Uluru

The most recognizable natural symbol of Australia, Uluru, also known as Ayers Rock, rises more than 1100 feet above the arid terrain of the Continent's Red Center. Composed of arkosic sandstone (rich in feldspar), this spectacular formation developed over the course of a half a billion years.

As the Precambrian gave way to the Paleozoic Era, some 600 million years ago (MYA), ancient mountains to the west and southwest of Uluru were eroding into the Amadeus Basin, producing vast alluvial fans of debris. By the Ordovician, 500 MYA, seas invaded the region, compacting these deposits beneath layers of ocean sediment. During the Silurian Period, about 400 MYA, the region underwent compression, likely related to collision with other continents, uplifting and tilting the various layers of rock. Over the past 300 million years, softer overlying and surrounding sediments have eroded away, leaving the massive Uluru monolith, almost 6 miles in circumference. As large as it is, Uluru is but the tip of a sandstone formation which extends outward and downward for several miles.

Kata Tjuta (the Olgas), 16 miles west of Uluru, formed in a similar sequence but is composed of conglomerate rock. Both formations, sacred sites for regional Aboriginal tribes, are protected within the Kata Tjuta-Uluru National Park, a World Heritage Site; the Park is about 280 miles southwest of Alice Springs.