A moraine looks like someone took a bulldozer and scraped up dirt and everything around it, creating patterns of land at different heights from rocks and debris. Some moraines have plants that grow on them over time.
Because glaciers have the ability to move, they collect debris in their travels. The glacier eventually has gathered up many different kinds of material including rocks and soil. The material is left behind as the glacier continues to move and melt, causing a delta to form.
Moraines are made from soil, rocks, and debris. Moraines are usually old because it takes time for the glaciers to move and change the landscape.
As explained by education.nationalgeographic.com, four types of moraines exist:
- lateral moraine: Formed from debris on the sides of a glacier; they usually have a similar height
- medial moraine: Formed when the debris on two glaciers becomes sandwiched between the two, causing a ridge or line of rocks
- supraglacial moraine: Formed when the glacier becomes covered in rocks, debris, soil, etc.
- Ground moraine: Consists of sediment collected on the underside of the glacier, has no ridges or points, and often has grass and plants growing on it
The most common type of moraine is a terminal moraine.
Glacial moraines are created as a glacier (which moves by definition) transports unconsolidated sediments across a landscape. At the front, or terminus, of a glacier, the unconsolidated sediments will collect. As a glacier retreats, it will melt (or otherwise ablate) and leave behind the debris at the terminus location.
Terminal moraines are very important because they indicate a glacier's greatest extent. Multiple terminal moraines in a single location (behind one another) indicate the presence of more than one glacier in a single location over time or a pattern of retreat, equilibrium, and retreat for a single glacier.