Proceedings of the Prehistoric Society 37 (2)

Several propositions are offered to ensure intelligent use of 14C dates. (1) Dates could be designated A, B, C or D to indicate the degree of certainty attached to the association of date with sample. (2) Another designator could indicate the likely age of the sample before its incorporation in an archaeological layer. (3) Degree of contamination or admixture with younger or older material can be reduced by appropriate pre-treatment; its effect can moreover be calculated according to a given table. (4) Different chemical fractions of one sample, or a series of determinations in a single profile, assist in checking reliability. (5) The various methods of different laboratories in determining and reporting dates should be remembered. (6) Averaging dates is inadvisable, especially as it is the start and finish of archaeological phases that are important. (7) Graphs should indicate the individual characteristics of separate determinations. (8) Only conventional, not calibrated or corrected, 14C dates should be compared with each other. Correction for best half-life is not worthwhile. In sum, Neustupný's "new epoch in radiocarbon dating" (70/768) is a long way off.

The use of models is traced from the technological through the subsistence-economic, evolutionary, ethnographic, diffusionist and hyper-diffusionist to the cultural. Today, with our understanding deepened by 14C chronologies, not even Childe's modified diffusionism can stand. Instead, a multilinear evolution makes better sense, and in years to come a more historical approach, rejecting outworn models and unsuitable labels, may emerge.

About 140 dates are charted with accompanying discussion in which the usefulness of clusters of determinations is stressed. Some forty dates relate to megalithic or sub-megalithic tombs, cover a span of at least 2000 years and confirm L'Helgouach's sequences of tomb- and pottery-types. A second chart gives dates for Neolithic settlement sites, land clearances and axe quarries. For BA burials some twenty dates mostly fall between 2500 and 1200 BC (calibrated 14C years), but the lack of chronological separation between EBA and MBA monuments gives problems. A group of LBA-EIA tombs provides satisfactory dates, and the final chart shows settlements, fortified sites, souterrains and industrial sites of Bronze to Iron Age date, plus late intrusions into passage graves.

Although Herity is undoubtedly right to emphasise the late, "para-Neolithic" status of much of the Irish Mesolithic, several new 14C dates suggest strongly that small groups of people had arrived in Ireland by about 5500 BC, a date that should be conventionally Mesolithic. Their tool-kit was extremely limited especially if, as experimental flint-knapping suggests, some "types" are really waste products. These people may have been in a cultural backwater until the first Neolithic settlers arrived about 3550 BC and eventually absorbed them.