Transcript Coastal Map Reading

Coastal Map Reading
Higher Geography
Describing a coastline - checklist
• Direction of trend of coastline: e.g. east / west, north / south
• Shape of coastline: e.g smooth, with long beaches?;
irregular, with bays and headlands?
• Type of coastline: Fjord?, Ria?, concordant / discordant?
• Width and type of shore: e.g. bare rock, mud, sand, shingle? Narrow
or wide shore (use scale on map).
• Height and steepness of coast: number of contours?; cliff or steep
slope symbols?; spot heights near coast?
• Distinctive landforms: e.g. erosional features such as stacks, caves,
headlands?; depositional features such as spits, bars, tombolos?
Conditions and Processes
• An exam question may ask about the conditions and processes
which influence coastal landscapes: these are often badly answered.
• Conditions include (i) the geology of the area: hard and softer rocks
will erode at different rates, leading to the development of different
features and coastlines. Do you know what concordant and
discordant coastlines are?
(ii) the fetch and common weather and sea conditions are also
important. Remember the fetch is the distance of open water over
which wind blows. The longer the fetch, the stronger the winds and
the longer they blow, the greater the erosion – and also the greater
the action of longshore drift.
(iii) the depth of the water is also relevant. Deep water tends to
have more powerful wave action, so more erosion: shallow water
areas more deposition.
• Processes are the processes of erosion (i.e. Hydraulic Action,
Corrasion, Corrosion and Attrition) and deposition (Longshore Drift)
Coastlines of Erosion
Durdle Door (arch) and Lulworth Cove (bay) – two
major landscape features of the Dorset coastline.
What other erosion features can you see?
The arch of
Durdle Door
Discordant
coastline –
erosion and
deposition
features,
formed due to
differences in
geology
Concordant coastline mostly erosion features
Old Harry and Old Harry’s Wife – sea stacks on the Dorset coast.
Longshore Drift, Groynes and Barton on Sea (Barton in Sea?)
Longshore drift is moving sediment west to east. The groynes
built to the west of Barton have starved its beach of sand and
the unprotected soft coastal rocks have been easily eroded by
the waves, often during periods of heavy rain.
Waves hammer the soft rocks of the unprotected coast at Barton on Sea
Rotational slumping of the coast at Barton on Sea
The Old Man of Hoy, Britain’s tallest sea stack
Coastlines of Deposition
Chesil Beach, in
Dorset (South Coast
of England). A
classic example of a
spit, created by
longshore drift from
the north west.
Spurn Head, a famous
spit on the east coast
of England. Longshore
drift direction is from
the north.
Tombolo, linking St
Ninian’s Isle with the
Shetland mainland.
Types of Coastline
• Ria coasts:
River estuaries submerged
by rising sea level
• Fjord coasts: Glaciated river estuaries
submerged by rising
sea levels.
A ria (an unglaciated river estuary, drowned by
rising sea levels) - on the Isle of Wight
Sydney Harbour – a ria (drowned river estuary)
Fjord coastline in the west of Scotland
(Fjord – a glaciated valley that has
been drowned by rising sea level).
High, steep-sided and very deep – Norwegian fjords.