Cross River Rail’s “Jurassic Bark” provides window into prehistoric Brisbane
16 Feb 2022
A petrified tree trunk dating back to the age of dinosaurs has been found in one of Cross River Rail’s tunnels, helping experts paint a clearer picture of prehistoric Brisbane.
Cross River Rail Delivery Authority CEO Graeme Newton said the stump found beneath Kangaroo Point – affectionately known as “Jurassic Bark” – was as old as 220 million years.
“While Cross River Rail will transform how we travel to, from and through Brisbane in the future, it’s also helping us understand what was here before us – long before the first primates had even begun to evolve,” Mr Newton said.
“When we started tunnelling beneath Brisbane we knew we were bound to come across some old material, but I never thought we’d find something that was alive while the supercontinent Pangea was only just beginning to break apart.
“It’s a massive find, and another great example of how Cross River Rail is far more than just a rail project.”
Queensland Museum Head of Geosciences and Principal Curator of Paleobotany Dr Andrew Rozefelds said the trunk was fossilised after being covered in ash flows from a volcanic eruption.
“Brisbane 220 million years ago was a pretty exciting place to be for all the wrong reasons, thanks to the active volcanoes in the area,” Dr Rozefelds said.
“This tree stump was petrified in South East Queensland’s equivalent of Pompeii – only it would have been early dinosaurs rather than humans fleeing the eruption.
“Ash falls, gas clouds and rock fragments would have covered all the vegetation in its path, entombing the tree trunk in sediment while the material slowly cooled into the rock that Cross River Rail is now tunnelling through.”
Dr Rozefelds said the find would help provide a more complete picture of what Brisbane was like over 200 million years ago.
“The trunk itself, as well as the fossil pollen from the sediments around it, can tell us a lot about the plants and flora that was around at the time,” he said.
“With this information, we can actually reconstruct the vegetation there 220 million years ago, which really helps our understanding of Brisbane’s geoheritage.”
The tree trunk is undergoing preliminary investigations at Queensland Museum.
The Cross River Rail Experience Centre has plenty of other archaeological finds on display and is open during the week, except Tuesdays and public holidays, between 10am and 4pm, and on the weekend from 10am to 2pm.
Jurassic Bark fast facts:
- The tree trunk was found in a cross passage between Cross River Rail’s twin tunnels beneath Kangaroo Point.
- The tree was buried in a tuff deposit – a type of rock formed from a volcanic eruption.
- The species of plant preserved resembles a conifer, the family of pines, cedars and yews.
- The stump is as old as 220 million years (technically the late Triassic Period). At that time:
- Early dinosaurs roamed the Earth.
- The supercontinent Pangea was only just beginning to split.
- The vegetation was dominated seed ferns that are not around today, while flowering plants such as Eucalyptuses and Acacias were yet to evolve.
- Insects, such as beetles, cockroaches, wasps and dragon flies, would have looked relatively similar to those around today.
- The earliest ancestor of humans, a hominid called Sahelanthropus tchandensis, was still over 200 million years away from evolving.