What the heck is this?

[Lone Hunter]

I am still new to the Grayson formation and not familiar enough to know if some things are specific to it or not.  There was a place with large areas of the curled up rubbery black mud with big spaces within of the flat rusty crust #1, and mounding crust like #2, last pic is back side #2.  Best I can describe it and curious what it is. 

[DPS Ammonite]

It looks like iron oxides and iron hydroxides that are products of pyrite weathering. 

[BobWill]

The "crusty" and "rubbery" descriptions suggest the possibility of recent algal growths that can occur in creek beds. 

[Lone Hunter]

I agree on the algea, just thought it was strange how it was intermingled with areas that had none.  I was thinking the shiny white things were some kind of shell,  what exactly are they?  Edit; there is no creek nearby I think it's from standing water, maybe that marl doesn't drain well?

Edited November 23, 2021 by Lone Hunter