Wind and Glacier Notes PDF

WIND  WIND EROSION Limited precipitation leads to an increase in the amount of wind erosion because precipitation holds down sediments and allows plants to grow. Wind transport and erosion primarily occur in areas with little vegetative cover, such as deserts, semi ari...

WIND  WIND EROSION Limited precipitation leads to an increase in the amount of wind erosion because precipitation holds down sediments and allows plants to grow. Wind transport and erosion primarily occur in areas with little vegetative cover, such as deserts, semi arid areas, seashores, and some lakeshores.  WIND EROSION Deflation is the lowering of the land surface that results from the wind’s removal of surface particles. The region known as the Dust Bowl was created through this process Abrasion, occurs when particles such as sand rub against the surface of rocks or other materials. Wind abrasion can be an effective agent of erosion (windblown sand particles eventually wear away rocks) Rocks shaped by windblown sediments are called ventifacts.  WIND DEPOSITION In windblown environments, sand particles tend to accumulate where an object, such as a rock, landform, or piece of vegetation, blocks the forward movement of the particles. Dune is the pile of windblown sand develops. Dune migration is caused when prevailing winds continue to move sand from the windward side of a dune to its leeward side, causing the dune to move slowly over time. GLACIERS GLACIERS A large mass of moving ice is called a glacier. Glaciers form near Earth’s poles and in mountainous areas at high elevations and they cover about 10 percent of Earth’s surface.  GLACIERS Valley glaciers are glaciers that form in valleys in high, mountainous areas As valley glaciers flow downslope, they carve V-shaped stream valleys into U-shaped glacial valleys. Continental glaciers are glaciers that cover broad, continent-sized. These glaciers form in cold climates where snow accumulates over many years and are presently only found in Greenland and Antarctica.  GLACIER SIZE Both valley glaciers and continental glaciers grow and move outward when snow gathers at the zone of accumulation (a location in which more snow falls than melts, evaporates, or sublimates) For valley glaciers, the zone of accumulation is at the top of the mountains. For continental glaciers, the zone of accumulation is the center of the ice sheet. Both recede when melting is faster than accumulation.  GLACIAL EROSION Of all the erosional agents, glaciers are the most powerful because of their great size and weight. When a valley glacier moves, it breaks off pieces of rock through a process called plucking. Cirques are deep, bowl-shaped depressions formed at high elevations where snow accumulates when valley glaciers scoop out rock. A horn forms when there are glaciers on three or more sides of a mountaintop, the carving action creates a steep, pyramid-shaped peak.  GLACIAL EROSION Hanging valleys are formed by valley glaciers when higher glacier converges with the lower primary glaciers and later retreat. A valley is left “hanging” high above the primary valley floor.  GLACIAL DEPOSITION Moraines form when the glacier retreats and they deposit unsorted ridges of till Outwash is the gravel, sand, and fine silt sediment that is deposited by melted water carried away from the glacier. An outwash plain is the area at the leading edge of a glacier where meltwater flows and deposits outwash. Kettle lakes form when water from runoff or precipitation fills a hole that formed when a large block of ice broke off a continental glacier and melted.  GLACIAL DEPOSITION Drumlins form when continental glaciers that move over older moraines form the material into elongated landforms. Eskers are streams flowing under melting glaciers leave long, winding ridges of layered sediments. A kame is a mound of layered sediment that forms when till gets washed into depressions or openings in the melting ice.