landforms Flashcards
what is a beach
accumulation of sediment, they are important temporary stores within sediment cells
where do beaches form
between high and low water mark
what are beaches formed of
material from offshore sand bars, longshore drift, wind blown sand and mass movement
what 4 types of beach are there
shingle vs sand
swash vs drift
what is the difference between shingle vs sand beaches
shingle : high energy, steeper, 10-20 degrees
sand : low energy, sloping, 5 degrees
what is the difference between swash align and drift align beaches
swash : waves approach parallel, swash and backwash same angle
drift : waves approach at an angle, retreat perpendicular, creates a zig zag motion
what is a discordant coastline
alternating bands of rock at a right angle
what is a concordant coast line
alternating bands of rock parallel to the coastline
what is the process of caves, arches, stacks and stumps forming
- wave action is concentrated on headlands (wave refraction) through erional processes cracks/faults are exploited
- over time this creates a cave
- where cave faces oncoming waves, force is applied directly to rear of cave forming a blow hole
- over time further erosion breaks through to create an arch
- weathering on top of the arch causes it to collapse making a stack
- further erosion and weathering creates a stump
what factors are involved in the formation of caves, arches, stacks and stumps
- high energy coastline, destructive waves
- erosional processes
- wave refraction
- amount/severity of cracks and faults
example of cave, arch, stack and stump
Old Harry in Dorset
how are wave cut platforms formed
- wave action concentrated at high tide line
- over time creates a wave cut notch
- weathering on top + further erosion of the hitch causes cliff to become unstable and collapse
- leaves behind a wave cut platform
- this process repeats
- they are fairly smooth and flat due to abrasion
why do wave cut platforms rarely extend further than 500m
longer the platform the further the waves have to travel, waves will break earlier and won’t reach the cliff, erosion of the cliffs won’t occur
what are the factors involved in the formation of wave cut platforms
- erosion
- weathering
- tides
- geology
what are cusps
crescent shaped indents in the shape of the coastline
where are cusps formed
sand and shingle beaches, heavier sediment is dropped at the horns
how are cusps formed
waves hit horns and drop heavier sediment, curved sides channel incoming swash into the centre of the cusp which creates stronger backwash flowing out of the centre, deepening it
what is a berm
raised, wide flat area at the back of a beach
what are ridges, runnels and ripples
ridges are raised lines on the beach
runnels are depressions that form behind ridges
ripples are smaller versions of ridges and runnels
why do ridges, runnels and ripples form
due to tide action moving back and forth
what are spits
long narrow ridges of deposited sediment that form where the coastline changes direction, typically over estuaries
how do spits form
longshore drift
where is the coarser sediment
proximal end
where is the smaller lighter sediment
distal end
