P1B 13Advancing and Retreating Coastlines

Front

What are advancing and retreating coastlines?

Back

Advancing coastlines occur when the sea moves further away from the land, while retreating coastlines occur when the sea moves inland and floods low-lying land.

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What are eustatic changes?

Back

Eustatic changes refer to worldwide shifts in the actual volume of water in the oceans.

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What causes eustatic drop?

Back

During an Ice Age, most precipitation falls as snow and gets locked up in ice sheets and glaciers, reducing water in oceans. Ocean temperature decrease also causes water to contract, decreasing ocean volume.

Front

What causes eustatic rise?

Back

After an Ice Age, glaciers and ice sheets melt, increasing ocean volume. Thermal expansion of warmer water also contributes to rising sea levels.

Front

What are isostatic changes?

Back

Isostatic changes relate to vertical land movement, often due to the weight of ice during an Ice Age or tectonic forces.

Front

What causes isostatic change during and after an Ice Age?

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During an Ice Age, ice sheets push the Earth's crust downward (crustal subsidence). After an Ice Age, as ice melts, the land rises back up (isostatic rebound).

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What are landforms created by advancing coastlines?

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Advancing coasts can result in emergent coastlines with features like raised beaches and relict cliffs.

Front

What are raised beaches?

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Raised beaches are former beaches now above current sea level, often formed by isostatic rebound or global sea level drop.

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What are relict cliffs?

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Relict cliffs are old cliffs located inland, formed when sea levels were higher and waves eroded the land. They may have caves and notches.

Front

What causes coastlines to retreat?

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Rising sea levels (eustatic change) and falling land levels (isostatic change) cause coastlines to retreat.