The Sierra Nevada mountains have been growing - and growing more quickly than expected. But why? That question has puzzled geologists for some time, but now they think they have an answer to the rapid growth of the mountains. And it's man made. For more than a century, the aquifer underneath California's Central Valley has been drained for irrigation. So much water has been removed that it has allowed the crust to be pushed upward.
Bill Hammond, research professor, Nevada Bureau of Mines and Geology, UNR
Geoffrey Blewitt, research professor, Nevada Bureau of Mines and Geology, UNR