A/Prof Malcolm Wallace says he loved fossils as a child, and wanted to become a palaeontologist. He also liked rocks, however, and at university chose geology. He has brought these interests together for of one of the most significant fossil discoveries in Australian history. If he’s right, this may soon lead to something even bigger.
Wallace was part of the discovery of an enormous reef at Arkaroola in the Flinders Ranges. The reef is ten times the size of something you would find on the Great Barrier Reef, and has been dated to 650 million years ago (AS, Nov/Dec 2008 p.7). A Canadian reef is more than 100 million years older, but Arkaroola dates from a particularly interesting point in the Earth’s evolution.
A little over 700 million years ago the planet experienced the Sturtian Glaciation, when almost the entire planet froze over, with the possible exception of a narrow band of water at the Equator. Eventually the planet emerged, only to experience the same thing happen in the Marinoan Glaciation roughly 50 million years later. Together these events are known as “Snowball Earth”. The Arkaroola Reef dates from between these periods.
Life was almost wiped out by the Sturtian event, yet ecosystems rebounded with such speed they were able to produce a reef 1 km high. Some species thrived on the sunlight in the shallower parts of the ocean while others...
