Coastal landscapes (P1- SEC C) Flashcards
(39 cards)
what are constructive waves?
LOW WAVES and LONG WAVELENGTH that surge up the beach and ‘spill’ with POWERFUL SWASH.
- carries/deposits large amounts of pebbles/sand to CONSTRUCT THE BEACH
what are destructive waves?
Formed by local storms close to coast
CLOSELY SPACED
HIGH/STEEP WAVES that PLUNGE INTO BEACH
LITTLE SWASH but POWERFUL BACKWASH - removes sand/pebbles so ‘destroys’ it
what is the FETCH?
how far the wave has travelled
attrition?
rock fragment carried by the sea knock against each other causing small/more rounded rocks.
abrasion?
‘sandpapering’ effect on pebbles grinding over a rocky platform - becomes smooth
solution?
dissolving of soluble chemicals in rocks
corrasion?
fragments of rocks are picked up/hurled by the sea at a cliff.
the rocks erode the cliff
hydraulic power?
POWER of waves as they smash onto the cliff. trapped air is forced into cracks In rocks making them break - cavitation
5 main processes that influence shape of the coastline?
EROSION
WEATHERING
MASS MOVEMENT
TRANSPORTATION
DEPOSITION
weathering?
weakening or decay of rocks in their original place on, or close to , the ground surface
2 types of physical weathering and explain?
freeze thaw - water collects in cracks of rock and freezes/expands making cracks bigger
- when temps rise, ice thaws , water seeps deeper into rocks
REPEAT - THEY BREAK
Salt weathering - seawater evaporates leaving CRYSTALS
- they grow/expand
- put pressure on rocks /breaks
chemical weathering ?
rainwater absorbs co2 from air and becomes acidic
- contact with alkaline rocks causes CHEMICAL REACTION , so rocks DISSOLVE
mass movement ?
downward movement or sliding of material under influence of gravity
types of mass movement?
ROCKFALL - rocks break away from cliff face often due to free thaw weathering
ROTATIONAL SLIP- slump of saturated soil/weak rock along a CURVED surface
MUDFLOW- saturated soil/weak rock flow down a slope
LANDSLIDE - blocks of rock slide downhill
coastal transportation - 4 ways ?
solution ; dissolved chemicals from limestone and chalk
suspension: particles carried in water
traction ; large pebbles rolled along a seabed
saltation ; a ‘bouncing’ motion of particles too heavy to be suspended
describe and explain the process of longshore drift?
- process where waves transport material
-the swash moves material up the beach at an angle - the material the moves back at 90 degrees due to gravity
- this movement carries on along the beach in a zig-zag motion
what types of rock form bay and headlands?
weaker rocks erode to FORM BAYS
tougher rocks erode SLOWER to form HEADLANDS
How do wave cut notches and platforms form?
when sea attacks base of cliff, erosion wears away the cliff at the base forming WAVE CUT NOTCH
overtime the notch gets DEEPER by corrasion, hydraulic action, abrasion /UNDERCUTS THE CLIFF - eventually the overlaying cliff can supports its weight/collapses
- as sequence continues cliff retreats and form a gentle sloping platform - WAVE CUT PLATFORM
how are caves , arches and stacks formed?
- crack in headland made larger by hydraulic action AND GROWS INTO CAVE
- cave breaks though headland forming arch
- base of arch becomes Widder and thinner through erosion and weathering/ roof of arch collapses leaving stack
how do beaches form?
DEPOSITION OF SAND /SHINGLE
- waves are constructive
- pebble beaches formed by high energy environments as they wash away fine sand and leave large pebbles
how do sand dunes form?
SAND DEPOSITED on th beach and blown INLAND by wind to form dunes.
- stabilised by vegetation to form FORE DUNES/YELLOW DUNES
HOW DO SPITS FORM?
- forms where there is ALOT of LONGSHORE DRIFT , where coastline suddenly changes shape
- SEDIMENT DEPOSITS out to sea and builds up - forms EXTENSION OF LAND
- this continues making it more extended until water becomes too deep
- strong winds /tidal currents causes CURVED END SPIT
HOW DO BARS FORM?
longshore drift can cause SPIT to grow ACROSS A BAY! - TRAPS LAKES BEHIND IT -BAR
CASE STUDY : SWANAGE , location , landforms
Seaside town in DORSET , SOUTH COAST OF UK
-located in a sheltered bay/broad sandy beach , between 2 headlands
SWANAGE BAY - because sand and chalk between the two bands of hard resistant rock erodes at a faster rate.
N of swanage - POOLE HARBOUR
- increased DEPOSITION at mouth of several rivers
- formed large esturary/salt marsh