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A classic example is the Canadian Shield. During the last ice age , the topsoil was scraped off, leaving mostly bare rock. The melting of the glaciers left land with many irregularities of elevation and a great deal of water to collect in the low points, resulting in the region's many lakes.
A practical definition of water pollution is: "Water pollution is the addition of substances or energy forms that directly or indirectly alter the nature of the water body in such a manner that negatively affects its legitimate uses." [1]: 6 Water is typically referred to as polluted when it is impaired by anthropogenic contaminants.
Denudation is the geological process in which moving water, ice, wind, and waves erode the Earth's surface, leading to a reduction in elevation and in relief of landforms and landscapes.
The terms river morphology and its synonym stream morphology are used to describe the shapes of river channels and how they change in shape and direction over time. The morphology of a river channel is a function of a number of processes and environmental conditions, including the composition and erodibility of the bed and banks (e.g., sand, clay, bedrock); erosion comes from the power and ...
Water pollution occurs when water bodies, such as rivers, lakes and oceans are contaminated with harmful substances. These substances degrade the water quality and are toxic to humans as consumers and to the environment. [7] The contamination in a river can come from a point source or non-point source pollution. [8]
As mentioned, when a river rejuvenates, it gains more energy and erodes vertically to meet its new base level. A river terrace is the remains of an old floodplain at a higher elevation than the present one. It typically results from river rejuvenation with further rejuvenation able to form new terraces, resulting in a step like profile around a ...
Examples of such islands are found in the Pacific, notably the three phosphate islets of Nauru, Makatea, and Banaba, as well as Maré and Lifou in New Caledonia; Fatu Huku in the Marquesas Islands; and Henderson Island in the Pitcairn Islands. The uplift of these islands is the result of the movement of oceanic tectonic plates.
The movement of water across the stream bed exerts a shear stress directly onto the bed. If the cohesive strength of the substrate is lower than the shear exerted, or the bed is composed of loose sediment which can be mobilized by such stresses, then the bed will be lowered purely by clearwater flow.