- News Home
17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
- About Us
Drought Pushed the Andes Higher
22 October 2003 (All day)
Many dramatic events in Earth's history are attributed to climate change, from mass extinctions to the drying up of inland seas. Now, two geologists suggest that climate change may also fiddle with events deep inside Earth. They propose that over the last 40 million years, bouts of cool and dry climate along the west coast of South America may have leveraged the towering Andes to much greater heights than other, similar ranges.
The Andes rose to 5 kilometers above sea level as oceanic crust slid beneath the lighter South American continent. That's a typical way to raise mountains, yet the towering peaks are a good 1 to 2 kilometers higher on average than mountains formed in similar situations around the Pacific rim. What caused the extra tectonic stress needed to bulk up the Andes is unknown.
Faced with this conundrum, University of Oxford geologist Simon Lamb and geologist Paul Davis at the University of California, Los Angeles, calculated how much stress would be needed to support the height and weight of various mountains along the length of the Andes. Lamb and Davis then made what they think is a key observation: The central Andes, where the peaks are highest, faces an extreme lack of rain and rivers. That means little sediment is carried offshore to settle in the oceanic trench where the ocean plate dives beneath the continent. In the 23 October issue of Nature, the pair suggests that less sediment equated to less lubrication. As the ungreased oceanic plate scraped beneath the continent, it provided the greater stress needed to build the mountains higher.
To see if dry conditions were also prevalent when the Andes were on their way up, Lamb and Davis checked records of deep ocean temperatures. These suggested that periodic pulses of cold water from the Antarctic along the South American coast could indeed have kept rainfall low, and these cold periods also seem to match times of very rapid uplift in Andean height.
The idea has merit, says geologist Richard Allmendinger of Cornell University in Ithaca, New York, and is certainly worth investigating further. But he cautions that it's hard to get accurate chronologies for climate and mountain uplift and the correlations may not hold up as more data come in.