Mountain ridges are long, narrow landforms that form when two or more mountain peaks are connected by a ridge line. Aretes are sharp, jagged ridges formed when two glaciers erode away at a mountain from opposite sides. OSAR is a term used to describe a ridge that is curved or bent in shape. Spurs are short, steep ridges that extend from the side of a mountain. All three of these terms refer to different types of mountain ridges.