ABSTRACT
Uranium-series disequilibrium dating methods: relevant isotopes in both leachates and residuum, may yield estimates of the sample ratios. Dating such travertines up to a limit of about 1 Ma depends upon the initial ratio; larger ratios allow to go farther back in time because it takes longer for the 234U/238U ratio to become indistinguishable from unity. Mass spectrometric analysis of 234U/238U will extend the time-range from such deposits even further. Uranium-series methods are applied to help to determine ages and sedimentation rates for deep-sea sediment cores from which oxygen isotope ratios of foraminifera establish the fundamental climatic record of the Quaternary. Uraniumdated oxygen isotope palaeotemperature profiles of speleothems have been published from southern France and a wide geographical range of sites in North America. Systematic investigations of the less tractable deposits such as surficial carbonate, bones and shells continue.
