The row of rocks and debris running from the left to the right side of the photo is an example of a medial moraine. Medial moraines form on top of existing glaciers. This is the Mendenhall Glacier in Alaska. Moraine sediments are typically unsorted, that is, all different sizes of rocks and sediment are mixed together.

This photo shows two medial moraines (blue arrows) as seen from the air. The black arrows point to lateral moraines that have formed along the sides of the valley wall. Where the two main glaciers shown in the photo flow together, their lateral moraines join to form a medial moraine. The medial moraine on the right formed in the same way, however we can't see where the glaciers flow together to form the moraine.