Age model and oxygen isotope ratios of sediment core V28-239

The entire 21-m long core has been analyzed at 5-cm intervals. Glacial stage 22, above the Jaramillo magnetic event, may represent the first major Northern Hemisphere continental glaciation of middle Pleistocene character.

Prior to this, higher frequency glacial events extend to near the level of the Olduvai magnetic event. Glacial events of less regular frequency extend ot the bottom of the core, which represents late Pliocene time. Fluctuations in carbonate dissolution intensity occur throughout the core with a similar frequency of the oxygen-isotope fluctuations.