uk physical landscapes Flashcards
what is weathering
process of rock being broken down by natural factors
weathering examples
-physical weathering e.g. freeze thaw = when water in small cracks freeze and expand creating bigger cracks
-chemical weather e.g. oxidation of iron in carstone at hunstanton
-biological weathering e.g. plant roots pushing down into rocks
what is erosion
when material is worn away
4 states of erosion
-hydraulic action= sheer force of water
-abrasion= scraping action caused by transported sediments
-attrition= knocking together of transported sediments
-solution= minerals are dissolved in water
how are headland & bays formed
1) headland is more resistant to erosion therefore it juts out to create it
2) bays are less resistant to erosion so it creates an indent
how is cave, arch, stack and stump formed
1) weaknesses in joints & bedding planes create cracks
2) HA + A widen crack to form a cave
3) HA + A & weathering cause cave to collapse forming an arch
4) HA + A & weathering cause arch to collapse forming a stack
5) HA + A cause stack to reduce to a stump
how is a cliff, wave cut notch platform formed
1) HA + A erode base off c;iff to create a wave cut notch
2) cliff now “hangs” as an overhang
3) as the base continues to erode, the overhang is no longer supported & collapses
4) process repeats. cliff retreats & material left forms a slip way known as a wave cut platform
how are spits formed
1) longshore drift causes beach sediment to be transported
2) sediment is deposited in direction of LSD (begins formation)
3) a change in wind direction causes the spit to curve
what is transportation
when material is moved from on place to another
4 states of transportation
-saltation= material bounces
-traction= material rolls
-suspension= floating material
-solution= dissolved material
what is deposition
when material is no longer transported and settles out. Happens when the waves lost energy and heaviest material is always deposited first
how are waterfalls formed
1)water flows down the hard and soft rock
2)HA + A erode the soft rock causing it to collapse
3)the unsupported hard rock then collapses
4)the debris is swirled around at the bottom of the waterfall creating a plunge pool
5)process repeats and waterfall retreats leaving a steep sided gorge
how are meanders formed
1)the current is fastest on the outside of the bend because the river channel is deeper (less friction to slow water down)
2)more erosion takes place on the outside bend forming river cliffs due to HA + A
3)the current is slower on the inside because the river channel is shallower ( more friction to slow water down)
4)eroded material is deposited on the inside forming slip-off slopes
how are ox-bow lakes formed
1)HA + A cause outside bends to get closer until theres only a small bit of land left between the bends (the neck)
2)the river breaks through the land and the river flows along the shortest course
3)deposition eventually cuts off the meander forming an ox-bow lake
flood management schemes (hard engineering)
-Lake reservoirs= release water for agriculture & homes
-dams= last long + hydroelectric energy
-embankments (raised land)= expensive to build & maintain
flood management schemes (soft engineering)
-restoring meanders= slows river - farm land lost + cheap
-afforestation= more tees,more rainfall, slows water into river - more soil saturation= more biodiversity
-flood warning (mitigation)
river management schemes (hard engineering)
-straightening channels= increase velocity to remove flood water
-artificial levees= heightens river so flood water is contained
-deepening OR widening rivers= increase capacity for a flood
river management schemes (soft engineering)
-afforestation= more tees,more rainfall, slows water into river - more soil saturation= more biodiversity
-demountable flood barriers
-managed flooding= naturally let areas flood - protect settlements
physical cause of flooding
-prolong and heavy rainfall= soil becomes over saturated causing surface runoff
-geology= impermeable rocks cause surface runoff to increase river discharge
human cause of flooding
-land use= tarmac and concrete are impermeable - prevents infiltration & causes surface runoff
how are waves formed
the wind blows over the surface of the sea and causes friction producing a swell in the water
how are tides formed
the moon and earth exert a gravitational pull on each other. on earth the pull causes the ocean to bulge out on both sides closest and farthest to the moon
why do waves break?
1) waves start out at sea
2) as waves approach shore, friction slows the base
3) causes orbit to become elliptical until top of waves break over
wave size depends on:
-wind speed (faster speed=larger waves)
-fetch= how far the wind blows (longer fetch=longer waves)
-wind duration (longer duration= larger waves)
-depth of water (deeper water=larger waves)
what are constructive waves
a swash that is stronger than the backwash therefore builds up the coast
what are destructive waves
a backwash that is stronger than the swash therefore erodes the coast
4 coastal erosions
-hydraulic action
-attrition
-corrosion= chemical reaction which wears rock
-corrasion= rocks act like sandpaper which away cliffs
what is a managed retreat (coastal defence)
-managed retreat= when the sea is allowed to reach its natural position by removing existing coastal defences
-disadvantages= settlements & farmland destroyed (compensation paid), little evidence it works
-advantages= maintenance costs low, nature conservation
other coastal defences (hard engineering)
-sea wall= prevents erosion / expensive
-gabions= cheap, easy to build / ugly, corrode
-groynes= wider beaches which slow waves / narrower beaches causing greater erosion and floods
other coastal defences (soft engineering)
-beach nourishment= wider beaches to slow waves / expensive, repeated process
-dune regeneration= wave energy absorbed / protection limited to small area
