Ground water carries the dissolved minerals in solution. The minerals may then be deposited, for example, as stalagmites or stalactites. If a stalactite and stalagmite join together, they form a column. One of the wonders of visiting a cave is to witness the beauty of these amazing and strangely captivating structures.
Caves also produce a beautiful rock, formed from calcium carbonate, travertine. Ground water saturated with calcium carbonate precipitates as the mineral calcite or aragonite. This transportation of eroded materials is carried in four ways :. Next in the series : Evolution of landforms due to glaciers. Enroll Now. ClearIAS provides online IAS coaching , guidance, strategies, books , online study-materials and mock tests with a vision that no candidate should be left out of UPSC exam competition due to in-accessibility of expensive IAS classroom coaching.
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At 2 places above: — 1. It would be really helpful! Under the heading courses of a river, I think the information is misinterpreted. It is land form which is at youth, middle and old ages but not the river. Your email address will not be published. What does Running Water do? The overland flow causes sheet erosion and depending upon the irregularities of the land surface, the overland flow may concentrate into narrow to wide paths. Plants break up earthen materials as they take root, and can create cracks and crevice s in rocks they encounter.
Ice and liquid water can also contribute to physical erosion as their movement forces rocks to crash together or crack apart. Some rocks shatter and crumble, while others are worn away. River rocks are often much smoother than rocks found elsewhere, for instance, because they have been eroded by constant contact with other river rocks.
Liquid water is the major agent of erosion on Earth. Rain, rivers, floods, lakes, and the ocean carry away bits of soil and sand and slowly wash away the sediment. Rainfall produces four types of soil erosion: splash erosion, sheet erosion, rill erosion, and gully erosion. Gullies carry water for brief periods of time during rainfall or snowmelt but appear as small valley s or crevasse s during dry season s. Valley erosion is the process in which rushing stream s and rivers wear away their bank s, creating larger and larger valleys.
The Fish River Canyon, in southern Namibia, is the largest canyon in Africa and a product of valley erosion. Over millions of years, the Fish River wore away at the hard gneiss bedrock, carving a canyon about kilometers 99 miles in length, 27 kilometers 17 miles wide, and meters 1, feet deep. The ocean is a huge force of erosion. Coastal erosion —the wearing away of rocks, earth, or sand on the beach—can change the shape of entire coastlines.
During the process of coastal erosion, waves pound rocks into pebbles and pebbles into sand. Wave s and current s sometimes transport sand away from beach es, moving the coastline farther inland. Coastal erosion can have a huge impact on human settlement as well as coastal ecosystem s. The Cape Hatteras Lighthouse, for example, was nearly destroyed by coastal erosion. At the time, the lighthouse was nearly meters 1, feet from the ocean. Over time, the ocean eroded most of the beach near the lighthouse.
By , the pounding surf was just 37 meters feet away and endanger ed the structure. Many people thought the lighthouse would collapse during a strong storm. Instead, thanks to a significant engineering feat completed in , it was moved meters 2, feet inland. The battering force of ocean waves also erodes seaside cliff s. The action of erosion can create an array of coastal landscape features. For example, erosion can bore holes that form cave s. When water breaks through the back of the cave, it can create an arch.
The continual pounding of waves can cause the top of the arch to fall, leaving nothing but rock columns called sea stack s. The seven remaining sea stacks of Twelve Apostles Marine National Park, in Victoria, Australia, are among the most dramatic and well-known of these features of coastal erosion. Wind is a powerful agent of erosion. Aeolian wind-driven processes constantly transport dust, sand, and ash from one place to another.
Wind can sometimes blow sand into towering dune s. Some sand dune s in the Badain Jaran section of the Gobi Desert in China, for example, reach more than meters 1, feet high. In dry areas, windblown sand can blast against a rock with tremendous force, slowly wearing away the soft rock. Wind can also erode material until little remains at all.
Ventifact s are rocks that have been sculpted by wind erosion. The enormous chalk formations in the White Desert of Egypt are ventifacts carved by thousands of years of wind roaring through the flat landscape. Ice, usually in the form of glaciers, can erode the earth and create dramatic landforms. In frigid areas and on some mountaintops, glaciers move slowly downhill and across the land.
As they move, they transport everything in their path, from tiny grains of sand to huge boulders. Rocks carried by glaciers scrape against the ground below, eroding both the ground and the rocks. In this way, glaciers grind up rocks and scrape away the soil. Moving glaciers gouge out basin s and form steep-sided mountain valleys. Eroded sediment called moraine is often visible on and around glaciers. These glacial periods are known as ice age s.
Ice Age glaciers carved much of the modern northern North American and European landscape. Ice Age glaciers scoured the ground to form what are now the Finger Lakes in the U. They carved fjord s, deep inlets along the coast of Scandinavia.
The snout of a glacier eroded Cape Cod Bay, Massachusetts, and formed the recognizable fishhook shape of Cape Cod itself. Today, in places such as Greenland and Antarctica, glaciers continue to erode the earth. Ice sheet s there can be more than a mile thick, making it difficult for scientists to measure the speed and patterns of erosion. However, ice sheets do erode remarkably quickly—as much as half a centimeter.
Thermal erosion describes the erosion of permafrost along a river or coastline. Warm temperature s can cause ice-rich permafrost to break off coastlines in huge chunks, often carrying valuable topsoil and vegetation with them. Mass wasting describes the downward movement of rocks, soil, and vegetation. Mass wasting incidents include landslides, rockslides, and avalanche s. Mass wasting can erode and transport millions of tons of earth, reshaping hills and mountains and, often, devastating communities in its path.
Some of the natural factors impacting erosion in a landscape include climate, topography, vegetation, and tectonic activity.
Climate is perhaps the most influential force impacting the effect of erosion on a landscape. Climate includes precipitation and wind. Climate also includes seasonal variability, which influences the likelihood of weathered sediments being transported during a weather event such as a snowmelt, breeze, or hurricane.
Topography , the shape of surface features of an area, can contribute to how erosion impacts that area. The earthen floodplains of river valleys are much more prone to erosion than rocky flood channels, which may take centuries to erode. Soft rock like chalk will erode more quickly than hard rocks like granite. Vegetation can slow the impact of erosion.
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