Coasts Flashcards
Define Bedding Planes
Horizontal breaks in the strata, caused by gaps in time during periods of rock formation.
Define Dips
The angle at which rock strata lies.
Define Faults
Formed when the stress or pressure to which a rock is subjected exceeds its internal strength causing it to fracture.
Define Folds
Formed by pressure during tectonic activity, which makes rock buckle and crumple.
Define Joints
Vertical cracks caused by contraction as sediments dry out, or by earth movements during tectonic uplift.
Characteristics of Low Energy Coasts
- Constructive Waves
- Depositional
- Gentle relief
- Sandy beaches and salt marshes
Characteristics of High Energy Coasts
- Destructive waves
- Strong winds and long fetches
- Erosional
- Rocky
Describe Discordant Coastlines
- Rock structures meet the coast at an angle, perpendicular to oncoming waves.
- Alternating rock types lead to formation of headlands and bays.
Describe Concordant Coastlines
Rock structures run parallel to the coast.
Describe Igneous Rock
- Not porous due to tightly packed crystalline structure.
- Not permeable due to no joints or bedding planes.
- Very resistant to marine erosion.
Describe Sedimentary Rock
- Soft and Porous due to permeable rounder crystals.
- Permeable due to large amount of faults, bedding planes and joints.
- Not very resistant as it dissolves in water and can be eroded both chemically and by marine processes.
Describe Metamorphic Rock
- Not very porous due to being marine erosion resistant and having many different layers of crystals.
- Not very permeable due to interlocking layers of crystals and no bedding planes or joints.
- Very hard and resistant to marine erosion and weathering.
Describe Sand Dune Ecosystems
- Formed by wind
- Need more low energy waves.
- Embryo dunes formed by Pioneer plants that grow with roots that hold sand together.
- Grass dies due to water being too salty.
- Maram grass which allows tall yellow dunes to be created.
- These dunes are too tall for water to pass.
- Grey dunes and a dune slack created behind yellow dune which holds fresh water.
- Forests can then eventually grow which aren’t salt tolerant due to lack of exposure to salty water.
Describe Salt Marsh Formation
- Found at river mouths and behind spits.
- River bring fine muds, clays and silts and deposit them at the side of an estuary.
- Tiny clay particles stick to one another (flocculation).
- Then they are colonised by algae which has to survive being covered in brackish water 2 times a day.
- Overtime, pioneer plants change the conditions by trapping more sediment, building the salt marsh up to a higher level.
Describe formation of Wave-Cut Notch/Platform
- Destructive waves cause abrasion which undercuts the cliff face, forming a curved indent in the cliff.
- Continued erosion eventually causes collapse.
- Waves wash away collapsed material and begin eroding the cliff away again, creating a new wave cut notch.
- Overtime, multiple collapses cause the cliff to retreat, creating a wave cut platform.
Describe formation of Cave-Arch-Stack-Stump Sequence
- Small cracks in the rock are eroded more rapidly into caves.
- Caves deepened by marine erosion until they connect up, creating a tunnel through the headland and forming an arch.
- The roof of the arch is eroded by weathering and sub-areal processes, leaving stacks.
- Marine erosion at the base of the stack will eventually cause it to collapse, leaving a stump.
Describe Constructive Waves
- Depositional
- Strong Swash
- Weak Backwash
- Low Energy
Describe Destructive Waves
- Erosional
- Weak Swash
- Strong Backwash
- High Energy
Describe Bar Formation
- Saturated gap in the coastline is present.
- Longshore Drift occurs, carrying material across the front of the bay.
- Material is pushed up the beach by powerful swash from longshore drift.
- Backwash takes sediment away from the sea at a right angle.
- Deposited material joins up with the other side of the bay and a strip of deposited material blocks off the water in the bay.
Describe Rock Fall
A section of the cliff face falls off and slides downwards due to gravity.
Describe Rock Slide
A section of the cliff snaps off and slides downwards due to gravity.
Describe Rock Slump
A section of the cliff becomes unstable due to being too soft which causes it to slope downwards.
Describe Abrasion
Eroded water particles scrape and rub against the rocks, removing small pieces.
Describe Attrition
Eroded particles in the water collide and break into smaller fragments. This creates rounder sediment.
