Exeposé News online (2 December 2015)
Mountains aren’t as static and unchangeable as previously thought – they actually evolve with the Earth’s climate, according to ground-breaking new research by a team including an Exeter academic.
The University’s Dr Ian Bailey took part in an international study investigating how climate and tectonic forces affect mountains over time.
The research showed that during ice ages, glacial erosion can sometimes wear mountains down faster than plate tectonics can build them.
The team – made up of researchers from ten countries – focused their study on the Alaskan St Elias mountain range.
Using seismic imaging tools and marine coring, they measured the material leaving and entering the range over five million years – and found that erosion increased sharply during a global cooling period about one million years ago. This was a period of stronger and persistent ice ages.
The research pulled together more than a decade of field work – and was published in the Proceedings of the National Academy of Sciences on 23rd November.
“Understanding precisely how the balance of climate and tectonic forces influences mountain building remains an outstanding unknown in Earth Sciences,” explained Dr Bailey, who lectures in Geology at the Camborne School of Mines at the University’s Penryn Campus.
“A tremendous amount of important information has been gained,” he added.
“Since the big climate change during the mid-Pleistocene transition when we switched from short (about 40,000-year) ice ages to super long (about 100,000-year) ice ages, erosion became much greater,” said Sean Gulick, lead author of the study and co-chief scientist at the University of Texas Institute for Geophysics (UTIG).
“In fact, there was more erosion than tectonics has replaced.”
Mountain ranges form through the collision of tectonic plates over millions of years. As plates collide, the Earth’s outer crust is effectively “scrunched”, forming ridges.
But, opposing forces can also break down the gathering crust – and in the past million years, erosion rates have eclipsed build-up rates by 50 to 80 per cent.
Funded by the U.S. National Science Foundation and the Integrated Ocean Drilling Program, this study highlights the key role climate plays in shaping the Earth’s landscape.