Drone footage flying through a wide U-shaped valley. The sides of the valley are covered in conifers. A wide rocky river runs through the valley.

Sam: Not every deposit survives long enough to become rock. Sometimes one sedimentary deposit will get recycled or broken up into pieces that are deposited again in a new setting. Here we see a modern river that passes through an ancient glacial valley. The valley was once full of glacial till deposits. Today, the river breaks up those till deposits, moves them downstream, and then redeposits them as river sediments.