A diagrammatic 400 km north–south cross-section through the southern portion of the Western Cape, South Africa, near Calitzdorp in the Little Karoo (approximately 21° 30’ E), showing the relationship between the Little and Great Karoos, separated by the Swartberg mountain range. The significance of the various geological layers (coloured layers) can be found in the articles on the Karoo Supergroup and Cape Fold Belt. The heavy black line flanked by opposing arrows is the fault that runs for nearly 300 km along the southern edge of the Swartberg Mountains. The Swartberg Mountain range owes some of its great height to upliftment along this fault line. The subsurface structures are not to scale.