Cave of the Mounds the Interior and the National Park Service. To be considered a NNL, "a site must be one of the best examples of a natural region's characteristic biotic or geologic features." Cave of the Mounds is home to many varieties of speleothems. As with most caves, stalactites and stalagmites are common. Formations found inside the cave include: These formations come in many different brilliant colors such as reds, browns, blues, and grays. The reds and browns are caused by the presence of iron oxide in the formation. Similarly, blues and grays are caused by manganese oxide. Some speleothems are even partially
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