Final answer:
The statement is true; U-shaped valleys are indeed characteristic of glacial erosion caused by the downward movement of valley glaciers between valley walls, leading to the formation of these distinctive valleys shapes.
Step-by-step explanation:
The statement that a U-shaped valley is characteristic of glacial erosion is true. Valley glaciers, which originate at a cirque at the head of a valley or in a plateau ice cap, flow downward between the valley walls. This process profoundly influences the landscape, notably by creating distinctive U-shaped valleys.
Glaciers like the Aletsch Glacier in Switzerland cause significant erosion, as they scratch and grind down rocks while transporting materials such as gravel and boulders. The removal of material by a valley glacier tends to form a U-shaped cross section, which contrasts with the V-shaped valleys typically formed by the action of rivers and streams.
Furthermore, these erosion features can be significant indicators of past glacial activity, as recognized by glaciologists like Louis Agassiz. Agassiz's observations of glacial imprints across northern Europe led to the understanding of the historical extent of these ice sheets and their erosive power.