4.1 Physical Landscapes, Geology And Past Processes and 4.2 Physical and Human Processes Flashcards
Past process: Tectonic Process
Roughly, 450 million years ago
Destructive plate boundary caused volcanoes
Volcanoes cause igneous rocks and metamorphic rocks to form
Volcanoes now form mountainous regions in the Uplands
Tectonic Plates force against each other. Folds and faults cause fold mountains to form. Anticlines are also formed in the Lowlands.
Past process: Geology
Roughly, 350 million years ago
The UK was under a tropical sea
Therefore there was lots of coral and fish
Fish and coral died so their skeletons and shells fell to the sea floor
As more organisms die, more skeletons and shells fell on the sea bed
The weight and pressure started to merge the skeletons and shells together with the calcium inside ‘cementing’ the remains together.
This formed layer or strata that has been compressed over millions of years.
Past Process: Glaciation
About 15 million years ago
The most recent Ice Age caused glaciers to form in the Uplands and the Lowlands becoming a tundra-like climate.
Glaciers carved deep ‘U-Shaped’ valleys through the process of plucking and freeze-thaw. Plucking is when water would enter a gap in the bedrock of the glacier; this water would then freeze and expand, also expanding the crack.
This would repeat and the rock would be ‘plucked’ and transported down the glacier and then deposited as moraines.
Three types of rock
Igneous: When magma (granite) or lava (basalt) cools they form igneous rocks. Lava cools faster, above ground, and the crystals in the rock will be smaller and not as hard- this is called basalt. Magma cools slower, below ground, and the crystals in the rock will be larger and harder. Igneous rocks are more resistant to erosion
Metamorphic:
When igneous rocks are under immense pressure and heat they reform into metamorphic rocks. Metamorphic rocks are much more resistant than igneous rocks as the crystals are enlarged. Shale becomes slate when compressed under heat and pressure.
Sedimentary:
When sediment is compressed in strata then it becomes sedimentary rock. Calcium in the skeletons is used as a ‘cement’ and this forms strata of sedimentary rock as it is compressed. Sedimentary rock is the weakest out of the rock types and the least resistant erosion.
Glaciation in the UK Lowlands
Glaciation from the Uplands caused high mineral rocks that have been plucked from the bedrock of the Uplands is deposited, during the end of the Ice Age, in the Lowlands. This means that the Lowlands have very flat and fertile land.
How does a scarp and vale form
In the Lowlands, the sedimentary strata is folded into an anticline from the tectonic plate movement. At the end of the Ice Age, the melt water from the Upland glaciers runs down, eroding the top layers of sedimentary rock. It leaves a flat plain, consisting of one type of rock, called a vale and two steep edges, that consist of different rock types, called a escarpment or scarp.
Weathering processes in the Uplands and Lowlands?
Uplands
Freeze thaw action occurs due to the cold temperatures in the Uplands. Water enters cracks, during the day, but when it turns night then the water drops below 4°C and expands. This also expands the crack and this is repeated until the crack enlarges and the rock finally breaks off. This contributes to scree slopes.
Lowlands
Chemical weathering is when the slightly acidic rain water dissolves the calcium carbonate, in the chalk and limestone, and this causes a lot of erosion but not a lot of sediment.
Biological weathering occurs when roots of trees and plants go into cracks. These expand and increase the size of the cracks and eventually cause the rocks to break off. Animals such as rabbits create many burrows so this also erodes the rocks.
Soil movement in Uplands and Lowlands
Uplands
Scree fragments are easily moved and usually cause rockfalls. Rain can add to the weight of the scree and increase the chances of a rockfall.
Lowlands
Soil creep is the slowest slope movement. Rain dislodges the soil and cause it to slowly move down the hill. The soil only moves 3mm per year.
Soils such as clays and sandstone are porous so they become saturated and become heavy so they start to move down the hill.
Misfit rivers and dry valleys?
Misfit rivers
Are found in the Uplands. They are small rivers found at the bottom of U-Shaped valleys. They will eventually erode the U-shaped valley into a V-shaped valley. They deposit silt and mud (alluvium).
Dry rivers
Are found in Lowlands.
1) before Ice Age: chalk is porous so water passes through it’s cracks and no river can form
2) ice age: water freezes inside of chalk. Chalk becomes impermeable and the water flows over it, eroding the rocks into a small V-shaped valley
3) after ice age: water inside chalk melts and the chalk becomes permeable again so the river water travels down through the cracks. The river dries up, leaving a dry valley behind
How has Glaciation affected the Uplands and Lowlands
Uplands
U-Shaped Valleys
Corries and Morraines
Lowlands
Dry rivers
V-shaped valley
Scarp and vale topography (eroded anticline)
How have humans effected the landscape in the Uplands
Farming- sheep have been allowed to roam free so they eat the grass down and stop any tree saplings from growing. Increase flooding as there is no resistance to surface run-off.
Building materials- limestones and sandstones are mined. Wood is farmed in large reserves
How have humans effected the landscape in the Lowlands
Farming- large flat areas are very fertile. This means that the surrounding settlements have lots of food, increasing the growth of the settlements. There are large irrigation channels
Economic activities- wood that was previously covering the flat land was cut down and used for buildings and other exports. There is an abundance of clay so that is used for pottery, however it is on a much lower scale. Lots of food is produced and also exported.
Compare Carboniferous Limestone to Granite?
Carboniferous Limestone
It is composed of many different layers of skeletal deposits when the UK was under a tropical sea. They were compressed and the calcium carbonate inside it was used as a ‘cement’. It is permeable and quite resistant.
Granite
It is composed of quartz, feldspar and mica. Granite forms when magma cools underground. Large crystals form inside the rock. Granite is very resistant.
Compare chalk to slate
Chalk
It is a younger form of limestone. It is very porous and allows water to flow through it. It is not as resistant as Granite but more resistant than Clays
Slate
It is composed mud or shale that has been under immense pressure and heat. It is very resistant. The crystals inside of the rocks have been reformed. Slate forms Schist.
