Radiocarbon dating of the Late-glacial Period in Britain

Abstract

Radiocarbon dating by means of a proportional gas-counter containing carbon dioxide at a pressure of 2 atm has been applied to the dating of deposits from several widely spaced sites in Great Britain. At each of these sites independent investigations of the stratigraphy and plant remains, and particularly systematic pollen analysis, had demonstrated that the deposits were referable to zones I, II and III of the Late-glacial Period. Organic samples were taken from carefully defined horizons at these sites. The datings are remarkably self-consistent and indicate that the zones as previously defined are synchronous throughout this country. It seems that the upper and lower boundaries for the cool temperate Allerod phase (zone II) fall approximately at 8800 and 10000 years B. C., whilst the succeeding colder phase (zone III) lasted until about 8300 B. C., approximately the time at which the ice-retreat began from the line of the Highland Re-advance in Scotland and from the Central Swedish moraines and Norwegian Raa in Scandinavia, as already suggested by varve-chronology. This is the Late-glacial/Post-glacial boundary. Brief comparison of published radiocarbon dates of the Late­ glacial zones in Denmark, north-west Germany and Holland indicate that these also are synchronous with one another and with the zones recognized in Britain. Attention is directed to five substantial sources of error to which datings of this kind are liable: contamination of the original samples by derived coal, the use of organic muds in which carbon has originated from photosynthesis of submerged plants in hard waters, failure to to observe gaps in the depositional sequence, the so-called ‘Suess’ effect, and the seepage of organic material from above into older layers.