Essentially, this is Random Plateaus, but with a river network, and a significantly upgraded terrain shader that does

- splatdetail distribution
- height blending for texture transitions [Spoiler]
- normals at full resolution
- hydraulic erosion with scouring, deposition, and channel carving, which also uses the above three tricks, so that e.g. sediment is height-blended against the native minerals
[Spoiler]

Here's 5 consequent runs to calibrate what it looks like atm:

[Spoiler]