Editing Uluru (section)

===Age and origin===
[[File:UluruRockWater.jpg|thumb|Rain water flows off Uluru along channels, marked by dark [[algae]], forming small ponds at the base]]
The Mutitjulu Arkose is about the same age as the [[Conglomerate (geology)|conglomerate]] at [[Kata Tjuta]], and has a similar origin, despite the different rock type. It is younger than the rocks exposed to the east at [[Mount Conner]],<ref name="Young_etal_2002"/> and unrelated to them. The strata at Uluru are nearly vertical, [[Strike and dip|dipping]] to the south-west at 85°, and have an exposed thickness of at least {{cvt|2400|m|-2}}. 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 Ranges|Musgrave]], Mann and [[Petermann Ranges (Australia)|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.<ref name="Young_etal_2002"/><ref name="Sweet_1992"/>

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 [[Orogeny|mountain building]] episode referred to as the [[Petermann Orogeny]] that took place in late [[Neoproterozoic]] to early [[Cambrian]] times (550–530 [[Megaannum|Ma]]), and thus the Mutitjulu Arkose is believed to have been deposited at about the same time, hence then in Gondwana (now in Australia).

The arkose [[sandstone]] that makes up the formation is composed of grains that show little sorting based on grain size and exhibit very little rounding; the [[feldspar]]s 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 [[Paleozoic|Palaeozoic]] age (400–300 [[Annum|Ma]]).<ref name="Young_etal_2002"/>