The Cape Supergroup rocks were laid down as sediments in a rift valley that developed in southern Gondwana, just south of Southern Africa, during the Cambrian-Ordovician Periods (starting about 510 million years ago, and ending about 330-350 million years ago). An 8 km thick layer of sediment accumulated on the floor of this rift valley. Closure of the rift valley, starting 330 million years ago, resulted from the drift of the Falkland Plateau back towards Africa, during the Carboniferous and Early Permian periods. This caused the rucking of the Cape Supergroup into a series of parallel folds, running mainly east-west, but with a short section running north-south in the west (resulting from the collision with the eastward movement of Patagonia into southern Africa). Continued subduction of the paleo-Pacific Plate beneath the Falkland Plateau and the resulting further compression of the latter into Southern Africa, raised a mountain range of immense proportions to the south of the former rift valley. The folded Cape Supergroup formed the northern foothills of this towering mountain range.