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1. Using Fig.9 on page 5, describe the distribution of igneous rocks in the British Isles. (3)
Igneous rocks are found in the west and north of the British Isles. The greatest concentration of these rocks is to be found across Scotland. There are relatively few outcrops of igneous rocks in England, with the exception of the south-west and the Lake District.
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There are lowland areas, below 200m, across the British Isles but the largest area of them is to be found in the south-east of England, stretching from the Vale of York south through the East Midlands and East Anglia to the lower Thames valley. This is to the south-east of the Tee-Exe line. Most other lowland areas are found along the coasts with relatively extensive lowlands to be found west of the Pennines on the Cheshire and Lancashire plains.
3. With reference to the geology map of the British Isles (fig.9, page 5) suggest reasons for the distribution of lowland areas in the United Kingdom. (4)
There appears to be a correlation between the rock types and the height of the land in the UK. Lowland areas tend to be found on areas with younger, sedimentary rocks which are relatively less –resistant to erosion than older, sedimentary rocks such as Carboniferous limestone found in the Pennines or the igneous and metamorphic rocks found further north. The crystalline structure of the igneous rocks and the glassy, semi-melted structure of metamorphic rocks makes them much more resistant to erosion, leaving these rocks as hills and mountains. Meanwhile, the less-resistant rocks of the south-east are eroded down to form the lowlands.
4. With reference to relief, explain why the south-east of England receives less rainfall than north Wales. (4)
Some parts of the north-west of the British Isles receive three times the rainfall of places in the south-west. This is because Britain’s prevailing winds travel west over the warm Atlantic Ocean, picking up moisture on the way. As these winds reach the hills and mountains of the west of Britain they are forced to rise. As the air rises it expands and cools, resulting in the water vapour condensing to form clouds. This leads to rainfall. The, as the air descends on the less side of the hills towards the eastern lowlands it warms and the rain clouds begin to evaporate resulting in a drier, ’rain-shadow’ in the east.
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