Blurb:

During the Dampier Archaeological Project (1980–1982), 9,244 petroglyphs were recorded. A study including 1,358 of these petroglyphs was conducted, in an effort to identify patterns relating to a mineral coating, or desert varnish, that is present in a relatively small percentage of the images (20 percent). Many more petroglyphs truncate the coating (34 percent). It was found that particular motif subjects were covered with the varnish, namely macropods, elaborate non-figurative designs, and certain types of anthropomorphic motifs, while marine subjects and different anthropomorphic forms cut through the varnish. Despite not being able to determine when the varnish may have formed, the subject dichotomy suggests that the early phases of the rock art predate the formation of the Dampier Archipelago around 7,000 BP, with a later production period occurring when a marine ecosystem became established.