LITHOSPHERE CORE COASTLINES

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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.

LITHOSPHERE CORE COASTLINES

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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 !

LITHOSPHERE CORE COASTLINES

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Feature of Emergent coastlines

Raised beaches– sea bed rising above sea level

LITHOSPHERE CORE COASTLINES

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Features of an emergent coastline

LITHOSPHERE CORE COASTLINES

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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!

LITHOSPHERE CORE COASTLINES

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Raised beaches in Gruinard Bay

LITHOSPHERE CORE COASTLINES

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Features of submergent coastlines

Fiords – submerged glaciated valleys

Rias – submerged river valleys in hilly areas

LITHOSPHERE CORE COASTLINES

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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.

LITHOSPHERE CORE COASTLINES

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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.

LITHOSPHERE CORE COASTLINES

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Classic fiord scenery in Norway

LITHOSPHERE CORE COASTLINES

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A fiord in the Scottish Highlands

Loch Torridon

LITHOSPHERE CORE COASTLINES

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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

LITHOSPHERE CORE COASTLINES

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Note the width and the many tributaries.

Rias make excellent sheltered harbours.

LITHOSPHERE CORE COASTLINES

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The mouth of the R. Dart at Dartmouth

LITHOSPHERE CORE COASTLINES

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The ria mouth at Salcombe in Devon

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