UK's Evolving Physical Landscapes Flashcards
Oldest rocks
Igneous
Extrusive igneous rocks
When magma from under the ground erupt and the lava cools to form rock.
Finely grained/ uniform/ glassy texture
Why are extrusive igneous rocks porous
Gas bubbles from eruption produce holes
Example of extrusive igneous rocks
Basalt
Intrusive rocks
When magma cools inside the earth, later exposed by weathering/erosion.
Coarsest grained
Little alignment
Example of intrusive rocks
Granite
Sedimentary
Formed over millions of years.
Made when sediments are compacted.
Contain eroded rocks/fossils/ minerals.
Example of sedimentary
Sandstone
Limestone
Chalk
Clay
Metamorphic
Other types of rocks subjected to extreme heat/ pressure vía igneous activity
Where is the majority of the UK’s upland areas? What type of rocks are these?
North and West
Metamorphic/ igneous (more resistant)
3 ways past tectonic processes have shaped today’s landscapes
ACTIVE VOLCANOES (magma cooled to form igneous rocks) PLATE COLLISIONS (folded/uplifted rocks forming mountain ranges) (intense heat/pressure forms metamorphic rocks) PLATE MOVEMENTS (long time ago Britain was in tropics and so submerged) (Carboniferous limestone from warm shallow seas and chalks/clays formed in shallow seas/swamps)
Granite characteristics and landscapes
V resistant and impermeable so forms uplands and moorlands.
Moorlands
Large areas of waterlogged land and acidic soil w low growing vegetation.
Carboniferous limestone characteristics and landscapes
Rainwater carbonation weathers it along joints to create pavement, caverns and gorges
Permeable (dry valleys/ resurgent rivers )
Resurgent rivers
Rivers that pop out at the surface when limestone is on top of impermeable rock.
Slate and schist characteristics and landscapes
V hard/ resistant/ layered/ big crystals/impermeable
Form rugged, upland landscapes w waterlogged/ acidic soils
Chalk and clay characteristics and landscapes
Chalk = harder than clay/ permeable
Forms escarpments in uk lowlands and cliffs at coast w one side steep/ one gentle
Water flows through and emerges as spring when meets impermeable rock.
Clay=soft/unresistant/impermeable
Forms wide and flat valleys, streams, rivers and lakes.
What happened to uk during last glacial periods?
Parts of uk covered in ice sheet (Scotland wales and majority of north)
Effects of ice on uk landscape
V powerful so erodes landscape via plucking/abrasion.
Deposited material as melted.
Physical processes that alter the landscape
WEATHERING (mechanical, biological or chemical)
EROSION
POSTGLACIAL RIVER PROCESSES- (melting ice contributed to river’s power in eroding the landscape, leaving distinctive landforms.
SLOPE PROCESSES (including mass movement)
CLIMATE
Soft rock characteristics
Easily eroded
Creates less rugged/steep cliffs
Creates bays
Hard rock characteristics
Resistant to erosion
Creates high/steep/rugged cliffs
Creates wave cut platforms/ headlands w caves, arches and stacks
Joints vs faults
Joint= small crack in rock
Fault = large cracks in rock
Both increase erosion rates in rock
Factors affecting erosion
Geology Geological structure ‘Wave climate’ Local currents/tidal range Ground water levels
Tidal range
Difference between high/low tide
Concordant coastline
When Alternating bands of hard and soft rock parallel to the coast.
Discordant coastline
When alternating band of hard/soft rock are perpendicular to the coast.
Features found on concordant coastlines
There are fewer as their coast is eroded at an equal rate, they produce coves.
Discordant coastline features
Headlands and bays
3 ways humans have changed the landscape
Agriculture
Forestry
Settlements
How has agriculture changed the landscape for the good?
:) generated income supports local economy, arable farming supports rare birds, hedges/field margins=bat wildlife corridors
How has forestry affected the landscape for the better?
Creates local jobs Provides timber Coniferous forests prevent soil erosion and afforestation (decrease in conifers?) Provides habitats for varying wildlife Enhance landscape?
Effects of settlements on landscape for good
Local materials are used
Settlements built are sheltered from naturally formed slopes
Weathering
Breakdown of rocks where they are
Erosion
When rocks are broken down and carried away by something.
Mechanical weathering
Breakdown of rock without changing its chemical composition.
How are fault scarps formed?
Plate moved forward.
Convection current caused pushed up land.
Rocks snapped/ tilted (over series of earthquakes) to create deep ridge known as fault scarp.
Example of fault scarp
Giggleswick scarp
Process of glaciation
Ice age creates glaciers which slowly move down valley.
They move/increase in size while eroding valley (plucking and abrasion) to make valley deeper/wider.
Postglacials results in wide and deep u shaped valleys
Can be used as upper course of river.
Weathering can make slopes less steep.
Physical processes that can affect a landscape
Weathering Erosion Deposition Slope processes Tectonic events Geology
Scarp
Slope
Vale
Valley
Scree
Lose and angular pieces of rock caused by freeze thaw weathering
Misfit stream
Small stream which is tiny in comparison to the landscape
Alluvium
Sediment
Where is freeze thaw weathering more common?
Why?
In north
Wetter/colder climates
Freeze-thaw weathering process
Water in cracks/joints freeze (and so expand) putting pressure on the rock.
Melts, leaving wider/weaker crack
Repetition of this results in rock shattering and scree at slope foot
Slope process examples
Rockfall Mudflow Landslides Glaciation Soil creep
Rockfall
Rock free fall from steep cliffs due to loosening from freeze-thaw weathering
Mudflow
After heavy rain, if no vegetation to hold soil, saturated soil flows over impermeable subsoil.
Landslides
Ocasional rapid movement of earth/rock along concave plane due to heavy rain soaking overlying heavy rock and sliding over impermeable rock.
Soil creep
Wet and dry causes expansion/contraction of soil particles which slowly move down slope.
Anticline
Dome of folded rocks
The Weald
Once was anticline, is now alternating strata of more/less resistant rock (scarp and vale topography)
Scarp and vale topography
Landscape consisting of roughly parallel scarps w intervening valleys.
Resistant = form steep escarpments
Softer= lower / flatter
Examples of physical weathering
Temp change (expansion / contraction weakens rocks)
Wind/rain/waves (wear rock over time)
Freeze-thaw
Examples of biological weathering
Plant roots expanding rock faults
Burrowing animals wearing down rocks
Chemical weathering
When a rock’s mineral composition is changed
Examples of chemical weathering
Acid rain dissolves alkaline rocks like limestone
Formation of dry valleys as a part of postglacial river processes
During/after ice age water froze in chalk (impermeable) so freshwater formed rivers/valleys which seeped through chalk when weather warmed.
Comparison of Lake District with The Weald
LD has rough, resistant and jagged igneous rocks while W has undulating hills w less resistant rock.
LD has cooler/wetter climate while W has warmer/drier climate.
LD has physical weathering while W has biological/chemical weathering.
Rockfalls/landslides/misfit streams occur in LD while soil creep/dry valleys occurs in W
How has agriculture changed the landscape for the bad?
Decline in arable farming= arable plant/wildlife reduction, scrub encroachment occurs due to traditional practice decline, agricultural chemicals = chalk grassland decline, farming harms environment, overgrazing=soil erosion=water pollution
Pastoral farming
Farming aimed at producing livestock
Arable farming
Where farmers low land, sow seeds and grow plants to harvest.
Conifer
A tree which bears cones/ needlelike leaves typically evergreen.
How has forestry affected the landscape for the worse?
May push out other vegetation
Debase landscape?
Deforestation leads to ancient tree extinction
Effects of settlements on landscape for bad
Loss of land distinctiveness Decline in community facilities Displacement of vegetation/wildlife Pollution Deforestation Water/power consumption
Why’s coast important?
Wildlife Trade Beauty Fishing Energy Jobs Tourism Transport
Transportation
Movement of eroded material up,down and along coastline
Deposition
When sea deposits material due to loss of energy
3 factors affecting waves
Wind duration
Fetch
Wind strength
Fetch
Distance travelled by wind
Destructive wave
High energy wave over long fetch, w high wave height in proportion to length.
Stronger backwash than swash
Erode coast and create flat beaches/cliff retreat/steep/narrow coast
Breaker of destructive waves
Plunging breaker
Constructive waves
Low energy waves w low heigh in proportion to length w stronger swash tan backwash. Deposits material on beach to create berms.