Coastal Recession
- Coastal recession is the retreat of the coastline inland, this may be due to:
- Erosion
- Sea level rise
- Submergence
- Where coastal recession is the result of erosion, this is dependent on the lithology of the coast
- Mineral composition
- Rock classification
- Structure
Mineral composition
- Some minerals are more reactive than others
- This affects the rate of chemical weathering for example:
- Calcite is reactive and so easily chemically weathered
- Quartz is not reactive (inert) so chemical weathering is much slower
- This affects the rate of chemical weathering for example:
Rock classification
- Sedimentary rocks form as a result of compaction and cementation of sediment called lithification
- Examples of sedimentary rocks include shales, sandstone, and limestone
- Sedimentary rocks:
- Erode and weather more rapidly than other types of rock
- Form in layers
- Have weak bedding planes
- They are clastic which means they are made of clasts (sediment particles)
- Are heavily jointed
- Often have many bedding planes and fractures
- Metamorphic rocks form when sedimentary and igneous rocks are altered through heat and pressure, but do not melt in the process
- Examples of metamorphic rocks include slate and marble
- Metamorphic rocks:
- Have a crystalline structure
- Are often folded and faulted
- Are more resistant than sedimentary rock and less resistant than igneous rocks
- The crystals have a parallel arrangement (foliation) which means they are weaker than igneous rocks
- Igneous rocks form when molten rock from the Earth's mantle cools and hardens
- Examples of igneous rocks include granite and basalt
- Igneous rocks:
- Erode and weather very slowly
- Can be categorised into two types:
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- Intrusive igneous rock - forms within the ground, cools slowly, and has large course crystals
- Extrusive igneous rock - forms on the Earth's surface, and cools quickly, forming smaller crystals
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- Has interlocking crystals
- Fewer joints and weaknesses than in other rocks