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Plucking, also referred to as quarrying, is a glacial phenomenon that is responsible for the weathering and erosion of pieces of bedrock, especially large "joint blocks". This occurs in a type of glacier called a "valley glacier".
While plucking has generally been thought of as a greater force of geomorphological change, there is evidence that in softer rocks with wide joint spacing that abrasion can be just as efficient. [9] A smooth, polished surface is left behind by glacial abrasion, sometimes with glacial striations , which provide information about the mechanics of ...
Kolks cause extreme local erosion, plucking bedrock and creating pothole-type geographical features called rock-cut basins. Examples can be seen in the flood regions result from glacial Lake Missoula, which created the channeled scablands in the Columbia Basin region of eastern Washington. [43]
Terminal moraine of Wordie Glacier, Greenland Map of the Salpausselkä terminal moraines in Southern Finland. A terminal moraine, also called an end moraine, is a type of moraine that forms at the terminal (edge) of a glacier, marking its maximum advance.
Plucking is common in jointed rocks, where this occurs. [2] Alluvial channels are much more common and can be large or small. All large rivers, and most small ones, have channels that are usually lined with alluvium, sediment that was carried to that channel reach by the river and that eventually will be carried farther downstream. [3]
The following affect the rate of abrasion: [1] The amount of rock debris embedded in the basal surface of the ice. If there is no rock in the basal surface of the ice there will be no abrasion, but if there is too much rock in the basal surface of the ice the motion of the glacier will be affected, thus affecting abrasion rates.
Multiple erratics on the terminal moraine of the Okanogan Lobe. The Cascade Mountains are in the background.. The term "erratic" is commonly used to refer to erratic blocks, which geologist Archibald Geikie describes as: "large masses of rock, often as big as a house, that have been transported by glacier ice, and have been lodged in a prominent position in the glacier valleys or have been ...
Also called Indianite. A mineral from the lime-rich end of the plagioclase group of minerals. Anorthites are usually silicates of calcium and aluminium occurring in some basic igneous rocks, typically those produced by the contact metamorphism of impure calcareous sediments. anticline An arched fold in which the layers usually dip away from the fold axis. Contrast syncline. aphanic Having the ...