• 13C Variation in Limestone on an Aquifer-Wide Scale and Its Effects on Groundwater 14C Dating Models

      Muller, A. B.; Mayo, A. L. (American Journal of Science, 1986-01-01)
      In modeling the initial 14C activity of ground waters, the delta-13C of marine limestone is taken conventionally to vary little about 0 per mil PDB. This variation was found to be 6.28 per mil in samples taken over intervals from 10^-2 to 1^5 meters in the Mooney Falls Member of the Redwall Limestone in northern Arizona. Such a variation will cause appreciable variability in the results of all four initial activity models tested. The variability, due primarily to a numerical instability in the models dependent on this parameter, can introduce significant uncertainty into groundwater "age" calculations.
    • A Discussion of an Alternate Approach to the Evaluation of Sample Contamination

      Gurfinkel, D. M. (American Journal of Science, 1986-01-01)
      An approach to the evaluation of sample contamination based on the monitoring of contaminant removal during pretreatment is described. Spot tests and colorimetric reactions which could be adapted for this purpose are suggested.
    • Chemical Isotope Dilution for 14C AMS and the Potential for GC/AMS

      Gillespie, Richard (American Journal of Science, 1986-01-01)
    • Index

      American Journal of Science, 1986-01-01
    • KSU Radiocarbon Dates I

      Yamada, Osamu; Kobashigawa, Akira (American Journal of Science, 1986-01-01)
    • Laboratories

      American Journal of Science, 1986-01-01
    • Lódź Radiocarbon Dates II

      Kanwiszer, Andrzej; Trzeciak, Pawel (American Journal of Science, 1986-01-01)
    • Pretoria Radiocarbon Dates III

      Vogel, J. C.; Fuls, Annemarie; Visser, Ebbie (American Journal of Science, 1986-01-01)
    • Radiocarbon Accelerator (AMS) Dates for the Epipaleolithic Settlement at Abu Hureyra, Syria

      Moore, A. M. T.; Gowlett, J. A. J.; Hedges, R. E. M.; Hillman, G. C.; Legge, A. J.; Rowley-Conwy, P. A. (American Journal of Science, 1986-01-01)
      The prehistoric settlement of Abu Hureyra in Syria was occupied in both the Epipaleolithic and Neolithic periods. It has provided significant evidence for changes in economy at the time of the inception of agriculture in southwest Asia. Twenty accelerator mass spectrometry (AMS) dates have been obtained to determine the duration of occupation of the Epipaleolithic settlement there and the precise age of samples of cereal grains and animal bones found within it. The results have demonstrated that the AMS technique can answer such questions because it dates exceedingly small samples with high precision. The dates indicate that the Epipaleolithic settlement was inhabited for about a millennium, from before 11,000 to nearly 10,000 BP, significantly longer than had been anticipated from study of the artifacts.
    • Radiocarbon Dates from an Upland Site of the Kona Field System, Hawai'i Island, Hawaii

      Kawachi, C. T. (American Journal of Science, 1986-01-01)
      The following samples were excavated in July 1985 in an upland (elev 609 m) prehistoric agricultural site in the Kona Field System on the west coast of Hawai'i Island. 14C measurements were done by Beta Analytic Inc, Coral Gables, Florida. The samples were first carefully examined and picked for rootlets and any other non-contemporaneous carbonaceous materials. They were then subjected to an alternating series of hot acid and alkali solutions, interspersed with washings to neutrality with hot distilled water to eliminate carbonates and humic acids. After gentle drying the clean charcoal was benzene synthesized and counting of the 14C activity with a liquid scintillation spectrometer measured for 14C content. All steps in the analysis proceeded normally. Soil descriptions are based on information supplied by Patti Spears and Jeff Yamauchi. Hawaii Puaa, North Kona series Charcoal from 2 loci within project site (19 degrees 38'30"N, 155 degrees 56'30"E).
    • Radiocarbon, Volume 28, Number 3 (1986)

      American Journal of Science, 1986-01-01
    • Sample Credentials Necessary for Meaningful High-Precision 14C Dating

      Jope, E. M. (American Journal of Science, 1986-01-01)
      Samples presented for high-precision 14C dating must satisfy stringent requirements if the 14C determinations are to yield meaningful sharp calendric dates, such as are now possible with the bidecadal high-precision calibration curve. The total carbon content should come from a confined time range 10-20 years (10-20 tree rings in wood or charcoal) appropriate for the bidecadal calibration curve. For accurate calendric dating the relation of these rings to the outer growth rings must be known. Application of the high-precision calibration curve to some archaeologic examples is discussed. It is now up to archaeologists and geoscientists to use this refined chronometric instrument to fullest advantage.
    • The Value of 210Pb in Dating Scandinavian Aquatic and Peat Deposits

      El-Daoushy, Farid (American Journal of Science, 1986-01-01)
      Sediment and peat chronologies have been further improved allowing alternative radiometric methods to complement 14C dating. Lacustrine and coastal marine sediments as well as peat deposits in various parts in Scandinavia are studied using 137Cs, 210Pb, 14C and other methods primarily to evaluate the 210Pb but also to extend the 14C chronology. The sampling sites have various sources of input and are characterized by different geochemical, depositional, and post-depositional conditions.
    • University of Granada Radiocarbon Dates III

      Gonzalez-Gomez, Celilio; Sanchez-Sanchez, Purificacion; Villafranca-Sanchez, Elena (American Journal of Science, 1986-01-01)
    • University of Lund Radiocarbon Dates XIX

      Håkansson, Sören (American Journal of Science, 1986-01-01)
    • University of Texas at Austin Radiocarbon Dates XV

      Valastro, S.; Mott Davis, E.; Varela, Alejandra G.; Lisk, Susan V. (American Journal of Science, 1986-01-01)
    • University of Wisconsin Radiocarbon Dates XXIII

      Steventon, Raymond L.; Kutzbach, John E. (American Journal of Science, 1986-01-01)
    • Using dBASE II for Retrieval of Radiocarbon Data

      Selsing, Lotte; Simonsen, Aud (American Journal of Science, 1986-01-01)
      A "C14" data base has been created for internal use of 14C dates with an Osborne-1 system. It uses a CP/M operating system, Z-80 CPU, and dBASE II software program. The structure meets the users' requirements of information and easy retrieval. The video display is quite compact, as a record of 32 fields is edited to fill a screen of 22 lines. A standard printout is edited to make room for two records per page and contains all information from these records. Searching may take place in all fields or parts of fields, in interval(s) in one or more fields and in various combinations of the prescribed methods of searching. A field called KEYWORDS is established to ease search operations. "C14" may be adapted to individual requirements and equipment with small adjustments