The long dirt track approach to the isolated range is only passable during the dry season. Last year s extraordinarily wet season kept the region closed until very late, so a helicopter was Fisher s only option to complete the survey. Initially a big blow to the budget, the helicopter later turned out to be the key to new discoveries and insights. The 360 million year old sandstone of the Bungle Bungles gets its unique stripes from alternating layers of rock that have a different clay content and porosity. The orange bands are the result of oxidized iron compounds in layers that are too dry for the bacteria.
Erosion is responsible for the shape of the unique domes and a network of associated canyons.
With the help of local helicopter pilots and park rangers, Fisher was able to make an extensive survey of Purnululu and its gegraphical features. Most visitors to the Bungle Bungle Range walk up the Piccanniny Gorge, which snakes through naked rock and along a creek before ending abruptly at an impassable waterfall ten miles from the mouth of the gorge. With the use of a helicopter, Fisher was able to explore beyond the falls. From the air he spied an unrecorded stone arch measuring some seventy feet high and thirty feet across. Later, investigations on foot revealed the arch is a natural bridge across a small creek an extremely rare geologic feature, considering the fragile nature of the rock.