"She could hear it, too. The beat rushing in her ears. Shoomp, shoomp, shoomp."The author used shoomp as a sound effect for the earths heart beat. He had to use the words because you cant hear a book. Example: The bomb went off BOOM!
"Then like a caterpillar, she slowly inched next to him."The author was not being serious when he said this. He meant that she went over slowly. And also she went over a little bit at a time.
"Did you know when you lie down on the land you can hear it breath? That you can hear its heart beating?"The earth could have been beating a little bit. All though it dose not have a heart. The author is trying to say that the land is beating like a heart.