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

What other erosion features can you see? 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

Concordant coastline - mostly erosion features 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) 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 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.