Australia wasn’t always as it is today. A short 65 million years ago, this continent was attached to Antarctica and located 7200km south of where it sits now, before tectonic forces triggered our continental drift to the north. In a world that was generally warmer than today, temperatures in the south of our embryonic land mass were generally much cooler, with what would become Victoria pretty similar climatically to northern Alaska today. Sea levels globally were as much as 168m higher than present and as a consequence there was a vast arm of the sea stretching down from what is now the Gulf of Carpentaria into the centre of the continent.
This inland sea was home to a range of marine reptiles, the skies were populated by leathery winged creatures, and along its shores stalked dinosaurs typical of the last great era of their reptilian dominance. Rivers carried sand and fine mud from the uplands around, forming thick layers of what would become the sandstone and shales that underlie the centre of our nation.
It was a very different world from that which we recognise, but it would leave Australia with a valuable gift which would one day attract a unique group of people and support outback towns and economies: opal.
Opal is a silicate rich in water. It is formed where slow moving ground water leaves silica deposits in cracks and fissures in the rock, or dissolves and replaces bone, shell or woody tissue of dead animals and plants deposited in
