Re: Fish Heads
David Campbell (bivalve@mailserv0.isis.unc.edu)
Thu, 15 Jan 1998 19:45:37 -0400>Tue, 13 Jan 1998 10:22:08 -0800 Arthur V. Chadwick wrote:
>>
>> Fish are found in the areas where the laminae are, but not everywhere.
>> THere are specific stratigraphic and geographic regions where the fish are
>> most common.
>
>Good. Then fish fossils are definitely associated with the laminae which
>have been interpreted as annual varves. Now, do we see annual varves
>accumulating today which also have interbedded dead fish which might
>potentially become fossils under the right conditions? We need a
>credible model/mechanism for the preservation of dead fish until they
>eventually get buried if the varve theory survives.
Do we see annual varves accumulating today that don't have interbedded
fish? I'm still not sure there's enough evidence yet in this discussion to
claim support in any direction.
>
>I am also surprised that the laminae were not destroyed by bioturbation
>if this was a lake-bottom environment of slow accumulation.
>
>Bill Payne
Lamination is not surprising if the bottom of the lake was low in oxygen
and thus uninhabitable by bioturbators. This is commonly the case in
modern lakes; all I know relevant about the Green River is that there are
some evaporites (indicating limited drainage and warm, low-oxygen water)
and oil shales (indicating low oxygen) in the area.
David C.