I made this crude example starting to learn the Procedural erosion shader. It is a small area that is masked off so it rendered fairly in this case. There are more settings then imagined. It is hard to understand how the flow map masks work but reading documentation is being worked on.
I was about to write something about maps, but won't take the honor away from Daniil, so I edited it out again.
Not a problem. I am plenty patient exploring this wonderful thing.
Daniil gave me permission, so it's now at his thread.