Theme 1 - Landform Process and Change Flashcards
fluvial?
referring to a river and it landforms
erosion?
the wearing away of the land
transportation?
movement of material by the flow of water
deposition?
dropping of the material carried by the river
bed load?
material carried by the river being bounced or rolled along its bed
meander?
a bend in the river formed by lateral erosion
why do river landforms change over time?
due to fluvial erosion, transportation and deposition
erosional processes of the river channel? 3
~abrasion
~hydraulic action
~solution
abrasion (river channel)?
stones and material carried by the river hitting the river bed and banks, wearing them away
hydraulic action?
the sheer force of water hitting the river bed and banks compressing air in gaps in the soil and rock which causes material to be washed away
solution?
slightly acidic river water dissolves chalk and limestone rocks which are made from calcium carbonate
erosional processes of the river bed load? 2
~attrition
~abrasion
attrition?
stones carried by the river collide together and are broken down becoming rounder and smaller
abrasion (bed load)?
stones and material carried by the river hitting the river bed and banks become eroded and turn smaller and rounder
when does deposition happen?
when the speed of flow is too slow for it to carry the load
where does deposition happen? 3
~where there is a lack of rainfall, so there is less water moving
~on the inside of a meander, as water here is moving slower
~at the mouth of the river, where the river water flows against the direction of the sea
river transportation? 4
~suspension
~traction
~saltation
~solution
suspension?
fine, light material is held up and carried within the rivers flow, this is called suspended load
traction?
large boulders and rocks are rolled along the river bed, load carried is called bedload
saltation?
small pebbles and stones are bounced along the river bed, this load is lifted then dropped alternatively
solution (transportation)?
minerals are dissolved in water, this s a chemical change affecting rocks such as chalk, load transported is called the solute load
examples of river landforms? 5
~meanders
~floodplains
~gorges
~waterfalls
~v - shaped valleys
where are v-shaped valleys found?
upper course of a river where the river is usually small and the land is steep
what creates the v-shape valley? 2 processes
~vertical erosion
~weathering
how is a v-shaped valley formed?
~water flows down a steep slope in a river
~flowing water carries sediment and starts to erode the sides of the valley
~over time the continuous erosion deepens and widens the valley creating a v shaped cross-section
processes used - hydraulic action, abrasion
waterfall?
water falling from a higher level to a lower level due to a change in rock structure or as a result of glacial erosion
gorge?
a steep sided narrow valley formed by a retreating waterfall
floodplain?
a flat piece of land on either side of a river forming the valley floor
vertical erosion?
erosion of the river channel that results n its deepening rather than widening
interlocking spurs?
hard resistant rocks that a river cannot easily erode and therefore the river goes around them
weathering processes that help develop a v shaped valley?
~freeze thaw
~biological weathering
what two ways can waterfalls be created?
~glacial erosion
~differential erosion
steps on how glacial erosion formed waterfalls?
~glaciers move slowly down slopes and valleys carrying rocks and sediments
~as the glaciers move it erodes the land beneath through plucking and abrasion
~eroded material is transported by glaciers
~when the glacier reaches a steep cliff or a change in slope, it starts to melt, and the water flows over the edge
~water flows in a waterfall creating a plunge pool
how are waterfalls formed by differential erosion?
~hard resistant rock is undercut by erosion of the soft rock
~the water falls over the hard rock lip and splashes against the soft rock on the back wall
~soft resistant rock is eroded on the wall causing it to move back
~a plunge pool is formed by the force of water and is deepened by abrasion
~the overhang collapses due to lack of support and the pull of gravity
~gradually the waterfall retreats upstream, leaving a steep sided gorge
when is a gorge formed?
when a waterfall collapses and retreats upstream
slip off slope?
a bank of gently sloping deposited material found on the inside bend of a meander
where are meanders usually found?
middle and lower course of a river valley
what are meanders caused by?
erosion on the outside of the bank and deposition on the inside of the bank
feature of a meander?
~fastest flow outside bend
~slowest flow inside bend
~shallow water inside bend
~deep water outside bend
~deposition inside bend
~erosion outside bend
what happens to a floodplain when a river floods?
it gets covered with water
what is commonly found on floodplains?
meanders
where are floodplains found?
middle and lower course of a river
3 types of weathering?
~physical
~biological
~chemical
2 types of physical weathering?
~freeze thaw action
~salt crystal growth
2 types of biological weathering?
~plant roots
~burrowing animals
freeze thaw steps?
~rainwater enters crack in cliff
~temp drops and water freezes and expands making the crack bigger
~temps rise water melts and more water flows in crack
~process repeats until the rock falls off
salt crystal growth steps?
~seawater left on rock
~water evaporates leaving salt behind
~salt crystals grow and exert pressure on rock
~rocks broken apart
plant roots steps?
~plants grow on top of cliff
~roots push into cracks of rocks
~rocks broken apart
burrowing animals steps?
~small animals burrow through soil and into cracks in the rock
~rock is broken apart
type of chemical weathering?
carbonation
carbonation steps?
~rainwater enters cracks on the cliff face
~the weak acid reacts with carbonates in the limestone
~cracks get bigger
slope processes?
processes involved in moving material from the cliffs on to the beach
weathering?
breakdown of rocks in place by elements of the weather
mass movement?
when soil, rocks or stones move down a slope
examples of mass movement? 2
~rockfalls
~landslides
what causes rockfalls on cliffs?
as waves erode the base of the cliff, a large section collapses
coastal erosion processes and what part they erode? 4
erode cliff
~hydraulic action
~abrasion
~solutions
erode beach material
~abrasion
~attrition
how does hydraulic action erode coasts?
waves crash into cliffs, trapping and compressing air in the cracks which break up the rocks
how does abrasion erode coasts?
waves hurl sand and pebbles against the cliff, which wears the land away
how does solution erode coasts?
salt water dissolves rocks made of calcium carbonate
how does attrition erode coasts?
pebbles are rolled back and forth, they collide with each other which makes them smaller and rounder, eventually turning into sand
sediment?
material carried by the sea
longshore drift?
process by which sediment is moved along the coastline
process of longshore drift?
swash - pushed up the beach at the same angle as the wind
backwash - moves straight down the beach due to the pull of gravity
what is a headland and how is it formed?
a headland is an area of land that juts into the sea and is formed due to harder, more resistant rock being eroded more slowly
how is a bay formed?
a bay is formed between the headlands due to softer, less resistant rock which erodes more quickly, beaches often form in sheltered bays
bay?
a recessed area of coastline often found between two headlands
wave cut platform?
a coastal landform made of a rocky shelf in front of a cliff
wave cut notch?
a slot with overhanging rocks that has been cut into the bottom of a cliff by wave action
bedding plane?
clearly seen layers of rock in a cliff face
how are wave cut platforms made?
~as waves pound the base of the cliff, hydraulic action and abrasion cut a wave cut notch into the base of the cliff
~with continued erosion the wave cut notch will make the cliff unstable and collapse due to gravity
~material from the cliff will then be moved by the sea, and in doing so abrasion will smooth the surface of the wave cut platform left behind
how are arches and stacks formed?
~two caves on either sides of a headland erode by abrasion and hydraulic action backwards until they cut through the back wall, this creates an ARCH
~weathering erodes the roof of the arch and wave cut notches erode the base of the arch to make it wider
~eventually the roof will collapse to leave a rock pillar called a STACK
swash?
movement of water up the beach as a wave breaks
backwash?
flow of water back into the sea after a wave has broken on to the shore
beach?
created by deposition and lies between the high water mark and low water mark
spit?
sand or shingle beach that is joined to the land but projects outwards into the sea in the direction of the prevailing wind
offshore bar?
an area of deposition that is slightly off the coastline in the estuary of a river
how is a spit formed?
~longshore drift carries sediment along a coastline, swash brings material on shore, backwash removes material
~this continues in a zigzag movement along the coast
~if the coast changes direction, material will continue to be deposited in the original direction in a shallow sea
~the built up material is a SPIT
offshore bars?
ridges of sand or shingle running parallel to the coast in an offshore zone
how are offshore bars formed?
destructive waves erode sediment and backwash transport it off the coast and deposit the material
example of a sand dune?
Ynyslas sand dunes
rock pool?
a pool of seawater between shoreline rocks
how are sand dunes formed?
sand dunes are formed by wind blown sand, when wind moves across a flat, sandy surface it lifts and transports loose grains of sand, as the wind slows down, it drops the sand creating dunes
what happens at high and low tide to rocks pools?
high - covered by the sea
low - some seawater remains forming the rock pools
cavern?
large underground cave which has been created due to enlargement of joints in carboniferous limestone
sink hole?
a hole in the ground caused by a collapse of the surface layer, often found in carboniferous limestone areas where caverns are present
what factors affect the rates of landform change? 3
~geology
~climate
~human activity
how can geology affect the rate of landform change?
they type of rock being eroded and the way in which rock types are laid down
~hard rock takes much longer to erode then soft rock
concordant coastline?
rocks are formed parallel to the sea so that erosion rates along the coastline are even
discordant coastline?
rocks are formed at right angles to the sea and so erosion rates vary along the coastline
how does climate affect the rate of landform change? 3
coasts - prevailing wind affects the angle at which the waves break on to the coastline, therefore the direction of erosion and transportation
rivers - the more flowing water in a river the higher the erosion rates - in UK during winter months as most rainfall
extreme weather events - a powerful storm can change the coasts overnight as it causes destructive waves
fetch?
distance waves have travelled before breaking onshore
how does human activity affect the rate of landform change?
~intended human activity includes management strategies to reduce erosion impacts of both river and coastal landforms
how are meanders managed?
using gabions, cages filled with rock which absorb the power of water reducing erosion on the outside bend
groyne?
a low wall or barrier on a beach built at right angles to the sea to restrict longshore drift
