Sierras of Cordoba
Sierras of Cordoba Geography & Climate
Geography
The Sierras of Córdoba are among the oldest mountains in Argentina, worn down over hundreds of millions of years into rounded granite ranges rising abruptly from the surrounding plain.
The ranges
Three roughly parallel chains run north to south. The Sierras Grandes in the middle are the highest, reaching 2,790 metres at Cerro Champaqui, with the Sierras Chicas to the east and the Sierra de Guasapampa to the west. The rock is Precambrian granite and gneiss — older than almost anything in the Andes, and shaped by erosion rather than by recent uplift.
The Pampa de Achala
A high granite tableland above 2,000 metres running along the top of the Sierras Grandes: treeless, wind-scoured, dotted with rock outcrops and tussock, and quite unlike the wooded valleys below. Rain falling here feeds most of the province’s rivers.
The Quebrada del Condorito
A gorge cutting into the Achala plateau, where the thermals rising off the walls make it the easternmost regular breeding site of the Andean condor — hundreds of kilometres from the Andes proper.
Rivers and reservoirs
Short, clear rivers run off the ranges into the valleys and are dammed for Córdoba city’s water. The Punilla valley holds the San Roque reservoir, and the rivers are what the holiday towns are built around.
Why the ranges run north to south
These are the Sierras Pampeanas, blocks of ancient basement rock pushed up along faults as the Nazca plate subducts unusually shallowly beneath this part of the continent. The same flat-slab subduction that raised them suppressed volcanism here, which is why there are no volcanoes in these mountains and why the rock is granite hundreds of millions of years older than the Andes to the west.
Salinas
North-west of the sierras, the Salinas Grandes of Córdoba — a separate salt flat from the northern one — covers a large depression.
Climate Patterns
The sierras have a dry temperate climate that has made them a health resort as much as a holiday destination.
Summer
December to February reaches 28 to 33°C in the valleys, cooler with altitude, and the humidity is low. Afternoon thunderstorms build over the ranges most days in high summer, arriving with sudden force and often with hail, and then clearing to a cold night.
Winter
June to August is the dry season proper: brilliant clear days of 15 to 20°C, and nights near or below freezing. The Pampa de Achala gets frost most nights and occasional snow. The dryness and the sunshine are why the valleys filled with tuberculosis sanatoria in the early twentieth century, and why the Guevara family moved to Alta Gracia for their son’s asthma.
The daily range
Wide, because the air is dry and the altitude moderate — fifteen degrees between afternoon and dawn is routine, and the evenings turn cold quickly even after a hot day.
Fire season
The combination of a dry winter, cured grass and spring wind makes August to November the fire season, and large fires burn in the sierras most years. Open fires are banned and access to some areas closes.
Why the sanatoria were built here
Before antibiotics, the standard treatment for tuberculosis was dry air, sunshine and rest, and these valleys had all three at a comfortable altitude with rail access from Buenos Aires. Dozens of sanatoria were built between 1900 and 1940, and several of the grander hotels in the Punilla valley began as them. The buildings are still there, and the region’s reputation as somewhere you go to feel better long outlasted the medicine.
Rain
Around 700 to 900 millimetres a year, almost all of it between October and March.