Hi! I am happy to contribute to all of you with a gift!
I made a node group with masks to help you create a landscape material.
It have:
- sea humidity mask
- grass mask
- snow mask
- sand mask
- and rock/mountain mask
It is a simple node group so you can use it as you want.
The node group have settings so you can adjust the level, the multiplier and more other options of each mask. Each mask have the corresponding attributes to touch.
I don’t provide any textures or shaders, it is a set of masks that automatically fits on a landscape mesh. It was created for Eevee, I don’t know if it will work with cycles.
You can create a landscape with A.N.T. and test it, but make sure to make it very big: ie. 100x times (don’t forget to apply the scale transform), if not you will need to touch the attributes in a very fine manner (les than 0.01).
I hope this will be helpful for your projects. 
Download it from: https://gum.co/fRUE