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.

In modeling the initial 14C activity of ground waters, the δ13C of marine limestone is taken conventionally to vary little about 0‰ PDB. This variation was found to be 6.28‰ in samples taken over intervals from 10-2 to 105m 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 “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.

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 advent of accelerator-based mass spectrometry (AMS) radiocarbon dating has reduced the minimum sample size required to ca 1 mg from the 1 g of traditional beta counting techniques (cf Wölfli, Polach & Andersen, 1984). However, it is clear that even smaller samples will be necessary for some fields of endeavor, particularly environmental work where the absolute quantities are small, perhaps of the order of a few micrograms (Currie et al, 1985). This raises serious problems in the handling and measurement of such small amounts, so that dilution will sometimes be required. Normally, sample dilution is accomplished by adding “dead” CO2 to the combusted sample CO2, which requires very careful measurement of two gas pressures for the calculation of a dilution ratio. By forming a chemical derivative of a sample before combustion, gas pressure measurement is not necessary and an exact dilution ratio can be selected by judicous choice of the dilution reagent. This paper demonstrates that such a technique is possible for the AMS 14C dating of derivatized amino acids.

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.

It was T Higashimura of Kyoto University who did the first liquid scintillation measurement for 14C in Japan. The External Standard Method (Higashimura et al, 1962) has been accepted the world over as an efficient method of measuring low-level radiation.

The following list consists of dates of archaeologic and geologic samples measured from January 1981 to December 1982. Measurements were continued with the same proportional counter system, pretreatment procedure, methane preparation, measurement, and calculation, as described previously (Kanwiszer & Trzeciak, 1984). Ages were computed on the 14C half-life of 5568 ± 30 years. Precision is reported as one standard deviation based only on statistical counting uncertainties in the measurement of the background, NBS modern standard, and sample activities. The dates are not corrected for 13C fractionation. Descriptions and comments are based on information supplied by submitters of samples.

Most of the 14C measurements reported here were made between October 1984 and October 1985. Equipment, measurement, and treatment of samples are as reported previously (R, 1968, v 10, p 36–37; 1976, v 18, p 290; 1980, v 22, p 1045) except that 23 separate GM-counters used as guard counters were replaced by a single iron multiwire ring-counter filled with 90Ar/10CH4 to ca 130kPa (ca 1.3atm). Background counts were reduced by ca 12% due to this change. High voltage supply for main detectors was replaced as well.

This list contains 14C dates pertaining to the Stone Age in southern Africa and covers the region from Zambia in the north to Natal and the northern Cape Province in South Africa. The southern and southwestern Cape Province are not included. Descriptions are based on information supplied by the submitters.

This list begins a program of publishing our large backlog of unpublished dates. The dates listed here are not a specific block of dates but simply those ready for publication. In many cases we have received comments from submitters, to whom we are grateful. Where no comment is included, none was received.

The following list includes some measurements made from December 1982 to May 1985 in the Radiocarbon Dating Laboratory, Faculty of Science, University of Granada, of samples from Spain, Portugal, and the Sudan. Sample preparation techniques and benzene synthesis remain as described previously (R, 1982, v 24, p 217–221) and equipment and measurement of samples was also reported previously (R, 1985, v 27, p 610–615). Radiocarbon ages are calculated using the 14C half-life of 5570 years and 0.95 activity of NBS oxalic acid is used as modern standard. Sample descriptions are based on information provided by submitters. Age determinations were made with the help of Research Project 0925/81, CAICYT, Spain.

Procedures and equipment used in the University of Wisconsin laboratory have been described in previous date lists. The preamplifiers and counting system were replaced in 1977 using modified EC & G Ortec components. 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; when noted 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.

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.

The following samples were excavated in July 1985 in an upland (elev 609.6m) prehistoric agricultural site in the Kona Field System on the west coast of Hawai'i Island.