Coastal recession Flashcards
What are clastic rocks?
Less resistant rocks that have been cemented together
What are crystalline rocks?
Resistant rocks that have interlocking crystal minerals
What is recession?
The rate at which the coastline is moving inland
What is an example of unconsolidated sediment?
Fluvial alluvium
Boulder clay
Why does the Holderness coast erode easily?
It is made up of boulder clay that is weak, soft and crumbling
What has occurred at the Holderness coast?
The coastline has retreated
The recurved spits are more noticeable
Deposits behind the spit have led to the formation of a salt marsh
Which rocks are igneous?
Granite, basalt and dole rite
What type of rock is igneous?
Crystalline
Why are crystalline rocks more resistant?
They have less jointing and less fractures, water is not able to enter
What other factors in rocks can make them less resistant?
Faults, joints, weak bedding planes and fissures
Give an example of a complex cliff profile?
The north Antrim coast
What are permeable rocks?
Rocks that allow water to flow through them
Why may a rock be permeable?
Porous
Numerous joints
Why are permeable rocks less resistant?
There is a larger surface area for chemical weathering
What is marine erosion?
Processes caused by waves
How are steep cliffs produced?
Marine erosion dominates
All of the material at the bottom of the cliff is broken down
Why some cliffs shallow?
Sub aerial processes such as weathering dominate
There is little marine erosion at the base
What is spring creating erosion?
Permeable rock is layered over impermeable rock
Water enters the permeable rock
Water accumulates which creates a spring
As the water leaves it causes fluvial erosion
What is fluvial erosion?
Erosion caused by material/water coming from surface run off
How can marine erosion weaken clastic rocks?
It can break down the cement that is holding the rock particles together
Why is vegetation important on coastlines?
It can stabilize unconsolidated sediment which prevents erosion
What is the role of pioneer plants?
Consolidate the sediment
Add humus to the soil
What is the name of the process of sediment getting colonized on sand?
Psammosere
What are xerophytic plants?
Plants that are especially adapted to dry conditions
Examples of xerophytic plants?
Marram grass
What is the name of plant succession in salty water?
Halosere
What is the name of plants adapted to wet conditions?
Halophytes
What are marine factors that influence coastal recession?
Types of waves
Wave energies
How can human activity exacerbate recession?
By disrupting the accumulation of sediment
How did the construction of the Aswan dam exacerbate recession?
The sediment volume was reduced from 130 million toneto 15 million tones
Delta was starved of sediment
Erosion rates jumped from 20 to 200 meters per year
