EQ1 2B.4 Flashcards
(9 cards)
What is a constructive wave
Strong swash, weak backwash
Low wave height, long wavelength
Low frequency
Depositional
(Summer)
What is a destructive wave
Strong backwash, weak swash
High wave height, short wavelength
High frequency
Erosional
(Winter)
What is beach morphology
shape of the beach
What is beach sediment profile
pattern of distribution of different sized or shaped deposited material
How do waves change on dif timescales
Daily - storm events produce destructive, anticyclonic events produce constructive
Monthly - 2x high tides + 2x low tides in a month?
Seasonal -destructive waves in winter, constructive in summer
Decadal - climate change, longer winter
Types of wave erosion processes
Abrasion - sediment moved along shoreline , causing it to be worn down over time
Attrition - wave action cause rocks and pebbles to hit against each other, wearing each other down
Hydraulic action - wave crashes onto a rock/cliff face, air forced into joints, high pressure forces joints apart as air expands
Corrosion - mildly acidic seawater can cause alkaline rock to be eroded
Formation of wave cut notches and platforms
1) Marine erosion attacks base of a cliff
2) Creates notch of eroded material between high and low tide
3) Sub-ariel weathering weakens cliff
4) As the notch becomes deeper, the cliff face becomes unstable and falls under its own weight by mass movement
Formation of retreating cliffs
Repeat wave-cut notches and platforms
Formation of cave, arch, stack, stump
1) Occurs in headlands
2) Hydraulic action exploits faults in the base of the headland, creates notch and then cave
3) Cave widens due to marine erosion and sub-aerial processes
4) Erodes thru other side of the headland, creating arch
5) Arch widens until it is unable to support
itself, falling under its own weight through mass movement
6) Forms a stack
7) Marine erosion attacks base of stack so it collapses into a stump
