Coastal processes Flashcards
Coasts
What are spring tides?
Spring tides occur after a full moon, where the sun & the moon are alligned. This results in larger tides as the gravity of both the moon and the sun exacerbates eachother.
What are neap tides?
Neap tides occur when the sun and the moon are at a right angle to eachother. This results in moderate tides as the sun’s gravity cancells out the moon’s gravity.
What are currents?
Currents are the large scale movement of water in the oceans.
The thermohaline circulation is a process driven by the different ___________ in water, as _____ water, as well as ______ water, is denser. It moves ______ than currents. It affects ________ by moving hot water to different areas.
densities
cold
salty
slower
climate
List five types of mass movement.
1= Rockfall
2= Landslip/slump
3= Soil creep
4= Mudflow
5= Landslide
_________ is the sudden collapse and breaking away of rock fragments at a cliff face.
Rockfall
What is rockfall.
Rockfall is the sudden collapse and breaking away of rock fragments at a cliff face.
What is a landslip? (a.k.a slump)
Where soil / rock fall down a slide surface. It normally involves weak clay or sands.
What is soil creep?
It is very slow movement of soil downhill.
What is a landslide?
Rock moving rapidly downhill along a plane, often triggered by an earthquake.
What is mudflow?
Flow over unconsolidated material. It is often caused by instability due to wet conditions (link to flooding).
What is corrasion?
Corrasion is the launching of rocks against a cliff face, weakening it.
What is abrasion?
Abraison is the sandpapering effect of rocks against a coastline.
What is caviation?
Caviation is where bubbles of air are compressed resulting in cracks in a cliff.
What is hydraulic action?
Hydraulic action is where waves break against a cliff and forces itself into cracks.
What is wave quarrying?
Wave quarrying is where waves break against unconsolidated material and scoop out loose material.
What is attrition?
Attrition is the smoothing and reducing of angular rock into pebbles.
What is solution (corrosion)?
Soultion is where acids in seawater dissolve alkaline rock.
What is weathering?
Weathering is the breakdown of rocks in situ.
_________ weathering is the breakdown of rocks due to their interaction with air, water or acid.
Chemical
___________ weathering is where rocks are broken down by physcial factors in the environment.
Mechanical
__________ weathering is the breakdown of rocks by plants, animals and micro-organisms.
Biological
What is freeze-thaw?
This is where water continuously seeps into rocks and expands.
What is exfoliation?
This is where cracks develop parallel to the land surface and break off in ‘sheets’.
What is crystallisation?
This is where water goes into holes and evaporates, turning into crytsalls which expand the rock.
What is transportation?
Transportation is the process of eroded material being moved.
What are the four types of transportation?
1= Solution
2= Suspension
3= Saltation
4= Traction
What is solution (transportation)?
Solution is where substances that can dissolve are carried along in the water, such as Limestone.
What is suspension?
Suspension is where very fine material, such as silt and clay particles, is whipped up by turbulence and caried along in the water.
What is saltation?
Saltation is where larger particles, such as pebbles or gravel, are too heavy to be carried in suspension. Instead, the force of the water causes them to bounce along the sea bed.
What is traction?
Traction is where very large particles, e.g. boulders, are pushed along the sea bed by the force of the water.
Explain the process of longshore drift.
The transportation of sediment along the shore is known as longshore drift. The swash carries sediment up the beach parallel to the prevailing wind and the backwash carries is back down at a right angle to the shore. When the wind is not parallel, it moves sediment along the beach in a zig-zag pattern.
What is deposition and what are it’s two types?
Deposition is where material being transported is dropped on the coast. It can be marine or aeolian.
What is marine deposition?
Marine deposition is when sediment carried by seawater is deposited.
What is aeolian deposition?
Aeolian deposition is where sediment carried by wind is deposited.
What causes deposition to occur?
Deposition occurs when the sediment load exceeds the ability of the water and/or wind to carry it. This could be because the sediment load increases or the wind or water flow slows down.
What are two ways in which wind and water may slow down?
1= When waves enter shallow water or wind reaches land, friction increases slowing it down.
2= If wind or water encounters an obstacle, flow becomes rougher and the overall speed decreases.
What is the likely effect of the wind slowing down?
The wave height, speed and energy will decrease as well.
