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Paleogeography II

In a previous post concerning paleogeography, I said:

> When your not dealing with cratons (stable continental interiors),
everything is pretty damn blurry.

Okay, I should also point at that true oceanic basins are relatively easy to
figure out, too: if you find Cenomanian aged sediments and/or basalts
between Africa and South America at a certain latitude, you can be pretty
darn secure that those two points of the continents were not in contact at
that interval (although they might have been north or south of it).

For the case of Beringia, though, oceanic basins are not present beween
Siberia and Alaska: it is contiental crust across (that's how they were able
to connect during the Pleistocene).  We cannot use this technique to sort
out ancient relationships beween these regions.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661