Shader for terrain wich that reacts to the height

Good day!Prompt please, whether really using Shader Forge shader to make terrain shader, which will impose the texture, depending on the altitude? For example, in the lowest part of the texture of grass, just above the rocks and very high snow texture.

Honestly I have no idea even which way to look. So I would like to know whether it is at all possible?

Thank you in advance!