How is the text structured? How does this structure lend the reader ease of comprehension?

The text is divided into three sections, "Down the River," "Into the Wild," and "Up in the Air." Each of these sections contains either two or three chapters. The "Down the River" section details Kolbert's explorations of the Chicago Sanitary and Ship Canal, the Plaquemines Parish, and the Mississippi River. The "Into the Wild" section details her explorations on land, including her studies of Devils Hole pupfish and Australia's cane toads. The "Up in the Air" section then describes Kolbert's research of atmospheric and climatic changes.

By organizing the text in this manner, the author guides her reader from water, to land, to sky. Each new environmental realm introduces a new set of human-inspired conundrums, and humans' attempts to mitigate these issues. This structure lends an otherwise complex text a neat formal...