The denuded remnants of an ignimbrite sheet which is reported to be comenditic, and originally covering at least 300 km2, are found around Lake Chamo and on islands in Lake Abaya (Levitte et al., 1974). A cluster of small intrusions, mainly of peralkaline quartz trachyte, west of Lake Chamo are referred to by Davidson (1983).
DAVIDSON, A. 1983. The Omo River project. Reconnaissance geology and geochemistry of parts of Ilubabor, Kefa, Gemu Gofa and Sidamo, Ethiopia. Bulletin, Ethiopian Institute of Geological Surveys, 2: 1-89.LEVITTE, D., COLUMBA, J. and MOHR, P. 1974. Reconnaissance geology of the Amaro Horst, southern Ethiopian Rift. Bulletin of the Geological Society of America, 85: 417-22.