A quaternary diatomite from the Western Sudan
Diatoms from a deposit in Western Sudan, North Africa were studied. The mass appearance of diatoms in this area might be linked with: (1) the eruption of the Jebel Marra group of volcanoes during Late Pliocene-Early Pleistocene times; (2) the increase of rainfall at the onset of the pluvials in the Early Pleistocene. The identified diatom species range from Tertiary to Recent times. They now occur, elsewhere, in fresh or slightly brackish water. Pelagic, epiphytic, and deep-water forms were found and they indicate the presence of a fairly deep and extensive Quaternary lake in an area which is today semiarid.