South Australia - March 13th, 2009
The interesting pattern of swirling brown lines between two white salt flats is actually a mountain range: the Flinders Ranges, the largest mountain range in South Australia.
The Flinders Ranges start approximately 200 km north west of Adelaide. They are discontinuous, and stretch for over 430 km from Port Pirie to Lake Callabonna.
The Flinders Ranges are largely composed of folded and faulted sediments of the Adelaide Geosyncline. This very thick sequence of sediments were deposited in a large basin during the Neoproterozoic on the passive margin of the ancient continent of Rodinia.
During the Cambrian, approximately 540 million years ago, the area underwent the Delamerian orogeny where the geosynclinal sequence was folded and faulted into a large mountain range. Since this time the area has undergone erosion resulting in the relatively low ranges today.
The lake to the west of the ranges is Lake Torrens, a 5,700 square kilometre endorheic saline rift lake. Lake Torrens is usually a dry salt flat. It has only been filled with water once in the past 150 years.
Lake Frome, also a large endorheic lake,to the east of the ranges, has similar characteristics. It is a shallow, unvegetated playa or saltpan, 100 km long and 40km wide, lying mostly below sea level and having a total surface area of 259,615 hectares. It only rarely fills with brackish water flowing down usually dry creeks in the Northern Flinders Ranges from the west, or exceptional flows down the Strzelecki Creek from the north.