Extension of the 14C calibration curve to ca. 40,000 cal BC by synchronizing Greenland 18O/16O ice core records and North Atlantic foraminifera profiles:: A comparison with U/Th coral data

For a better understanding of pre-Holocene cultural history, archaeologists are in need of an absolute time scale that can be confirmed and duplicated by different dating methods. Proxy data available from archaeological sites do not, in themselves, allow much reflection on absolute age. Even when founded on supporting radiocarbon data, Paleolithic chronologies that are beyond the actual limits of C-14 calibration still remain relative ones, and thus are often quite tentative. Lacking the possibility of calibration for the Paleolithic, archaeologists often attempt to correlate their data with different time scales from different archives that are thought to be absolute or calendric. The main result of this paper is that the GISP2 and U/Th chronologies duplicate each other over their entire range of data overlap, while other time scales (ie., GRIP, most varve sites) differ significantly. The context-derived C-14 calibration curve provides a large potential to correlate the various climate archives as recorded in ice cores and deep ocean drillings with terrestrial sequences.