The Goboboseb Mountains represent a southern remnant of the Etendeka Formation volcanics. They consist of a 600 m thick sequence of quartz latites .and basalts which almost completely enclose the Messum Complex, a multistage gabbro-granite-rhyolite-syenite ring structure. The volcanic sequence is: Tafelkop basalts (lowest); Quartz Latite (QL) units -I to -III (with intercalated basalts); Messum Mountain basalts; QL unit-IV. These volcanics are intruded by numerous dolerite dykes and sills, less often by plugs, dykes and sills of quartz monzonite (chemically equivalent to the quartz latites) and carbonatite dykes. The Goboboseb volcanics dip gently towards the Messum Complex, steepening in dip adjacent to its margin. North of Messum the volcanics deine a north-north-east trending trough-like feature which plunges south towards the complex. The quartz latites are interpreted as high-temperature rheoignimbrites, with well deined vertical lithological changes. The Messum Complex is the inferred source for the quartz latites, and at least some of the basalts, based on various lines of ield and chemical data. This implies that the Goboboseb quartz latites are proximal deposits. Based on chemical and mineralogical data, correlations are proposed between the Goboboseb and Springbok quartz latites, the latter exposed in the southern Etendeka: This implies large volumes for these quartz latite units, well in excess of 2000 km³ for the Upper Springbok unit.