The Wollumbin caldera, with Wollumbin, the largest extinct volcano in the southern hemisphere, on the horizon
Image: © Tao Jones

The Rainbow Region

If you had two weeks and sturdy shoes, you could walk the entire rim of the southern hemisphere’s largest ancient volcano. This is the “Northern Rivers” region of Australia, including the southeast of Queensland and the northeast of New South Wales. With some careful observation, you would also move through deep earth time and even get glimpses of the future.

Dominating this landscape is Mt. Wollumbin, named ‘Wild Turkey’ by some, the ‘Cloud Catcher’ by others, sacred to the aboriginal tribes of the area. That peak, often lost in weather, is the plug for the volcano. It rose up 23 million years ago (mya). This volcano was active on and off for about three million years before its walls collapsed. It had come up through Brisbane siltstones laid down between 500-250 mya. It poured over Mesozoic sediments, which had been set down earlier (210-135 mya). Finally the area gave over to the power of water: erosion by rain, by new rivers, the silts of flooding and the sea level changes of the Quaternary years. So now - these valleys, ravines, waterfalls, coastal plains.

In places the soil, product of untold years of erosion, is said to be 12 metres deep. In other places, the ancient Brisbane rock is visible. And along the coast is white sand, itself an erosion product of eons.

Looking up to Wollumbin, you can see eons unreeling. Looking over the caldera, there are 366,507 hectares of Gondwana Rain Forests. Their heritage goes back some 200 million years when continents now separated were one land. Half of today’s unique Australian plants and a third of its mammals and birds are here, scattered over 50 World Heritage listed national parks and rainforests.

From some 40,000 years ago, there are tales by the first people here, who marked some of their social divisions with the land: the women’s business to the seaside lakes, the men’s to the Wollumbin mountain. From several hundred years ago, there are Captain Cook’s tales and his new name for the plug. As it marked a treacherous coastline, he called it Mt. Warning.

Colloquially, the present day inhabitants know the area as the ”Rainbow Region”. In the ever-changing weather, the colours arch, marking bridges and promises. These are expressed in vivid arts, active citizenship and environmental innovations. There, did you see that? That local something? It’s the first appearance of what we will soon know as “tomorrow”.

Mary Gardner, writer & biologist, Byron Bay