When a glacier retreats, does the ice move back up the valley?

No, it does not. The term actually refers to changes in the position of the glacier’s terminus over a period of time. Like water, ice flows down its surface gradient and never goes back up valley. Retreat occurs when melting or calving removes ice more quickly than glacier flow replenishes it.


Photo that shows calving glacier


Learn more: about retreating glaciers and repeat photography.