This list includes most of the measurements made in 1977 and 1978 using the two Packard liquid scintillation spectrometers described in Lyon VII (R, 1978, v 20, p 19). The backgrounds of both spectrometers decreased by about 30% with new photomultipliers, giving 1.9 ± 0.1cpm and 2.4 ± 0.2 cpm, respectively, for 3ml C6H6 (depending on counting vessels). Proportional detectors are only used for very small samples. Counting procedures are described in the text. Dilution ratios indicate the amount of sample versus the total quantity of C6H6 or CO2 introduced in the detectors. No change was made either in chemical treatment or in the calculation method (half-life: 5570 ± 0, one standard deviation, standard 13C correction only for bones).

The dating equipment and operating conditions remain essentially as described in R, 1970, v 12, p 285-286, except that the samples are now measured at either 76, 152 or 380cm Hg at 20°C to allow for the variation in sample size. The calculation of results and correction for isotopic enrichment remain as previously described in R, 1973, v 15, p 212.

The following list includes some measurements made during 1975-1978 since our last list (R, 1978, v 20, p 62-67) in the National Radiocarbon Laboratory of the Ecole Nationale Supérieure de Géologie Appliquée et de Prospection Minière (ENSG) de Nancy.

Radiocarbon measurements have been continued on a variety of projects and materials. Chemical and counting procedures remain the same as indicated in R, v 20, p 274-282. Dates are calculated using the Libby 14C half-life of 5568 years; errors are reported as one-standard deviation (1σ) based only on statistical counting uncertainties in background, modern standard, and sample activities. All samples for which 13C/12C ratios are available are corrected for isotopic fractionation by normalizing to —25‰. A 400 year reservoir age correction has been applied to marine carbonates.

The following list contains dates of organogenous sediments (peat and sapropel from the Karelian ASSR) made in 1972 to 1977 with the aim of studying the history of the development of peat bogs in the Holocene (Elina, 1969; 1971a,b; Pyavchenko et al, 1976). Samples were collected with Hiller or Instorf samplers. Borings were made in the deepest parts of the peat bogs.

Procedures and equipment have been described in previous date lists. Except as otherwise indicated, wood, charcoal and peat samples are pretreated with dilute NaOH and dilute H3PO4 before conversion to the counting gas methane; marls and lake cores are treated with acid only. Very calcareous materials are treated with HCl instead of H3PO4.

Measurements have continued with the same proportional counter system, pretreatment procdure, methane preparation, measurement, and calculation, as described previously (R, 1970, v 12, p 298-318). Uncertainties quoted are single standard deviations originating from standard, sample, background counting rates and half-life. No 13C/12C ratios were measured.

The following list contains dates of samples measured since our previous list (R, 1977, v 19, p 465-475). As before, age calculations are based on the Libby half-life, 5570 ± 30 years, and reported in years before 1950. The modern standard is 0.95 of the activity of NBS oxalic acid. Solid sample pretreatment, combustion and counting technique are essentially the same as described in R, 1971, v 13, p 135-140. Groundwater samples were prepared following the procedure adopted by the IAEA (IAEA, 1977). Carbonates and hydrocarbonates from water samples were precipitated by adding saturated barium chloride solution while the alkalinity was adjusted to pH = 8 by adding carbonate-free saturated solution of sodium hydroxide. The precipitation was enhanced by adding iron salts and Praestol as coagulating medium. Carbon dioxide was evolved by acidification of the precipitate and converted to methane. Statistical processing of data has been computerized (Obelić and Planinić, 1975). Sample descriptions were prepared with collectors and submitters. The errors quoted correspond to 1σ variation of sample net counting rate and do not include the uncertainty in 14C half-life.

Temple's radiocarbon dating facility is housed in the Department of Geology on the Main Campus. The laboratory was established to support research in late Pleistocene and Holocene Geology, Archaeology, and Anthropology.

Ninety-six new 14C dates are reported for carbonized roots and other plant material coll from beneath prehistoric lava flows and ash deposits from Mauna Loa (ML) and Kilauea volcanoes. Before 1976, only 10 flows from these volcanoes had been dated by radiocarbon methods. Collection of dateable material has been facilitated by an improved understanding of the conditions of charcoal formation and preservation beneath basaltic lavas (Lockwood & Lipman, 1979).

Radiocarbon measurements have been continued on a variety of projects and materials. Chemical and counting procedures remain the same as indicated in R, v 20, p 274-282. Dates are calculated using the Libby 14C half-life of 5568 years; errors are reported as one-standard deviation (1σ) based only on statistical counting uncertainties in background, modern standard, and sample activities. All samples for which 13C/12C ratios are available are corrected for isotopic fractionation by normalizing to —25‰. A 400-year reservoir age correction has been applied to marine carbonates.