Snowball Earth

• Evidence of how it came to be so beautiful and nurturing is locked in the rocks of South Australia’s Flinders Ranges – a site now vying for World Heritage listing.
• Their legacy is the oxygen we breathe and the evolution of the first animals more than 500 million years ago.
• The soft bodies of these animals have been exceptionally preserved at the new Nilpena-Ediacara National Park, which opened in April 2023.

A superbasin on the shores of the Pacific

• The rocks of the Flinders Ranges formed at the same time as the Pacific Ocean basin.
• The plate tectonic “dance of the continents” tore North America away from Australia 800 million years ago.
• Geologists call this the Adelaide Superbasin.

Land of fire and ice

• The planet plunged into an 80-million-year Ice Age, the likes of which has never been seen again.
• The Cryogenian contains a least two global glaciations when the planet became covered in ice - an occurrence earth scientists refer to as “Snowball Earth”.
• Read more:
  Ancient volcanic eruptions disrupted Earth's thermostat, creating a 'Snowball' planet

Part One: Picturing the world before the first animals

• The glaciers ploughed through hills and valleys, planing off the country and leaving behind vast swathes of boulder clay that now forms rocks over much of the Flinders Ranges.
• We used these variations to build a picture of highly saline shallow seas rich in bacterial life, but devoid of much else.

Part Two: Dating Snowball Earth

• Using established methods we can date one of the minerals in the sand (zircon).
• This enabled us to more accurately date the Snowball Earth rocks in the Flinders Ranges called the Sturt Formation.
• It is the first study to directly date sedimentary rocks that formed during the Snowball Earth event.
• So the planet experienced more of a cold period rather than a completely frigid snowball.

The rise of the algae

• The geological processes and their timing helps us understand how the Earth system came to be.
• The frozen world of the Cryogenian stressed the microbial life that dominated the oceans way back then.
• This newcomer was algae, life with cells containing a nucleus.

A place of true world heritage

• Our research into these rocks links the interdependence of Earth systems.
• The stories locked in the hills of the Flinders Ranges undoubtedly give the region a heritage value to the world.
• We eagerly await news of world heritage listing, which is not expected until 2025 at the earliest.