Rock formations of the Adelaide Rift Complex are visible in the South Australian Outback. The swirling patterns are composed of folded and faulted sediments that were deposited there in a large basin more than 540 million years ago. Since then, the land folded and faulted to become a large mountain range and then underwent extensive erosion to become the relatively low ranges that we see today. For a sense of scale, this Overview is approximately 100 square miles.