The moraine that piles up beside the glacier is called a lateral moraine.

Here's why:

* Lateral means "of or relating to the side".

* Moraine is a pile of rocks, sediment, and debris that has been transported and deposited by a glacier.

So, a lateral moraine forms along the sides of the glacier, where the ice scrapes against the valley walls and picks up material. As the glacier moves forward, this material is carried along the sides and deposited as a ridge.

Let me know if you'd like to know more about other types of moraines!