Guimarães Rosa published the novel in 1956, and it did to Portuguese roughly what Joyce did to English — invented words, folded syntax, a voice that will not sit still. The whole book is one unbroken monologue: Riobaldo, an old former jagunço, telling a visiting city man about his years as a hired gun in the backlands, about the war between bandit chiefs, about a pact he may or may not have made with the devil at a crossroads, and about Diadorim, the companion he loved and did not understand. The sertão, Riobaldo says, is the size of the world. In 2002 the Norwegian Book Club put it on a list of the hundred greatest books ever written, chosen by a hundred writers from fifty-four countries. It was the only Brazilian title on it. The country that produced it decided the land it described was worth the same protection as the text.

The word in the title is the key to the landscape. A vereda is a wetland strip that forms where the water table meets the surface at the foot of a sandstone slope, and in the cerrado it announces itself from a great distance: a narrow, brilliant green ribbon running through dry, grey-gold savanna. What makes it visible is the buriti, Mauritia flexuosa, a tall fan palm that grows nowhere but in standing water. Where you see buritis in a line, there is a vereda under them. The park holds these by the hundred. Some are little more than boggy seeps; others gather into oxbow lakes or feed out into full rivers. In a biome defined by drought, they are where everything comes to drink.

Between the veredas the terrain rises into broad sandstone plateaus, flat-topped and covered in savanna vegetation, with the drainages tucked into the lower ground between them. Elevation across the park runs from about 660 to 900 metres — not dramatic in numbers, but enough that standing on a tabletop gives you a horizon in every direction and very little in it. Annual rainfall averages 1,400 millimetres, almost all of it in the wet season. Temperatures range from around 16 degrees Celsius to the low thirties, averaging 23. The vegetation shifts with the ground: open field, cerrado, dense cerrado closing toward woodland, and gallery forest along the water.

The park exists partly to protect a river most Brazilians could not place on a map. The Carinhanha rises here, along with its tributaries the Itaguari, the Mato Grande, the Preto and the Canabrava, and it feeds the São Francisco — the great north-flowing river that irrigates and supplies a large stretch of Brazil's semi-arid northeast. Protecting the upper basin means protecting a water supply hundreds of kilometres downstream, which is the quiet, practical argument sitting underneath the literary one. The catchment sits on the Minas Gerais side of the Bahia border, spread across the municipalities of Formoso and Chapada Gaúcha in the state's northwest, and is administered by the Chico Mendes Institute for Biodiversity Conservation as an IUCN category II national park.

The species list reads like an inventory of everything the cerrado is losing. Maned wolves, jaguars, cougars, ocelots and the small spotted colocolo all hunt here. Marsh deer wade the veredas. Giant anteaters cross the open ground; giant armadillos and the Brazilian three-banded armadillo dig it. Carterodon sulcidens, Owl's spiny rat, is a cerrado endemic almost nobody outside mammalogy has heard of. Rarest of all is the Brazilian merganser, a slender fish-eating duck of clear, fast, unpolluted streams and one of the most endangered waterfowl on Earth — a bird that survives in a handful of river systems and disappears the moment the water is silted or dammed. Its presence is the strongest single argument that the veredas here are still working as they should.