There are several words that emphasize the desolation of the valley of ashes. For one thing, the valley is described as "a desolate area of land." The word "ashes" is suggestive of death, and the description of the cars as "grey" and the men as "ash-grey" contribute to the feeling of desolation. The words "dimly," "crumbling" and "ghastly" help us see the valley as a desolate place. Also, notice that everything else "shrinks away" from this area. Have you looked up the word "desolate" in the dictionary yet? If you have not, now would be a good time to do so. This will help you see how all of these words create a desolate scene.