>At the base of the Coconino is the Hermit shale. What is the widely
>accepted environment of deposition for the Hermit? Isn't it marine? I
>didn't look because I figured you knew. If it was marine, then synaerisis
>cracks would be expected but this would have nothing to do with the
>overlying Coconino which, filling the cracks, came later than the Hermit
>depostion.
Hermit is generally accepted to be terrestrial in origin. It has lots of
plant fossils and lots of mud cracks in lots of units. But none of them
penetrate more than part of a single unit. The presence of the giant
sinaresis cracks that penetrate many layers of the shale indicates that the
Hermit was still fully hydrated when the cracking occurred, which would
require a lot of water. I should mention for your edification that there
are some marine limestone units interbedded with the Coconino in the
northern part of the basin.
Art
http://chadwicka.swau.edu