Two million years ago a relentless and endless battle began between the Pacific crust and the Indian-Australian crust. The resulting rapid mountain building created one of the world's most spectacular alpine faults, the Southern Alps. The Pacific plate is literally being rammed up over the Australian plate along a huge crack in the crust of the Earth. At the same time, the pressure is squeezing the rim of the Pacific Plate upwards at an extreme rate of about 20mm per year.
However, the Southern Alps are eroding almost as fast as they have been rising. What remains of them today is tiny compared with the total amount of rock uplifted and eroded away. Around half a million cubic kilometres of rock is missing. If no erosion of the mountains had ever taken place, the Southern Alps would extend more than 20 kilometres into and beyond the stratosphere.
Information and diagrams supplied courtesy of Glen Coates and Geoffrey Cox. For more information see 'The Rise and Fall of the Southern Alps', Canterbury University Press, (2002) or visit www.kahupublishing.co.nz
