What kind of terrain and landforms would indicate the prior existence of a valley glacier

Mountainous terrain with horns, cirques, arêtes, hanging valleys, lateral moraines, and u-shaped valleys indicate the prior existence of a valley glacier.

When a glacier moves, it forms different landforms because of erosion. Movement of a big mass of glaciers carries material in its way and carve shapes on the land and plucking out rocks either big or small. This movement causes different shapes such as bowl-shaped and carving of depression of steep gradients from a mountainside.  

These depression are called cirque and if three or more meet they form a mountain peak. The depressions also form valleys which are U-shaped and V-shaped. Glacier flow may be short or may rich as far as the coastline and craves a narrow trough as it moves. A glacier that melts at the valley and fills it with water is called fjord.