coasts Flashcards
what does the littoral zone consist of?
backshore,foreshore, nearshore and offshore
describe a rocky coast and a coastal plain
result from resistamt geology
-high relief
-withstand erosive forces
-often in high enegry env
result from a supply of sediment
-different terrestrial and offshore sources
-low relief
-low enegry env
sandy and eastury coast
igneous and examples
created by volcanic activity when magma or lava cools, forming crystals that are normally hard- granite and basalt
sedimentary and examples
formed by small particles that ahve been eroded, transported and deposited in layers (sandstone) or from remains of plants and animals (limestone and chalk)
metamorphic and examples
form from other rocks changing by extreme heat and pressure usually form from layers/bands of crystals and very hard. Shale can be compressed into SLATE and limestone can be transformed into MARBLE
what coastline does sedimentary rock have?
and landforms
flat low lying relief, salt marshes and lagoons, low energy env
beaches spits slat marsh
low lying sandy beaches
what coastline does igneous rock have?
and landforms
rocky outcrops, resistant to ersion, high energy env
stack stump, wave cut platform
what is costal morphology
the shape and form of costal landscape and their feature.s
what is lithology
type of rock, sedimentary, metamprphic uncolidates, igenous…
what is geology
concordant dicordant coasts
joiting, dipping, faulting, folding ( e.g. these can form caves)
what is strata
layers of rock
what are bedding planes
(horizontal cracks) these are natural breaks in the strata,, caused by gaps during periods of rock formation
what are joints
(vertical cracks) these are features caused by either contraction as sediments dry out or by earth movements during uplift.
what are folds
formed by pressure during tectonic activity, which makes rocks buckle and crumple
what are faults
Faults are major fractures in rock created by tectonic forces
what’s a dip
this refers to the angle at which the strata lie (horizontally, vertically, dipping towards the sea or dipping inland)
what is the relief ( or height or slope of the land) affected by
geology and lithology
what are the 3 things that lithology includes
- rock type metamorphic sedimentary igneous
- how porous the rock is (permeability) linked to grain size and rock structure (crystal)
- composition ( if acid acid rain affects it)
erosion rate of igneous rock?
1mm per year
erosion rate of sedimentary rock?
2.5cm per year
erosion rate of unconsolidated material?
1m per year
what’s a discordant coastline eg
where the geology alternates between more resistant bands of rock with less resistant bands, cut at right angles to the coast (perpendicular)
east facing dorset=isle of purbeck
headlands and bays
what’s a concordant coastline eg
where bands of more resistant and less resistant rock run parallel to the coast.
south facing dorset
a real life example of a concordant coast?
and explain formation process
litholgy, dip,small features, creates sea cave.
lulworth coast/crumple- is created by the collison of the african and eurasion plates. pressure and cooling may crack a rock to form joints and larger faults. joints are made as sedimentarty rock, formed from pressure or ignesous and metaphoric rock. sedi-bedding planes create points of weakness.
dip- if rock layer dips towards the sea- blocks of rock to slide under the influence of gravity(Mass M) if dip landwards- weathering and erosion may attachk bedding planes- creating irregular profile.
cliffs may create protruisions(sticking out) and indentations, blowholes, geos
weka point(joint), weathered or eroded creating a sea cave.
describe Dalmation coastlines
-concordant coastline
submerged landform
-valleys and ridges run parallel to each other
-past valleys have flooded and ridges are left over
produce long islands and inlets.
describe haff coastlines
- concordant
- long spits and lagoons aligned parallel to the coast
what are the two types of vegetation that protect the coast
salt marshes and sand dunes
what are salt marshes
+ detailed explaination
areas of flat, silty sediments that accumulate around estuaries or lagoons
- tidal conditions bring seawater and sediment in and out,
- rivers bring fine mud deposit at side of estruy
flocculation occurs- colonised by algae
3.pioneer plants survive with brackish water
more sediment is trapped builfing uo salt marsh
where do salt marshes develop
- in sheltered areas where deposition occurs
- low enegry env
- where there are no strong tides or currents
what are pioneer plants referred to as
the first colonizing plants
what do pioneer species do
modify the environment by binding sand or soil with their roots and adding nutrients when they die or decay
what helps retain moisture for sand dunes, mud dunes and salt marshes.
creeping plants or those with leaf cover
what helps slow down tidal flow and trap more mud and salt
halophytes (salt tolerant species)
-eg cordgrass
what are the first dunes to form called?
embryo dunes
how does vegetation help protect the coast
it modifies the environment by binding the sand and soil with its roots. More vegetation means less erosion as sand and soil becomes more stabilized and less vulnerable
constructive waves lead to ______
deposition
destructive wavs lead to ______
erosion
what is the crest
the peak of the wave
what’s the wave trough
the lowest point of the wave
what’s the wave height
the distance between the crest and wave trough
what’s the fetch
the distance of water that a wave can build up
state the wave form, wave break and frequency of constructive waves
low surging wavs with a long wavelength.
string swash, weak back swash
beach gain with 6-9 per min