Lec #1. Controls on coatal formations and barrier Islands Flashcards
Define a Physical Process
The forces that create coastal habitats which create stressed, biodynamic and dynamic habitats
Explain a barrier island
Form parallel to land, could be attached at one end or not at all, normally made up for sand sized particles. Habitat could be diverse or desolate.
What key conditions are needed for barrier island formation (4)
Coastline Gradient
Sediment type
Tidal Conditions
Input of sediment
What are the two possible inputs of sediment for barrier island formation
Fluvial and Longshore drift
What relationship between erosion and deposition does there need to be for barrier island formation
Deposition must be occurring faster than erosion
Which wave form brings eroision
Larger waves
What wave size or form brings depostion
Small to medium sized waves
What factor effects the size of the waves
Waves are effected by the gradient of the slope, a shallower slope pushes waves up (shoaling) which causes erosion due to friction
Discuss the importance of plate tectonics for barrier island formation
These can cause the steep gradient needed for depositional waves
Explain the importance of rivers in barrier island formation
Can bring the deposition of sediment. more rivers = more discharge = more sediment
Explain the signifcance of tidal ranges in barrier island formation
High energy enviorments so a small tide allows for accullation
Give an example (real world) of a barrier island
Galveston, Texas
Explain the differences between the land facing and sea facing side
Land side would have vegetation as it is more stable where as the sea facing side is constantly changing and lacks stablilty
Explain the imporatnce of storm surges in barrier island formation
Storms surges have the power to overtop the barrier island taking sediment from the seaward side to the landward side as a method of replenishment
How does sea level rise effect barrier islands
As tides change a barrier island undergoes movement either toward or away from the land
Explain how tectonic activity effects coastal enviroments (2 points)
1) Sea level rise through sea floor spreading and uplift of mid oceans ridges.
2) nature of the sea floor topography dictated by tectonic activity
Explain the theory of isostatic rebound
During the last glacial maximum a lot of land was covered by ice, as this melted the weight of the ice decreased and now the plates are rebounding as compression of sediment is reversed
How does isostatic rebound effect the UK
The North of the UK is rising by 3mm a year and the South is sinking by 1mm a year
Explain thermoexpansion
As atoms in water molecules become warmer they become more excited which causes an expansion in volume
How much does thermoexpansion account for in terms of eustatic sea level rise
60%
How does glacial melting effect sea level rise
Obviously because the ice is fucking melting there will be more water
What can oxygen isotopes tell us
Oxygen isotopes (O18) will change in concentration depending on sea level rise
What numerical values can show how isotope concentration has changed with sea level
a 0.1 concentration change means a 10m rise in sea level
What can be created with oxygen isotopes
Oxygen isotope curves which show the change in sea level throughout history
What are the two geological controls on coastlines?
Placements on continents and sea floor spreading rates
What are the three climatic controls on coastlines
Isostatic rebound, glacial melting and thermoexpansion
what are the two sedimentation processes that control coastlines
Longshore drift and fluvial deposits
What is the difference between transgressive and regressive sea level change
Transgressive pushes coast in land and regressive land is reclaimed as sea retreats
What are the two types of sea level rise
Relative and Eustatic
Explain relative sea level rise
Reference to sea level changes relative to land, operates on a regional and local level
What is eustatic sea level rise
References to a change in the world wide sea level rise, unrelated to local climate changes
What are the four evidence for sea level rise?
Deposition of marine sediments now on land,
Oxygen isotopes,
Submerged marine coastlines,
coastal features now well above sea level
What are coastal plains?
The are physiographic provinces between the land and the ocean which contain sediments from marine origins
Discuss fossil evidence as evidence (evolution)
As sea levels rise species can become isolated and evolve in different ways (Galapagos Islands)
Discuss the evidence from facies sequences
Discomformities in the rock record give evidence for sea level rise
What evidence does submerged coasts show
Obviously that sea level has rise
what evidence does emerged coasts show
Obviously that sea level has fallen
Is James a cunt?
Yes, James is a massive massive cunt.
