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Wind erosion of soil at the foot of Chimborazo, Ecuador Rock carved by drifting sand below Fortification Rock in Arizona (Photo by Timothy H. O'Sullivan, USGS, 1871). Aeolian processes, also spelled eolian, [1] pertain to wind activity in the study of geology and weather and specifically to the wind's ability to shape the surface of the Earth (or other planets).
Blowout located 6.5 km south of Earth, Texas (1996). Blowouts are sandy depressions in a sand dune ecosystem caused by the removal of sediments by wind.. Commonly found in coastal settings and margins of arid areas, blowouts tend to form when wind erodes patches of bare sand on stabilized vegetated dunes.
A group of hikers encountering quicksand on the banks of the Paria River, Utah Quicksand warning sign near Lower King Bridge, Western Australia. Quicksand is a shear thinning non-Newtonian fluid: when undisturbed, it often appears to be solid ("gel" form), but a less than 1% change in the stress on the quicksand will cause a sudden decrease in its viscosity ("sol" form).
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Any trees that in the mound area are cut away, and the roots and stumps retained. The surface of the area for the mound is then roughened with a chisel plow. This prepares the area for the sand. Work is done from upslope of the mound area so that the ground downslope of the mound does not get compacted.
The removal by erosion of large amounts of rock from a particular region, and its deposition elsewhere, can result in a lightening of the load on the lower crust and mantle. Because tectonic processes are driven by gradients in the stress field developed in the crust, this unloading can in turn cause tectonic or isostatic uplift in the region.
The "swirl and dump", or wet harrowing cleaning technique, is used to restore flow rate. About 1 US gallon (3.8 L) is poured into the filter before cleaning (assuming the filter is empty). The upper layer of sand is then swirled in a circular motion. Dirty water from the swirling is dumped out and the sand is smoothed out at the top.
Subsurface wetlands provide greater pathogen removal than surface wetlands. [3] There are two main types of constructed wetlands: subsurface flow and surface flow. The planted vegetation plays an important role in contaminant removal. The filter bed, consisting usually of sand and gravel, has an equally important role to play. [4]