Lithological factors of coasts

  • Structure- ‘the way the rocks are disposed or geologically arranged’

  • Lithology- ‘make up’ of each individual rock type

Lithological factors:

  • Mineral composition of rock

  • Solubility - more soluble rocks erode quicker e.g. chalk and limestone have calcium carbonate content that is soluble in saltwater - more weathering and erosion

  • Hardness - Harder more resistant rocks erode less e.g. granite which is a hard resistant rocks which is less susceptible to erosion and weathering

Structure of rock

  • How the rocks are put together including bedding planes, faults, folds, dips, joints

Types of rock:

  • Igneous rock is formed through the cooling and solidification of magma or lava. The magma can be derived from partial melts of existing rocks in either a planet's mantle or crust. Typically, the melting is caused by one or more of three processes: an increase in temperature, a decrease in pressure, or a change in composition. Solidification into rock occurs either below the surface as intrusive rocks or on the surface as extrusive rocks. These are generally hardest and most resistant to weathering.

  • Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles to settle in place. The particles that form a sedimentary rock are called sediment, and may be composed of geological detritus (minerals) or biological detritus (organic matter). These are generally the least resistant to weathering and erosion.

  • Metamorphic rocks started out as some other type of rock, but have been substantially changed from their original igneous, sedimentary, or earlier metamorphic form. Metamorphic rocks form when rocks are subjected to high heat, high pressure, hot mineral-rich fluids or, more commonly, some combination of these factors. These are usually as resistant or more resistant than igneous rocks.

  • A bedding plane is a line in rocks separating two different layers: one usually more resistant to erosion, one usually weaker. The layers, deposited horizontally millions of years ago as sediment on the sea bed, have often been tilted through earth movements (tectonics), creating an angle of dip.

  • Bedding Planes are weaknesses in the rock structure and for this reason makes the rock more susceptible to erosion and weathering and therefore more likely to create more erosive landforms such as retreating cliffs, caves, arches etc...