Botswana. Occurrences of modern groundwater in the Kalahari Formation aquifer, suggest current recharge taking place in the dry river channels, as well as through thin sand cover, where the pre-Kalahari erosional surface is shallow or exposed. In the pan belt of the western part of the area studied, the Kalahari Formation seems to form a common aquifer with certain parts of the underlying Dwyka Formation. It is presumed that the large pans there, are superimposed on a pre-existing drainage system, dating back to a pre-Kalahari epoch. The highly concentrated brine in the Dwyka Formation in the pan belt is a shallow phenomenon, caused by insufficient flushing of the low-lying pans. Seasonal fluctuations in the pans force the brine up to where it undergoes evaporation, resulting in evaporites, which occasionally leach back to the ground. The occurrence of brines, however, does not prove that these are outlets of a basin which is recharged in the east and hence represent apparent salinity growth. It only suggests a dry period which followed the pre-Holocene high lake level and caused the brine formation. These brines will remain unflushed as long as the current climatic conditions prevail.