Africa, North: Figure 1. The main karst regions and locations of the major caves in the Moroccan and Algerian sectors of the Atlas Mountains in North Africa.

Middle and Upper Jurassic limestones are also very common in the High Atlas, Middle Atlas, and Eastern Morocco (c. 20000 km2). They are thinner and are less homogenous. Some interesting karst landforms have been described on these limestones including “wave karst”, a succession of small parallel dry valleys with asymmetrical dolines on the Ait Abdi pleateau (Azilal), which are aligned with the main wind direction due to control by snow accumulations (Couvreur, 1974; Perritaz & Monbaron, 1998). On this plateau, an ancient cave network with vertical shafts suggests that climates were wetter in the past. Radiometric dating of speleothems yielded ages between 3200 and 220000 years, and some beyond the range of the U-Th method (>400000 years). The lateral flow is conducted by an interstratal network, inactive and dry in the upper part, but active at the base near the regional aquiclude, attesting three karstification phases. Morocco’s longest cave, the Wit Tamdoun underground river, is developed in Malm limestone, in the Western High Atlas, near Agadir.