A passage into deep time
Beneath the flat, treeless expanse of the Nullarbor Plain, a sinkhole measuring 80 by 50 meters opens into the earth. This is the entrance to Koonalda Cave, a system of vast chambers and passages stretching some 1,600 meters. Seventy-six meters below the surface, in a zone of absolute darkness, the soft limestone walls are covered with thousands of abstract markings. These are not paintings and engravings of animals, but grids, lattices, and herringbone patterns drawn with human fingers into the soft, white calcium carbonate surface, a material sometimes called "moonmilk".
The markings, known as finger flutings, cover an area of several hundred square feet. They were created during the Pleistocene epoch, with radiocarbon dating of associated charcoal and artifacts placing human activity in the cave between 25,000 and 14,000 BCE. The discovery and dating of Koonalda Cave in the 1950s by archaeologist Alexander Gallus dramatically pushed back the accepted timeline for Aboriginal occupation of Australia. Before his work, the oldest known sites were dated to around 8,700 years ago. Gallus's controversial claim of 22,000 years was later confirmed, transforming the understanding of Australian prehistory.