Situated 335 km south-west of Alice Springs in the Northern Territory, this large rock mass is an erosional remnant made of a sedimentary rock, a feldspar-rich sandstone called arkose. It was originally laid down as a sediment in an inland sea in Cambrian times, about 500 million years ago. Earth movements such as uplifting and folding about 300 - 400 million years ago have pushed up the rock and tipped the original horizontal strata into a vertical position, so we see sets of prominent vertical banding. The arkose has impurities of iron oxide, so there are strong red and brown colours in the rock. The present smooth outline is the result of spalling, where sheets of rock have peeled off as a result of expansion and contraction from continual heating and cooling. The rock mass emerges from a wide sandy plain, but it is not just sitting on top of the ground, it is continuous with the same kind of rock under the ground. The perimeter of the base of the rock is 8.8 km, the rock mass itself is 3.6 km long and 2.4 km wide, and stands 348.7 m above the surrounding plain. At sunrise and sunset the colours of Uluru are constantly changing, from pink to red, purple and brown.
Copyright © Australian Museum, 2004