Glacial Lake
Lakes are common in regions that experience glaciation. Repeated advance and retreat of a glacier scours the bedrock preparing the way for the formation of lakes. There are three types of glacial lakes resulting from alpine and continental glaciation. Alpine glacial lakes include paternoster lakes and tarns and are found in mountainous areas. Kettle lakes are the result of continental glaciation and are found in northern areas of North America and Europe.
Tarn Lakes
A tarn is a lake that forms in the depression of a cirque. They are sometimes referred to as cirque lakes. The most basic of all alpine glacial landforms is the bowl or amphitheater-shaped valley head called cirque. These bowls result from the scouring of the mountain by glaciers. The head and sidewalls of a cirque may be nearly vertical, while the floor is often carved into a shallow basin. When water seeps down into the basin along with additional snowmelt, a tarn lake develops. The word tarn comes from an Old Norse word meaning pond. Tarns lakes in North Cascades and Rocky Mountain National Parks provide excellent examples.
Paternoster Lakes
A chain of lakes may develop in a valley with glacial steps; often each step will have a lake. These chains of lakes are known as paternoster lakes, since they resemble the beads on a rosary. They are formed by the scouring of the glacier and are connected by a single stream system that was dammed by glacial debris. Examples of paternoster lakes occur in the Sierra Nevada Mountains in California and Glacier National Park in Montana.
Kettle Lakes
Among the most varied features left by glaciers are ice-contact deposits due to continental glaciation. These landforms develop along the margin or outwash of the glacier, leaving behind ice deposits. A kettle lake forms when a large piece of ice leaves a depression in the glacial drift; as the ice melts a kettle like hole is formed. The hole fills from river flow or from underground water sources. Most kettle lakes are found in Minnesota, Wisconsin, Michigan, New York, Pennsylvania and New England. An example is Walden Pond in Massachusetts.
Natural Reservoirs
Glacial lakes can also result from buildup of glacial till or sediment. In alpine or mountain areas the advance and retreat of a glacier pushes sediments into river creating a dam. Ice can also build up blocking the flow of a river forming an ice-dammed lake.
Tags: continental glaciation, advance retreat, advance retreat glacier, glacial lakes, paternoster lakes, result from, retreat glacier
