Non Life Sciences > Geology, Palaeontology & Archaeology
South America
DoctorBeaver:
another_someone - that's almost exactly what it says in the link I posted.
another_someone:
quote:Originally posted by DoctorBeaver
another_someone - that's almost exactly what it says in the link I posted.
Apologies if I have duplicated your response.
I was responding to Dino's response, which came in later than yours.
Dino:
Thanks, guys for your help. The quotes have helped me narrow down my search. However not so very long ago there was some controversy regarding the accuracy of Wikipedia, and I wonder if once again it is not quite accurate or sufficiently up to date.
I've been skimming through a book by J.D. Macdougall: 'A Short History of Planet Earth' John Wiley & Sons 1997. and I think I've found an interesting passage.
quote:
As the rift then extended further westwards and South America became separated from North and Central America the bodies of water on either side of Pangea finally met up with each other.
quote:
As time went on the rift extended further west and south. It cut through that part of the US which is today the Gulf of Mexico and at the end separated South America from North America. It was only relatively late in the Jurassic that the enormous salt sediments of the Gulf of Mexico were deposited. Presumably the water, from which the evaporite originated, forced its way into the rift from the Pacific side of the continent..
Well, that's the best I could do of a reverse translation, as I'm having to work from a German translation of the English text.
Progress so far
1. I have diagrams out of the book taken from the 'Atlas of Mesozoic and Cenozoic Coastlines' A.G. Smith, D.G. Smith, and B.M. Funnell Cambridge University Press 1994. Diagram 120 Ma shows S America definitely separated from N America. Diagram 170 Ma shows S America still tenaciously joined to N America.
2. The time of separation is given as being relatively later in the Jurassic period. So this means that 140 Ma the Americas were already separated.
Conclusion Separation took place in the period 170 Ma to 140 Ma. This narrows down the time of the separation as having taken place within a period of 30 million years.
So, what do you guys think? Would dinosaur divergence between the Americas make for a finer distinction?
Navigation
[0] Message Index
[*] Previous page
Go to full version