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Question 1
The figure shows the age of the ocean floor. When was possible for a dinosaur that
cannot swim to go from Argentina to South Africa? Why the ages of the ocean floor are
symmetric respect to an axis? What is that axis? Which age would you expect to
correspond to the deepest seafloor? Why?
Bonus question: How fast has been spreading the southern Atlantic Ocean at ~30° S since
the beginning of the spreading ~140 Ma (Million of years ago)? (From the map you can
see how many degrees apart are Africa and South America and you must remember the
how long is the circumference of the Earth. Remember you are not at the equator!)
(Answer to bonus question they are ~60° apart => distance in km ~
40000*60*sin(60)/360~3333km => spreading 24 mm/yr (the real value for half spreading
is ~15 mm/yr)
Question 2
The figure shows 3 stages of the formation of an ocean. Assuming that each time
correspond to a magnetic reversal and that time 3 correspond to today, color on the
figures the ocean floor corresponding to the normal polarity ocean floor. Why do the
ocean floor became deeper moving away from the ridge? If the 3 times on the figure
correspond to interval of 1 Myr (1 Million year) what would be a reasonable scale for the
horizontal axis?
Question 3
The figure shows the internal composition of the inner planets of the Solar system.
Describe the Layers of Planet Earth. Describe 3 observations that you can use to justify
that the center of the earth is denser. As you can see the other inner planets do not have
outer core (or it is very small), how would you expect the magnetic field to be?
Question 4
The figure is a cartoon scheme of the experiment of Eratosthenes to measure the
circumference of the Earth. Assuming that it is correct and that the figure shows the
situation at noon of the summer solstitium day, what are the coordinates of the 2 places
(in theory they should be Alexandria and Syene but for that couple of city does not work
too well…)? Since today we know the radius or circumference of the Earth, how distant
are the 2 cities?
Question 5
What is the Elastic Rebound theory?
Question 6
Why do you think we can find deep earthquake only in subduction regions?
Question 7
What are lithosphere and asthenosphere? How are thy related to plate tectonic?
Question 8
The figure from Fowler shows different kind of gravity anomalies for different amount of
Isostatic compensation. What is a gravity anomaly? What is Isostatic compensation? Can
you make an example of Isostatic equilibrium? Why in general big mountains chain do
not have the big gravity anomalies that we should expect from the excess of mass related
to the mountain itself?
Question 9
The figure shows a schematic view of
the formation of the Hawaiian
seamountain chain. How can you use
the seamountain chain to say something
about plate motion? Where would you
expect to see the oldest volcanic rocks?
Which assumption are we making when
we speak of hot spot reference frame?