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Re: Dino Feathers

Jerry Harris wrote:


>Geologically, they say, that in facies
>upstream from the lagoon is just such a wooded area, and that likely the
>terrestrial fossils from the lagoon originated there and were transported
>via stream to the lagoon.  This sounds plausible to me, although I'd be
>prone to ask how a freshwater stream emptying into a restricted lagoon
>would effect the supposed hypersalinity in the lagoon itself, which has
>been used to explain the deaths of the benthic marine organisms there...

Actually the short answer is "not very much" :-)

Saline water is denser than freshwater (due to the amount of salts disolved
in it), and hypersaline water is denser than normal sea water. Therefore
the freshwater entering the lagoon will tend to stay separate from, and
flow over the much denser hypersaline water (cue horrible ascii diagram).

    *          Freshwater/Normal Saline   **
      *----------------------------------*   *
        *       Hypersaline             *      *
           *  *  *  *  *  *  *  *  *  *          *

Thus the benthic (bottom) conditions remain hypersaline despite freshwater


cnedin@geology.adelaide.edu.au                  nedin@ediacara.org
Many say it was a mistake to come down from the trees, some say
the move out of the oceans was a bad idea. Me, I say the stiffening
of the notochord in the Cambrian was where it all went wrong,
it was all downhill from there.