Stretching roughly 65 kilometers north to south and 24 east to west, the Pampa de Achala covers about 150,000 hectares of high plain hemmed by Argentina's tallest peaks east of the Andes. Mount Champaquí, 2,770 meters, marks its southern edge; the jagged massif called Los Gigantes guards the north. Because the region catches more precipitation than anywhere else in the province, Argentina declared it a Provincial Water Reserve in 1999, drawing its boundaries along the 1,500-meter contour. The plateau's gentle eastern slopes let water pool and trickle slowly downhill, while its steep western face drops away in cliffs. That asymmetry is no accident. It is the signature of an ancient collision that shoved these mountains skyward.

The plateau is gashed by deep ravines with vertical walls 600 to 800 meters high, some more than a kilometer across. The most famous is the Quebrada del Condorito, the Little Condor Ravine, and the name is literal. The Andean condor, the largest flying bird on Earth, with a wingspan that can exceed three meters, nests on the most inaccessible of these cliffs and rides the canyon's thermal updrafts. In 1996 Argentina set aside the gorge and its surroundings as Quebrada del Condorito National Park, created expressly to protect this population. From the rim, you watch the birds appear as black specks below you, then rise on the warming air until they pass at eye level, unhurried, scarcely beating their wings.

Biologists call places like this sky islands: high ground so cut off that life evolves in isolation, marooned above the lowlands like an island in a sea. The Pampa de Achala is full of creatures found nowhere else. There is a green lizard named for the plateau, a local frog, a high-altitude toad, even an endemic scorpion. Eleven kinds of songbird of Andean-Patagonian lineage are exclusive to these heights, sharing the cliffs with peregrine falcons and black-chested buzzard-eagles. Twisted tabaquillo woodlands, relatives of trees that run the spine of the Andes from Venezuela southward, find their farthest reach in the bottoms of the ravines, while species from cool Patagonia push their northern limit here. The plateau is a crossroads where two worlds overlap and a few things belong only to themselves.

The name Achala comes from Quechua, and in one reading it means something like fancy dress or striking adornment, perhaps a nod to the heavy clothing the original inhabitants wore against the cold. Those inhabitants were the Comechingones, who left their names scattered across these mountains. A still older culture, the Ayampitín, left traces nearby thousands of years before that. Today almost no one lives on the plateau. Roads are steep and often impassable; electricity comes from the sun; water vanishes into bedrock so fast that gathering it is a daily chore. The families who remain raise goats, cattle, and sheep, selling leather and wool, and a few small schools shift their calendars around the winter, when snow and wind force classes to wait for spring.

Reaching Achala means climbing. The paved Camino de las Altas Cumbres, the Road of the High Peaks, lifts travelers out of Villa Carlos Paz and over the summits before dropping into the Traslasierra valley beyond. It follows the line of a far older route, a public trail of footbridges pushed through this country by the priest José Gabriel del Rosario Brochero, the legendary Cura Gaucho who is now an Argentine saint. The modern road has carried stages of the World Rally Championship, and one of its sections honors Jorge Raúl Recalde, a rally driver born in these hills. Few drives in Argentina rise so high so quickly, or open onto such emptiness at the top.