coasts Flashcards
4 examples of depositional landforms💓🏝️
beaches, sand dunes, spits, bars
4 examples of erosional landforms🌴💞
headlands, bays, arches, stacks, stumps, wave-cut platforms
example of discordant coast line?🌍
dorset
sand dunes💞🦎
where are the mobile and fixed dunes in relation to the beach?
what 2 types of plants do sand dunes contain?
mobile dunes nearest the sea, fixed dunes near the back of the beach
xerophytes and halophytes
what are xerophytes?
what are halophytes?
🏝️🌴🌿💐🪷🌱
xerophytes: needs very little water, can withstand periods of dry temperature
halophytes: can withstand high concentrations of salt from saltwater
constructive waves🌊💓
-low and long
-stronger swash
-forms gently sloping beaches
-beach gains material
-found in sheltered bays
-more common in summer
destructive waves🌊💓
-steep and high
-backwash more powerful
-high frequency
-steep beach
-removes material from beach
-more common in winter
what is corrosion?🫧🩷
when there is a chemical reaction between the seawater and susceptible rocks like limestone
(the acids in seawater dissolve alkaline rocks)
what is hydraulic action?🎀
when water is being compressed into the cracks of the rocks repeatedly, air is trapped under high pressure in the cracks. this leads to the breakdown of the cliff
what is abrasion?😸😼
where pieces of rock are picked up by waves and hit against the bed, beach or cliffs. this wears them away over time
what is attrition?🛤️
when rock particles carried in the sea are hit against one another, causing a reduced particle size making them more rounded
what is mechanical weathering?
what is chemical weathering?
💐
mechanical- process of breaking big rocks into smaller ones
chemical- changes that some substances can cause on the surface of the rock
at holderness, weak boulder clay has been eroded by ___ metres in a century
⛴️💞
120
are beach profiles steeper in summer or winter? ❄️🏝️
summer
how are berms created by constructive waves?🌊🌊🌊
the swash deposits larger material at the top of the beach.
as the berm builds, the backwash becomes weaker so beach material becomes smaller towards the shoreline.
why are berms eroded in winter by destructive waves?🎀
the strong backwash drags sediment back
how is a wave cut notch formed?⭐️
when waves break against the foot of a cliff, erosion is concentrated close to the high tide line, creating a notch which begins to undercut the cliff.
how is a wave cut platform formed?🌫️☁️
as the notch grows, the rock above becomes unstable and eventually the cliff above collapsed.
as the processes repeat, the notch migrates inland leaving behind a platform
in longshore drift, which direction do the swash and backwash carry material?💞
swash carried material up the beach, in the direction of the prevailing wind
backwash carried material directly down
what are the 4 methods of marine transport? 🪼🐠🐟🐬🐳🐋💞
traction
saltation
suspension
solution
caves, arches, stacks and stumps formation???🩷
cave: faults are exploited by hydraulic action and abrasion
arch: cave is eroded through
stack: top of arch becomes unstable (often by biological weathering) leaving a pillar
stump: when the stack is eroded further and collapses
how is a spit formed?🌷
sediment is moved by longshore drift
if the coastline changes direction, sediment will build up
current from river stops it extending all the way
wave refraction carries material into sheltered water to form a recurved spit
salt marsh occurs where finer sediment is deposited (between the spit and the coastline) they’re salt tolerant
what’s eustatic sea change?🐬
when ice on land melts and returns to the ocean, increasing the volume of water in the sea.
usually accompanied by thermal changes which melts land ice
what is isostatic sea change?🪼
the downward movement of land, causing localised sea level rise.
land can be stressed down from post-glacial adjustments and accretion
