The life of E. Annie Proulx is almost as magical and exotic as her fiction. At an age when most people are settling for a slow retirement, she is engaged in a fever of activity: rising at 4am to write, skiing, hunting, canoeing, building and hiking. “Oh, and mountain-biking,” she cuts in, with no trace of irony. “I’ve recently taken up mountain-biking. It’s terrific fun.” It is worth pausing to remember that this is a woman soon to celebrate her 62nd birthday.

Proulx (pronounced to rhyme with Crewe) is accurately acclaimed as a pioneer spirit, a writer from the frontier for whom the great outdoors is a redemptive arena. She lives alone in a large, echoing house high up in the Rockies at Wyoming. The air is thin and bracing there; from her front porch she can see for miles. She loves the rugged terrain and the extremes of the climate. There is snow on the ground for at least eight months of the year, and for much of the time there is a big, dipping wind.

After three failed marriages and many restless years roaming across America, Proulx feels settled in Wyoming and is enjoying a period of remarkably sustained creativity. Her visit to London coincides with the appearance of her new novel , Accordion Crimes , which was shortlisted for the Orange Prize. She strides into the foyer of her central London hotel with an intimidating vigour and purpose. Tall and big-boned, she carries herself like a man. Her handshake is firm.

Though it is a hot, humid afternoon, she is dressed entirely in black, down to the frames of her wire-rimmed spectacles. She has the pallor of Andy Warhol, her blonde eyebrows incongruous beneath her dark fringe. She has (unfairly) been tagged an awkward customer, one who unashamedly terminates interviews if asked a “banal or idiotic” question. Such as? “Oh, I don’t know,” she says. “Something like, ‘what is this book about?’ ” Oh dear, there goes my next question.

A woman of paradoxes, Proulx craves solitude but also surrounds herself with a close network of friends - people who share her exuberance and violent energy. “My friends are the kind of people who step over borders, move in and out of several languages easily,” she says.

“They are people who keep residence in gritty places and like music and food and cooking; people who have lots of boyfriends and girlfriends and are always entangled and in libellous situations. These are the kind of people I like, and this is the kind of life I have.”

Proulx speaks as she writes: in tumbling torrents of words. She is a writer in a hurry, haunted by lost time, the years she spent “doing things that I never wanted to do, things like getting married”. She feels the lost years like a burden. “I came to writing late and am racing to get everything down; my head is full of stories.”

Asked about her marriages, she becomes shy and evasive. “I always hated domestic situations. I don’t think I was a particularly good or diligent mother (she has four adult children). I grew up at a time when you were supposed to get married and I guess I was a slow learner. It took me a long time for the obvious to become obvious: I could not operate in a conventional family.

“When you are in a domestic situation, you can’t get up in the middle of the night, turn the music on and start writing; or go to bed in the middle of the afternoon. So it wasn’t until my last child left home - when I had no responsibilities beyond myself - that I began writing.”

As a result, her first novel, Postcards, was not published until she was 56. It is about a man who kills his girlfriend, buries her body on the family farm and then flees from his guilty secret. Like all of her books, it features a long, anguished journey across America. For Proulx, America remains a “vast continent of discovery”, a vessel of migration and new beginning.

Postcards, though full of good things, offered no hint of what was to come. For Proulx’s second book, The Shipping News, is one of those rare things: a narrative so fresh and unexpected that its author’s life is utterly transformed by it.

Abig, sprawling, exuberant treat of a book, it is set in Newfoundland and concerns the struggles of Quoyle, a bumbling journalist, as he brings up his children after his adulterous wife is killed in a car smash.

The real subject of the book, though, is Newfoundland, a wilderness of winds, ice and fog. Proulx’s descriptive writing has a disconcerting power; her book reads like an elegy to a vanished world. “The force of contemporary life is rushing in on Newfoundland,” she says. “The community and way of life I describe in the novel is already disappearing.”

The Shipping News won many major fiction prizes, including the Pulitzer, US National Book Award and the Irish Times Award. It was translated into 20 languages and sold about three million copies worldwide, a figure more usually associated with a pop record. Proulx is humbly flummoxed by its success. “People tell me that I have a global readership, but I just can’t explain why; I just don’t get it. I expected the book to sell no more than a thousand copies.”

The fortune she must have earned is invested in a trust fund for her children. “I am not a money person,” she says. “I pay myself a not very staggering salary and I live very modestly. So it’s there, but I don’t use it. It’s not my thing.”

Accordion Crimes spans 100 years and follows the fortunes of five generations of immigrants. They are linked by a green accordion, which serendipitously passes from hand to hand, across the country and down the years. The book is constructed on an epic scale, rather like America itself. There is music and dance, murder and mayhem.

It is exhausting to read - precisely because Proulx has inexhaustible energy. There is no risk that she will not take. No facet of life in which she is not interested. “The book is an examination of the American obsession with self-discovery, with self-invention,” she says. “In no other country is it given that you will reinvent yourself - and you can. I mean, you can change your face, your shape, your state, your name, even your relatives. I find this rather intriguing and wonder if the seminal point of departure for this whole attitude wasn’t the immigrant experience, where people were forced, as soon as they set foot on shore, to start reinventing themselves.”

Proulx knows all about self-reinvention. Born in August 1935, she grew up in rural Vermont. Her Quebecois father was a travelling textiles executive; her mother a resolute Yankee. Her early years were marked by constant upheaval and movement. She was the eldest of five sisters and her peripatetic childhood left her with an inability to put down roots. She dropped out of various colleges, had “terrible marriages”, drifted and travelled, brought up her children in poverty while all the time harbouring a “secret desire” to write.

Proulx refuses to acknowledge that there is a streak of obsessiveness in her character, despite the contradiction in her reply: “I’m not obsessed with writing,” she says. Then, in the next breath, she explains that she is simultaneously working on three books - a novel, a novella and a collection of stories - that she travels across the country compiling thousands of pages of research material for each book, and frequently becomes hooked on certain writers so that she “gorges on their work until I feel sick with excess”.

“You know, the best part of writing Accordion Crimes was that it gave me a chance to roam about America listening to music for a year or two,” she says.

“To get the background right for the Tex-Mex section, for instance, I hung out in Texas with my friend Pat Jasper. Together we went down to the nightclubs in Houston, San Antonio and Austin and we just went for it. I gathered so much material that I had to leave 90 per cent of it out of the book. I had a great time, though.”

After what she calls the “fabulous distraction” of her visit to London, Proulx is anxious to return to Wyoming and to her writing. Time spent away from her desk is wasted time, for E. Annie Proulx waited so long to become a writer that her greatest fear is that she will die before she can complete “all those books that I’ve got stacked up in my head”.