Landforms caused by Glaciers

LANDFORMS CAUSED BY GLACIERS

There are two major geology features that are seen geologically because of glaciers. These cluster into depositional phenomena and erosional phenomena. They are named differently based on where you live on earth.

The landforms you see from erosion happen when glaciers slide over hard bedrock. Glaciers tend to pick up stuff along the way and drop them in various places that they travel to. Fine sediment is called rock flour. This is like the fine grit you'd use in a rock tumbler. This is how you get glacial polished rocks. Glacial striations are grooves made by larger pieces that scrape over rocky surfaces.

Alpine glaciers can carve out their own valleys. They will not be V-shaped like streamcarved valleys but will be U-shaped instead.

If you see two side-by-side valleys made from glaciers, you can see a ridge between them called an arete. The bowl at the top of the valley is known as a cirque, where the glacier carved out a section of the mountain. Figure 61 shows a cirque carved out by a glacier:

Figure 61.

Cirques will fill with precipitation and form a lake millions of years later. This lake was known as a tarn. When a small glacier feeds into a larger one, the small glacier doesn't cut down as much. Millions of years afterward, you can get a hanging valley, which is a valley that has a drop off at the end of it, where the larger glacier was. This hanging valley might have a nice waterfall at the end of it that flows into the larger main valley.

Depositional land forms involve stuff left over after a glacier has retreated. There are a lot of these in areas where glaciers once were. All glacial sediment is called till after it has been dropped. It is not well sorted as it drops. Tillite is any rock that started out in a glacier at some point. Diamictite is rock made from glacial till that has become lithified into a bigger rock.

A moraine is a big ridge of deposits left by a mass wasting event after a glacier carved out a valley. Glaciers are a lot like conveyor belts. They pick stuff up at one end and dump it off at the other. Remember that glaciers have internal flow so moraines exist even if a glacier isn't advancing in any way. Terminal moraines are at the end of a