2b.3 Rates of coastal recession and stability depend on lithology and other factors. Flashcards
What is lithology?
Rock type
Lithology determines the physical and chemical properties of rocks, affecting erosion and weathering processes.
What are reactive minerals that can be easily broken down by chemical weathering?
Calcite in limestone
Reactive minerals are more susceptible to chemical weathering, leading to faster erosion rates.
What are examples of inert minerals that weather slowly?
Quartz in sandstone
Inert minerals resist chemical weathering, contributing to slower erosion rates.
What are sedimentary rocks?
Conglomerates, sandstones, limestones, clays
Sedimentary rocks are clastic, made of cemented sediment particles.
What term describes sedimentary rocks with very weak cementation?
Unconsolidated
Unconsolidated sediments are more easily eroded than consolidated rocks.
How fast does boulder clay erode?
1 m p.a.
Boulder clay is highly unconsolidated and erodes rapidly.
What is the rate of recession influenced by?
Bedrock lithology, geology of unconsolidated sediment, reactivity of minerals, clastic vs. crystalline structure, presence of cracks and fissures
These factors determine how susceptible rocks are to weathering and erosion.
What defines igneous rocks?
Formed from solidified lava or magma
Examples include granite, dolerite, basalt, and pumice.
What is the erosion rate of metamorphic coasts?
0.1-0.3 cm p.a.
Metamorphic rocks are formed through heat and pressure, making them relatively resistant.
What is sedimentary rock formed from?
Compaction and cementation of deposited material
This process involves fragments of other rocks or organic matter.
What are examples of unconsolidated sediment?
Fluvial alluvium, glacial boulder clay, aeolian loess
These sediments are easily eroded and have high recession rates.
What are complex cliff profiles produced by?
Differential erosion of alternating strata
This occurs in cliffs with varying lithology and resistance.
How do permeable rocks affect erosion?
They allow water to flow through, increasing susceptibility to weathering
Examples include chalk and sandstones.
What happens when groundwater accumulates in a permeable layer above an impermeable stratum?
A spring forms on the cliff face
This can lead to erosion of the cliff profile.
What does pore water pressure lead to?
Slumping and sliding
It reduces friction and destabilizes rock layers.
What are the two main types of cliff profile?
Steep, unvegetated cliffs and shallow-angled, vegetated cliffs
Each type is produced by different erosion processes.
What is the role of vegetation in coastal stabilization?
Stabilizes sediment and protects it from erosion
Plant roots bind sediment, while stems and leaves reduce wind and wave erosion.
What are pioneer plants?
The first plants to colonize freshly deposited sediment
They modify the environment by stabilizing sediment and adding organic matter.
What is dune successional development?
Plant succession on sandy coastlines
It involves stages of colonization by different plant species.
What is halosere?
Plant succession in salty water
Halosere occurs in estuarine areas where fresh and saltwater mix.
What is the climax community in plant succession?
The final stable plant community in equilibrium with climate and soil conditions
In the UK, it may be deciduous oak forest or coniferous pine forest.
Fill in the blank: The erosion rate of Carboniferous limestone is _______.
1 cm p.a.
This rate is relatively slow compared to unconsolidated sediments.
True or False: Igneous rocks erode faster than sedimentary rocks.
False
Igneous rocks typically erode more slowly due to their crystalline structure.
