The following list of dates contains the majority of measurements made during 1974, ie, since our last list (R, 1974, v 16, p 285–303).

The measurements presented in this list are part of the joint research program “Sonderforschungsbereich 95” of Kiel University for interdisciplinary research on problems of “Interaction Sea-Sea Bottom”, sponsored by the Deutsche Forschungsgemeinschaft. They are directed 1) to the study of the path of 14C from the atmosphere into argillaceous sediments, and 2) to date stratigraphic records within sediment. Associated problems are to identify sources of different 14C activity that contribute to recent deposits, and to learn about effects of morphologic and hydrographic factors, especially of bottom currents, on sedimentation sequence. Even short term processes can be successfully studied by analyses of bomb produced radiocarbon in the marine environment.

The dates presented in this paper comprise results of determinations made at the University Radiocarbon Dating Research Laboratory, mostly during the latter half of 1974. Radioactivity was measured with proportional counters using pure carbon dioxide at 2 atmospheres pressure as filling gas. Effects of cosmic and local environmental radiation on the counters were reduced by surrounding them completely with 1) a plastic scintillator anticoincidence shield, 7.5cm thick, viewed by 2 photomultiplier tubes operating in coincidence mode, the output pulses of which were in anticoincidence with the proportional counters signals, and 2) by a 17.5 ton lead castle.

This list includes the second group of age measurements made from September 1972 to July 1974 using the benzene scintillation method. All archaeologic and geologic samples come from Italian territory. Chemical apparatus for benzene synthesis and the liquid scintillation spectrometer are unchanged (Alessio et al, 1970a, 1973). Charcoal and wood samples underwent standard pretreatment by boiling with 5 to 10% HCl; α-labeled samples were given additional leaching with .2N NaOH. The counting rate of approx half the samples was corrected based on the 13C/12C ratio, mass-spectrometrically measured on CO2 obtained in combustion line set up after Broecker et al (1959), according to previously described procedure (Alessio et al, 1969).

This series reports some of the measurements made since the previous list. Methods essentially remain as described in Saskatchewan II (R, 1960, v 2, p 73) with expanded facilities and new electronic equipment since 1973. The laboratory operates commercially, administered by the Saskatchewan Research Council under the direction of A A Rutherford.

All samples described in this date list have been dated from November 1973 to January 1975. Only the benzene liquid scintillation installation was used during this time. For the combustion of soil and fossil bone samples containing a high content of sulfur (ie, in the form of pyrite), a new CO2 extraction and cleaning system was built. The gases released by the combustion are dried in ice and dry ice traps, passed through hot copper oxide and bubbled through KOH solution. Following the combustion, the K2CO3 precipitate is acidified in the same vessel where it formed and the released CO2 is again dried in a dry ice trap and by passing it through ascarite. This CO2 gas is quite clean and can be brought to the original system where the gas volume is measured. Further processing is as previously described (Haynes and Haas, 1974).

Most dates in this list were obtained in the period 1970 to 1972. Treatment of samples and counting equipment have remained essentially the same as described previously (R, 1972, v 14, p 418–419).

UCR I (R, 1974, v 16, p 395–401) previously reported measurements carried out jointly by the UCR and UCLA radiocarbon laboratories between November 1972 and September 1973 and interlaboratory check samples used to calibrate the UCR 1.7L counter. This list reports the measurements of the UCR laboratory from September 1973 to August 1974.

The following list of dates are selected from geologic and archaeologic samples measured in late 1974. The technique employed is liquid scintillation counting of wholly synthesized benzene as described in (R, v 16, p 402–408). Errors are reported as one standard deviation. Sample descriptions and comments were written in collaboration with collectors and submitters.