How to use "valleys" in a sentence

Basically maps that show the lay of the land - hills, valleys, the courses of rivers and streams, footpaths, abandoned logging trails, that sort of thing

Entering the formidable mountains, they had become aware of how soon darkness would settle over the sheltered valleys and ravines, and they had discussed the wisdom of proceeding

It was heavy, this smoke, so when it began to sink down it behaved like a liquid, running down hills and into the valleys

They look for him in the hills and in the valleys