What does a valley glacier do?

A valley glacier primarily flows down steep-sided valleys, typically found in mountainous regions. These glaciers form in high elevations where snow accumulates, compacts, and eventually turns into ice. The force of gravity causes the glacier to move down the valley, shaping the landscape through processes of erosion and deposition.

As the glacier flows, it carves out U-shaped valleys, steepens valley walls, and transports sediment. The movement can be slower in certain areas and faster in others, influenced by factors such as the gradient of the valley and the geothermal conditions at the base of the glacier. By primarily following the contours and slope of the valley, valley glaciers play a crucial role in shaping mountainous terrains and influencing local ecosystems.

The other choices refer to different glacial behaviors or settings. Flat plains are associated with continental glaciers, not valley glaciers. Glacier extensions over oceans pertain to ice shelves formed by ice sheets, while melting into lakes is more relevant to the end processes of glacial retreats rather than the primary activity of valley glaciers.