Glacial Lakes

glacier, while recessional moraines are left by retreating ones. Lateral moraines are seen along the sides of a glacier as ice wastes from its edges. You can even get a medial moraine if two glaciers merge to form one. The medal moraine will run between the two halves. Ground moraine is just the random trail of stuff left behind as the glacier melts.

Other terms used to describe the depositional landforms of glaciers are these:

• Outwash plains are mixtures of sand, silt, and gravel made by glacial grinding and carried along by water.

• Glacial erratics are large boulders glaciers deposit far from their origin.

• Kettles are depressions left behind when a large ice block melts and leaves till around it.

• Kettle lakes are kettles that are formed by these kettles.

• An esker is a long, snake-like deposit of sediment in a ridge that was once a stream under a glacier.

• A kame is a mound of till from dripping meltwater off the edge of a glacier or through the glacier itself.

• Drumlins are teardrop-shaped hills with a steep side pointing to the upstream area of an ice flow. The low side points in the direction of ice movement. They may be due to a combination of deposition and sculpting.

GLACIAL LAKES

A lake within a cirque you already know is a tarn. There are many of these lakes in the Western part of the US after alpine glaciers retreated. Recessional lakes leave behind isolated basins along a glacial valley. These cause a chain of lakes known as paternoster lakes. Long carved lakes are called finger lakes.

Large proglacial lakes exist when a continental glacier exists. These are found along the glacier edges. Lake Agassiz in Manitoba was a giant proglacial lake at one time but now has shrunk in size with Lake Winnipeg as its only major remnant. Lake Missoula is another proglacial lake from the Laurentide ice sheet.

Pluvial lakes were proglacial lakes found in more humid environments when evaporation wasn't as prevalent. This was the case in the last ice age in the western US. Several lakes in Nevada, Utah, and nearby areas were pluvial lakes. Lake Bonneville was one of these. It breached at one point to create the Snake River in Idaho. This breach drastically lowered the lake levels over a short period of time. The five Great Lakes we see in North America are proglacial lakes from the last ice age. The remnants of Lake Bonneville is the Great Salt Lake.