The gigantic granite boulders piled just east of the Stuart Hwy, 105km south of Tennant Creek, are known as the Devil’s Marbles (Karlu Karlu in the local Warumungu language) and they’re one of the more beautiful sights out here. The Marbles are a sacred site to the traditional Aboriginal owners of the land, who believe the rocks are the eggs of the Rainbow Serpent. On 27 October 2008 ownership of the land was returned to their care.
Although the owners are the Alyawarre people, the Marbles also carry great spiritual significance for other Aboriginal groups, including the Kaytetye, Warumungu and Warlpiri people.
Such are the extremes of temperature out here that the boulders undergo a constant 24-hour cycle of expansion and contraction, hence the large cracks in many of the boulders.
There are five signposted walks around the Devil's Marbles, from the 20-minute, 400m Karlu Karlu Walk departing the day-use area to the 1½-hour, 4km Nurrku Walk that takes you away from the crowds. If you've only time for one walk, make it the 30-minute, 800m Mayijangu Walk from the day-use area to the campground, with a 20-minute, 350m add-on up to Nyanjiki Lookout. Unless specifically permitted to do so by signposts pointing you in that direction, respect local beliefs by not climbing on the rocks. A 15-minute walk loops around the main site.
Wildlife possibilities include small black-headed goannas in the rocky clefts, while birds to keep an eye out for include zebra finches, painted finches and fairy martins that build bottle-shaped mud nests on the underside of some boulders.
Complementing Aboriginal explanations for the existence of these strange formations, scientists argue that the boulders are made of granite that originated with the hardening of volcanic magma beneath the earth's surface; this could have occurred nearly two billion years ago. The granite then pushed through the surface thanks to the complex interaction beneath the granite and softer, surrounding sandstone. Once atop the earth's surface, the boulders' shapes were formed over millions and millions of years by the weathering of wind and water, as well as extremes of temperature. This process changed the outer layer, although the core of each boulder remains largely unchanged. They range in size from barely 50cm across to those with a diameter of 6m.
This geological phenomenon is particularly beautiful at sunrise and sunset, when these oddballs glow warmly. The campground has remarkably hard ground, pit toilets and fireplaces (BYO firewood).