Fluvioglacial landforms

Landforms moulded by glacial meltwater

Outwash plain

Description: This is the area in front of a glacier. It consists of gravels, sands, and clay (furthest away from the glacier). They can be 75m deep. An outwash plain has a gradient of around 2°. There may be other landforms on the outwashed plainFormation: Material is deposited by meltwater streams leaving the glacier. These deposit material with the largest material deposited first.

Varves – Vertical grading of the outwash plain

Description: A varve is a distinct layer of silt lying on top of a distinct layer of sand. Formation: In the summer, there is more meltwater so heavier material such as sand can be deposited. In the winter, temperatures are colder so there is less meltwater. This means that only fine silts can be deposited. This forms seasonal layers. If the summer is early, then the layer of sand will be deeper. If the winter is early, then the layer of silt will be deeper.

Kames

Description: Kames are irregular mounds or hummocks of sand and gravel on the valley floor. They are composed of sand and gravelsFormation: They are formed when a surface river on a glacier runs over a depression in the ice. This causes a decrease in velocity and therefore material to be deposited. When the ice melts, these deposits form kames.

Esker

Description: These are long, narrow ridges of stratified sediment marking the former location on a glacial tunnel. They are aligned parallel to the direction of ice flow. They are formed of sands and gravels and are usually over 10m high and can stretch for several km, but most are short.Formation: A glacial tunnel may have water flowing through it. This water is often filled with debris. When the velocity drops, the material is deposited. When the ice melts, the material forms an esker where the tunnel was.

Kettle holes

Description: They are circular lakes on the outwashed plain. They are usually no more than 2km in diameter, and 10m deep but may be much larger.Formation: These are formed when a piece of ice separates from the main glacier. The blocks of ice become fully or partially covered by material on the outwash plain. When the ice melts, a deep hollow is left. They may then fill with water, making a kettle lake.