Babba Olou is a large silicic volcanic centre essentially comprising rhyolitic flows which are probably peralkaline but details of which have not been found. The 1:500,000 geological map accompanying Varet (1978) indicates other areas of rhyolitic rocks to the north and in a narrow strip east of Babba Olou at Eger Aleyta and extending eastwards to the Ghoubbat al Kharab.
BARBERI, F., FERRARA, G., SANTACROCE, R. and VARET, J. 1975. Structural evolution of the Afar triple junction. In A. Pilger and A. Rosler (eds), Afar Depression of Ethiopia. 38-54. Inter-Union Commission on Geodynamics, Scientific Report 14. E. Schweizerbart'sche Verlagsbuchhandlung (Nagele u. Obermiller). Stuttgart. VARET, J. 1978. Geology of Central and Southern Afar (Ethiopia and Djibouti Republic). Editions du Centre National de la Recherche Scientifique, Paris. (Explanation accompanying Geological map of central and southern Afar. 1:500,000).