1. 1. Formation of Distinctive Landforms
1.1. Erosional
1.1.1. Cliffs
1.1.1.1. Wave Cut Notch
1.1.1.1.1. When destructuve waves break repedetly on relatively steep sloping coastlines undercutting can occur between high and low tide levels forming a wave cut notch
1.1.1.2. Strata
1.1.1.2.1. Horizontally bedded strata
1.1.1.2.2. Landward dipping strata
1.1.1.2.3. Seaward dipping strata
1.1.2. Shore Platforms
1.1.2.1. Weathering like freezethaw and hydrolysis weakens the top of a cliff
1.1.2.1.1. At the high tide levels erosional forces create wave cut notch
1.1.3. Bays and Headlands
1.1.3.1. Occur along discordant coastlines where weak lithology rocks retreat at an increased rate
1.1.3.1.1. The retreat is caused by sub aerial processes such as freezethaw weathering and hydrolysis which weaken the structure and chemistry of the rock
1.1.3.2. Erosional forces such as hydraulic action and abrasion remove sediment and create wave cut notches atr the base of the cliff
1.1.3.2.1. The sections of rock more resistent form headlands either side of bay
1.1.3.3. Wave refraction and orthogonals
1.1.3.3.1. As bay retreats it increases orthogonal wave refraction where energy is concentrated at the headland
1.1.4. Blowholes and Geos
1.1.4.1. Occasional splashing of the waves against the roof of a cave may enlarge joints when compressed air is trapped inside as part of hydrulic action
1.1.4.1.1. A natural shaft is thus formed which may eventually pierce through to the surface
1.1.4.2. The enlargement of blow holes and continued action of wave pound and hydraulic action weakens the cave roof
1.1.4.2.1. When the roof collapses a long narrow inlet or creek develops
1.1.5. Caves Arches, Stacks and Stumps
1.1.5.1. Due to wave refraction energy is concentrated on the sides of headlands, with joints in the sides of the headland exposed to erosion processes like hydraulic action
1.1.5.1.1. This develops a small cave on the side of the headland, if a cav enelarges to such an extent that it opens up on the other side of the headland, and arch is formed
1.1.5.2. Continued abrasion, hydraulic action widens the arch, while weathering (freezethaw) may cause the arch roof to collapse leaving a stack
1.1.5.2.1. Further erosion at the base of the stack may cause further collapse, forming a stump
1.2. Depositional
1.2.1. Beaches
1.2.1.1. Formation of a beach
1.2.1.1.1. Beaches are made up from eroded material that has been transported via longshore drift from elsewhere
1.2.1.1.2. Accumulation of material deposited between lowest tides and highest storm waves results in accretion of the beach
1.2.1.2. Shingle Beaches
1.2.1.2.1. Rocky, cobble pebble beaches, typically have a steep gradient of over 10 degrees
1.2.1.2.2. Often form where cliffs are being eroded, and where there are higher energy waves
1.2.1.3. Sandy Beaches
1.2.1.3.1. Typically flatter and wider as the smaller particles are evenly distributed, sloping at around 5 degrees
1.2.1.3.2. Typically form in bays where water is shallower and the waves have less energy
1.2.1.4. Features
1.2.1.4.1. Ridges and Runnels
1.2.1.4.2. Berm
1.2.1.4.3. Cusp
1.2.2. Deltas
1.2.2.1. Formation
1.2.2.1.1. Rivers spread out and slow down as they approach sea
1.2.2.2. Types include Cuspate, arcuate, birds foot
1.2.2.2.1. Form in low energy environments, with rivers carrying significant sediment load and a low tidal range
1.2.2.3. Upper Delta Plain
1.2.2.3.1. Levees
1.2.2.4. Lower Delta Plain
1.2.2.4.1. Where you find distributaires and crevasse splays
1.2.2.5. Submerged delta plain
1.2.3. Salt Marshes
1.2.3.1. Salt Marshes are vegetated areas of deposited silts and clays that occur on shores between the highest and lowest tide
1.2.3.1.1. Found in low energy environments like estuaries
1.2.3.2. Factors that affect the formation of salt marshes
1.2.3.2.1. Sediment supply
1.2.3.2.2. Weather
1.2.3.2.3. Wave frequency and type
1.2.3.2.4. Concentration of salt
1.2.3.3. Formation of a saltmarsh and its features
1.2.3.3.1. Preconditions for a salt marsh to form
1.2.3.3.2. Flocculation
1.2.3.3.3. Primary succession
1.2.3.3.4. Once established the salt tolerant plant species trap sediment and increase the height of the salt marsh
1.2.3.4. Definitions
1.2.3.4.1. A salt pan is a flat area of ground covered with salt deposited by the deposition of evaporated saline water
1.2.3.4.2. A halophyte is a plant adapted to growing in saline conditions
2. 2. Influence of flows of energy on geomorphic processes
2.1. Erosion and Mass Movement
2.1.1. Wave Processes
2.1.1.1. Abrasion, Attrition, hydraulic action
2.1.1.1.1. Transported by soluition, suspension, traction and saltation
2.1.1.2. Physical factors influencing process
2.1.1.2.1. Wave velocity, Shape of coastline, tidal range and geology
2.1.2. Fluvial Processes
2.1.2.1. Similar erosional processes to waves, with sediment derived from weathering and material from valley sides
2.1.2.1.1. Transported by the same ways as waves
2.1.2.2. Physical factors influencing process
2.1.2.2.1. River Profile, river velocity
2.1.3. Aeolian Processes
2.1.3.1. Pick up sand particles by deflation and erodes by abrasion. Attrition based erosion is also effective as particles tend to travel further distances
2.1.3.1.1. Air can transport material in the same ways as wave processes, like saltation, or traction (surface creep)
2.1.3.2. Physical factors influencing process
2.1.3.2.1. Wind speed and geography of landscape (more obstacles hence surface friction)
2.2. Weathering
2.2.1. Physical weathering
2.2.1.1. Freezethaw
2.2.1.1.1. Water enters cracks and expands splitting rocks
2.2.1.2. Thermal expansion
2.2.1.2.1. Rocks expand when heated and contract when cooled
2.2.1.3. Physical factors that influence process
2.2.1.3.1. Degree of rock fracturing (more cracks more weathering), frequency of frosts, temperature and environment
2.2.1.4. Influences the system more than chemical weathering as physical weathering actually breaks off chunks of rock
2.2.2. Chemical weathering
2.2.2.1. Oxidation, carbonation, solution, hydrolysis, hydration
2.2.2.1.1. Carbonation is where rainwater combines with co2 in the atmosphere to produce a carbonic acid reacting with limestones calcium carbonate which is soluble
2.2.2.2. Physical factors that influence the process
2.2.2.2.1. Rock porosity , temperature (10 degree warmer temps result in a 2.5 times increase in rate of reaction)
2.2.2.3. Doesnt add sediment to the system, as the rock often dissolves as a result of chemical weathering
2.2.3. Biological weathering
2.2.3.1. Tree roots growing into cracks and exerting outward pressure
2.2.3.2. Organic acids produced in decomposition of plant and animal litter makes soil more acidic and react with minerals
2.2.3.3. Physical factors that influence this process
2.2.3.3.1. Soil cultivation may change the composition of the soil and the entry of organisms
2.2.3.4. Leads to mass movement processes so increases sediment in the system
3. 3. High Energy Coastline Case Study (North Yorkshire coast - Saltburn to flamborough head)
3.1. High energy Coastline
3.1.1. Wave heights range from 0.2m - 3.5m on average
3.1.1.1. North west dominant wave direction
3.1.1.1.1. 1500km fetch (large!)
3.1.1.2. 6-8 waves per minute on the Flamborough head coastline
3.1.1.2.1. Erosion rate of clay at 0.8m and limestone 0.1m a year
3.1.2. Stacks are found isolated at the end of headlands
3.1.2.1. Rainfall averages 40mm a month
3.1.2.2. Cliffs between Saltburn and Robin Hood's Bay are higher with a stepped profile
3.1.2.2.1. These areas are north facing and exposed to high energy waves
3.2. Sources of sediment
3.2.1. Sediment Cell 1D
3.2.1.1. Sediment has been driven onshore as sea level rose at the end of the last ice age
3.2.1.1.1. Sediment is also supplied by cliff erosion, sandstone, liemstone and boulder clay
3.2.1.2. River Esk supplies a limited amount f sediment due to the construction of weirs and reinforced banks
3.2.1.2.1. Saltburn has experienced a net increase in beach sediment of 9245m3 between 2008 and 2011 while filey bay has experienced erosion
3.2.2. Geology
3.2.2.1. Mudstones
3.2.2.1.1. Weka lithology, vulnerable to hydraulic action, pounding and abrasion
3.2.2.2. Clay
3.2.2.2.1. Weak lithology vulnerable also to abrasion, hydraulic action and pounding
3.2.2.3. Limestones
3.2.2.3.1. Vulnerable to weathering, carbonation and solution
3.2.2.4. Sandstone
3.2.2.4.1. More resistant to geomorphic processes, providing larger sediment
3.3. Erosional Landforms as a result of Physical factors
3.3.1. Headlands and Bays (geology)
3.3.1.1. Disconcordant coastline leading to variations in headlands and bays
3.3.1.1.1. Selwicks Bay
3.3.1.2. Geos and Blowholes (50 Found across the coastline)
3.3.1.2.1. Blowholes are formed when major joints in the chalk enlarge
3.3.2. Shore Platforms (waves)
3.3.2.1. Shoreline Platforms
3.3.2.1.1. Shore platform has formed at robin hoods bay
3.3.3. Beaches (waves)
3.3.3.1. Very few well developed beaches only really found in sheltered low energy environments
3.3.3.1.1. Because of low input of sediment from rivers and slow rate of erosion from the resistant rocks on the coastline
3.3.4. Cliffs (geology)
3.3.4.1. Cliffs made of strong chalk, tightly bonded mineral particles, about 20-30 metres high
3.3.4.1.1. Geologically the cliffs are horizontally bedded with a vertical face overlain by weak glacial till
3.3.4.1.2. Cliffs between saltburn and robin hoods bay
3.4. Changes over time
3.4.1. Short Period of time
3.4.1.1. Limestone present, leads to lots of joints and cracks and then blowholes/geo's
3.4.1.1.1. Hard rock erodes about 10cm a year
3.4.1.2. Mass movement
3.4.1.2.1. Soft coastline like at Filey Bay rotational slumping ofent occurs
3.4.2. Long Period of time
3.4.2.1. Lack of formation of depositional landforms like spits, tombolos and bars
3.4.2.1.1. Due to the high energy environment and low sediment accumulation
3.4.2.2. Formation of bays and headlands
3.4.2.2.1. Leading to the development of erosive landforms like caves, stacks and stumps
3.4.3. Human influences
3.4.3.1. For example pakiri beach
3.5. Interrelationships
3.5.1. Tidal range
3.5.1.1. High Tidal range
3.5.1.1.1. Marine processes attack larger area
3.5.2. Wave refraction
3.5.2.1. Orthogonal wave refraction focusses energy on the headlands
3.5.2.1.1. Increases rates of erosion and sediment input
3.5.3. Prevailing Wind
3.5.3.1. Long Fetch of 1500km leads to more erosional landforms
3.5.4. Limestone cliffs
3.5.4.1. The strong structural integrity of these structures leads to geos and blowholes forming
3.5.4.1.1. As it has lots of joints and cracks and a complex structure
3.5.4.2. Cliff retreat and wave cut platforms
3.5.4.2.1. Wave cut platforms rely on cliff retreat for their formation, like robinhoods bay 500m wide platform
4. 4. Low Energy Coastline Case Study (Nile)
4.1. Low Energy Coastline
4.1.1. Waves are not as powerful
4.1.1.1. Rate of depsoition exceeds rate of erosion
4.1.1.1.1. Characteristic landforms indlucde beaches and spits
4.1.2. Nile Facts
4.1.2.1. 6650KM in length
4.1.2.1.1. Nile catchment area is about 3 million KM2
4.1.2.1.2. Average nile discharge is 86 billion m3 a year
4.2. Change to the Sediment Budget
4.2.1. Aswan High Dam (1964)
4.2.1.1. Reduced the nile discharge resulting in increased coastal erosion along the delta
4.2.1.1.1. Resulted in rapid reduction of sediment accretion, increasing erosion rates across the delta, for example in the north west of the delta erosion rates have hit 150 centimetres a year
4.2.1.2. The Aswan high Dam was designed without sluice gates meaning its trap efficiency is 98%
4.2.1.2.1. The only sediments to travel through it are fine silts and clays
4.2.2. Sea Level Rise
4.2.2.1. In the past century sea level of mediterranean has risen by 10 to 15 cm
4.2.2.1.1. As a result of eustatic changes like melting of sea and land ice
4.3. Change to the Delta itself overtime
4.3.1. Long Term
4.3.1.1. Delta is eroding faster than forming
4.3.1.1.1. Delta and drift aligned beaches disappearing over the course of the next thousands of years
4.3.1.2. Distributries lessening, there was 7 now 2
4.3.1.2.1. less inputs and less sediment accretion
4.3.1.3. Sea Level Rise
4.3.1.3.1. In the past century sea level of mediterranean has risen by 10 to 15 cm
4.3.2. Short Term
4.3.2.1. Crescentic sand bars form in minutes and change quickly because of rip currents
4.3.2.2. Seasonal events
4.3.2.2.1. Winter winds higher, more erosion and vice versa with summer
4.3.2.3. Natural fluctuations in rainfall in Ethiopian highlands has reduced sediment load of nile
4.3.3. Human influences
4.3.3.1. With the Aswan high dam already capturing 98% and depositing it in lake Nasser there is even less accretion of nile delta
4.3.3.1.1. More erosion as there is less sediment input and sea level rise is causing marine processes to attack more of the cliff
4.3.3.2. Pakiri beach for example
4.4. Influence of Physical Factors on Landforms
4.4.1. Tide
4.4.1.1. Low tidal range in the mediterranean allows for depositional processes to dominate allowing for accretion and extension of delta
4.4.1.1.1. Mostly associated with the fact that the mediterranean has a very narrow inlet into the atlantic
4.4.1.2. Significant
4.4.1.2.1. Diurnal tides with low tidal range leads to deposition and accretion of delta
4.4.2. Winds
4.4.2.1. SE direction forms drift aligned beaches
4.4.2.1.1. Modification of the delta fron reuslting in the formation of spirts and bars as a result of longshore drift
4.4.2.2. Wind
4.4.2.2.1. Very significant
4.4.3. Geology
4.4.3.1. Less Significant
4.4.3.1.1. Limestone ridges to the west of Alexandria result in formation of headlands (Abu Qir) and bays
4.4.4. Waves
4.4.4.1. Very Significant
4.4.4.1.1. Higher energy waves in winter cause greater erosion
4.5. Depositional Landforms as a result of physical factors
4.5.1. Rosetta and Damietta Deltaic Lobe (Tidal and fluvial)
4.5.1.1. A river moves more slowly as it nears the mouth or end
4.5.1.1.1. This causes sediment, solid material carried downstream by currents to fall into the river bottom
4.5.1.2. The low tidal range in the med allows for depositional processes to dominate, allowing accretion and the extension of the delta
4.5.1.2.1. High tidal ranges are too strong for deltas to form
4.5.1.3. Erosion rates have increased eight fold in the rosetta lobe after 1970 construction of Aswan high dam
4.5.2. Abu Qir Headland and Bay (Geology)
4.5.2.1. Near alexandria, is composed of limestone ridge which has a more resistant lithology and lower rates of retreat
4.5.2.1.1. To the west the bay is composeed of alluvium, which is less resistant to erosion
4.5.3. Lake Edku Lagoon and Burullus lagoon (waves)
4.5.3.1. Longshore drift moving sediment eastward, spit forms which grew until it reached the other side of the bay forming a bar
4.5.3.1.1. This then resulted in gradual evaporation reducing its size
4.5.4. Burullus Sand Dunes (Wind)
4.5.4.1. Prevalence of SE winds enhances the eastward movement of sediment, which carries sediment onto the mound shaped dunes
4.6. Interrelationships
4.6.1. Roestta promontory
4.6.1.1. Longshore drift and ocean currents carry eroded sediment to the east leading to deposition and the formation of spits and bars across burullus lagoon
4.6.1.1.1. Promontories provide shelter and low energy environment
4.6.1.2. Forms as a result of deposition where the nile enters meditteranean
4.6.2. Burullus lagoon
4.6.2.1. The bar prevents access to the sea, so evaporation effects dominate the equilibrium and the lagoon shrinks
4.6.3. Gamasca
4.6.3.1. Increased deposition in Gamasca due to aeolian transport and deposition due to the promontories providing a sheltered bay
4.6.4. Dune systems
4.6.4.1. Onshore winds blow sediment inland and develop the dunes