29/08/2026
Volcanic Geology, what are they really?
Three of the Glasshouse Mountains.
The mountains are an iconic cluster of 13 rugged volcanic peaks rising abruptly from the Sunshine Coast hinterland. The mountains are ancient volcanic plugs formed 25 to 27 million years ago.
Millions of years ago, these were enormous volcanoes. Molten magma pushed through the earth's surface and solidified into incredibly hard rock (trachyte and alkali rhyolite) within volcanic vents. As time passed, the softer surrounding sandstone and exterior cones eroded away, leaving only these dramatic, hardened pillars behind.
Columnar jointing can be seen. Many of the peaks, such as Mount Beerwah and Mount Ngungun, feature spectacular vertical columns. These formed naturally as the thick magma slowly cooled and contracted underground.
Not known as a great fossicking area but I sure someone has found something.
