Glacial erosion changes internal mountain structure, responses to plate tectonics

November 18th, 2008 - 5:30 pm ICT by ANI  

Washington, Nov 18 (ANI): A new research has proven that glacial erosion can not only change internal mountain structure, but also bring out a structural response to plate tectonics.

The subject of study for the researchers, which were from seven universities, was the highest coastal mountain range on earth, the St. Elias range in Alaska.

Here, intense glacial erosion has not only carved the surface of the mountain range, but has also elicited a structural response from deep within the mountain.

This interpretation of structural response is based on real-world data now being reported, which supports decades of model simulations of mountain formation and evolution regarding the impact of climate on the distribution of deformation associated with plate tectonics.

The St. Elias range is a result of 10 million years of the North American plate pushing material up as it overrides the Pacific plate, then the material being worn down by glaciers.

A dramatic cooling across the earth about three million years ago resulted in the onset of widespread glaciation.

A million years ago, glacial conditions became more intense and glaciers grew larger over longer periods, and transitioned into more erosive ice streams that changed the shape and evolution of the mountains.

The process continues today, resulting in the particularly active and dramatic St. Elias orogen geologists word for mountains that grow from collision of tectonic plates.

According to James A. Spotila, from the Virginia Tech geosciences department, the research showed how a change in climate led to a change in the way the motion of tectonic plates is accommodated by structural deformation within the orogen.

The wedge is still present but has narrowed with the eroded material deposited across the toe. Some faults, which previously responded to the push of the plow or tectonic plate, are relocated to respond to the erosion, he said.

It is remarkable that climate and weather and the atmosphere can have such a profound impact on tectonics and the behavior of the solid earth, he added. (ANI)

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