2.b. Coastal landforms are inter-related and together make up characteristic landscapes Flashcards
Case study of a low energy coastline- The Nile Delta- key facts about the Nile
- rates of fluvial deposition exceeded rates of marine erosion for over 3000 years
- length 6650km
- average rainfal 600mm a year
- widely accepted source Ethiopia
- seasonal monsoon rains contributer flow
Case study of a low energy coastline- The Nile Delta- what is sedimnt like
- low discharge but a huge amount of sediment
- 30% clay, 40% silt and 30% fine sand
- annual sediment yield 91.3 million tonnes
- low dischatge and low settling velocity significant factor in the development
The Northern part of the Delta that runs parallel to the coastline is called the coastal plain. This coastal plain is split into 3 things, what are they?
- foreshore plain- elongated, ridges parallel to the coastline
- frontal plane- located south of Foreshore plain with scattered limestone outcrops and clay deposits
- sandy zone- composed of a variety of different sand formation including dunes
Case study of a low energy coastline- The Nile Delta- why and how as the delta been managed
- the delta splits into distributaries at Cairo
- before consturction of Aswan Dam in 1964, the Nile’s annual flood covered delta
- deposits silty mud, 4m at Aswan
- wave action in Mediterranean redistributes sediment at front
- forms curved barrier bars and close off segments of the Meditteranean Sea
Case study of a low energy coastline- The Nile Delta- what changes to the sediment budget has the delta experienes
- since building of Aswan Dam, imbalance between erosion and accretion
- rapid reduction in sediment, from 120 million tonnes/year to only trace amounts today
- caused changes along shoreline and rates of coastal retreat as high as 148m/year
- rising sea levels of 1.2mm/year contributed to higher erosion
Case study of a low energy coastline- The Nile Delta- coastal landforms
- prevailing of northwestly winds over the Mediterranean sea enhanced eastward movement of sediment and water
- surface velocity of water highest in winter due to strong winds
- waves approach Nile Delta coastline from west, northwest and north 55-60% of the time
- led to formation of nearshore sand bars and beachs west of Abu Qir headland
- rip currents influence these landforms
- bars form shape of cresent, nearshore more parallel with coastline
Case study of a high energy coastline- Saltburn to Flamborough Head, Yorkshire- key facts
- coastline between Saltburn and Flamborough Head is a rocky, upland area
- 60km long
- receives high wave energy
Case study of a high energy coastline- Saltburn to Flamborough Head, Yorkshire- GEOLOGY
- the New York moors rise up to 400m above sea level so compromise sandstones, shales and limestones formed during Jurassic period
- Flamborough Head is at southern end. It is a large chalk headland and its cliffs are topped with till. Till is left behind from the Devensian glacial period
- differences in rock resistance mean the coastal scenery is varied
Case study of a high energy coastline- Saltburn to Flamborough Head, Yorkshire- energy
- dominant waves affect coastline from noth/north west. Have a fetch of over 1500km
- north facing are most exposed parts and recieve highest inputs of wave energy
- erosion rates due to variations in resistance of the different geologies
- areas of weak sale and clay experience erosion rates of 0.8m per year
- monitoring of wave height using buoys in Whitby Bay during 2010/11 revealed wave height exceeded 3m
- high energy inputs resonsible for longshore drift from noth to south
- sand/shing accumulate to form beaches in bays e.g. Filey bay
Case study of a high energy coastline- Saltburn to Flamborough Head, Yorkshire- sediment sources
- sub cell 1d
- some of the sediment has come from the nearshore area, driven onshore as sea levels rose at the end of the glacial period
- sediment is supplied by cliff erosion, including sandstone anc chalk from the resistant rock outcrops and boulder clay deposits
- the Esk supplied limited amounts of sediment because of weird/reiforced banks
- net increase of 9245m³ between 2008-2011. Winter storm systems with erosion were significant in the winter 2010-11
Case study of a high energy coastline- Saltburn to Flamborough Head, Yorkshire- headlands and bays
- formed due to variations in rock type
- clay flanked by more resistant limestone and chalk
- prominent headland at Flamborough is formed of chalk with deep bays either side formed from clay
Case study of a high energy coastline- Saltburn to Flamborough Head, Yorkshire- landforms on headlands
- because of wave refraction, wave energy is concentrated on resistant headlands that lean out to the North Sea
- weak landforms e.g. joints are exokiited by the erosion action of waves, causing them to turn into caves and arches
- over 50 geos formed along coastline
- blowholes developed where vertical master joints in the chalk have been enlarged
- chalk and boulder clay have collapsed into underlying sea caves
Case study of a high energy coastline- Saltburn to Flamborough Head, Yorkshire- cliffs
- sedimentary rocks horizontal- causes cliff profiles to have a vertical face
- most cliffs have layer of weak glacil till
- cliffs strong due to being made of chalk, a tighly bonded material
- vertical cliffs normally 20-30m high with the till being lowered due to mass movement
- Saltburn cliffs higher with varied geology
- steeper stones formed with more resistant sandstones and limestones
Case study of a high energy coastline- Saltburn to Flamborough Head, Yorkshire- beaches
- not many beaches
- Scarborough is a sheltered low energy environment along the coastline
- deposits of sand and shingle that collect slowly with low input from sediment in rivers
- high energy waves remove sediment before they can collect
- no longshore dift due to high tidal range and lack of spits and drift alligned features
