Process Of Marnie and aeolian deposition

Question 1

Marnie deposition often takes place when?

Answer 1

Where waves are low energy or where rapid coastal erosion provides an abundant supply of material.

Question 2

The sea lays down what?

Answer 2

Material when there is a reduction in energy resulting from a decrease in velocity or volume or water.

Question 3

Situations where deposition occurs include?

Answer 3

When sand and shingle accumulate faster than they are removed.
As waves slow following breaking.
As water pauses at the top of the swash before backwash begins.
When water percolates into the beach material as backwash takes it back down the beach.

Question 4

What’s are aeolian processes?

Answer 4

They refer to the entertainment,transport, and deposition of sediment by wind.

Question 5

Why does wind play an important role in shaping the coastline.

Answer 5

It drives the prevailing winds that drives most waves. During the day the wind on the coastal fringe is generally from the sea.
Air moves in response to the small pressure differentials set up by the warmer land and colder air.

Question 6

What happens when there is a large tidal range?

Answer 6

Large amounts of sand may be exposed at low tide thus providing a supply of sediment to be entrained by the wind.

Question 7

What type of sediment is the most significant in terms of depositional features at the coast?

Answer 7

Sand-sized sediment

Question 8

Once entrained the sand is what?

Answer 8

Is generally transported close to the ground and over relatively short distances.

Question 9

Sand is transported by what?

Answer 9

By wind in two ways, which are depended on the wind speed and how dry or moist the source of sand is.

Question 10

What is soil creep?

Answer 10

A process similar to traction, where wind rolls or slides sand grains along the surface.

Question 11

What is saltation?

Answer 11

Where the wind is strong enough to temporarily lift the grains into the airflow to heights of up to one metre for distances up to 20 to 30m

Question 12

What are sub-aerial processes?

Answer 12

Land based processes which shape the coastline.

These come under heading of weathering and mass movement.

Question 13

What is sub-aerial weathering ?

Answer 13

Sub-aerial weathering included processes that slowly breakdown the coastline, weaken the underlying rocks and allow sudden movements or erosion to happen more easily.

Question 14

Material is broken down in what?

Answer 14

In situ, remaining in or near its original position.

Question 15

Weathering processes are common at the coast due to the presence of air and water and cycles of wetting and drying, and can be categories as what?

Answer 15

Mechanical/physical weathering
Biological weathering
Chemical weathering

Question 16

Mechanical/ physical weathering is what?

Answer 16

Processes that occur at coasts depend on the nature of the climate.

Question 17

What is biological weathering ?

Answer 17

Includes processes that lead to the breakdown of rocks by the action of vegetation and coastal organisms.

Question 18

What is chemical weathering ?

Answer 18

Is common on coastlines as it occurs where rocks are exposed to air and moisture so chemical processes can breakdown rocks.

Question 19

What is the main chemical process in chemical weathering ?

Answer 19

Solution is the main chemical process and was included in the above as it combines with erosion to produce many distinctive features.

Question 20

What is oxidation ?

Answer 20

Causes rocks to disintegrate when the oxygen dissolved in water reacts with some rock minerals, forming oxides and hydroxides.

Question 21

What does oxidation affect ?

Answer 21

Ferrous, iron-rich rocks, and is evident by a brownish or yellowish staining of the rock surface.

Question 22

What is hydration?

Answer 22

It makes rocks more susceptible to further chemical weathering, although it involves the physical addition of water to minerals in the rock.

Question 23

Hydration- what does the physical addition of water to minerals in he rock cause it do?

Answer 23

Causes rock to expand, creating stress, which can itself cause the rock to disintegrate. The process weakens the rock and can create cracks, or widen joints allowing further chemical weathering to occur.

Question 24

What is hydrolysis ?

Answer 24

Mildly acidic water reacts or combines with minerals in the rock to create clays and dissolvable salts; this itself degraded the rocks but both are likely to be weaker than the parent rock, thus making it more susceptible to further degradation.

Question 25

What is carbonation ?

Answer 25

Occurs where carbon dioxide dissolved in rainwater makes a weak carbonic acid. This reacts with the calcium carbonate in rocks like limestone and chalk to create calcium bicarbonate, which then easily dissolves in water.