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COASTLINES OF SEA-LEVEL CHANGE

COASTLINES OF SEA-LEVEL CHANGE. Over geological time, sea levels have risen and fallen many times, sometimes by hundreds of metres. These changes are often caused by glaciations locking up water that would otherwise have filled the oceans.

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COASTLINES OF SEA-LEVEL CHANGE

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  1. COASTLINES OF SEA-LEVEL CHANGE Over geological time, sea levels have risen and fallen many times, sometimes by hundreds of metres. These changes are often caused by glaciations locking up water that would otherwise have filled the oceans.

  2. Glacial ice is very heavy and weighs down the land. After the glaciation is over, the land slowly returns to its former height. This is known as ISOSTATIC RECOVERY. It is still going on in Scotland !

  3. Feature of Emergent coastlines Raised beaches– sea bed rising above sea level

  4. Features of an emergent coastline

  5. A raised beach is caused when the land rises after glaciation. The sea has created a beach, and maybe cliffs, that get lifted up above sea level. They are good sites for settlements, roads and farmland. There are three raised beaches here and one present one!

  6. Raised beaches in Gruinard Bay

  7. Features of submergent coastlines • Fiords – submerged glaciated valleys • Rias – submerged river valleys in hilly areas

  8. Fiords: glaciated valleys drowned by sea level rise Where glaciers were able to erode below sea level, subsequent sea level rises produced long, deep, narrow inlets of the sea with steep sides and hanging valleys.

  9. FIORDS are caused when a U-shaped, glacial valley reaches the sea and is flooded as the ice melts at the end of glaciation. They are very deep and make good harbours for very big ships. Ports are difficult to build because of the steep sides.

  10. Classic fiord scenery in Norway

  11. A fiord in the Scottish Highlands Loch Torridon

  12. Rias : drowned river valleys commonly found in SW England Sea level rise produces a wide tidal inlet which can extend far inland The mouths of rias can provide sheltered harbours e.g. Falmouth and Dartmouth

  13. Rias make excellent sheltered harbours. Note the width and the many tributaries.

  14. The mouth of the R. Dart at Dartmouth

  15. The ria mouth at Salcombe in Devon END

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