Lecture 3 + 4 Flashcards
When is rate of change high and 0, when does it have a large -ve rate of change?
High when base level is going up, 0 at max and min turning points. large -ve as base level drops
Draw an actual base level wavelength diagram and label on: rates of change, normal regression, transgression.
Draw a rate of base level change illustrating regression, forced regression, transgression and sedimentation rate
See notes
What are the 3 external forcing factors that control RSL?
Tectonics (uplift or subsidence), eustasy (global sea level) and sediment supply (sc or carbonate)
What two rates tell you what RSL is doing (with close reference to RSL graph) When would a forced regression be present in these graphs?
Subsidence and eustatic sea level.
Forced regression present when the eustatic sea level fall is greater than rate of subsidence.
Look at RSL change graph (revision sheet lec 3) Where is the sea level rising at its max rate, falling at its max rate and where is the RSL change 0?
Rising at max rate: D
Falling at max rate: B
Rate of change 0 = A + C
Some RSL graphs show a superimposed blue line on them, what does this show/mean?
The superimposed blue line shows minor fluctuations and reflects parasequences. These fluctuations are showing changes in A & S.
Give one way that you could determine what the global sea level was around the world in the past?
By interpreting sedimentary sequences you can determine past sea levels. These sequences can show variations from hot to cold climates which reflects in the sea level, whilst the icehouse effect if identified would show the time of the largest expected sea level change.
When did sea level drop the most, the icehouse or greenhouse period? How can you determine this?
Sea level dropped most during the icehouse period, this is clear from identifying O18 curves.
The magnitude of GSL changes is mostly controlled by what factor?
Global climate.
The effect RSL has on deposition depends on what?
The morphology of the continental margin
Ocean temperature change can cause global sea level change without the influence of glaciation/deglaciation. True or False?
True. Ocean temperatures will cause a GSL change independent of glaciation or deglaciation, this is because when temperatures rise they cause water to expand which causes GSL to rise.
Name the primary drivers of eustasy and discuss these.
Ice volume change, ocean temperature, seafloor spreading rate.
Ice volume change (glaciation/deglaciation) produces rapid changes, melting of land ice influences water volume in sea.
Ocean Temperature: Warming global conditions causes water to expand, this causes the sea level to rise.
Seafloor spreading rate: The rate of new crust growth changes ocean volume, faster spreading has a hotter crust which expands and displaces water.
