page_title: Uluru
section_title: Age and origin
hierarchical_section_title: Uluru / Geology / Age and origin
caption_attribution_description: English: Rock formations and water features. Uluru (Ayers Rock), Australia.
context_page_description: Uluru, also known as Ayers Rock and officially gazetted as Uluru / Ayers Rock, is a large sandstone rock formation in the southern part of the Northern Territory in central Australia. It lies 335 km south west of the nearest large town, Alice Springs.
  Uluru is sacred to the Pitjantjatjara, the Aboriginal people of the area, known as Anangu. The area around the formation is home to an abundance of springs, waterholes, rock caves and ancient paintings. Uluru is listed as a UNESCO World Heritage Site. Uluru and Kata Tjuta, also known as the Olgas, are the two major features of the Uluṟu-Kata Tjuṯa National Park.
context_section_description: 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, 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.
  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 tilted to their near vertical position during a later episode of mountain building, possibly the Alice Springs Orogeny of Palaeozoic age (400–300 Ma).
caption: Rain water flows off Uluru along channels marked by dark algae, forming small ponds at the base
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