From Nat Geo –
“A moraine is material left behind by a moving glacier. This material is usually soil and rock. Just as rivers carry along all sorts of debris and silt that eventually builds up to form deltas, glaciers transport all sorts of dirt and boulders that build up to form moraines.
To get a better idea of what moraines are, picture yourself with a toy bulldozer on a lawn that has a bunch of dry leaves all over it. When you run the bulldozer through the leaves, some of them get pushed aside, some of them get pushed forward, and some of them leave interesting patterns on the grass. Now think of these patterns and piles of pushed-away leaves—moraines—stretching for kilometers on the Earth.
Moraines only show up in places that have, or used to have, glaciers. Glaciers are extremely large, moving rivers of ice. Glaciers shape the landscape in a process called glaciation. Glaciation can affect the land, rocks, and water in an area for thousands of years. That is why moraines are often very old.
Moraines are divided into four main categories: lateral moraines, medial moraines, supraglacial moraines, and terminal moraines.”