AYERS ROCK

giant monolith, one of the tors (isolated masses of weathered rock) in southwestern Northern Territory, Australia. It is perhaps the world's largest monolith. The monolith, which the Aborigines of the region call Uluru, is composed of arkosic sandstone, which changes colour according to the attitude of the Sun. The rock is most impressive at sunset, when it is coloured a fiery orange-red by the sun's rays. Rising 1,100 feet (335 m) above the surrounding desert plain, Ayers Rock is oval in shape, 2.2 miles (3.6 km) long by 1.5 miles (2 km) wide. Its lower slopes have become fluted by the erosion of weaker rock layers, while the top is scored with gullies and basins that produce giant cataracts after infrequent rainstorms. Shallow caves at the base of the rock, which is within Uluru National Park (first established, in 1958, as the Ayers Rock-Mount Olga National Park), are sacred to several Aboriginal tribes and contain carvings and paintings. Sighted in 1872 by Ernest Giles, the rock was named for former South Australian premier Sir Henry Ayers. In 1985, official ownership of Ayers Rock was given to the Aborigines, who thereupon leased the rock and Uluru National Park (surrounding it) to the government for 99 years. Visitors come to the rock via Alice Springs, 280 miles (450 km) northeast by road. The buildings of the tourist resort near Ayers Rock are coloured to blend in with the surrounding desert.