Although not the first on my list of columnar jointing locations, it was however, the most recent. After a rained out weekend (14/05/2017), Elisha and I could not climb the mountain as there had been massive rockfalls and mud slides on the route up, which was a bit of a shame, we’ll have to visit again soon!
Mount Beerwah, SE QLD, Australia. Photo taken at the car park at the base of the mountain.
So, Mount Beerwah is one of ten volcanic plugs that dot the Glass House Mountains. It formed around 26 million years ago when southeast Queensland was over a hotspot that caused prolonged volcanic activity throughout that Glass House Mountain Region. The regional geology in the area prior to the volcanic activity is sandstone, with these volcanic plugs intruding into the sandstone. Over time, erosion has worn away the sandstone leaving the harder igneous rocks exposed. The composition of the Mount Beerwah columnar jointing is apparently, according to signage in the area, Trachyte. However, without a hand sample I couldn’t say for sure.