Cave formation

The caves at Sterkfontein were formed in dolomitic limestone over millions of years. They began to form as early as 20-million years ago. Most caves including Sterkfontein – are formed by the dissolving action of weakly acidic rainwater, which seeps into the soluble rock through the soil.

Visitors to Sterkfontein learn about the formation of caves

In ancient Neoarchaen times, 2.58-billion years ago, dolomite formed in the bed of a shallow sea. Within the last 20-million years, the Sterkfontein Caves were formed within the dolomitic rock. Slightly acidic groundwater dissolved solution cavities beneath the water table. This zone beneath the groundwater surface or water table is known as the phreatic zone.

Over time, the water table dropped and the caves became air-filled voids in which stalactites and stalagmites could form. Water from the surface percolating through cracks in the dolomite absorbed calcium carbonate. On reaching the cavern ceiling, carbon dioxide was released, and a thin film of calcium carbonate was deposited. The deposits built up over time to form stalactites and other formations.

Stalactites and stalagmites

The term stalactite comes from the Greek word stalaktos, which means “dripping”, because these other-worldly formations are produced by “drips” from the ceilings of limestone caves. Water reacts with chemical elements in the ground and rock, and seeps slowly through the roof of the cave, depositing calcium carbonate, which hardens and builds up over time to form a stalactite.

Stalagmites are corresponding formations on the floors of caves, rising up over time as drops of water, rich in calcium carbonate, fall from the roof of the cave. The term stalagmite comes from the Greek word, stalagma, to “drop”.

How to remember the difference

StalaCtite has a “c” for “ceiling”
StalaGmite has a “g” for “ground”
Stalactites hang “tite” to the ceiling above
Stalagmites “mite” grow all the way to the ceiling

Bones and breccia in caves

Solution and roof collapse created entrances to the caves in the form of vertical shafts. Soil, rocks, bones and vegetation fell in from the surface – the animals and plants from which fossils formed did not actually live in the caves.

Example of a fossil of a sabre-tooth cat encased in breccia, found in the Sterkfontein Caves

The bones that found their way into these shafts were often just fragments left by the activities of predators and scavengers around the shaft entrances. But sometimes – far less often – a whole animal would fall down a cavity and be fossilised in the infill. The famous australopithecine skeleton “Little Foot”, which was found deep inside a Sterkfontein grotto, is an example of this.

Over time, the material that fell into the cave shafts built up to form talus cones, which look like giant, inverted ice-cream cones, on the cave floor. These deposits were cemented by lime-charged water to form concrete-like breccia, a type of rock. Bones within these talus cones were mineralised by calcium carbonate and stained with manganese and iron from the dolomitic soil.

Sometimes floor collapses into lower caves or erosion by surface water disrupted the stratified layers, mixing the deposits. This means that even if some deposits are deeper than others, they are not necessarily older than those nearer the surface.

The bulk of the Sterkfontein cave deposits were not disrupted in this way. University of the Witwatersrand geologist Professor Tim Partridge classified the deposits from oldest to youngest as geological Members 1 to 6 of the Sterkfontein formation. The infills span a period from about 4.2-million years ago to less than 200,000 years ago. The different infills have characteristic fossil and/or artefact (stone tool) content.

Over time, the water table dropped and the caves became air-filled voids in which stalactites and stalagmites could form. Water from the surface percolating through cracks in the dolomite absorbed calcium carbonate. On reaching the cavern ceiling, carbon dioxide was released, and a thin film of calcium carbonate was deposited. The deposits built up over time to form stalactites and other formations.

Visitor Information

Opening times

Maropeng 09h00 - 17h00 every day

Sterkfontein Caves 09h00 - 17h00 every day

Rates and specials

Maropeng

Adults: R120 | Children (4-14): R65
Children under 4: free
Pensioners: R65 (for both sites)
Students: R75
School groups: R65 per pupil

Sterkfontein Caves

Adults: R165 | Children (4-14): R97
Children under 4: free
Pensioners: R65 (for both sites)
Students: R100
School groups: R90 per pupil

Combination ticket

Adults: R190 | Children (4-14): R125

Pensioners: R65 

School groups: R120 per pupil

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Please note: No pets are allowed at Maropeng and Sterkfontein. Service dogs and guide dogs are the exception

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