Mock Revision 2B.2 Geological structure and Coastal landscapes Flashcards
What is a concordant coastline and give an example
Strata arranged parallel to coastline (Lulworth Cove, Dorset).
Name the more and less resistant rock at Lulworth Cove
More - Purbeck Limestone
Less - Wealden Clay
What started the formation of Lulworth Cove?
Marine erosion exploited the weakness via hydraulic action to form a joint/fracture.
What occurs when the purbeck limestone is breached?
More rapid lateral erosion to wealden clay due to wave refraction.
What does the dissipation of wave energy lead to at Lulworth Cove?
Deposition - beach.
What is a discordant coastline?
Strata arranged perpendicular to coastline.
Name the 2 headlands of the discordant coastline and their rock
Durlston Head - Purbeck limestone
Ballard Points - Portland limestone
Name the bay of the discordant coastline and its rock
Swanage Bay - Wealden clay
What happens to the less resistant rock at Swanage Bay?
Receeds faster which leaves protruding headlands - creating a crenelated pattern.
What occurs to the ocean in a discordant coastline?
Wave refraction - wave energy is concentrated on the front and sides of headlands, leading to the dissipation of wave energy into the bay, deposition occurs which creates a beach.
Name the concordant coastline in Croatia as a result of sea level change
Dalmatian.
Describe the plate boundary at the Dalmatian
Convergent
African and Eurasian plates
What do the tectonic forces produced by the convergence of Africa and Eurasian plates create?
Folds in the carboniferous limestone, forming upfolded ridges and downfolded synclines.
Why do the synclines flood?
Sea level rise.
What is the name of the landform in the Baltic Sea?
Haff.
Where was water locked in the Devensian period?
Cryosphere.
How much lower were sea levels in Devensian period compared to today?
120m.
What occured after the Devensian period in Haff?
Global average temperature rose, causing glaciers to thaw and deposit sediment onto the outwash plain.
What occured between Devensian period and early holocene in Haff?
Global release of water from cryosphere cuased eustatic seal level rise. Constructive waves transported sediment from outwash plain back towards land.
What occured between early holocene and present day in Haff?
Unconsolidated ridge formed parallel to coast, forming a lagoon (haff) between it.
Name the spit and how long it is at the Haff
Coronian Spit - 98km.
What is the largest form of weakness?
Faults.
Name the ria from the result of a fault
Bantry Bay.
What rock is weakened by faulting at Bantry Bay?
Carboniferious limestone, allowing for fluvial erosion.
How long is Bantry Bay?
35km.
What are folds and how are they formed?
Bends in rocks produced by sedimentary rock layers being squeezed by tectonic forces (i.e anticlines and synclines).
Why is folded rock more easily eroded?
Heavily fissured and jointed.
Name the 4 types of dips
Horizontal
High angle seaward
Low angle seaward
Landward
What is the only dip in which the profile corresponds to the strata dip?
High angle seaward dip.
What occurs at high angle seaward dips?
Rockslides.
What forms at low angle seaward dip?
Undercutt and an overhang which is vulnerable to rockfall.
Why is landward dipping strata stable?
Force of gravity pulls loosened rocks back towards land.
What are joints?
Fractures in rocks created without displacement.
