Radiocarbon dating of calcareous gyttja sediments of north Polish lakes.

Due to contamination of present biosphere by large quantities of ¹⁴C isotope produced during test explosions of nuclear and thermonuclear weapons it is impossible to find an apparent age directly by measurement of concentration of ¹⁴C isotope in a surface layer of a sediment. The method described in this paper depends on a two-stage smoothing of values of radiocarbon dates found for samples taken at various depths and allows consideration of an apparent age, and estimation of sedimentation rate. Resulting values of the apparent age of carbonaceous sediments from 3 lakes equals 430, 1315 and c.5000 years, and corresponding sedimentation rates are 17.5, 6.8 and 7.5 cm/100 years. - from Authors