4. UK Evolving Physical Landscape: Physical Rock & Landscape Processes Flashcards
What are the 3 types of Rock?
Igneous
Sedimentary
Metamorphic
What is Igneous Rock?
Molten Rock - cools down and hardens
Rock forms crystals - Hard e.g. granite
What is Sedimentary Rock?
Sediment compacted together - solid rock
2 types:
Carboniferous limestone and Chalk - tiny shells and skeletons of sea creatures - Limestone hard but chalk softer
Clays and Shales - mud and clay minerals, very soft
What is Metamorphic Rock?
Formed by other rocks or older metamorphic rocks changed by heat and pressure - become harder and compact eg shale becomes slate -> more pressure becomes shist
Rock type influences landscape - what also influences landscape?
Active volcanos - 520 million years ago the Uk land now used to be much closer to a plate boundary - Active volcanos forced magma through repartee crust - cooled into igneous rock e.g. granite
Plate collisions - caused rocks to be folded and uplifted - forms mountain ranges - mostly remain as upland areas - igneous granite is hard and more resistant to erosion -
Intense heat and pressure forms hard metamorphic rocks
Plate movements - 345 - 280 million years ago Britain was in tropics and partly underwater as higher sea levels. Carboniferous limestone formed in warm shallow seas - can be seen in uplands of Peak District - youngest rocks in UK are chalks and clays - found in shallow seas and swamps - softer rocks so more easily eroded - form lowland landscapes
Rock types create different landscapes - what are characteristics of different Rock types?
Granite - very resistant - forms upland landscapes - lots of joints which aren’t evenly spread - areas with fewer joints - weathered slower and stick out at the surface forming tors
Slate and schist - slate forms in layers creating weak planes in the rock. Hard and resistant to weathering - easily split into thin slabs. Schist has bigger crystals than slates and splits easily into small flakes. Both form rugged, upland landscapes - impermeable which leads to waterlogged and acidic soils
Carboniferous Limestone - rainwater slowly east away at Limestone through carbonation weathering - most weathering happens along joints creating limestone pavements, gorges and caverns. Limestone is permeable - dry valleys and resurgent rivers
Chalk and clay - Chalk is harder then clay - forms enscarpments in UK lowlands and cliffs - one side of hill usually steep, other is more gentle - chalk is permeable - water flows through and emerges as a spring where it meets impermeable rock - clay is very soft - easily eroded - forms wide flat valleys in UK lowlands - impermeable so water flows over surface - lots of streams, lakes and rivers
What used to cover most of the UK? Explain..
Ice :
Last 2.6 million years - lots of glacial periods - pasts of these periods the UK was covered in massive ice sheets
Ice - powerful - able to erode the landscape - U shaped valleys
Glaciers deposited lots of materials as they melted - landscapes formed by glacial meltwater and deposits extend south of the ice sheets e.g. large parts of eastern England covered in till
Explain what Physical processes alter the landscape?
Physical processes are constantly changing the UK landscape
Weathering - process of breaking down rocks - biological, mechanical or chemical
Erosion - wearing away rocks - glacial period - ice eroded landscape - rivers the the sea are constantly eroding the landscape
Post glacial river processes - melting ice at end of glacial period - rivers get bigger - more power to erode - ice leaves distinctive landforms when melted
Slope processes - mass movements e.g. rockfalls, slides, slumps and soil creep
Physical processes are affected by climate - cold climate leads to freeze thaw weathering whereas wet climate increases number of rivers and stream
Explain how Physical processes interact to create Distinctive Upland landscapes?
Snowdonia - an upland landscape - rocky crags
Llyn Idwal - tarn - sit-in in Corrie which was hollowed out by ice during glacial times
Freeze thaw weathering - occurs on steep back wall of Corrie - rocks are broken up - rock falls - form scree slopes
U shaped valley - eroded by ice - flag floor and steep sides - valley contains misfit river
Lots of rain in snowdonia- rocks are mainly impermeable - lots of streams eroding steep sides of Corrie - forming gullies
Explain how Physical processes interact to create Distinctive Lowland landscapes?
The downs and Weald are lowland landscape - chalk enscarpments - either side of a large flat area of clay - valley is flat
Large rivers - meander on the impermeable clay, widening the valley floor
UK has a wet climate- heavy rain - flooding - overflowing river deposits silt on the valley floor - flood plain
Dry valleys - found in UK lowland landscapes - valleys with no stream visible - (flow underground in the permeable chalk) - formed glacial periods when colder climate lead to more freeze thaw weathering and glacial snow melt - meant streams had much more water in them compared to today
What are the 3 main Human processes that have changed the landscape?
Agriculture
Forestery
Settlement
How has Agriculture changed the landscape?
People have cleared the forest for farming space - overtime hedgerows and walls have been put in to mark out fields
Different landscapes Better for different types of farming -
Arable - flat land - good soil - grow crops
Dairy - warm and wet areas - dairy farming - large, grassy fields
Sheep - harsher conditions - upland - steep slopes - cold weather - lack of trees
OS maps show influence of agriculture - field boundaries and drainage ditches
How has Forestery changed the landscape?
Forestry - management of area of woodland - used for timber, recreation or conservation UK used to be covered in deciduous woodland - very little natural woodland left. Coniferous forests - planted for timber - trees often planted in straight lines - areas are felled therefore landscape is left bare - deciduous trees replanted in areas
OS maps show forestry plantations and areas that are being managed
How has Settlement changed the landscape?
Lots of factors influence where settlements have developed- early settlers needed water supply
Factors like bridging points over rivers and availability of resources
Settlements grew and influence landscape - land was concreted fir roads and buildings - affects drainage patterns - rivers diverted through underground channels - some river channels were straightened or had embankments to stop flooding - big cities - ports - industrial areas
Buildings railways canals and embankments - settlement on OS maps
