Thanks for your feedback. I too prefer the one with a little sand here and there, as it is less boring, but it really depends on the customer (who should tell me what underground she needs). I prefer a river with large sandy and bouldery areas, with higher elevations grown by veggies, but that may not be the case here.
Yes, Kadri, even to get this simple river, needs a lot of nodes and masks. Growing more complicated as I want more. Like the offstream polygonal elevations, with rotting low areas in between, and small cracklike watery areas in those, where the vegetation is also less pronounced. These showed better in my previous post with the more detailed marshland, however. The upland area I gave a little more greens, and since the elevation is so gradual (read from the maps) I made it a bit random indeed. Maybe I can make it tighter.
I still need the pollen data from this era, so it may all change (to more vividnes too).
The elevation of terrain to distance should work, but I don't know how strong I would need to make the effect to be helpful, and if it wouldn't be a bit strange, so I'll leave it like this for the moment.