ISBN978-0-582-46341-7.. "It is hypothesized that in the late Pliocene or early Pleistocene, a coastal Lower Guinean river captured Malebo Pool, connecting the previously interior Congo Basin to the ocean." Thieme et al., Freshwater Ecoregions of Africa and Madagascar: A Conservation Assessment Ecoregions Assessments, Island Press, 2005, p. 297.