1. Melting: As a glacier melts, the ice releases the sediment it has been carrying. This can happen at the glacier's terminus (end), where it melts faster due to warmer temperatures, or along the sides and bottom where friction from the surrounding landscape causes melting.
2. Calving: Large chunks of ice break off the glacier's terminus and fall into a body of water, like a lake or ocean. This process releases the sediment trapped within the ice.
3. Deposition by meltwater: Glacial meltwater flows along and beneath the glacier, carrying sediment downstream. When the meltwater reaches a flatter area or a change in gradient, it loses energy and deposits the sediment it carries.
4. Ablation: This term describes the process of ice loss due to melting, sublimation (ice turning directly into vapor), and wind erosion. As the glacier ablates, it releases sediment.
The type of sediment deposited depends on the size and type of rock fragments carried within the glacier:
* Till: A mixture of unsorted sediment, including clay, silt, sand, gravel, and boulders, directly deposited by a glacier.
* Outwash: Sorted sediment deposited by meltwater streams flowing from the glacier.
* Erratics: Large boulders transported and deposited by glaciers, often far from their original source.
Where glacial deposits are found:
* Moraines: Linear ridges of till deposited at the edge of a glacier.
* Outwash plains: Flat, gently sloping areas covered with outwash sediments.
* Eskers: Long, winding ridges of sand and gravel deposited by meltwater flowing in tunnels beneath the glacier.
* Kames: Small, conical hills of sand and gravel deposited by meltwater flowing on top of a glacier.
* Drumlins: Elongated hills of till molded by the moving glacier.
These deposits shape the landscape in dramatic ways, creating distinctive features like valleys, lakes, and fertile farmland.
