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BOB HIRSHON (host):
Mountain-sculpting salmon. I’m Bob Hirshon and this is Science Update.
Many mountains of the Pacific Northwest are thirty percent lower than they should be. And according to a study in Geomorphology, the culprit is salmon, who once migrated by the tens of millions upriver to their ancestral mountain streams. Indiana University geologist Brian Yanites explains that female salmon energetically clear their spawning area of excess gravel and rocks.
BRIAN YANITES (Indiana University):
What it does is it allows the river to export that sediment and expose the underlying bedrock to the river’s erosive power that can then cut down and incise into that bedrock more efficiently than if the salmon weren’t there.
The researchers calculated that over five million years, salmon could have eroded the mountains by hundreds or even thousands of feet—an example of how organisms can re-shape the very bedrock of the planet. I’m Bob Hirshon, for AAAS, the science society.
Story by Bob Hirshon