Cenozoic Paleoclimatic Record from Paleosols of Eastern Oregon and Washington

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0000953RetallackLong records of climate change well back into geological time are important for understanding the nature and direction of global change. To date one of the most important records has come from the oxygen isotopic composition of foraminifera from deep sea cores. The three-year project proposed here is to obtain a comparably complete and long-term record of paleoclimate on land. This record comes from a long sequence of fossil soils (paleosols) ranging in age from modern back to 45 million years old in the high desert of northeastern Oregon and southeastern Washington states. The methods used to determine paleoclimate, and particularly ancient rainfall regimen, include depth tyo horizon of calcareous nodules in the paleosols and also the chemical composition of well-weathered parts of the paleosols. Several parts of the record have already been studied successfully as pilot studies for the project, and the rate of progress is encouraging for completion of a 45 million year record complete to a resolution of gaps of no more than 200,000 years. Such a long-term paleoclimatic record will be relevant to wider questions of global paleoclimatic change, and will be important for reassessing computer models of climate and ideas about plant-animal coevolution. The proposed record will also be an important new record of paleoclimatic data for land that can be compared with existing long records from the sea.