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The height and width of an esker are determined by the water and ice pressure and sediment load at the time of formation. [36] Eskers form in ice tunnels within or under a glacier, as shown in Figure 1, and are composed of the sediment deposits from the streams that occupy these tunnels. [37]
Glaciers erode and deposit sediment by advancing and retreating. [4] Erosion occurs by abrasion and plucking. [4] These processes are dependent on a variety of factors such as plate tectonic movement, volcanic activity, and changes in atmospheric gas composition. [5]
Fluvioglacial deposits differ from glacial till in that they were deposited by means of water, rather than the glacial itself, and the sediments are thus also more size sorted than glacial till is. The stone walls of New England contain many glacial erratics, rocks that were dragged by a glacier many miles from their bedrock origin.
In the case of basal sliding, the entire glacier slides over its bed. This type of motion is enhanced if the bed is soft sediment, if the glacier bed is thawed and if meltwater is prevalent. Bed deformation is thus usually limited to areas of sliding. Seasonal melt ponding and penetrating under glaciers shows seasonal acceleration and ...
Subglacial streams can transport, deposit, and remove sediment from the glacier bed; this process is influenced by water supply and the amount and characteristics of the available sediment. [12] The size of sediment particles, the slope of the subglacial stream’s channel, and the roughness of the bed all contribute to whether sediment is ...
The sediments carried by a glacier will eventually be deposited some distance down-ice from its source. This takes place in the ablation zone , which is the part of the glacier where the rate of ablation (removal of ice by evaporation, melting, or other processes) exceeds the rate of accumulation of new ice from snowfall.
Glaciers also pulverize rock into "glacial flour", which is so fine that it is often carried away by winds to create loess deposits thousands of kilometres afield. Sediment entrained in glaciers often moves approximately along the glacial flowlines, causing it to appear at the surface in the ablation zone.
Over time the glacial lake sediments are subjected to change. As seen in the English Lake District, the layers of the sediments at the bottom of the lakes contain evidence of the rate of erosion. The elemental make up of the sediments are not associated with the lakes themselves, but by the migration of the elements within the soil, such as ...