The road from Chos Malal climbs up a valley towards the southern flank of the Cordillera del Viento, the Mountains of the Wind, in the far, north-west corner of Argentinian Patagonia. Wind is the defining element in Patagonia. Birds fly backwards, trees grow horizontally, car doors are ripped off. The most turbulent winds are here in the Precordillera, or foothills, of the Andes; winds blowing in off the Pacific plough into the mountains causing a collision of hot and cold air masses. Steep valleys act like wind tunnels, causing extreme turbulence and violent changes of direction. Several years ago, a hurricane-force wind tore into Chos Malal, shaving roofs of their tiles, overturning cars and flattening the power lines.

To keep the wind out of the shack where she lives, high on a bluff an hour-and-a-half's drive on dirt roads from Chos Malal, Doña Dominga tapes newspaper over the windows. "I have lived here for 32 years," she says, from her perch on a low wooden stool covered with a lamb's fleece. It is almost dark inside the room, and though it is high summer, Doña Dominga keeps feeding sticks into the soot-covered stove in front of her. To keep out the wind, she is also bundled up in several layers of clothing - a faded lime green sports shirt, a burgundy red sweatshirt, an old blue fleece jacket and dark blue cotton sweatpants. A pair of slip-on shoes made of black velvet and decorated with silver buckles adorn her feet.

Doña Dominga's face is a map of the world she inhabits. Etched with a pattern of fissures and cracks from a lifetime's exposure to Patagonia's fierce sun and winds, it looks like the bed of a dried-up river. An inch-long scar, which she had got when an axe she was using to chop wood jumped back into her face, climbs like a briar from the corner of her upper lip to the edge of her nose. These disfigurements only add to her character. Her deep-sunk eyes are full of humour, her eyebrows permanently arched in an expression of lively amusement.

Her full name is Doña Dominga Rosa Guajardo. She does not know how old she is. Her birth certificate says she was born in 1930. But her parents only registered the birth several years after the event. According to legend, when she was a young woman, she left her fiancé standing at the altar, saddled a horse and rode up into the mountains.

"He was a good-for-nothing!," she says, with a chuckle. "The marriage had been arranged by my family. But I did not care for him. So, on the day of the wedding I got up early and dressed in my bridal clothes. The family went on ahead to the church. But I stayed at the house, waiting to be collected by a horse-drawn buggy that would take me to the ceremony. Instead, I slipped out of my wedding dress and put on some trousers, a work shirt and a pair of riding boots belonging to my brother. I went down to the kitchen and took some bread and cheese and water and a good poncho. Then I went out to the stables and saddled my horse."

When Doña Dominga first came to the Mountains of the Wind she lived in a stone and mud hut, which had been used as a byre for animals. Set into a bank to protect it from the wind, it had a door at the front, no windows or toilet, and a roof made of sticks and branches weighted down with rocks.

Doña Dominga lived there, and in another structure like it, for more than 25 years, until one of her sons built her a tin-roofed shack. She has always worked as a puestero - or in her case, puestera - a Patagonian term that roughly translates as shepherd (-ess). A large estancia can have as many as six puesteros scattered across the land. They live in small huts, without electricity or running water, almost completely cut off from the world. Very few are women.

"I always worked like a man," says Doña Dominga, lifting a blackened kettle off the stove and pouring hot water into a red enamel mug to make yerba maté, the traditional drink of Argentina. Adding some sugar, she begins to suck contentedly at the hot liquid with a metal straw. "I looked after the animals, collected firewood, fixed fences. I also washed clothes to make money."

Though she never married, she did have seven children, by several different men. All but one were born at home in her hut with a female neighbour acting as midwife. "I have nine grandchildren as well," she says, proudly, fetching a tray piled with six mounds of bread dough, which she puts in the oven to bake for the evening meal. For the first time, a look of sadness passes across her face. "But their parents don't let them come and visit me."

Was it because her children disapprove of her because she had borne children by different men but never married? Or was it just because she is different; a cantankerous old woman who defied convention and therefore set a bad example to the young? She won't say.

The room we are sitting in has a dirt floor and smoke-blackened walls made of mud and rough-hewn stone. An old dresser along the back wall contains a few cups, some tin plates, a small collection of battered cooking pots and some basic kitchen utensils. A dust-covered transistor radio hanging from a nail is the only piece of modern technology in sight. I ask Doña Dominga if she ever dreamed of being rich, of having a car and a house with a swimming-pool, and all those other things that are held up as the non plus ultra of human existence. She snorts with laughter at this.

"No, I don't want to be rich," she says, as a gust of wind lifts the newspapers, bringing with it a cloud of fine dust and grit that gets in my hair and eyes and into the seams of my notebook. "Rich people are all selfish and greedy!" She grows serious. "I was born with a paso corto, a 'short step'," she says, with quiet pride, using a local metaphor to describe her humble beginnings. "And I would like to die like that." Her face breaks into a smile. "Though I would like to have electricity!"