Oldoinyo Sambu

Oldoinyo Sambu is the most northerly of the Tanzanian volcanoes and forms a broad dome. The eastern slopes are cut and exposed by the main north-south boundary escarpment of the rift immediately west of Lake Natron. Much of the eastern half of the volcano now lies beneath Lake Natron. The volcano consists mainly of olivine basalt flows with subordinate trachybasalt and phonolite. Lenses of tuff and agglomerate are locally interbedded with the basalts in the rift escarpment.