MARS2014 Lecture Notes - Lecture 2: Euryhaline, Estuary, Tidal Power
Unit 2: Coastal Ecosystems
1. What are the two types of coasts?
o Erosional
o Depositional
2. What is an erosional coast?
o Waves take stuff away
o Usually rocky
o Coasts that are attacked and shaped by waves
o Generally in SA/WA/VIC (lower half of Australia)
o Make up 40% of Australian coasts
3. What is a depositional coast?
o Waves deposit new stuff
o A groig coast
o Made up of sediment deposition or biological growth
4. What are the three types of depositional coasts?
o Beaches
o River deltas
o Estuaries
5. Beaches
o What are they?
▪ Highly dynamic
▪ Waves push sediment (or swash) onto beaches
▪ Sediment is dragged off by backwash
▪ In winter/storm season, often backwash is greater than swash (beach
retreats and creates sandbars), and in summer/fine season swash is often
greater than backwash (beach grows)
▪ There is a large range of sediment sizes, from pebbles to fine grains
▪ Higher energy coasts have larger sediments
▪ Lower energy usually results in flatter beaches and finer sediments
o What kind of ecosystem do they support?
▪ Beaches provide an environment for plants and animals, but usually this life
is based on the detritus cycle
o What kinds of beaches are there in Australia?
▪ Wave-dominated
▪ Tide-dominated
▪ Tide-modified
o What are wave-dominated beaches?
▪ At south of Australia
▪ Roaring 40s
▪ Huge waves
▪ Unprotected from waves, with small tides
o What are tide-dominated beaches?
▪ At north of Australia (protected from waves, high tides)
▪ The springtide (highest tide) is less than 10x the height of an average wave
▪ (tide dominates wave, not beach)
o What are tide-modified beaches?
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