Wonder
The blue peaks are dead volcanoes
Those steep blue hills on the skyline are the burnt-out plumbing of volcanoes that stopped erupting 26 to 27 million years ago.
Look west from almost anywhere on the coast and you'll see them: a row of steep blue-grey domes and spires standing up out of flat farmland like something dropped there by mistake. They are the Glass House Mountains, and they are the worn-down cores of volcanoes that last erupted 26 to 27 million years ago.
When a volcano dies, the soft ash and lava that built its slopes wear away first. What lasts is the hard plug of rock that cooled solid in the throat. The plumbing. Everything softer around it has simply been rained away over the 26 million years since, leaving the plug standing alone. Every one of those peaks is a volcano turned inside out: the outside gone, the inside left pointing at the sky.
Hard rock stands up; soft rock wears down. That is the first lesson in reading this coast, and once you know it the whole skyline reorganises itself in front of you.
From Chapters 2–3 · The making of the rock · Read the guide → · See them on the map →