Terrain color varying with height

[Anthony Appleyard]

The attached zipfile contains a Terragen job that makes a scene with a lake. The land is covered with grass - including the bed of the lake. Please, in detail, what must I do (inserting nodes, etc) to make the land below altitude 0 (= the bed of the lake) grey and steep slopes brown (bare rock) and the flattish dry land green?

[yossam]

Distribution shaders work wonders..............look at the wiki. 

[Upon Infinity]

Go into the shaders panel, and switch your base colour to your stone colour.  Add a new surface layer.  Make this your "grass" colour.  The surface layer has built-in limits to control slope and height parameters.