Chemical composition of phosphorites and host sediments

Two series of curves yield similar results. These data confirm that isotope composition of oxygen reflects primarily temperature, and not isotope composition in ocean water.

Temperature of the upper layer of ocean water increased from north to south both during the last two glaciations and in the interglacials. All three sediment cores collected from different latitudes show approximately the same amplitudes of fluctuation of mean annual temperature during times of their accumulation, as determined independently by different methods; these amplitudes are estimated as 5-7°C.