Your thoughts about rate are most interesting:
>>What do you see as sure evidence for slow rates?
>>
>
>The sheer thickness of the deposits (knowing that evaporation is a slow
>process), the presence of alternating seasonal layers like tree rings, the
>presence of different kinds of impurities deposited at different times of
>the year forming descreet layers, the lack of significant amounts of
>sediment mixed with the salt (which would have occurred if deposition had
>been rapid), etc.
>
The great thickness --
Knowing that evaporation is a slow process, and would presumably have to
occur at about sea level, would you postulate a large coastal salt flat
that gradually sank (or a sea level rise) at just about exactly the rate of
the buildup of the salt? Why would the salt layers that had crystalized
not re-dissolve when they went below sea level?
Or if it were inland salt flats, like we find in deserts today but larger,
are you postulating that there would be so much salt in the surrounding
hills, that the layers of crystalized salt would eventually reach 100 ft.
thick, in a long period of time without any tectonic disturbances?
Alternating layers --
Are you saying that yearly seasonal variation is the only possible
interpretation of the observation of alternating abundances of the
impurities?
Lack of significant amounts of sediment --
Do you really think _less_ sediment in the salt indicates _more_ time?
What rate would be optimal for the least sediment (wind blown or water-borne)?
Thanks for your input.
Karen