Lake Acraman Meteorite Impact Crater - SA

The Acraman Impact structure, centred on a crater at Lake Acraman in the Gawler Craton, South Australia, is one of the largest known in Australia and in the top ten known globally. The bolide diameter was approximately 4.8 km with a collapse crater 85-90 km across, and the ejecta is spread over a radius of greater than 560 km. The estimated impact energy is greater than 106 megatons, which exceeds the threshold for global catastrophe. The Acraman Impact Event occurred just prior to the evolution of animals, which preceded the Cambrian explosion, and is therefore a critical event in the evolution of Earth's biosphere.
The area is on Private Station property and is inaccessible.

However, deposits of the ejecta from this impact (dust, gravel, rocks) were located and reported on by South Australian university based geologists, in 1985. One instance that is easily accessible by the public is adjacent the Bunyeroo scenic drive, at Bunyeroo Gorge in the central Flinders Ranges. At the time of this impact, the Flinders Ranges had not been formed and that area was covered by a shallow sea; petrified mud from the floor of that sea now holds deposits of this ejecta. To see this particular deposit, take the Bunyeroo scenic drive from either end and look for the SA National Parks signposted car park at Bunyeroo gorge. Two gazetted and signposted walks start from this car park, one of which is the Bunyeroo Gorge West geological trail. The first signposted feature on the trail is the Acraman ejecta.