Pennsylvanian and Permian glacigenic deposits of the Dwyka Group occur within Karoo basins throughout southern Africa. The largest, the main Karoo Basin, evolved into a foreland basin during Dwyka accumulation. Tectonism along the convergent margin of Gondwana resulted in the formation of a foreland basin bounded by southern (Cape fold belt) and northern (Cargonian Highlands) uplands. Glaciers carved deep paleovalleys into the northern highlands that were later filled by glacigenic and post-glacial strata. Within this basin, a platform facies association composed of four deglaciation sequences occurs. These sequences, which are hundreds of meters thick, consist of thick, massive, basal diamictite lithofacies that grade upward into stratified lithofacies (stratified diamictites, dropstone-bearing mudrocks, and rhythmites). Interpretations depict grounded ice advancing into the basin followed by gradual retreat of the ice front resulting in ice-proximal followed by ice-distal glaciomarine sedimentation. Sensitive high-resolution ion microprobe (SHRIMP) dates of juvenile zircons obtained from tuff beds indicate that the deglaciation cycles were 3.6–8.2 m.y. in duration. Such cycles were likely the result of tectonic development of the foreland basin. Paleocurrent and provenance studies indicate that Dwyka glaciation asynchronously emanated from multiple glacial centers in upland areas, and in Antarctica. Therefore, southern Africa was not covered by a single ice sheet, but instead, smaller ice sheets, ice caps, and alpine glaciers waxed and waned along basin margins during the late Paleozoic. Despite a long history of study, many questions concerning Dwyka glaciation remain.

The Carboniferous-Permian Dwyka Group in southern Namibia is subdivided into four upward-fining deglaciation sequences, each of which is capped by fine-grained glaciolacustrine or glaciomarine deposits. Both the second and the third deglaciation sequences are associated with mudstone units that are particularly widespread—the Ganigobis Shale Member and the Hardap Shale Member. An abundance of marine macrofossils and ichnofossils and extrabasinally derived fallout tuff horizons characterize these mudstones and provide the basis for an integrated high-resolution biostratigraphic and tephrostratigraphic framework. Juvenile magmatic zircons separated from tuff horizons at the base of the Ganigobis Shale Member (top deglaciation sequence II) yield 206 Pb/ 238 U sensitive high-resolution ion microprobe (SHRIMP) ages of 302.3 ± 2.1, 302.0 ± 3.0 Ma, and 299.5 ± 3.1 Ma, whereas a tuff associated with the upper part of the Hardap Shale Member (top deglaciation sequence III) reveals a SHRIMP age of 297.1 ± 1.8 Ma. Since macrofaunal occurrences reveal the Hardap Shale Member to be a correlative of the Gondwana-wide Eurydesma transgression, this datum is an important age calibration for a well-established global event. Tuff beds sampled next to the boundary between the glacial Dwyka Group and the postglacial Ecca Group yield SHRIMP ages of 290.9 ± 1.7 Ma and 288.5 ± 1.6 Ma, providing an age proxy for the end of the late Paleozoic ice age in southern Africa.