How do plains and valleys located between mountains help?

Question

How do plains and valleys located between mountains help?

Answer 1

It is actually the mountains that help the plains and valleys. Mountains cause airflows to rise, and in rising the air loses its moisture in the form of rain and snow. The run-off irrigates the land below. Without the mountains the air would just pass over the low land, taking its moisture with it.

Answer 2

They are good for shade, and reseviors, like round about the trees.  Where ever their is  a tree their is water.  Same with plains and valleys, that allow life for other creatures.  Makes the world even out with life and nature.