dates will now be reported as "cal BP" or "cal AD/BC" according to the consensus of the Twelfth International Radiocarbon Conference, Trondheim, Norway, 1985. S14C. Meaning of In Volume 3, 1961, we endorsed the notation A (Lamont VIII, 1961) for geochemical measurements of 14C activity, corrected for isotopic fractionation in samples and b14C in the NBS oxalic-acid standard. The value of that entered the calculation of A was defined by reference to Lamont VI, 1959, and was corrected for age. This fact has been lost sight of, by editors as well as by authors, and recent papers have used 6140 as the observed deviation from the standard. At the New Zealand Radiocarbon Dating Conference it was recommended to use S14C only for age-corrected samples. Without an age correction, the value should then be reported as percent of modern relative to 0.95 NBS oxalic acid (Pro- ceedings 8th Conference on Radiocarbon Dating, Wellington, New Zealand, 1972). The Ninth International Radiocarbon Conference, Los Angeles and San Diego, 1976, recom- mended that the reference standard, 0.95 times NBS oxalic acid activity, be S1sC normalized to = -19%0. '4C In several fields, however, age corrections are not possible. 6 and A, uncorrected for age, have been used extensively in oceanography, and are an integral part of models and theories. For the present, therefore, we continue the editorial policy of using A notations for samples not corrected for age. *Suggestions to Authors of the Reports of the United States Geological Survey, 6th ed, 1978, Supt of Documents, U S Govt Printing Office, Washington, DC 20402. Vol 28, No. i Radiocarbon 1986 CONTENTS Spatial and Temporal Distribution of Radiocarbon Ages on Rodent Middens from the Southwestern United States Robert H Webb ......................................................................................... 1 DATE LISTS Gif Georgette Delibrias, M-T Guillier, and Jacques Labeyrie Gif Natural Radiocarbon Measurements X ............................................ 9 IRPA Michele Dauchot-Dehon, Mark Van Strydonck, and Jos Heylen Institut Royal du Patrimoine Artistique Radiocarbon Dates XI ............. 69 ISGS Chao Li Liu, Kerry M Riley, and Dennis D Coleman Illinois State Geological Survey Radiocarbon Dates VIII ....................... 78 ISGS Chao Li Liu, Kerry M Riley, and Dennis D Coleman Illinois State Geological Survey Radiocarbon Dates IX .......................... 110 KN Th Schulte im Walde, JC Freundlich, Hermann Schwabedissen, and Wolfgang Taute Koln Radiocarbon Dates III .................................................................. 134 Lu Soren Hakansson University of Lund Radiocarbon Dates XVIII........................................ 141 NOTES AND COMMENTS Glassy Microspherules from Bomb Combustion of Charcoal Richard Burleigh and Nigel Meeks ............................................................ 165 14C Announcement of a New Collaborative Study for Intercalibration of Dating Laboratories EM Scott, MS Baxter, TC Aitchison, DD Harkness, and GT Cook ................. 167 Radiocarbon Dating Blood Residues on Prehistoric Stone Tools DE Nelson, TH Loy, JS Vogel, andJR Southon........................................... 170 Radiocarbon Proceedings of the 12th International Radiocarbon Conference Trondheim, Norway, June 24-28, 1985 Radiocarbon, Volume 28, Number 2A & B, 1986 @ $60.00 Please order from: Radiocarbon Kline Geology Laboratory Yale University PO Box 6666 New Haven, CT 06511 11 [RADIOCARBON, VOL 28, No. 1, 1986, P 1-8] Radiocarbon 1986 SPATIAL AND TEMPORAL DISTRIBUTION OF RADIOCARBON AGES ON RODENT MIDDENS FROM THE SOUTHWESTERN UNITED STATES ROBERT H WEBB U S Geological Survey, 300 W Congress Street, FB-44 Tucson, Arizona 85701 INTRODUCTION The analysis of rodent middens, principally deposited by packrats (Neo- toma sp), has rapidly become the most important paleoecologic and paleo- climatologic tool in the southwestern United States. The recent discovery of rodent middens created by stick-nest rats (Leporillus sp) and rock walla- bies (Petrogale sp) in Australia (Green et al, 1983; P S Martin, oral commun, 1984) and by dassie rats (Petromus typicus) in South Africa (L Scott, oral commun, 1984) portends the use of midden analysis in arid regions world- wide. Several recent reviews of southwestern paleoecology (eg, Spaulding et at, 1983) rely heavily on rodent middens for ecologic and climatic recon- structions. Here I provide a compilation of the spatial and temporal distribution of 14C dates on rodent middens from the Southwest, superseding that of Mead, Thompson, and Long (1978). Packrat middens are usually unstrati- fied, are possibly occupied at different times, and commonly require multi- ple 14C dates (Spaulding, 1983). Therefore, the chronology of rodent mid- dens depends entirely upon 14C dates. The sampling bias and statistical distribution of 14C dates in time and space strongly affect regional paleo- ecologic interpretations derived from rodent middens. METHODS I4C dates and the latitude, longitude, and elevation were collected from all published and selected unpublished studies of rodent middens in the southwestern United States and northern Mexico (see Bibliography). "Rodent middens" refers to predominantly indurated deposits formed by packrats (Neotoma sp) and also include several porcupine (Erethizon dorsa- tum) middens from New Mexico, Arizona, and Colorado (Van Devender, Betancourt & Wimberly,1984). Unpublished dates were obtained from the files the Paleoenvironmental Laboratories at the University of Arizona of 14C and from many individuals associated with midden research. Multiple dates for several middens were included as separate samples because each date, not necessarily each midden, is the basis for age determinations. 1 2 Robert H Webb RESULTS A total of 910 14C dates on rodent middens was obtained for analysis and an additional 42 "modern" middens were dated by the presence of chlorophyllous materials. The University of Arizona analyzed 57% of the dates; 15 other laboratories analyzed the remaining 43%. During 1983-84, researchers obtained 39 of the 91014C dates from small samples using the University of Arizona tandem accelerator mass spectrometer (TAMS) (Don- ahue et al, 1983). A histogram of 14C dates (fig 1) indicates a bimodal distribution