What happens to the walls of a V shaped river valley as a glacier moves through it?

As a glacier moves through a V-shaped river valley, it erodes the valley walls, transforming the V shape into a broader U shape. The immense weight and movement of the glacier scrape and pluck rock and sediment from the sides, leading to steepened and smoothened valley walls. This process also results in the widening of the valley floor, creating a more expansive glacial trough. Over time, the glacier's movement reshapes the landscape, leaving behind features such as hanging valleys and moraines.