The last climatic cycle and past ocean changes

ABSTRACT

During the last 150.000 years, the earth's climate alternated from warm conditions to cold conditions. The peak of the last glaciation occurred about 18.000 years ago and a deglaciation led to the present climatic pattern. In order to reconstruct past climatic and past oceanographic conditions, geologists must define proxy - data, which describe various climatic parameters in the past and dermine the time scaleof the records of these proxy - data. The age of the sediment is determined by absolute dating either by the carbon - 14 method (for the last 40.000 years) or by uranium series disequilibrium (for the last 300.000 years). A good stratigraphy for marine sediments can also be deribed from the oxygen isotope record of planktonic and benthic faraminifera, which partly reflects the variations of the volume of ice stored over the high - latitude continents. (AU)