In "Suspended in the Air," what is the rhetorical purpose of the extended discussion of vizcachas?

China Iron uses the unseen burrowing, gathering, and building of the vizcachas as an illustration of the largely invisible hard work that makes the pampas fertile. When people in wagons--perhaps representing a more Western approach to the land--roll over, sometimes crushing these burrows and their occupants, they cannot see this hard work taking place, but they certainly intend to take advantage of the fertility it creates. This echoes her earlier concerns for the unseen laborers who harvest and transport tea and cotton and her analogy about Argentina as a womb.