African pluvial periods

The sedimentary deposits left by ancient lakes in East Africa had enabled Louis Leakey and post-war paleontologists to define major climatic periods considered wet, interspersed with drier periods.

Of progressively decreasing durations, they each bore the name of the site where the first clues had been collected: Kageran (Kagera), Kamasian, Kanjeran (Kanjera) and Gamblian.

Paleontologists believed that the quasi-arid zones then became wooded savannahs where animals and prehistoric hunter-gatherers could thrive.

These ancient climatic periods have been gradually replaced in the scientific literature by the isotopic chronology in force since the end of the 20th century, which defines the alternation of glacial and interglacial periods on a global scale.

The latter, however, themselves experience alternations of more or less heavy rainfall, but at a much faster rate (on a geological scale) than what had originally been imagined for East Africa.