Stalactite a cave it will drip down. When the solution comes into contact with air the chemical reaction that created it is reversed and particles of calcium carbonate are deposited. The reversed reaction is: An average growth rate is a year. The quickest growing stalactites are those formed by a constant supply of slow dripping water rich in calcium carbonate (CaCO) and carbon dioxide (CO), which can grow at per year. The drip rate must be slow enough to allow the CO to degas from the solution into the cave atmosphere, resulting in deposition of CaCO on the stalactite. Too fast
Blombos Cave terrain abruptly drops down towards shoreline that lies some 34,5 meters below the cave entrance. The talus, which primarily consists of Middle Stone Age deposit, rock fall and unconsolidated sediments, is stabilised by an area of large, exposed blocks (14m²). At some stage - and in between the prehistoric occupation of the cave site - these blocks have fallen down from the rock face above, effectively preventing site erosion and allowing sediments to stabilize and accumulate in front of the cave's drip line. Calcium carbonate (CaCO3) rich ground water seeps in from the cave roof and percolates through the interior