4.1 and 4.2. Why does the physical landscape of the UK vary from place to place Flashcards
Glacial erosion
There are three main types of glacial erosion - plucking, abrasion and freeze thaw. Plucking is when melt water from a glacier freezes around lumps of cracked and broken rock. When the ice moves downhill, rock is plucked from the back wall
Deposition
Deposition is the processes where material being transported by a river is deposited. Deposition occurs when a river loses energy.
Igneous rock
Igneous rock or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or lava
Metamorphic rock
metamorphic rock is a result of a transformation of a pre-existing rock. The original rock is subjected to very high heat and pressure, which cause obvious physical and/or chemical changes.
Sedimentary rocks
Rock that has formed through the deposition and solidification of sediment, especially sediment transported by water, ice, and wind
Upland lanscapes
Glaciated upland landscapes. Corries, pyramidal peaks and u-shaped valleys form due to glaciation.
Lowland landscapes
All glacial landforms in the British Isles are fossil landforms. Although the exact number of glacial and interglacial periods in the British Isles is still a matter of scientific debate
Compare metamorphic and igneous rock
Minerals make up rocks. Igneous rock , formed by the cooling of magma (molten rock) inside the Earth or on the surface. Sedimentary rocks, formed from the products of weathering by cementation or precipitation on the Earth’s surface. Metamorphic rocks, formed by temperature and pressure changes inside the Earth.
Explain how glacial deposition shaped the UK Lowlands
The intense erosive action of a glacier produces vast volumes of sediments. Very fine material, called rock flour, is produced by the scraping and grinding or rock surfaces, whilst larger particles are produced by plucking and freeze-thaw. Massive rocks that fell from the valley walls onto the moving ice can also be transported, and then deposited hundreds of miles from their origins.
Geographers classify glacial sediment according to it’s mode of deposition. The collective name for all the sediments and debris deposited under glacial conditions is Glacial Drift. Sediments that were deposited by melting ice or by glacial streams are called Fluvio-glacial. Debris deposited directly by the glacier, such as moraine and intra-glacial material dropped ‘in situ’ by retreating ice, is known as Till
Compare the weathering that is found in the uplands and lowlands
The base of glacier ice melts because of pressure and friction. This allows water to freeze into cracks in the rocks and when the glacier moves it pulls out chunks to leave a jagged surface.
This provides material for abrasion and this process is called plucking. Rocks which get stuck in the ice grind away the bedrock under the glacier and this is known as abrasion.
Freeze thaw, or frost shattering, is a process of weathering that also occurs in upland areas. Water in cracks in the rock freezes and expands, forcing open the gap. When the ice melts more water can get into the crack and freeze again.
After many cycles of freezing and thawing lumps of rock are broken off the surface - this is called freeze thaw. These small pieces of rock are called scree and often build up forming scree slopes on mountainsides.
Explain how glaciers have affected both landscapes
A glacier’s weight, combined with its gradual movement, can drastically reshape the landscape over hundreds or even thousands of years. The ice erodes the land surface and carries the broken rocks and soil debris far from their original places, resulting in some interesting glacial landforms.
Explain 2 ways humans have affected the Upland landscape
Highland glacial valleys, such as those found in the Cairngorms in Scotland, the Pennines in England or Snowdonia in Wales, provide opportunities for different activities. These activities all have advantages and disadvantages for communities and the environment.
Explain 2 ways humans have affected the Lowland landscape
Farming. Till (boulder clay) can be fairly fertile allowing arable farming or dairy farming on heavier clays. Outwash sands and gravels are less fertile, but the finer deposits can be farmed.
Quarrying. Outwash sands and gravels provide important sources of aggregate for making concrete because they are already fairly well sorted and werelaid down by fresh water. Unlike sea-dredged gravels which have to be washed to remove salt contamination.
Forestry. Moraines are usually too rocky for farming and may be forested. Large areas of outwash which cannot be farmed may be forested.
Settlement. Till usually provides good foundations and where there is farming settlements will have grown up.
Communications. Fairly easy. Land is fairly level, routes may wind between drumlins. Eskers and moraines are fairly easy to cut through if needed.
Explain how scarp and vale topography forms in the UK Lowlands
Bournes are streams that occasionally flow down the dry valleys in times of prolonged wet weather, when the ground may have become saturated.
Clay vales are the valleys between the chalk escarpments. The clay, when drained is a fertile soil suitable for a range of farming methods. Clay vales are flat, and have a number of streams meandering through them.
Dry valleys, such as Devil’s Dyke, were formed in periglacial times, when the ground froze, so melt water rivers ran over the surface of the chalk rather than flowing down through it. These rivers carved out steep sided valleys. Once the climate had warmed again a dry valley was left behind. These also are common features of limestone landscapes.
Escarpments or cuesta’s are the main landform of chalk and clay areas. Initially the layers of chalk and clay were tilted by the collision of the African and Eurasion plates. The soft clay was then eroded faster than the more resistant chalk, leaving escarpments (chalk hills) behind. Because of the angle of the tilt, these escarpments have two distinctive sides. The steeper side is called the scarp slope, whilst the gently sloping side is called the dip slope.
Springs form at the bottom of the escarpment, where the chalk meets the clay. This is why many settlements can be found along spring lines in chalk and clay areas.
Explain when and how sedimentary rock was formed across the UK Lowlands
Sedimentary rocks are formed from sediments that have settled at the bottom of a lake, sea or ocean, and have been compressed over millions of years. The sediment comes from eroded rocks carried there by rivers or ice, and from the skeletons of sea creatures.
Examples of sedimentary rocks include sandstone, limestone, chalk and clay.
