geography - physical landscapes, no human geography

exclusively terms + the like for coasts and glaciers.

waves

disturbances on the surface of the sea or ocean in the form of a moving ridge or swell, caused by energy transfer from the wind.

wave strength is dependant on fetch (distance travelled), wind speed and wind duration.

wave terms (types of wave, how they move sediment, top and bottom of waves)

crest: top of wave

trough: lowest gap between waves

swash: forward motion of waves, dragging material up the beach. in constructive waves this is stronger than backwash

backwash: backward motion of waves, dragging material away from the beach. in destructive waves this is stronger than swash

constructive waves: long wavelength, low frequency, strong swash. deposits sediment on the coast

destructive waves: short wavelength, high frequency, strong backwash. erodes the coast

coastal weathering - two types each containing 3 subtypes

mechanical - physical breakdown of rocks without altering the chemical composition. includes:

freeze thaw (water entering cracks in rock, freezing and expanding the cracks, refilling and repeating the process)

salt crystallisation (salt entering cracks in rocks, water evaporating and leaving the salt behind, exerting pressure on the rock and causing shattering)

thermal expansion (rocks expanding in high heat and shrinking in low heat, weakening the rocks and causing breaking)

chemical - rocks breaking down due to chemical reactions. includes:

hydrolysis (minerals in the rock reacting with water, causing them to break down. can form weaker minerals that are more susceptible to weathering)

carbonation (CO₂ from the air dissolves in water, forming carbonic acid which reacts with limestone and other calcium carbonate rich rocks, dissolving them)

oxidation (minerals containing iron react with oxygen, weakening the rock)

effects of coastal weathering - mostly what structures it forms

cliffs become prone to collapse, and wave-cut platforms, caves arches and stacks form.

mass movement - four types

rock fall - fragments of rock breaking away from the cliff due to weathering. fallen fragments are called scree

landslide - blocks of rock sliding downhill. wave-cut platforms are formed by this

mudslide - saturated soil flowing down a slope

slumping - saturated soil slumping along a curved slip plane, caused by rotational slip.

erosion - four types. primarily things hitting cliffs.

corrasion - destructive waves hitting cliff bases with large sediment. can form a wave-cut notch

abrasion - sandpaper effect, waves with smaller sediment hitting cliff bases and wearing them away

hydraulic action - waves hitting cliff bases and causing air to be compressed. repeated rapid pressure changes causes material to break off

attrition - rocks being bashed into each other in waves

longshore drift

wave swash approaches the beach at an angle while backwash is always at a right angle. causes sediment to be dragged up the beach. contributes to the formation of spits and onshore bars

transportation - how waves move sediment

traction - larger rocks rolled along the sea bed

suspension - fine material floating in the sea

solution - dissolved minerals carried by the sea

saltation - smaller pebbles bounced along the sea bed

deposition

constructive waves dropping material. often happens when waves enter shallower or sheltered areas, areas with little wind, a river or estuary flowing into the sea reducing wave energy

rock type and structure effects on landforms

hard rocks: headlands

soft rocks: bays

concordant: high cliffs and coves

discordant: headlands and bays

erosional landforms - things formed when waves erode cliffs (or don’t)

headlands: harder rock bands sticking out into the water. paired with bays: eroded bands forming sheltered beaches.

wave cut platforms: sea attacks a weakness in the cliff base, forming a wave-cut notch which increases in size, causing cliff instability and collapse. its material is eroded away, the cycle continues, and the remaining platform is known as a wave-cut platform.

waves attack weaknesses in headlands, forming cracks widening into caves into arches. these collapse, forming stacks, which collapse to form stumps.

depositional landforms

beaches - generally material deposited on wave cut platforms. gentle sandy beaches are generally formed from constructive waves in sheltered areas, steep cobbled beaches from destructive waves.

spits - extended stretches of beaches sticking out into the sea formed from LSD. can develop hooks if wind changes

bars - similar to spits, just cutting off bays forming lagoons. also forms offshore:

Dorset coast landforms

old harry rocks: stack

east coast of the isle of purbeck - headlands and bays

management strategies - hard engineering (3)

groynes: wooden barriers at right angles to the beach. prevents LSD. also acts as windbreaks without restricting beach access, and are relatively cheap to maintain with ~40 lifespans. however they look ugly, impede walking, the sand height difference on each side can be dangerous, need regular maintenance, are ineffective during storms and negatively impact the beach downshore

sea walls: recurved walls on the front of cliffs to lessen wave effects. gives people a sense of safety and promenades are popular, they have long lifespans and do not impede LSD. however, they can affect beach access, are expensive to produce and maintain, can increase erosion of the beach and destroy habitats, reduce sediment input etc

rock armour: boulders placed before cliffs/sea walls to absorb wave energy and reduce backwash. does not impede beach access, cheaper than sea walls, quicker to install, lasts a long time, does not impede LSD but can limit beach access, costs increase with imported rock, can be perceived as ugly, need quarrying (harms environment).

management strategies - soft engineering (4)

beach nourishment: importing sand and shingle to LSD affected areas. cheap, retains natural look and use of the beach but increases erosion in other areas and effects the marine ecosystem.

managed retreat: allowing low value areas of coast to erode. maintains the natural balance, but people lose their livelihoods in the area

dune regeneration: encouraging dune growth. improves biodiversity and is not intrusive, but can be costly and complicated

beach reprofiling: redistributing sediment from lower parts of the beach to upper parts. cheap and simple, but only works for low energy waves and needs to be repeated

glacial erosion (3) - what the glacier itself does to erode things

plucking - glacial meltwater freezes around pieces of rocks, breaking them off. often combined with freezethaw

abrasion - rock frozen to the glacier base drags along the bedrock, creating scars known as striations

both plucking and abrasion form moraine (broken off rock fragments)

rotational slip forms hollows which deepen into corries

glacial movement - how the glacier moves

rotational slip - ice accumulates and the intense gravity causes it to flow over the rock lip.

basal flow - intense pressure on the base of the glacier causes melting, and the meltwater allows sliding.

glacial transport - how the glacier moves other stuff

bulldozing - material pushed by the glacier’s snout (front)

moraine: rough mixed size rock deposits. more info later

outwash: light small sized rock or sand deposits transported by meltwater. rounded by attrition, sorted (larger pieces closer to glacier).

till: deposited sediment, sometimes called boulder clay. varied particle sizes. prone to erosion

erratics - rock or boulder unlike surrounding rock transported by a glacier. indicates route taken

upland glacial landforms - from glaciers being formed

corrie - deep, armchair shaped hollows found on the side of the mountain where the glacier first formed. snow accumulates in a hollow, is compressed into ice. abrasion and plucking deepens and steepens the corrie. ice flows down from the hollow

arete - knife-edge ridges from two corries being formed back-to-back

pyramidal peak - 3+ carries forming a sharp point

lowland glacial landforms - from glaciers moving ‘downstream’

u-shaped valleys - rivers form V shaped valleys, and glaciers passing through causes them to get deeper and wider. plucking and abrasion also contribute.

hanging valleys - tributaries into U-shaped valleys that are cut off, forming waterfalls

truncated spurs - meanders from the river cut off by glaciers passing through leaving truncated spurs

ribbon lakes - lakes found in U shaped valleys

drumlins - egg shaped hills! blunt at one end (towards the ice flow), tapered at the other. forms from sediment catching on an obstacle and forming an egg shape. collective noun is basket of eggs or swarm (not needed).

moraine types

lateral - towards the side of glaciers, formed from freeze thaw dropped rocks landing on the glacier.

medial - two glaciers meeting side by side causing two bands of lateral to form medial.

ground - material frozen to the glacier’s base

terminal - found at the snout, material that has been bulldozed. usually a large ridge indicating how far the glacier has travelled

Lake District case study

striding edge - arete

red tarn - corrie

Windermere - ribbon lake