29. Folds in Basement Rocks, Flinders Range, Australia
The continent of Australia has behaved as a stable continental block for much of recent geological history. This has not always been the case, however. The continent was assembled from several smaller, ancient nuclei, and the sutures between older blocks were the sites of intense deformation. Illustrated in the photograph are some superb folds in the Flinders Range, north of Adelaide. The rocks concerned are late Precambrian (Eocambrian) sediments (the same age as those that have yielded the classic Ediacara fossil assemblage) that were laid down on the margins of a stable cratonic block and deformed on north-south axes in the Paleozoic during the process of cratonization of the Australian continent.
South Australia is arid and barren, but this provides favorable geological exposures. The style of the folding is well seen in the picture, with thickening of strata in fold closures, and thinning on fold limbs.
STS-8, August-September 1983. Picture #8-42-2074.