1b - Coastal landscape systems are influenced by a range of physical factors

Question 1

Winds

Answer 1

• source of energy for coastal erosion and sediment transport = wave action
• Wave energy (kinetic energy) = generated by frictional drag
• Longer fetch = larger the waves
• Aeolian processes contribute the shape of the coast landscapes - wind can carry out erosion, transportation and deposition
• Causes longshore drift as sand builds up the beach at an angle accumulating at one end

Question 2

Waves:

Answer 2

• Destructive waves - more in winter, happen less often, they have a strong backwash but erodes the beach making it smaller
• Constructive waves - more in summer, they are gentle waves that build up the beach due to a strong swash energy so sediment is deposited
• Wave significance - The weather and seasons, prevailing winds caused stronger waves due to destructive waves causing more erosion and a greater impact on coastal landscapes
• waves start out at sea and have a circular orbit —> waves approaching shore slow down at the base —> orbit then becomes more elliptical until the wave breaks over (friction as sea bed gets shallow, wave breaks and water is removed)—> water then moves up the beach (swash) —> speed falls, uphill gradient until no more energy = backwash

Question 3

Tides:

Answer 3

• tides are the periodic rise and fall of the sea surface
• When the sun moon and earth are aligned the gravitational pull is at its strongest, this means spring tides with high tidal range (happens twice each lunar month = spring tides with higher tidal range)
• moon pulls water towards it = high tide and compensatory bulge on opposite side of earth - between 2 bulges = low tide
• as moon obits the high tide follows
• The sun and the moon at 90° means gravitational pull is the weakest this means neap tides with low range
• Tides determine The position at which waves break on a Beach, also range of wave action that can occur
• Big tidal range means the tides move so fast waves rarely hit the same place = less erosion = deposition is main sediment output
• Small tidal range means waves hit the same spot = more erosion

Question 4

Geology:

Answer 4

• Strength of the rocks determine the rate of erosion which can create headlands and bays
• The cliff equals hard rock and the Bay in Beach Inlet equals soft rock
• Jointing (limestone and chalk) can cause more erosion which leads to the formation of Arches stumps and stocks
• Significance - Constant means more significant as it determines the rate that wind and waves erode
• 2 key aspects = lithology and structure

Lithology:

• its physical and chemical composition of rocks
• weak lithology eg clay = increased erosion due to weak bonds between particles that make up rock
• strong lithology = strong bonds = forms prominent coastal landscapes eg steep cliffs
• chalk and carboniferous limestone = composed of calcium carbonate = soluble in weak acids = vulnerable to chemical weathering

Structure:

• properties of rock - jointing, bedding and faulting and permeability of rocks
• porous rocks eg chalk pores separate mineral particles, these pores can absorb = permeable
• carboniferous limestone - water seeps into its joints and joints are enlarged (secondary) permeability
• rock outcrops - parallel to coast = concordant coastline
• rock lie 90 degrees to coast = discordant coastline

Question 5

Ocean currents:

Answer 5

• ocean currents are large scale phenomena that are generated by convection from the Earth’s rotation
• currents can either be local currents such as rip currents or tidal currents
• or much larger ocean currents such as the North Atlantic Drift
• Rip currents are output because they drag sediment away
• Rip Currents have an important role in transporting sediment. they are caused by tidal motion or waves breaking at right angle to shore
• Current strength = heat energy = air temp = sub aerial processes like freeze thaw/weathering
• Significance - little, no power - small fetch
• warm ocean currents = transfer heat energy from low latitudes towards poles (affect western facing coastal areas) - driven by onshore winds
• cold ocean currents = transfer cold water from polar regions towards equator - driven by offshore winds = reduced influence on coastal landscapes