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Foraminifera have been studied from 39 long deep-sea cores and from 53 undisturbed surface sediment samples collected from the North Atlantic. Mid-latitude and low-latitude planktonic assemblages can be differentiated, with at least five different distribution types. The long cores contain faunas normal for their latitude alternating with faunas typical of higher latitudes. These are suggested as representing alternating cold and warm epochs, mostly Pleistocene; correlation of these epochs appears possible in a mid-latitude series of cores.
Several cores contain shallow-water Foraminifera which have been displaced from shallow water. It is suggested that much of the mud in the deep ocean may be the finer fraction of sediments displaced from shallow water. Four cores contain planktonic Foraminifera of Miocene age. There is abundant evidence of solution of calcium carbonate; it is suggested that most of this solution occurred at the sediment surface and is related to the rate of production of Foraminifera.
A mixed high and low latitude planktonic fauna occurring off Africa between 15° and 20° N. Lat. is attributed to mixing at the convergence of the Equatorial Counter Current and the Canaries Current. Mixed planktonic faunas occur in lower sections of cores off Africa between 0° and 7° N. Lat.; this suggests that the convergence area was displaced southward during the past.
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