Geomagnetic variations for the interval 7000–25,000 yr B.P. as recorded in a core of sediment from station 1474 of the Black Sea cruise of “Atlantis II”

Palaeomagnetic measurements have been carried out on 474 specimens taken at about 2.5-cm intervals along an 11 m long piston core.The magnetic inclination exhibits variations with a period of approximately 2800 yr deduced from five radiocarbon age determinations along the core. The assumption that this period was regular allows “magnetic” ages to be assigned to the core and when these are plotted against depth, two straight lines are obtained indicative of steady rates of deposition of 0.4 mm yr^?1 since about 15,000 yr B.P. and 0.8 mm yr^?1 before then. The radiocarbon ages, except that at 16,800 yr, fit these lines suggesting that the assumption that the magnetic inclination fluctuated with regular period is justified. These swings correlate well, but on a two to one basis, with swings in inclination described for core V10-58 from the Aegean Sea (N.D. Opdyke, D. Ninkovich, W. Lowrie and J.D. Hays, 1972). The extra detail carried by the Black Sea core is possibly explained by the faster rate of deposition.The close correspondence of the periodity of these inclination swings with that observed in declination at Lake Windermere (F.H. Mackereth, 1971) is noted and the possibility that they are both caused by oscillations in intensity of the same geomagnetically active region in the core is discussed.The ratio of NRM intensity to susceptibility varies between about 0.4 and 25 within the banded lutites. This range of values may reflect different magnetic mineralogy in the two types of band, of which there are typically 3–7 per specimen, as well as variations in geomagnetic field intensity.