Distribution of radiocarbon dates

[This analysis is intended to demonstrate the potential of the database's geographical location fields it should not be read as a definitive interpretation of the information held in the database.]

It was apparent during the data gathering for this project, that some areas took more time to process than others. But we could not be certain whether this was because there was just more discussion of radiocarbon dates in some geographical areas, or whether there was a genuine unevenness in the number of radiocarbon dates which had been produced.

This analysis shows the distribution of over 5,000 radiocarbon dates across the study area, and demonstrates that the unevenness is a genuine phenomenon.

Map showing distribution of radiocarbon dates across study area (grid = 25km squares; dates, n = 5049)

Colour scale.

0 dates (no colour)
1-23 dates (lightest)
24-56 dates
57-105 dates
106-190 dates
191-373 dates (darkest).
Dots show location of individual radiocarbon dates.

The coloured squares show the number of radiocarbon dates available within a 25km area. Inevitably, those 25km squares which only fall partly within the study area show the lowest number of dates (eg, parts of the Cerdigion, Glamorgan and Pembrokeshire coasts, and the eastern edge of those English counties within the study area).

In absolute numbers, the greatest concentrations of dates are in the Severn Estuary, the Somerset Levels, and Snowdonia. The first two of these areas have been the subject of long term projects, most notably by Professors J R L Allen, Martin Bell and John Coles, all of whom have made good use of radiocarbon dating. In both of these areas the majority of dates are later prehistoric. The concentration in Snowdonia is more unexpected and seems to be the result of a large quantity of medium sized palaeoenvironmental and archaeological projects all contributing dates to the 25km square. Unlike the southern concentrations, the Snowdonia dates span the entire Holocene, making them a very valuable resource for writing the long term history of a region.

Another feature of note is the relatively high concentration of dates along the coast of north Wales, despite very little of the 25km squares covering these areas actually falling on land. In this area the concentration is a consequence of medium-sized archaeological, rather than palaeoenvironmental projects.

Although it is good to see that all squares have at least one date, it is disappointing that some squares still have less than 25 dates within them, notably in central Wales. These tend not to be high upland areas, which have generally been a focus for palaeoenvironmental work on peat bogs, but might be characterised as areas with a sparser population, and hence less opportunities for development-provoked archaeological work.