The Middle and Upper Cambrian Bowers Group consists of two major sequences separated by an unconformity. The older sequence comprises the SIedgers and Mariner Formations, a regressive marine succession at least 4500 m thick. The rocks of the Sledgers Formation are mudstone, thin cross-Iaminated sandstone, graded-bedded sandstone, thick-bedded sandstone, and granule conglomerate in the south; to the north much of the sequence is replaced hy a basaltic lava and breccia facies. The overlying Mariner Formation (?shallow marine) comprises thick muds tone, quartzose and calcareous sandstone, and limestone. The dominantly fluvial younger sequence is exposed in two strips, on the east and west flanks of the Bowers Group. In the eastern strip the Camp Ridge Quartzite (minimum thickness 3000 m) consists of quartzose sandstone and conglomerate resting sharply on the eroded surface of the Mariner Formation. In the western strip at least 800 m of polymictic conglomerate (Carryer Conglomerate), quartzose conglomerate, and alternating sands tone and mudstone infill deep channels in and are locally discordant with the underlying Mariner Formation. The Bowers Group is folded into a north-west trending major antic1inorium in the west, and a major sync1ine in the east. The Bowers Group is less deformed and metamorphosed than the adjacent undated Robertson Bay and Wilson Groups, and is inferred to be younger.