Coarse clastic, mainly arkosic, sediments of Karoo age are exposed around the periphery of the Erongo Mountains. These deposits can be subdivided into two, approximately coeval, formations: (i) Krantzberg Formation - a massive to poorly layered, terrestrial sedimentary breccia with intercalated finer material. Patchy occurrences, less than 150 m thick, fill valleys on the pre-Karoo land surface. (ii) Lions Head Formation - mainly sub-angular to sub-rounded, pebbly to fine-grained, alluvial fan deposits that accumulated at the base of an escarpment. This formation, which is about 700 m thick, can be subdivided into five informal units: Lower Unit, Gritstone Unit, Middle Unit, White Quartzite Unit and Upper Unit. During deposition, these two formations were separated by an active fault that is part of the Omaruru Lineament Zone which continues farther north-eastwards as the Waterberg Thrust. Sediment for both the Krantzberg and the Lions Head Formations was derived from the Damara metasediments and associated granites. Lithology, depositional environment, source area and tectonic setting of the Lions Head Formation is strikingly similar to that of the Omingonde Formation with which it is therefore correlated. From this relationship it is inferred that the Lions Head Formation is of Triassic age.