English: Looking north over the Upper Karoo in the Northern Cape, South Africa, during a flight between Dubai and Cape Town. The Ongers River enters the view at the bottom left side of the picture, then skirts the edge of a dark, oval-shaped dolerite saucer. It eventually has a confluence with the Brak River near the top right hand corner, near the edge of another dolerite saucer known as Biega se Berg. The river beds of the Ongers and Brak rivers are densely vegetated with Acacia trees which benefit from occasional floods and subterranean water, giving the illusion of standing water. It is possible that the dolerite sills were once more continuous and gently folded, so that areas folded into higher areas were eroded, leaving only the dolerite troughs with their resultant oval shapes.