Posted on 05/20/2008 1:31:16 PM PDT by blam
Ice flow alone explains why fjords are cut so deep
20 May 2008
NewScientist.com news service
Fjords form when ice sheets gouge out a valley below sea level - but what makes the ice bite so deep?
A variety of factors was thought to be behind the rapid and deep incisions made as ice sheets flow down from the mountains. For example, if the sheet moves from a region where it is frozen to the bedrock to a region where the rock surface is slightly warmer, the ice might start to slide against the rock, eroding it more rapidly.
Mark Kessler of the University of Colorado at Boulder and his colleagues now reckon the process is simpler than that. The team built a computer model of a mountain range, with saddles representing valleys cut by rivers. This showed the ice sheets that covered the mountain range moving towards the sea via the saddles with the steepest slope. Erosion by the ice made these valleys deeper and steeper, encouraging even more ice to flow along that route, causing further erosion. This well-known positive feedback mechanism was enough to explain how fjords get so deep, Kessler says (Nature Geoscience, DOI: 10.1038/ngeo201).
"They convincingly show that one single feedback loop explains the creation of one of the most spectacular landforms on the planet," says Johan Kleman of Stockholm University in Sweden.
(Excerpt) Read more at environment.newscientist.com ...
Dang, that picture makes me think Neanderthals were descended from Jar-Jar Binks.
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