OCEANS, MOUNTAINS AND ASTEROIDS: THE SECRET GEOLOGICAL HISTORY OF SOUTH AUSTRALIA
As part of this years Convergence on the Coast, the SGTSG proudly present a public lecture by emeritus Associate Professor Victor Gostin.
All are welcome to attend this free event at the Port Lincoln Hotel on Tuesday the 19th of November, starting at 7:30 pm.
What's it about
The geology of South Australia can tell stories of fluctuating sea levels, violent impacts from space and the rise of animal life on Earth, if you know where to look. From a time known as the Ediacaran Period, around 580 million years ago, until now, there is a secret history recorded in the rocks that geologists have been decoding. During that time a huge meteorite impact occurred when a 5 km diameter asteroid hit the Gawler Ranges, resulting in a crater 90 km across at Lake Acraman followed by significant environmental and evolutionary effects.
In this Ediacaran Period, much of south-east South Australia was underwater, slowly depositing sedimentary rocks, such as the Wonoka limestone. These limestones record a strange world-wide chemical anomaly associated with a major change in global oceanic circulation, possibly from changes in the Earth’s axial tilt. In this same ocean, animal life on Earth was evolving, now found as fossils in the rocks of the Flinders Ranges.
During the last million years sea levels and deformation of the Earth’s crust have affected the shape of South Australia’s coastline. Eyre Peninsula’s relative stability contrasts with the ongoing rise of the Mt Lofty Ranges, and the Mt Gambier region. This history, recorded in the geological and fossil record, tells us that events recorded in South Australian geology were globally important, but can also tell us how the South Australia we know today was formed.