Quote:
Originally Posted by sjastro
Carl,
Do we know the following.
Let's reference it to the Carboniferous period.
(1) Was there a supercontinent during this period?
(2) What was the "mean" angle of Earth's rotational axis to the orbital plane during this period?
(3) If this supercontinent existed where was it's position relative to the surface of the Earth?
Regards
Steven
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Yes we do know about the state of the planet at the time. Without hunting for the particular references (as I don't have them on me and it'll take time to get them), I can tell you that the continents were assembling into Pangaea...Laurasia (that's Nth America and much of Eurasia) was moving towards the equator, whilst Gondwanaland was situated mostly over the Sth Pole and was covered in a large ice sheet.
I've got some maps (see below) for you to give you an idea of what the situation was in so far as the positions of the continents are concerned, as well as a climatological map. The situation is very similar as it is today, climatologically. You may have to download the graph and climatological map...they don't look so great when you click on them to display!!! (just tested them).
The Earth's average axial tilt in the Carboniferous was pretty much the same as it is now. They've been able to deduce this from the varve deposits from lake sediments of the period. What a varve is...is the annual deposits of fine clay and other particle sediments that build up as layers in the bottom of lakes in cold climates. The size of each layer, the types of minerals and such present and their internal physical characteristics can be used to determine many things...lengths of the year and hence orbital motion, length of the day at the time of deposition, how long the seasons lasted etc. From these, they've been able to determine the length of the day (from memory about 23 hours) and an orbit about the same as now.