The line of low hills formed by rock pushed at the front of a glacier is called a terminal moraine.

Here's a breakdown:

* Moraine: A moraine is a landform made of glacial debris (rock, sediment, and other material).

* Terminal Moraine: This specific type of moraine marks the furthest advance of a glacier. As the glacier pushes forward, it collects and carries debris, which is deposited at the glacier's edge as it melts. This deposited material forms a ridge or series of hills.

Let me know if you have any other questions about glaciers or landforms!