Oliyamur volcano is situated within a fault complex marking the western margin of the East African rift and to the east of the Kanatim (No. 085-00-019) and Kachila (No. 085-00-024) volcanoes, both of which it overlies, but it is itself partly obscured in the north by basalts that emanated from Emuruangogolak (No. 085-00-022). It rises to a central peak (Lomelo Hill) and is not as deeply incised as the somewhat older trachyte volcanoes nearby. Oliyamur is composed of trachyte lavas but in the southern half trachytic pumice tuffs are abundant. According to Webb and Weaver (1976) thin mugearite flows also occur. There is a swarm of trachyte dykes that seem to have been the feeders for the lavas.