Paleo Slide Set: The Ice Ages
Fjord, Baffin East Coast Mountains, Nunavut, Canada.
U-shaped valleys were another observation that could be explained by 
the ice-age theory. Scientists knew that rivers carved V-shaped valleys, 
but not U-shaped valleys, which are found only in alpine regions 
or high latitudes where glacial ice is formed.

Photo Credits:
John T. Andrews
INSTAAR and Department of Geological Sciences, University of Colorado, Boulder.