How does Robert E. Sherwood use imagery in The Petrified Forest?

Imagery:

'I tell you here. You can't tell a killer except by the chin. There's a funny thing about that. A killer always holds his chin in. You ever notice that?"

You better come with me, Duke. I'm planning to be buried in the Petrified Forest. I've formed a theory about that that would interest you. It's the graveyard of civilization that's shot from under us. The world of outmoded ideas. They're all so many dead stumps in the desert. That's where I belong and so do you Duke. For you're the last great apostle of rugged individualism.