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  • I need a good title for this paper, and does it look ok? Glacial Effects Glaciers are responsible for the largest amount of shaping to our surface landscapes. The ways that they shape our land are many. First it is important to understand what glaciers are. A Glacier is a large mass of ice that forms when snow accumulates and recrystalises on land. There are 4 main types of glaciers, Ice Sheets that cover large bodies of land such as Antarctica, Ice Caps which cover high plateaus, Valley Glaciers that are formed in high V shaped mountain valleys with streams flowing through them, and Piedmont glaciers that cover bases of steep mountains that were formed by valley glaciers that flowed down and remained frozen. They form and expand, flow through the land collecting debri, find a balance and eventually fully recede, at which points they deposit all of the debris that they collected. Glaciers have an accumulation zone, where the snow builds, and a wastage zone, where the ice melts, breaks apart and deposits debris. This is described as a glaciers budget, which depends on the accumulations versus the wastages and dictates how far the glacier will travel. If the snow does not accumulate at the same speed that the ice melts throughout the year there will be a deficit that causes the glacier to flow farther or shorter distances. A glacier begins in an abundant accumulation phase and snow builds, packs and freezes into a mass of at least 165 feet deep, because at this depth the pressure on the ice changes it from being hard and brittle into a plastic material that is more of a liquid than solid, at this point glaciers begin to flow. Ice sheets flow outward, towards the edges of the land, as with Antarctica the glacier flows out over the land and onto the ocean. When out over the water the glacier breaks into icebergs and any debris collected is deposited as the ice melts. With Valley glaciers the slowly moving ice follows the path previously set out by the stream and widens and deepens it into a U shaped valley by collecting small debris as well as large boulders from the walls and floor of the valley. While flowing they erode the land they are travelling over by plucking large and small debris and running it over the land, essentially sanding the ground and leaving behind polished rocks, large holes and glacial striations gouged into the bedrock. The glaciers move very similarly to a river, the ice in the center of the glacier has a faster flow compared to the outer edges because of less friction from the valley walls. Ice Cap and Piedmont glaciers behave in a similar fashion. Glaciers also create many landforms during the balance and receding phases. The balance phase is when the accumulation matches the wastage of ice. Glaciers will advance or recede until they are in balance with their surroundings. Once they become balanced the ice will continue to flow and melt, however will not advance farther than its current distance. It is while in this phase that glaciers create many forms such as glaciated troughs, hanging valleys, glacial striations as well as cirques, arĂȘtes, and tarns. Another interesting formation that is more accessible in nature is moraines. Moraines are created at the edge of a glacier; they are accumulations of all of the debris drifting down the ice. The debris is deposited as the ice melts and forms mainly lowland hills and lakes. There will be many more moraines that form as the glacier recedes and forms a new balance elsewhere, you can follow the path that the glacier took by following them. When the glacier recedes it creates and reveals the most amazing landforms yet. As the glacier melts away it makes visible all the landforms and deposits previously mentioned as well as creating new ones. One of them is a Drumlin field. This is flat land that has streamlined asymmetrical shaped hills composed of till deposited in clusters all over it by the glacier. They look like teardrops with the steep side of the hill facing the direction that the ice advanced from and the gentle slope points in the dire

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    05.12.08, 11:30 PM [ Flag ]
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