Coasts 3 Flashcards
CLIMATE CHANGE
what causes the warming of the climate
- variations of sun energy
- changes in the composition of the atmosphere due to volcanic eruptions
CLIMATE CHANGE
what are the two types of climates
warming - sea level rise
cooling - sea level lowering
CLIMATE CHANGE
who types of features
emergent - formed before ice age, can see when sea level lowers
submergent - formed after ice age, when sea levels rise
CLIMATE CHANGE
milankovich cycles summery sentance
- when each of the 3 milankovich cycles are in a certain state eg: obliquity at 22 degrees so seasons are less dramatic, so an ice age can begin and sea levels can start to drop
CLIMATE CHANGE
ice age formation summery sentence
- formed over throusands of years of cooler summers, leaving a layer of unmelted ice sheets, these can continue to accumulate in the northen hemisphere due to having more land space
CLIMATE CHANGE
two causes of sea level change
- eustatic change = change in ocean volume - due to change in density, increasing volumes in which mollecules ocupy
- isostatic change - change in land weight, placing pressure on the liqid mantle
CLIMATE CHANGE
tyrrhenian interglacial
- sea level rise 20m
- emergent features eg; raised beaches
CLIMATE CHANGE
Riss glacial
- 7 degrees lower
- submergent features due to low sea level
CLIMATE CHANGE
flandrian transgression
significant rise in sea level after last ice age, when features are submerged or altered
UNINTENTIONAL IMPACTS
where abouts
Mangawai - pakiri
UNINTENTIONAL IMPACTS
reasons for mining
high quality clean sand
construction, concrete making, glass manufacture
UNINTENTIONAL IMPACTS
sediment budget
- operated for over 70 years
- current rate of extraction 75,000m3 a year
- large proportion to replenish Auklands beach
closed system, not replenished by fluvial inputs, dynamic equilibrium disrupted = sand supply depleted in dunes and beaches
UNINTENTIONAL IMPACTS
impact on coastline
unsustainible = beaches starved of sediment, becoming wider and flatter
meaning they are less affective in absorbing waves
more erosion = positive feedback making dues and spits vunerable
sediment loss = instability and loss of vegetation
UNINTENTIONAL IMPACTS
overall consequences
evident coastal retreat - due to sand extraction and sea level rise
long term retraeat = predicted 35m by end of centuary
UNINTENTIONAL IMPACTS
evaluation
major storms = blue water now stagnant and polluted
lack of negative feedback to reform broken spits
sand dune erosion spoiling natural characteristics
2.3 mill visitors 2015
INTENTIONAL IMPACTS
what is a shoreline management plan and 3 types
Overall strategic plan for a section of the coast
Advance the line - new defences, multi layered
Hold the line - maintain and repair defences
No active intervention- no investing
INTENTIONAL IMPACTS
Examples of hard and soft engineering
Hard - groynes and sea walls
Soft - beach nourishment and dune stabilisation
INTENTIONAL IMPACTS
Important sentence on affects
Wave energy and marine process are prevented from interacting with the natural coastline fully or in part. As a result there is gojng to be change in sediment input and the consequence transport and output within the sediment cells.
INTENTIONAL IMPACTS
Why does Felixstowe need protect and Bawdsey doesn’t
Bawdsey - no defence, soft lithology, important imput of sediment
Felixstowe - soft lithology, needs defences as the beaches bring in tourism ( defended via large fishtail groynes ) aswell it’s the largest port in the Uk
SUBMERGENT LANDFORMS
Summery sentence
Due to sea levels rising as a result of warming climates. The landforms are formed during the riss glacial and become submerged during the flandrian transgression.
EMERGENT LANDFORMS
Summery sentence
During cooling climates, the coastal features formed during the tyrenian interglacial are emerged during the lowering of sea levels as abandoned cliffs and raised beaches
Ria formation
- flooded estuary eg Sydney harbour
- during flandrian transgression the sea levels rise and move inwards causing flooding
Modified via marine and subarial processes
Fjord formation
Eg: sog he fjord
Submerged glacial valley, v shaped valley carved into U shaped valley
Modified: marine and subarial processes, freeze thaw weathering
Shingle beaches
CHESIL beach
Not a true submergent landform but the theory involves sea levels rise
Sediment accumulated and push on shore via glacier
Modified: present day LSD
Raised beaches and abandoned cliffs
Eg isle or Jura
From as former shore platforms or sediment deposition
Modification:
Not inputs of sediment due to no marine processes
Lichen grow on stationary pebbles
Biological weathering
