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.
Industry and art in the dark
Koonalda Cave was not a place of habitation. Instead, it was a destination for two specific activities: flint mining and the creation of the finger flutings. Hundreds of meters inside the cave, well beyond the reach of any natural light, Pleistocene people quarried high-quality flint and chalcedonic quartz. This material was essential for making stone tools and was traded over long distances. Evidence of this ancient industry includes quarry pits up to six meters deep, leftover stone debris, and the remnants of wooden torches used for light.
The finger markings are found in the same deep, dark passages as the mining operations, some 300 meters from the entrance. Creating them required a deliberate trip into the dangerous subterranean world. The abstract nature of the lines has led to many interpretations. They may have been part of rituals, a form of mapping, or simply a tactile exploration of the cave's unusual textures in complete blackness. While similar finger flutings exist in Paleolithic caves in Europe, their precise purpose at Koonalda is unknown. The markings are traces of human touch from the last Ice Age.