coasts eq1 Flashcards
littoral zone
boundary between land and sea which stretches out to sea and onto the shore
rias
coastal inlet formed by the partial submerge of an underglaciated river valley
sediment cells
length of coastline and its associated nearshore area within which the movement of sediment is largely self- contained.
rocky plains
- can have high or low reliefs
- created by resistant geology
- often in high energy environments
coastal plains
- alluvial coasts
- sand + estuary coasts
- low relief areas where land slowly slopes towards the sea
- low energy environments
formation processes- primary coasts
- formed by land-based processes such as deposition or lava flows.
- material comes from land
formation processes- secondary
- created by marine erosion or deposition
- material comes from sea
geology
- coastlines can be classified according to:
- sedimentary, metamorphic, igneous
- concordant, discordant
sea level change - emergent
where the coasts are rising relative to sea level, for example due to tectonic uplift.
sea level change - submergent
are being flooded by the sea, either due to rising sea levels and/or subsiding land.
tidal range
varies hugely on coastlines,, coasts can be:
- micro tidal coasts (tidal range 0-2m)
- mesotidal coasts (2-4m)
- micro tidal coasts (more than 4m)
high energy
- high energy exposed coasts, facing prevailing winds with long wave fetches = powerful waves.
- destructive, storm conditions
- erosion, strong backwash weak swash,
- headlands, cliffs, arches
- atlantic, pacific
low energy
- low energy sheltered coasts with limited fetch and low wind speeds = small waves.
- constructive waves, calm conditions
- deposition + transport + LSD. - - spits, bars sand dunes, marshes
- Mediterranean Sea
igneous
- formed by fire
- formed from magma (minerals in mantle)
- extrussive: magma reaches surface + cools.
- intrussive: magma cools below surface.
- few joints = few weaknesses
- are crystalline: interlocking crystals = resistant rock
examples igneous
- granite
- basalt
- tuff
- pumice
metamorphic
- high levels of heat changes some minerals to new rock
- thermal metamorphism: on a small scale near volcanoes or intrusive.
- regional metamorphism: affects larger areas of rock as it creates big amounts of pressure + heat.
- may have foliation: crystals areorientated in 1D = weakness.
- some are crystalline
examples metamorphic
- slate
- marble
- gneiss
- schist
sedimentary
- by layers of sediment (bits of rock broken down by W + E)
- layers upon layers = compacted + lithified (turned to rock)
- clastic: made up of broken rock fragments stuck together.
- non-clastic: formed from sediment that was dissolved in water during W or E and D due to a chemical reaction nor biological process
- young rocks + with many bedding planes tend to be weaker
examples sedimentary
- sandstone
- limestone
- shale
- rock salt
- mudstone
concordant
bands of different rocks run parallel to the coast.
- coves: due to the factions + strata, erodes faster
discordant
bands of different rocks run at different angles (right angles) to the coast.
- headlands and bays
haff coastlines
- along concordant
- with long spits or bars of sand and lagoons behind them.
- e.g: Haffs in southern shore of Baltic Sea
dalmation coastlines
- concordant
- due to rise in sea level
- valleys have flooded + ridges have remained forming islands
- e:g: Dalmation coast in Croatia
morphology
shape + form of coastal landscape and their feature
lithology
physical characteristics of particular rocks
strata
layers of rock
bedding planes
horizontal cracks, natural breaks in strata, caused by gaps in time during periods of rock formation
- eg: Grand Canyon
joints
vertical cracks, caused by contraction as sediments dry out or by earth movement during uplift.
folds
formed by pressure during tectonic activity, makes rocks buckle and crumple
- eg: Lulworth crumple
faults
formed when stress or pressure put on rocks exceeds its internal strength (it fractures). the faults then slip/move along the fault planes
dip
angle at which rock strata lie (horizontally, vertically), dipping towards the sea or inland.
- eg: mount Rundle in canada
fissures
smalls cracks in rock
microfeatures
small caves and holes in a rock
recession
how fast a coastline is moving inland
what affects coastal recession?
- rock type
- weathering
- mass movement
- wave energy
- rising sea levels
- absence of beach
- human activity (coastal defences elsewhere lead to increase erosion)
permeable rocks
allow water to flow through them, can remove the cement that binds sediment together + can cause PWP
pore water pressure
PWP
pressure water experiences at a particular point below the water table due to the weight of water above it.
unconsolidated sediment
material such as sand, gravel, clay and slit that has not been cemented to become sedimentary rock (no lithification), loose = easy erosion
impermeable rocks
do not allow groundwater flows, includes clays, mudstones and most igneous and metamorphic.
physical factors influencing coastal recession
- tidal range
- vegetation protection
- location
- discordant/ concordant
- high/low energy
- coastal morphology
- relief
- lithology
- geology
- permeability/impermeability
flocculation
tiny clay particles sticking to one another
halophytes
- tolerant to salt water, either around their roots or salt spray from the sea
- help to slow down tidal flow and trap more mud and silt
- form when mud flats develop, as they begin to colonise area
halosere
a salt marsh ecosystem
salt marshes
- in low-energy coastline of estuaries + spits
- tidal conditions bring sea water + sediments in + out
- rivers bring muds + silts = deposited sides of estuaries
- flocculation occurs + is colonised by algae
- pioneer plants have to survive brackish water
- plants change conditions by trapping more sediment = builds the salt marsh up = other plants can colonise
- mud contains invertebrates, many plants can be grazed by migrating wildfowl (Brent geese) + waders (oystercatchers)
brackish water
- slightly salty water
- river + sea mixed
- yellow/brown
salt marsh stages
- algae stage
- pioneer stage
- establishment
stabilisation - climax vegetation
algae stage (SM)
- growth and and within bare mud, brinding it together
- eelgrass
- gut weed
pioneer stage(SM)
- roots begin to stabilise the mud, allowing further mud accsetion
- glass wort
- cordgrass
establishment stage (SM)
- a continuos carpet of veg is established and the salt marsh height increases
- sea aster
- marsh grass
- pickleweed
stabilisation stage(SM)
- this area of the salt marsh is rarely submerged
- sea thrift
- sea lavender
climax vegetation (SM)
- developed soul profile and only submerged once or twice each year
- rush sedge
psammosere
sand dune ecosystem
sand dune
- low energy coastline
- aeolian processes cause sand to move
- sand is accumulated due to an obstacle (pebble)
- deposition occurs and forms an embryo dune, pioneers grow such as sea rockets.
sand dune stages
- embryo dune, marram grass
- as these develop, grow + form fore dunes (lyme grass and sedge + marram)
- at first the dunes are yellow (lyme grass + sedge)
- then darken to grey as decaying plants add humus (low shrubs)
- depressions between dunes can develop into dune slacks - damper areas where the water table is closer to, or at the surface (aquatic plants)
- climax community - woodland (scots pine, oak trees)
