Uluru is one of Australia's most recognisable natural icons. The world-renowned sandstone formation stands 348 m high above sea level with most of its bulk below the ground, and measures 9.4 km in circumference. Uluru appears to change color as the different light strikes it at different times of the day and year. The local Pitjantjatjara people call the landmark Uluṟu (IPA: [uluɻu]). This word has no particular meaning in their language, also known as Pitjantjatjara, but it is also used as a local family name by the senior Traditional Owners of Uluru. On 19 July 1873, the surveyor William Gosse visited Uluṟu and named it Ayers Rock in honour of the then-Chief Secretary of South Australia, Sir Henry Ayers.[2] Since then, both names have been used, although Ayers Rock was the most common name used by outsiders until recently. In 1993, a dual naming policy was adopted that allowed official names that consist of both the traditional Aboriginal name and the English name. On 15 December 1993, it was renamed "Ayers Rock/Uluru" and became the first officially dual-named feature in the Northern Territory. The order of the dual names was officially reversed to "Uluru/Ayers Rock" on 6 November 2002 following a request from the Regional Tourism Association in Alice Springs.
The Mutitjulu Arkose is believed to be of about the same age as the conglomerate at Kata Tjuta, and to have a similar origin despite the rock type being different, but it is younger than the rocks exposed to the east at Mount Conner,[4] and unrelated to them. The strata at Uluru are nearly vertical, dipping to the south west at 85°, and have an exposed thickness of at least 2,400 m (7,900 ft). The strata dip below the surrounding plain and no doubt extend well beyond Uluru in the subsurface, but the extent is not known. The rock was originally sand, deposited as part of an extensive alluvial fan that extended out from the ancestors of the Musgrave, Mann and Petermann Ranges to the south and west, but separate from a nearby fan that deposited the sand, pebbles and cobbles that now make up Kata Tjuta.[4][5] The similar mineral composition of the Mutitjulu Arkose and the granite ranges to the south is now explained. The ancestors of the ranges to the south were once much larger than the eroded remnants we see today. They were thrust up during a mountain building episode referred to as the Petermann Orogeny that took place in late Neoproterozoic to early Cambrian times (550-530 Ma), and thus the Mutitjulu Arkose is believed to have been deposited at about the same time. The arkose sandstone which makes up the formation is composed of grains that show little sorting based on grain size, exhibit very little rounding and the feldspars in the rock are relatively fresh in appearance. This lack of sorting and grain rounding is typical of arkosic sandstones and is indicative of relatively rapid erosion from the granites of the growing mountains to the south. The layers of sand were nearly horizontal when deposited, but were later tilted to their near vertical position during a later episode of mountain building, possibly the Alice Springs Orogeny of Palaeozoic age (400-300 Ma)
Uluru (also Ayers Rock or The Rock) is a large rock formation in central Australia, in the Northern Territory. It is located in Uluru-Kata Tjuta National Park, 350 km southwest of Alice Springs at 25 degrees 20' 41" S 131 degrees 01' 57" E. It is the second-largest monolith in the world (after Mount Augustus, also in Australia), more than 318 m (986 ft) high and 8 km (5 miles) around. It also extends 2.5 km (1.5 miles) into the ground. It was described by explorer Ernest Giles in 1872 as "the remarkable pebble".' Uluru is an inselberg, literally "island mountain", an isolated remnant left after the slow erosion of an original mountain range. Uluru is also often referred to as a monolith, although this is a somewhat ambiguous term because of its multiple meanings, and thus a word generally avoided by geologists. The remarkable feature of Uluru is its homogeneity and lack of jointing and parting at bedding surfaces, leading to the lack of development of scree slopes and soil. These characteristics led to its survival, while the surrounding rocks were eroded. For the purpose of mapping and describing the geological history of the area, geologists refer to the rock strata making up Uluru as the Mutitjulu Arkose, and it is one of many sedimentary formations filling the Amadeus Basin.
