Coasts Eq1 Flashcards
What is the littoral zone
Area of shoreline where land is subject to wave action
What is the littoral zone made up of
4 zones:
Backshore - only affected during storm events
Foreshore - tidal zone
Nearshore - friction influences sea bed
Offshore - open ocean
What is a coastal plain
Low relief, deposition is dominant process, has sand dunes, beaches, salt marshes
What is a rocky coast
Resistant rock, erosion is dominant process
What is an emergent coast
Sea level is dropping
What is a submergent coast
Sea level is rising
What is a low energy coast
Area with a smaller wave fetch, constructive waves, deposition, beaches can be found
What is a high energy coast
Area with large wave fetch, destructive waves, high erosion, headlands can be found
What is a sediment cell
Self contained section of coast where sediment can move, but it cannot move from one cell to another. Each cell is made up of inputs (e.g waves, wind speed and direction), transfers (erosion, deposition) and outputs (e.g beaches, sand dunes)
What is a concordant coast
Stripes of alternate resistant and less resistant rock parallel to the coast line
What is a discordant coast
Stripes of alternate resistant and less resistant rock perpendicular to coastline
What is a Haff coast
Found on southern fringes if baltic sea, long sediment ridges with sand dunes run parallel to the coastline just off the shore, creating lagoons
What is a Dalmatian coast
Bands of resistant rock where soft layers have been eroded, producing parallel islands
What is strata
Layers of rock, found in sedimentary rock, lines of weakness can be found between layers
What are bedding planes
Horizontal cracks between strata, also known as lines of weakness, found in sedimentary rocks
What are joints
Vertical cracks in rock caused by either contraction as sediments dry out or by the earth’s movement
What are folds
Formed by pressure during tectonic activity which causes rock to buckle and crumple
What are faults
Formed when pressure and stresses that a rock is subject to exceeds it’s internal strength causing it to fracture
What is dip and how does it affect the cliff profile
Angle at which rock strata lie
Horizontal strata = steep sided vertical cliffs
Seaword dipping strata = shallow cliffs
Landward dipping strata = steep, sometimes overhanging cliffs
What is sedimentary rock
Formed in strata, can be permeable or porous, not resistant
What is igneous rock
Crystalline, impermeable, resistant e.g granite
What is metamorphic rock
Very hard, very resistant, impermeable rock e.g marble
What is unconsolidated material
Loose and easily eroded, however if compacted the particles can stick together and form and impermeable layer e.g boulder clay
How has geology affected the Dorset coastline
South coast is concordant, made up of coves where differential erosion occurs e.g lulworth cove
East coast is discordant, made up of bays and headlands e.g Swanage bay, durlstone head
How are sand dunes formed (4 steps)
- Sand gathers around obstacles on the strand line
- Plants known as pioneers colonise embryo dunes
- These dunes grow into larger fore or yellow dunes as sand accumulates, plant diversity increases
- Eventually, climax community is reached, which marks end of succession
How is vegetation significant in the creation of sand dunes
Xerophytes (adapted to dry conditions) and halophytes (adapted to salty conditions) bind sand particles, forming protective layer over sediment and reducing erosion
What are salt marshes
Coastal wetlands that are flooded and drained by salt water brought in by tides
Made up of deep mud and waterlogged decomposing plant matter
