This paper is the third of a series detailing the general features of 14C distribution in the world oceans. In the preceding papers, we discussed the 14C activities of Atlantic and Pacific Ocean waters (Stuiver and Östlund, 1980; Östlund and Stuiver, 1980). We now give an outline of the 14C distribution of the Indian Ocean and profiles for one Mediterranean and three Red Sea stations.

14C ages were obtained for the Australian lakes recorded below in order to complement research into their magnetic stratigraphy and sedimentology. It has been possible to establish precise 14C chronologies in six separate lakes, and also to compare ages obtained from stratigraphically equivalent horizons in different parts of the same lake so as to determine the reproducibility of these ages.

The following list consists of dates for archaeologic and geologic samples mostly measured from June 1981 to June 1982. The dates were obtained by liquid scintillation counting of benzene using the laboratory procedures outlined in previous lists (see, eg, BM-VIII, R, 1976, v 18, p 16). Dates are expressed in radiocarbon years relative to ad 1950 based on the Libby half-life for 14C of 5570 yr, and are corrected for isotopic fractionation (δ13C values are relative to PDB). No corrections have been made for natural 14C variations (although in some instances approximate calibrated dates taken from the tables of R M Clark (1975) have been given in the comments where this aids interpretation of results). The modern reference standard is NBS oxalic acid (SRM 4990). Errors quoted with dates are based on counting statistics alone and are equivalent to ± 1 standard deviation (± 1σ). Descriptions, comments, and references to publications are based on information supplied by submitters.

This list includes most of the measurements made in 1979 through 1981 and some values obtained during preceding years. The reporting of results, their calculation (half-life: 5570 ± 0, standard 13C correction only for bones), and the dilution ratios are as previously described in Lyon VIII (R, 1979, v 21, p 402–452).

The measurements reported in this date list form the chronometric framework for obsidian hydration and trade studies in California (Ericson, 1975; 1977; 1978; 1981; Ericson et al, 1975; Singer and Ericson, 1977). All samples were analyzed as CO2 gas at close to 1 atm in a 7.5L proportional counter with three energy channels. Radiocarbon ages are based by convention on the 5568 ± 30 yr half-life. The biospheric standard is 95% the count rate of NBS oxalic acid for radiocarbon laboratories. Background is based on CO2 obtained from marble. Counter operation is checked against a historically dated wood sample from the funerary boat of Sesostris III, 1872 +4−8 BC (Hayes, 1962). All samples were subjected to accepted NaOH, HCl or other special chemical treatments to exclude contamination. No tree-ring calibration was applied to any of the samples listed.

The following radiocarbon dates are a partial list of samples measured for a variety of projects and materials since August 1980. Chemical and counting procedures remain the same as indicated in R, v 20, p 274–282.

The analyses in this list were performed between 1977 and 1979. The laboratory utilizes gas counting of carbon dioxide in counters installed 9.5 meters below the ground surface for background reduction. The reported results closely follow the guidelines of Stuiver and Polach (1977), although the standard error for analyses earlier than USGS-500 are based solely upon counting statistics and do not include uncertainty in voltage, pressure, temperature, and δ13C.

Procedures and equipment have been described in previous date lists. Except as otherwise indicated, wood, charcoal, and peat samples are pretreated with dilute NaOH–Na4P2O7 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. Pretreatment of bone varies with the condition of the bone sample; solid bone with little deterioration is first cleaned manually and ultrasonically. The bone is treated with 8% HCl for 15 minutes, then dilute NaOH–Na4P2O7 for 3 hours at room temperature, washed until neutral, and the collagen extracted according to Longin (1971). Charred bone is treated with dilute HCl, NaOH–Na4P2O7, and then dilute HCl again.