Editing Uluru (section)

===Composition===
Uluru is dominantly composed of coarse-grained [[arkose]] (a type of sandstone characterised by an abundance of [[feldspar]]) and some [[Conglomerate (geology)|conglomerate]].<ref name="Young_etal_2002"/><ref name="engovaugeology">{{cite web |url=http://www.environment.gov.au/parks/uluru/nature-science/geology.html |title=Uluṟu-Kata Tjuṯa National Park – Geology |publisher=Australian Department of the Environment and Water Resources |access-date=3 April 2007 |url-status=dead |archive-url=https://web.archive.org/web/20071028194412/http://www.environment.gov.au/parks/uluru/nature-science/geology.html |archive-date=28 October 2007}}</ref> Average composition is 50% feldspar, 25–35% [[quartz]] and up to 25% rock fragments; most feldspar is [[Feldspar#Alkali feldspars|K-feldspar]] with only minor [[plagioclase]] as [[Roundness (geology)|subrounded]] grains and highly altered inclusions within K-feldspar.<ref name="Young_etal_2002"/> The grains are typically {{cvt|2|–|4|mm}} in diameter, and are angular to subangular; the finer sandstone is [[Sorting (sediment)|well sorted]], with sorting decreasing and with [[grain size]] increasing.<ref name="Young_etal_2002" /> The rock fragments include subrounded [[basalt]], invariably replaced to various degrees by [[Chlorite group|chlorite]] and [[epidote]].<ref name="Young_etal_2002"/> The minerals present suggest derivation from a predominantly [[granite]] source, similar to the [[Musgrave Block]] exposed to the south.<ref name="Sweet_1992"/> When relatively fresh, the rock has a grey colour, but weathering of iron-bearing minerals by the process of [[redox|oxidation]] gives the outer surface layer of rock a red-brown rusty colour.<ref name="Young_etal_2002"/> Features related to deposition of the sediment include [[cross-bedding]] and [[Ripple marks|ripples]], analysis of which indicated deposition from broad shallow high energy [[fluvial]] channels and sheet flooding, typical of [[alluvial fan]]s.<ref name="Young_etal_2002"/><ref name="Sweet_1992"/>