A. W. Magee, S. J. Culver; Recognition of late Precambrian glaciogenic sediments in Liberia. Geology ; 14 (11): 920–922. doi: https://doi.org/10.1130/0091-7613(1986)14<920:ROLPGS>2.0.CO;2
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Late Precambrian glaciation in West Africa is now suggested to have extended as far south as Gibi Mountain in west-central Liberia, 200 km farther south than previously recognized glacial deposits in central Sierra Leone. The Gibi Mountain Formation includes a basal diamictite, interpreted as a probable tillite, and overlying shallow-marine laminites containing isolated, ice-rafted dropstones and dropgrains. These rocks rest on Late Archean age gneisses and are overlain by Late Archean? age quartzite klippen emplaced during the pan-African orogeny (ca. 550 Ma).