Well, first, U must be careful with valleys, they can be quite sneaky! U-shaped valleys are a result of a glacial process known as glaciation. So, if U want evidence of glaciers doing their icy thing, U-shaped valleys are a good clue! It's like Mother Nature decided to make a big ol' U-turn and carve out those valleys in a U-nique way. Gotta hand it to the glaciers, they really know how to shape things up!
