Coasts Flashcards
What is the littoral zone
the zone from the highest tide mark to the permanently submerged areas
What makes up the littoral zone
- in land
- backshore
- foreshore
- nearshore
- offshore
What are the types of coasts
- rocky coasts
- coastal plains
- high and low energy coast
- erosional and depositional coasts
- reef coasts
- deltaic coast (dominated by river sediment)
What are emergent coasts
when sea levels fall, leaving behind more land
What are submergent coasts
when sea levels rise, inundating the land
What are characteristics of igneous rocks
- crystaline
- resistant
- impermeable
- rate of recession = 1mm/year
- cooled and solidified magma or lava
What are the characteristics of sedimentary rocks
- jointed sedimentary (sand+limestone) are permeable
- porous (chalk)
- but shale is fine and compacted=impermeable
- recession rate = 1cm-1m/year
- formed in strata
What are the characteristics of unconsolidated material
- easily eroded
- if compacted an impermeable layer is formed in strata
- recession rate = 1m+/year
What are the characteristics of metamorphic rocks
- hard
- resistant
- impermeable
- recrystalization in a solid state
- formed when igneous or sedimentary rocks are either compressed or heated
What is a concordant/Pacific coastline
when strata is parallel to the coast
What is a discordant/Atlantic coastline
when strata is perpendicular to the coast
what is lithology
rock type:
1. composition
2. what minerals are inside
3. type of rock
what is geological structure
the arrangement of the rock
what is strata
the layers of rock
what are bedding planes
- natural horizontal cracks and breaks in strata
- caused by gaps in time formed during periods of rock formation
What are joints
- vertical cracks and fractures
- caused by either contraction as sediments dry, or earth movement during uplift
What are faults
- large cracks formed when pressure or stress is subjected to a rock
- this happens when the rock exceeds its internal strength, allowing the fault to move along the fault plain
What are folds
- curves in rock
- caused when pressure from tectonic activity buckles and crumples the rock
What is the dip of strata
the angle at which strata lies
What types of cliffs do horizontal strata produce
steep-sided cliffs
What type of cliffs do seaward dipping strata produce
steep-sided cliffs that are more susceptible rowards mass movement
What types of cliffs do landward dipping strata produce
stable, steep-sided cliffs
What are dalmatian coastlines
narrow lines of islands seperated by narrow sea channels
What are Haff coastlines
long shallow lagoons seperated from the sea by a narrow sand bar or barrier beach
How are embryo dunes formed
sand gathers around obstacles on the strand line
what is the fetch
the distance from open water over which the wind blows
How do embryo dunes develop into fore and then yellow dunes
more sand accumulates, and plant diversity increases
How are climax communities formed
after a series of plant changes
What is the term for sand dune succession
psammosere succession
What is the term for salt marsh development
halosere succession
What are salt marshes
coastal wetlands which are flooded and drained by salt water from tides
Why are salt marshes marshy
soil could be composed of deep mud and peat
What is peat made of
decomposing plant metter, often several feet thick
What are the characteristics of peat
- waterlogged
- root-filled
- very spongy
what is wave refraction
when waves bend as they move over different depths
what is a seidment cell
a self contained stretch of coastline
how are drift aligned beaches formed
waves break perpendicular to the coast
how are swash aligned beaches formed
waves break parallel to the coast
what is mechanical weathering
the break down of rocks due to an exersion of physical force
What is biological weathering
the process of speeding up mechanical or chemical weathering through the actions of organisms
what is chemical weathering
the breakdown of rocks through chemical reactions, resulting in a new chemical compound
what is mass movement
the downslope movement of sediment due to gravity
what is mass movement dependent on
- geology
- marine processes
- weathering
- water content
- saturation
- density
what is rockfall
pieces of rock falls off the cliff face due to weathering (usually freeze-thaw)
what is mudflow
when saturated soil flows downhill
what is a landslide
when large blocks of rock slide downhill
what is a rotational slip/slump
when saturated soil slumps down a curved surface
what is scree
broken rock fragments at the base of a cliff
what is dynamic equilibrium
a state of constant change to keep balance
what cause short-term changes to sea level
- tides
- low pressure systems
- strong winds
What is eustatic change
the exchange of water between oceans and ice sheets/glaciers
what is isostatic change
when the Earth’s crust changes to seek equilibrium after the (un)loading of ice
How do tectonic processes change the sea level
displace the crust
what is accretion
when new land mass is created through the addition of sediment
what is subsidence
small scale land sinkage
what is the thermohaline circulation
a large scale movement of sea water
what is thermal expansion
as water gets hotter, it expands
what is adaptation in regard to flooding
making changes to reduce the impacts of flooding when it occurs
