January 7, 2019

Monday Geology Picture: Kangaroo Point Cliffs, Brisbane, Australia

Posted by Evelyn Mervine

A view of Kangaroo Point Cliffs, taken from across the river, December 2018.

Happy New Year! I’m going to try to keep up with my “Monday Geology Picture” posts in 2019. I did okay with these in 2018, although I missed some weeks here and there when I was very busy with work or family life.

To start off a new year of pictures, here is a picture that I took during a recent visit to Brisbane, Australia. This picture shows a place known as Kangaroo Point Cliffs. These cliffs are not completely natural but were rather formed by a combination of river erosion and quarrying for stone that was used to make several buildings throughout the city. The geology of the cliffs is quite interesting — the cliffs are comprised of Brisbane tuff, a welded ignimbrite that is Triassic in age. I’ll blog more about these fascinating rocks in future.

Here’s a little more information from a sign located across the river from the cliffs:

Sign with some information on the Kangaroo Point Cliffs. Click to enlarge.

The first paragraph says:

The rocks in the Kangaroo Point Cliffs are the debris of an ash flow from an exploding volcano 220 million years ago. The cliffs have been slowly carved by the river and from the 1820s stone was quarried from the cliffs to build the new Brisbane Town.