How does Samuel R. Delany use imagery in Dhalgren?

Example of Imagery:

I crouch in the smoggy terminus. The streets lose edges, the rims of thought flake. What have I set myself to fix in this dirty notebook that is not mince?

I am mad again, he thought. Tears brimmed. He swallowed in a tightened throat. I don't want to be. I'm tired.