The Australian Alps cover a large area, displaying a wide range of rock types and a complex geological history spanning 520 million years. This makes them a wonderful topic for study through two different educational formats - a factsheet and a video. Each describes the events that formed the different types of rocks and the distinctive landscape of the Australian Alps.
Download the factsheet
Narrator: The origin of Australia's highest mountains is something of a geological mystery. But geologist Dr. Vincent Morand thinks there is an answer.
Dr Vincent Morand: I'm standing here on top of Mt Hotham, right in the heart of the Australian Alps. But looking around here you may well ask, 'Just where are the mountains?'. What we're looking at is a high plateau. This is nothing like the sort of peaks we see in the Alps of Europe, or the Himalayas. Mountains like the Himalayas form when one continent collides with another, but the Australian Alps formed by a completely different process. They weren't formed by the colliding of continents, they were formed by the splitting apart of one gigantic continent - the ancient super-continent of Gondwana.
Narrator: 160 million years ago, India, Antarctica, Australia and New Zealand formed part of Gondwana. At this time, the Australian Alps didn't exist. In their place was a low, flat plain. But Gondwana then started to stretch apart from lines of weakness. Under the flat plain, the Earth's crust became thinner and weaker. This allowed hot magma from deep below to rise up. The magma heated the crust and added new lighter rocks, so the crust expanded upwards to form a plateau nearly two kilometres high. This new highlands was the beginning of the Australian Alps.
By 100 million years ago, stretching turned into wholesale splitting. India moved west, Antarctica headed south. Large faults started to form along the uplifted plateau. The plateau split down the middle and a rift valley formed. A whole new environment was created along eastern Australia.
Dr Vincent Morand: At this stage, eastern Australia looked similar to the great rift valley of Africa. But the animals in Australia were unique. Dinosaurs like Austrosaurus and Muttaburrasaurus - the animals were evolving, and so was the land.
Narrator: By 80 million years ago, the sea invaded the expanding rift. Zealandia sank away to the east, but the western side of the plateau remained, now forming Australia's eastern coastline. Gondwana's stretching created the highlands, but it was the weather that would finally shape the mountains. Over the next 60 million years, frost, wind and water carved deep valleys out of the plateau, gradually moulding it into the Australian Alps.
Dr Vincent Morand: Mountains formed in this way are found along many coastlines around the world - for instance in South Africa and Norway. Like those mountains, the Australian Alps form a gently rolling landscape of high plains, which stop abruptly at the plateau edge, then tumble steeply down into deep valleys, like we see here.