A library etched in stone
On the Burrup Peninsula in Western Australia, known as Murujuga to its traditional custodians, lies the densest concentration of rock engravings on Earth. Estimates place the number of individual petroglyphs at over one million, with some potentially dating back 50,000 years. The geology of the peninsula provides an ideal medium for this ancient art. The landscape is covered in hills of hard igneous rocks like gabbro and granophyre. Over millennia, these rocks develop a dark, iron and manganese-rich outer layer called a rock varnish or patina. The artists created the petroglyphs by pecking, pounding, or scratching through this dark skin to expose the lighter-colored, weathered rock underneath.
This vast outdoor site is the work of the region's Aboriginal peoples, and the land is important to five local groups: the Ngarluma, the Mardudhunera, the Wong-Goo-Tt-Oo, the Yaburara, and the Yindjibarndi. The Murujuga National Park, covering over 5,000 hectares, was declared in 2013 and is jointly managed by the Murujuga Aboriginal Corporation and the Western Australian government.
A record of extinction and climate change
The petroglyphs of Murujuga are a continuous record of environmental and cultural history spanning the last ice age. The oldest engravings depict land animals, including now-extinct megafauna like the fat-tailed kangaroo. There are also many depictions of the thylacine (Tasmanian tiger), which vanished from mainland Australia thousands of years ago. The collection includes some of the earliest known engravings of the human face.
As the Pleistocene epoch ended and sea levels rose, the peninsula was transformed into an archipelago. The subject matter of the rock art shifted to reflect this change. Newer layers of art show marine species such as turtles, fish, and dugongs, documenting the changing environment and the adaptation of the people who lived there. This long, unbroken sequence records the history of life and ecological transformation recorded directly on the landscape.
The art is now threatened by its proximity to one of Australia's largest industrial hubs. Emissions from nearby gas and fertilizer plants produce airborne pollutants like nitrogen oxides. Scientists have raised concerns that these emissions create acidic conditions that accelerate the weathering of the rock surfaces, potentially erasing the petroglyphs. This has led to ongoing monitoring and debate as Murujuga is considered for UNESCO World Heritage status.