Janet Ambers

Re-evaluation of British Museum radiocarbon dates issued between 1980 and 1984.

Dates issued by the British Museum radiocarbon laboratory between 1980 and 1984 are known to have been in error. This paper outlines the cause of the problem and the procedures adopted to revise the results affected. Where revision has been possible, on average this has given dates older by 200 to 300 radiocarbon years. The individual revised results are tabulated.

British Museum natural radiocarbon measurements XVI.

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 (613C 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 (± lo-). Descriptions, comments, and references to publications are based on information supplied by submitters.

Radiocarbon Results for the British Beakers

The beginning of the Bronze Age in the British Isles has traditionally been marked by the appearance, in the archaeological record, of Beaker assemblages, mainly characterized by the Beaker pottery form itself. Ceramic typologies based on this style, which is undoubtedly continental in origin, have been used both for relative dating and as evidence of the social and economic developments of the period. Systematic radiocarbon dating has been attempted for the continental European Beaker material (Lanting, Mook & van der Waals 1973), but no such program has been carried out on British material. An examination of the existing radiocarbon results for the British Beakers showed many to be flawed in some way, particularly in the use of materials, such as mature wood, where there is no a priori reason for assuming a direct relationship between sample death and context. An attempt has been made at the British Museum to test the validity of archaeologically derived chronologies for the Beaker pottery of the British Isles. This involved analysis of a group of carefully selected human bone samples from Beaker burials, where there is a known direct association between ceramic usage and the cessation of carbon exchange. Twenty such samples have been identified and measured. The results presented here, combined with other previously produced determinations, show no obvious relationship between pottery style and calendar date of deposition.

British Museum natural radiocarbon measurements XII.

The following list consists entirely of dates for archaeologic samples from the British Isles, mainly measured over the period from May 1979 to June 1980. 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). The 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 (b13C values are relative to PDB). No corrections have been made for natural 14C variations. The modern reference standard is NBS oxalic acid. Errors quoted with the dates are based on counting statistics alone and are equivalent to ± 1 standard deviation (± 1cr) Descriptions, comments, and references to publications are based on information supplied by the persons who submitted the samples. The results published here represent the first stage of a research program devoted to the British Bronze age, initiated in 1979. This program derived from a growing awareness that traditional chronologic schemes were coming increasingly under attack, and that the existing framework provided by radiocarbon dates was insufficient as it was of sporadic coverage and depended heavily upon single determinations. At the same time, renewed activity in the excavation of settlement sites provided an ideal opportunity for the collection of multiple stratified samples. The criteria adopted for selection of samples for the program were as follows:

British Museum natural radiocarbon measurements XIX.

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 (613C 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 (± lo-). Descriptions, comments, and references to publications are based on information supplied by submitters.

Dating Grimes Graves

More radiocarbon analyses have been produced for the Neolithic flint mines of Grimes Graves than for any other site with which the British Museums Radiocarbon Laboratory has been involved. Despite this heavy concentration of effort, a recent review of these figures concluded that poor sample selection, combined with a lack of sufficient quality assurance procedures, severely limit the use that can be made of this database. To overcome these difficulties, a redating program has been undertaken using a carefully selected subset of the original material. In this paper I discuss the flaws in the original data set, due to both technical and sampling problems; set out ways to avoid similar problems in the future, with particular reference to quality assurance; and discuss the new results and their archaeological implications.