Why does the book begin and end at the pond/river?

It is a peaceful place full of foreshadowing. At the end the story comes full circle to the same spot where a gunshot will destroy the same peace and tranquility the place holds. It represents a place for the two of them away from the dangers of other men and women,

George rolled on his side. "No reason at all for you. I like it here. Tomorra we're gonna go to work. I seen thrashin' machines on the way down. That means we'll be bucking grain bags, bustin' a gut. Tonight I'm gonna lay right here and look up. I like it." pg 60