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Using Case Studies And Examples, Describe And Explain The Landforms Found In The Glacial Landscape

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Introduction

Using Case Studies And Examples, Describe And Explain The Landforms Found In The Glacial Landscape It appears that roughly every 200-250 million years in the Earth's history there have been major periods of ice activity. The most recent of these occurred during the Pleistocene period of the Quaternary era. In the 2 million years since the onset of the Quaternary, there have been fluctuations in global temperature of between 5�C and 6�C, which have led to glacials and interglacials. In these periods, glaciers form and create many different landforms, either through erosion or deposition. Glaciers are capable of moving large quantities of debris. The rock debris may be transported in one of three ways: - Supraglacial debris is carried on the surface of the glacier as lateral and medial moraine - Englacial debris is material carried within the body of a glacier - Subglacial debris is moved along the floor of the valley by the ice, or by meltwater streams formed by pressure melting. Ice that is stationary or contains little debris has limited erosive power, whereas moving ice carrying with it much morainic material can drastically alter the landscape. Virtually all the glacial processes of erosion are physical, as the climate tends to be too cold for chemical reactions to take place. There are five main processes associated with glacial erosion: - Frost Shattering - Abrasion - Plucking - Rotational Movement - Extending and Compressing Flow These processes produce many different landforms. ...read more.

Middle

This left an enlarged hollow, which the glacier could form in. The glaciers that occupy cirques are called cirque glaciers. Horns are pyramidal peaks that form when several cirques chisel a mountain from three or more sides. The most famous horn is the Matterhorn found in the Swiss Alps. An example of a pyramidal peak is Machhappuchare in Nepal. Ar�tes are the narrow serrated ridges found in glaciated alpine areas. Ar�tes form when two opposing cirques back erode a mountain ridge, such as Striding Edge in the Lake District, or Karakoram Mountains, Northern Pakistan. Talus and other foot-slope deposits are also common in a glaciated valley. Because of the enhancement of freeze-thaw processes bedrock in alpine areas is weathered by the growth of ice crystals. This type of weathering shatters the bedrock into sharp angular fragments that accumulate at the bottom of rock slopes as talus. Much of the debris carried by an alpine glacier comes from valley sides where talus accumulates. The erosional landforms produced by continental glaciers are usually less obvious than those created by alpine glaciers. Like alpine glaciers, the movement of continental glaciers followed topographic trends found in the landscape. Continental ice sheets were very thick, between 1000 to 3000 meters. The mass of these glaciers covered all but the highest features and had extremely strong erosive power. ...read more.

Conclusion

Many kames are often found on or at the edge of moraines. Glaciers can also contain sinuous flows of meltwater that occur in ice tunnels at the base of the ice. The beds of these sub-surface glacial streams are composed of layers of sand and gravel. When the ice melts from around the meltwater tunnels, the beds of sand and gravel are deposited on the Earth's surface as long twisting ridges known as eskers. When glaciers are rapidly retreating, numerous blocks of ice can become detached from the main body of the glacier. If glacial drift is then placed around the ice, a depression on the surface called a kettle holes can be created when the ice melts. Kettle holes are commonly found on moraine and outwash plain deposits. Large kettle holes that reach below the water table can form into lakes. Some very prominent kettle holes are located in the Northwestern District of Mackenzie, NWT, Canada. Some kettle holes develop into wetlands such as bogs, swamps, and marshes. Glacial retreat also creates hill shaped deposits of till known as drumlins. Drumlins often occur in large congregations across areas of New York and Wisconsin, USA and Ontario, Canada. The streamline shape of these glacial features resembles a protracted teaspoon-laying bowl down. The narrow end of the drumlin points to the general direction of glacial retreat. Drumlins also come in a variety of dimensions. Lengths can range from 100 to 5000 meters and heights can sometimes exceed 200 meters. ...read more.

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