Jalapão is a microregion in the easternmost corner of Tocantins, bordered by Piauí, Maranhão, and Bahia. The state park occupies 158,885 hectares within the municipality of Mateiros, one of the most sparsely populated parts of Brazil. No paved road reaches the park directly. To get there, travelers bump for hundreds of kilometers over rutted dirt roads in four-wheel drive vehicles, crossing rivers on small wooden ferries and wading others in the shallower months. That remoteness is both the park's protection and its principal barrier to visitors. The plateaus - chapadas in Portuguese - rise from flat savanna in steep-walled blocks, their tops bounded by cliffs that the constant action of wind and monsoon rain has been carving for geological ages. Most of the park drains into the upper basin of the Do Sono River, part of the vast Araguaia-Tocantins river system.

At the park's ecological center are the Espírito Santo dunes - a small but distinctive desert of red-orange sand rising in rounded waves amid the otherwise grassy plain. The dunes are fed by sand eroding from a nearby sandstone plateau, blown into shape by the steady Cerrado winds. They rise to perhaps forty meters above the surrounding land, high enough that climbing barefoot through the loose sand takes real effort, and in the late afternoon the sun turns the whole formation into a warm copper color that locals photograph obsessively. The dunes support their own sparse vegetation - a few grasses and small shrubs adapted to mobile sand and year-round heat - and they contrast startlingly with the green that surrounds them. Flying over the park, the dunes register as a small, impossible patch of Martian color in the middle of the savanna.

The park's vegetation is a textbook of Cerrado variants. There are dry grasslands and wet grasslands, campo sujo - open grassland dotted with small woody plants - and cerradão, a taller, denser cerrado that verges on forest. Gallery forests line the blackwater rivers in narrow green ribbons. Along seasonal lakes, semi-deciduous vegetation loses its leaves in the dry months. Rare and economically important plants crowd the species lists: cashew relatives, pequi trees, mangaba fruit, and of course the golden grass. Three endemic plants grow here: Acosmium subelegans, Andira cordata, and Parkia platycephala. The hoary fox, Lycalopex vetulus, is a small cerrado canid endemic to this kind of habitat. Two endangered birds - the Brazilian merganser and the Chaco eagle - still find refuge in the park, their populations thin but persistent.

Scattered across the region are fervedouros - literally "boilers" - natural springs where groundwater rises through quartz sand with such force that it creates a buoyant column no swimmer can sink through. Step into one and you find yourself suspended, floating upright, held by the pressure of water moving up. The sand at the bottom roils visibly. The water stays a steady temperature all year and is so clear you can see your toes ten feet below. The fervedouros have become Jalapão's signature attraction, more widely photographed than the dunes. They are, strictly speaking, just outside the state park, in the surrounding protected landscape, but they are inseparable from any story of the place.

The park was created by state Law 1203 on 12 January 2001 and is administered through agreements with the Nature Institute of Tocantins. It forms the centerpiece of the Jalapão ecological corridor, which includes the Serra Geral do Tocantins Ecological Station - a core zone of the Cerrado Biosphere Reserve - and several smaller protected areas. On 21 July 2009, a cooperative agreement between the federal Chico Mendes Institute for Biodiversity Conservation and the state nature institute established joint management for the corridor. The advisory board for the state park was appointed on 15 December 2011. These administrative details matter because the Cerrado, despite hosting nearly five percent of all species on Earth, receives only a fraction of the protection granted to the Amazon. Jalapão is one of the larger and more intact pieces still standing.