>Evaporites are common in the Green River Formation.
>Evaporites occur in several of the Green River Formation basins. In the
>Green River Basin of Wyoming numerous units of halite, trona, and oil
>shale occur interbedded. The trona is mined commerically. Some of the
>trona contains up to 1% brine shrimp eggs, suggesting an autochthonous
>paleoenvironment. The process of preconcentration of brines via spring
>origin could have increased the rate of brine evolution, but certainly
>not putting it into the framework of the short spans of time being
>discussed here. At Lake Natron (African Rift) trona is erupted directly
>from a volcano, covering it's slopes with a white snow of "evaporite".
>Springs rich in disolved salts also contribute to the lake brines.
>There is abundant evidence of springs in Lake Gosiute (Green River
>Formation in Wyoming), some with dolomitized crusts indicating evulsion
>of highly concentrated spring water. Again, however, when you consider
>the abundant beds of evaporites, stromatolites, and other in-situ
>ecologic factors, it is clear that the Green River deposits represent a
>significant time span.
It has been a while, but it is good to find agreement again. The book I
cited showed two cores of this material from wells which were 5 km apart and
the laminae were corelatable.
glenn
Adam, Apes, and Anthropology: Finding the Soul of Fossil Man
and
Foundation, Fall and Flood
http://www.isource.net/~grmorton/dmd.htm