Lithology + Coastal Recession

Question 1

Bedrock lithology

Answer 1

Physical properties of diff rocks = bedrock lithology
Existence = sedimentary, igneous, metamorphic rocks affect the rate of recession along a coastline

Question 2

Igneous rocks

Answer 2

Such as basalt + granite form from crystallisation of magma. More resistant 2 erosion + weathering
Because igneous rocks contain crystals which Inc the strength of the rocks + reduce the number of lines of weaknesses that would be exploited by physical processes
Igneous rocks can either be intrusive (formed from magma inside the Earth) or extrusive (formed when magma escaped through vents on the Earths surface)
Average rate of erosion of igneous rocks = 0.1-0.5cm per year

Question 3

Sedimentary rocks

Answer 3

Such as limestone + sandstone form from the build-up compacting + hardening of sediments into layers over time by lithification
Sedimentary rocks have been formed in a shorter geological time scale tend 2 be more susceptible to erosion + weathering + erode at a faster rate compared w/ those formed over a longer geological time
E.g. limestone + chalk
Average rate of erosion of sedimentary rocks = 2-6cm per yr

Question 4

Metamorphic rock

Answer 4

Such as slate + marble are formed from the change in the structure of sedimentary + igneous rocks caused by variations = heat + pressure
Process of change is referred to as the rocks having been metamorphosed
Marble = e.g. of a metamorphic rock that has been formed from changing structure of limestone caused by the re-crystallisation of calcite
Metamorphic rocks are resistant to erosion

Question 5

Vegetation

Answer 5

Important in supporting the development of sandy coastlines + plays an important role in the rate of coastal recession

Question 6

Sand dunes

Answer 6

Need a continuous supply of sand, powerful winds to transport sand + obstacles to trap the sand like plants
A typical sand dune transfer goes from the mobile dunes nearest the sea (embryo) to the fixed dunes nearest the backshore (grey dunes)
Sand dunes contain 2 types of plants:
- Xerophytes = withstand periods of dry weather
- Halophytes = withstand high concs of salt from sea water

Question 7

Vegetation succession on dunes

Answer 7

Typical plants that colonise embryo + foredunes are sea rocket + sea crouch. These plants have deep roots + can tolerate high conc of salt
Yellow dunes tend 2 be colonised by marram grass. These plants also have long deep roots + are salt tolerant
Heathers are commonly found = grey dunes because of higher rates = humus