The UK's evolving physical landscape Flashcards
What are the types of rock?
Igneous
Sedimentary
Metamorphic
Describe the makeup of igneous rocks
Form from volcanic activity, meaning all igneous rocks form at plate boundaries. Magma cools on the surface, or lava cools within the chamber and is flung out of the volcano during an eruption.
It is hard and made of crystals.
Mostly found in upland areas in the north of the UK.
In the UK, all igneous rocks are very old and not near plate boundaries, meaning the rock has moved over thousands of centuries (due to tectonic drift).
Examples include: Granite (used for kitchen worktops), Basalt (formed Giant’s Causeway)
Describe the makeup of sedimentary rocks
Form gradually over time as dead organic matter and eroded rocks are transported out to sea. The sediments are deposited on the seafloor, which over time accumulate and compress under pressure. The weight of the sediment on top will push the sediments together under pressure.
Found mostly in lowland areas.
Resistances vary, since there are various types of sedimentary rocks based on the type of sediment used to form the rock.
Give some examples of sedimentary rocks
Examples include: Chalk (made from plankton), Sandstone (formed from sand, which cements together under intense pressure, can be found from the Highlands of Scotland across the length of the UK), Limestone (made from calcium carbonate, vulnerable to chemical weathering), Conglomerate (mix of conglomerate rocks containing large rocks and pebbles cemented with sand and mud)
Describe the makeup of metamorphic rocks
Begin as sedimentary rocks, found close to tectonic activity. Formed under extreme pressure and temperature, which compresses the rocks further and squeeze out many faults.
Often banded (alternating, thin layers of 2 different mineral compositions). This means the rocks don’t erode quickly but can split if force is applied between the horizontal layers (bedding planes).
Give some examples of metamorphic rocks
Slate - quarried largely in the UK.
Formed from a mixture of clay, shale and volcanic ash.
Marble - formed from limestone, heated at a continental plate boundary. Consists of interlocking crystals which make this rock resistant to erosion and extremely dense.
What is the UK’s geology like?
UK has varied relief and landscape due to the geology of the bedrock. Historically, the UK used to be close to a plat boundary where there was a large amount of rock formation.
What are the processes that shape the UK’s landscape?
Weathering and Erosion - continuously break down rock faces and surfaces. Weathering happens to all rocks on the surface, erosion is caused by water bodies.
Glacial erosion -
Slope processes - any highlands or hills will have slope processes acting to drag rocks down to a lower level. They include mass movement and can occur on any hill/rockface, not just along the coast.
Rock falls
Landslides
Mudflow
Rotational slip
What are rock falls?
Occur on sloped cliffs (over 40 degrees to the beach floor) when rock becomes exposed to mechanical weathering e.g. freeze thaw.
What are landslides?
Water between sheets of rock (bedding planes) and rock face reduces friction and allows large chunks of rock to slide down the cliff.
What is mudflow?
Waterlogged (saturated) soil flows down the face of a hill like a fluid, bulging at the bottom in a lobe.
What is rotational slip?
Slumps - soil and rock fragments become saturated with water, however, instead of sprawling down the hill like a mudflow, chunks of rock and soil slip, creating stepped ‘heads’ down the cliff face.
Describe the upland landscapes of the UK
Located in the north and the west of England, Wales and Scotland. These are areas that are usually higher above sea level.
You would find the majority of igneous and metamorphic rock in the UK. Upland landscapes are usually older and more resistant to weathering and erosion.
Past tectonic processes have created faults and uplifts here.
Describe the distribution of lowland landscapes in the UK
Located in the south and east of England. Areas located at lower levels (duh).
Sedimentary rocks, such as clays and sands are usually found in the lowlands. Landscapes are much younger than the highlands, and sedimentary rocks erode easily, creating landscapes formed through erosion and weathering processes.
Describe the characteristics of the Weald
Consists of gentle rolling hills that are located at low elevations. The Weald used to be a large mound of layered rocks (anticline) caused by tectonic updrift. Over time this has eroded away to create the hilly landscape seen today.
Chalk is resistant to weathering and erosion, and only affected by slow chemical weathering when rainwater dissolves the calcium carbonate.
Post glacial river processes - When the climate was much colder, the ground over the Weald was completely frozen. Rivers flowed and created valleys and other river landforms over the landscape. When the climate warmed, the frozen land melted and water from the rivers seeped into the permeable chalk and disappeared. This left dry valleys in the Weald.
