Sterkfontein is one of the world's most productive and important palaeoanthropological sites. It is the place where the very fist adult ape-man was found by Dr Robert Broom in 1936. This ancient cave system has over the years revealed a sequence of deposits with fossils dating from about 3.5 to 1.5 million years ago, a period of time which spans the early development of the family of man-the hominids. In addition to almost 500 skull, jaw, teeth and skeletal fossils of these early hominids, there are many thousands of other animal fossils, over 300 fragments of fossils wood, and over 9,000 stone tools which include some of the earliest manifestations of human culture on earth. Some of the youngest deposits in the cave also contain fossils and tools from the period just prior to the emergence of modern humans, the period ca. 100.000 to 250,000 years ago, most widespread of which are the dolomites of the Transvaal Supergroup. Dolomite, as well as limestone, is slightly soluble in acidic groundwater (groundwater that contains carbon dioxide in solution) and readily forms caves and sinkholes.

Although the dolomites were deposited more than 2000 million years ago, the caves were formed relatively recently, within the past few million years. Older caves have been gradually destroyed by erosion.

The environment inside caves is fragile, and the locations of many caves are kept secret in order to protect them. Some systems, such as the Echo Caves in Mpumalanga and the Cango Caves near Oudtshoorn, are notable for their beautiful limestone formations and are major tourist attractions. Others are sites of major scientific importance, owing to their accumulation of fossil remains, which include some of humankind's earliest ancestors.