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Ice thrusting – the glacier freezes to its bed, moving large sheets of frozen sediment at its base along with it. Glacially induced spalling – layers of rock are spalled off the rocks below the glacier during ice lens formation. This provides smaller debris, which is ground into the glacial basal material, to become till. [3] [4]
The movement of these continental glaciers created many now-familiar glacial landforms. As the glaciers were expanded, due to their accumulating weight of snow and ice, they crushed and redistributed surface rocks, creating erosional landforms such as striations , cirques , and hanging valleys .
If the glacial action erodes through, a spillway (or col) forms; Horn: a sharp peak connecting multiple glacier intersections, made up of multiple arêtes. Valley step: an abrupt change in the longitudinal slope of a glacial valley; Hanging Valleys: Formed by glacial meltwater eroding the land partially, often accompanied by a waterfall. [2]
Glacial polishing is the result of clasts embedded in glacial ice passing over bedrock and grinding down the top of the rock into a smoother surface. The small rocks entrained by plucking act like sandpaper to the downhill slope. [7] This creates an almost mirror like surface in the rock.
[45] Proglacial lakes may be dammed by a moraine, glacial ice, or may be trapped at the snout of a glacier by the isostatic depression of the crust by the glacier. [ 46 ] , [ 47 ] A tarn is a specific term for a proglacial lake that forms in the over-deepened bowl of a cirque .
Till is a form of glacial drift, which is rock material transported by a glacier and deposited directly from the ice or from running water emerging from the ice. [1] It is distinguished from other forms of drift in that it is deposited directly by glaciers without being reworked by meltwater.
Glacial abrasion is the surface wear achieved by individual clasts, or rocks of various sizes, contained within ice or by subglacial sediment as the glacier slides over bedrock. [9] Abrasion can crush smaller grains or particles and remove grains or multigrain fragments, but the removal of larger fragments is classified as plucking (or ...
A fluted moraine, also called a fluted moraine surface, is a glacial moraine whose surface exhibits parallel ridges, glacial flutes. They are typically tens of centimeters to a few meters in width and height, and tens of meters in length. The long axes of the flutes are parallel to the flow direction of the glacier. Fluted moraines mainly ...