How to grow a mountain (just add water)
Here's an odd discovery: mountains that experience heavy rainfall actually grow because of it, scientists say.
My first guess was that it was due to a build-up of plant life and compacting soil over millions of years, but apparently it's due to the way in which a mountain's summit is eroded by water. Fascinating stuff.
July 8, 2008 -- The more it rains on some mountains the faster they grow, say geologists studying the fault-riddled, intensely rainy Eastern Cordillera of Colombia, South America.
This discovery has nothing to do with water actually growing rocks and everything to do with how mountains buoy upwards when extreme rains scour away the summits.
Using mineral and paleo-plant data, researchers have now measured high growth rates of Columbia's northeastern limb of the Andes. They show that the area which has been exposed to the heaviest rains on the planet also reveals signs of having been pushed up by tectonic forces at a much faster rate over the last few million years than surrounding areas.
"The Himalayas, the southern and central Andes, and the New Zealand Alps are premier examples of (mountain ranges) where interactions between tectonics and climate have been documented and where the interplay between them may have fundamentally influenced the evolution of individual mountain ranges...," report Potsdam University's Andrés Mora and his colleagues in the July/August issue of the Bulletin of the Geological Society of America.
The tectonic principle behind the mountain growth is referred to as isostatic rebound. It is analogous to how a canoe rises up higher when a person steps out of it. Mountain ranges can rebound upwards in the same way when a load is lifted from their tops.