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Glaciated Uplands and Glaciated Lowlands

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Glaciated Uplands and Glaciated Lowlands

Arran is an ideal place to look at when examining the validity of the

statement. During the Devensian Glacial, the ice sheet covering

Britain reached its furthest extent, totally covering Arran. This

helped to shape the landscape. In around 11,000BP the Loch Lomond

Readvance occurred. This time Arran was not covered by an ice sheet

but its valley glaciers grew. This formed many of the features still

clearly seen on the island today. They show fresh and visible signs of

the glacial erosion and deposition that once occurred.

Map of Arran

Glacial erosion is caused by ice movement combined with material

within it. One type of erosion is abrasion. This occurs when pieces of

rock held within the ice rub against

other pieces of rock wearing them down. Another type of erosion is

plucking. This occurs when ice freezes onto a piece of rock on the

valley side. When the glacier moves away it may then be broken off.

For these processes to occur it helps to have a steep gradient, as

this will lead to ice flow. A harsh climate is also needed, which is

cold, to encourage ice formation and accumulation. These conditions

are often found in upland areas.

Glacial deposition is caused by melting when material is dumped in

situ. It leads to unsorted material as when it melts everything is

just deposited in no particular order. The material is also

unstratified and unconsolidated. It is a mix of all sizes and shapes

of rocks. The a-axis of the rocks tends to be found parallel to the

direction of the ice flow. Glacial deposition tends to occur in higher

temperatures as this is when the ice will melt....

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...o long since the ice was found there. The Loch Lomond Readvance

didn't really affect the lowland areas and since that is the last time

glaciers were present in Arran the erosional features are bound to be

more prominent in upland areas. Also many of the depositional features

that formed in the upland areas have been more easily weathered as the

climate tends to be harsher at higher altitudes.

Although in many cases the statement is correct, there are many cases

where it is not. It contrasts upland and lowland areas and suggests

that erosional and depositional features can not occur in the same

location. In many ways it appears true as more erosional features are

probably found in upland areas and more depositional feature in upland

areas. The reasons behind there location though, is often more to do

with the climate.
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