Coastlines 1 Flashcards
Berm
Terrace of a beach formed in the backshore above the high tide water level. Common on accredting beaches.
Lagoon
Body of water separated from the ocean by a natual barrier
Spit
Formed where the prevailing wind blows at an angle to the coastline resulting in longshore drift
Headland
Coastal landform, point of land usually high with sheer drop that extends into teh ocean.
Tombola
Spit that connects the mainland to an island.
Wave cut platform
Narrow flat area often found at the base of a sea cliff.
Cliff
Mass rock that rises very high and vertical from the ocean.
Storm bar
Sand bar formed by storms and progressive breaking and reforming of waves as they approach the beach.
Erosion Scarp
Line of cliffs that has been formed by erosion.
How are coastlines shaped
Tectonic plate movements
Shifts in climate patters and sea levels
Weather patterns
Movement of sediments and water (waves, currents, storms)
What causes tidal movements
Gravitational lpull
Current strength
Wave action
Define sand budget
Coastal management tool used to analyse and describe the different sediment inputs (sources) and outputs (sinks) on the coasts to predict change in a coastline over time.
Define longshore drift
Geological process that consists of the transportation of sediments (clay, silt, sand and shingle) along a coast parallel to the shoreline.
What causes longshore drift
Caused by wind, along with wave refraction can set up currents running parallel with the beach.
Define refraction
Waves slow down and change direction in shallower water near the coast due to interaction with the seabed
Define reflection
Waves bound back where there is a steep cliff or seawall
Define diffraction
Waves bend when they get to a barrier such as an offshore rock or opening to a harbour
Describe the processes of coastal erosion
HYDRAULIC ACTION - impact by wind, water on cliff face
CORROSION - cliffs erode as a result of weak acids in the sea.
ATTRITION - waves cause rick pieces to collide and grind down
SOLUTION - acids in sea water dissolve some types of rick
ABRASION - also known as corrasion when waves break on cliff faces and erode it.
CORROSION - clemical weather when seas ph is below pH 7.0 and corrode rocks.
Characteristics of Accreting beach with constructive waves
Wider
Gentle slope
Microridges
Possible berm
Characteristics of Eroding beach with destructive waves
Steep and hard
Black minerals appearing
Erosion scarp may be visible
3 types of waves
Swell
Breakers
Tsunami
Types of Breakers
Spilling waves - crumble from top on shallow beaches. Glentle waves
Plunging waves - throw from the top where bottom rises sharply. High energy, fast waves.
Surging waves - break from the full face as deep swells meet a cliff or rock. Strong backwash.
Collpsing waves - blend of plunging and surging waves causing lots of whitewater
How do groynes prevent coastal erosion?
Acts as a physical barrier to interrupt wave action and protect the beach from being washed away by longshore drift. The Groyne traps the sediment and material being moved by longshore drift.
Groyne
Built perpendicular to the shore is a rigid structure built from the ocean shore or bank that interrupts water flow and limits the movement of sediment or sand.
Difference between a spit and tombolo
Tombolo is when a spit connects the mainland to an island
Spit is not connected to an island
Both formed by longshore drift or a river estuary depositing sand.
