Table Mountain Sandstone is made up predominantly of quartzitic sandstone laid down between 510 (Cambrian Period) and 400 (Silurian Period) million years ago. It is the hardest, and most erosion resistant layer of the Cape Supergroup. It therefore forms most of the highest and most conspicuous peaks in the Western Cape, as well as the steepest cliffs of the Cape Fold Mountains, despite being the oldest, and, therefore, lowermost of the Cape Supergroup sequence. The folding of the sequence into the parallel mountain ranges of the Western Cape started about 330 million years ago, affecting the Cape Supergroup from about Clanwilliam (approximately 200 km north of Cape Town), to about Port Elizabeth (approximately 650 km east of Cape Town). The Cape Supergroup sediments beyond these points are not folded into mountain ranges, but do, in places, form steep cliffs or gorges, where the surrounding sediments have been eroded away (see, for instance, Oribi Gorge in KwaZulu-Natal).