AMERICANS WHO regularly visit France in the summer can't be blamed if they spend a good deal of time in Provence--after all, southern France with its sun, sea and civility seems well suited for leaving winter behind. This was the way I spent vacations in France until last summer when my wife, Cathy, who is French, insisted we alter our routine to include a visit to her grandmother in the Alps.

Grandmere has a cottage in Prelles, a speck of a village nestled in a mountain valley five miles southwest of Brianc,on. I had misgivings about spending my holiday in the company of glaciers, but I decided to keep an open mind; besides, we owed Grandmother a visit.

A six-hour train ride from Marseille brought us into Brianc,on, a picturesque fortress town dating back to pre-Christian times. Taking its name from a Greek tribe--the Brigiani--that had settled in the region before the Roman invasion, Brianc,on owes its present shape to the ingenuity of the Marquis de Vauban, Louis XIV's military architect. Commissioned by the king to refortify the town that guards the pass into Italy, Vauban threw a series of daunting walls around Brianc,on that included seven forts.

Looking like a man-made extension of the mountains it dominates, Vauban has proved a bane to all would-be conquerors. Shortly after Waterloo, an Austrian army 20 times the size of the defending French force failed to take the town, and more than 100 years later Mussolini's troops were likewise repelled from its ramparts.

We promised ourselves a return to Brianc,on later and hired a taxi for a 15-minute ride to Prelles. Enfin, vous voila! (There you are, finally!), cried Mamie, as she came running down to greet us. Mamie turned out to be a storybook grandma in a neat calico dress and apron. She's not very tall--most Montagnards aren't--and her kind weather-worn face is ruddy from hours spent working outdoors. She keeps her wispy white hair in a thin little bun. Her bright eyes shone with pleasure as she welcomed us.

Mamie wouldn't hear of letting me restoke her wood-burning stove for dinner, and after checking the evening's menu with me, she shooed me out of the kitchen and onto the porch with a drink. I sat down on the back step and let the mountains work their magic on me. The evening sun poured a golden cast over the Alps, etching their jagged peaks in progressively warmer tones during the final moments of twilight. If I hadn't been called for dinner, I might have stayed put until nightfall just to watch the crags vanish in the dark.

Dinners in the Alps were often sumptuous affairs. That night, for instance, we sat down to a feast that included artichokes fried in olive oil, leek and potato soup, a savory rabbit stew served with a gratin daupinois, a garden salad and cheese. We finished the meal with poached pears and homemade butter cookies.

After dinner we moved our bags across the road to la chambre du ruisseau (bedroom-by-the-stream), where Mamie had rightly assumed we would want to stay. A tiny one-room stone house built on the rock embankment of a stream, la chambre has always been Cathy's summer lodging in the Alps. Its foundation is a stone-vault cellar used in summer to cool milk and butter. The stream gurgles past the cellar door, so we stepped carefully to avoid a foot-numbing soak in snow water.Next morning, standing at the doorstep of the bedroom, I got my first glimpse of Prelles. The village looks as if it had been spilled out of a child's toy bag. The houses fall into one of three clusters separated by stretches of land under cultivation; all three clusters huddle against the Salcette, a looming outcrop of schist studded with mountain shrubs and pine. A stream--the same that coursed by at my feet--flows down the outcrop and straight through the village.

Mountain dwellings in the Alps are three-story structure--stable, house and grange stacked one on top of the other. Mamie's house is typical of the area: no one knows how old it is, and while she says it has been in her family for over 100 years, the crude masonry of the vaulted stable suggests a structure at least 200 years old. Many of the houses are embellished with dainty wooden stairs and balconies.

But if some of the houses have been modernized in the process of restoration, Prelles' water fountains, perhaps more than any other feature, have stood up to the elements. Built as miniature obelisks, fountains appear at every third corner or so, spilling cold mountain runoff into ample stone basins. Some are decorated with iron crucifixes, others with small urns, all of them furnished with broad wooden scrubbing boards that make fine seats when they aren't being used for laundry.

To enjoy the Alps in the summer you have to enjoy walking. The Parc National des Ecrins, one of France's largest parks, and quite possibly its most scenic, lies just west of Brianc,on. The hiker can choose among a number of trails that meander across some of Europe's most dramatic alpine terrain. Paths are carefully marked for ordinary hiking, and an excellent guidebook describing 10 itineraries and the natural history of the region can be obtained by writing to the park headquarters: Ecrins, 7 rue du Colonel Roux, B.P. 142, 05004 Gap, France. The book, simply called Parc National des Ecrins, 10 Itineraires, is also sold at the Brianc,on tourist office right inside the Porte de Pignerol, gate to the old town. Abundant information about lodging, tourism and cultural events is available at the same office.

Because the Alps come right up to Mamie's doorstep, we did most of our hiking outside the national park. Our most ambitious trek--10 hours round trip--took us well above the tree line to a pair of shimmering mountain lakes.

Rising at 5 one morning, dressed against the morning chill, we crossed the village and wound our way up the first of many hills on our way to the lakes. For the first hour we scrambled up pebble-strewn slopes, following paths etched into the mountainside by sheep and cattle moving up to the summer pastures.

Spring and summer are short seasons in the Alps, but what they lack in duration they make with a short and sudden superabundance of flowers. No place on earth could smell sweeter or appear lovelier than the Alps when its trees and wildflowers are in bloom. We stepped into a sweet-scented forest of deciduous pines called melezes. Ramrod straight with luxuriant boughs, these trees have left thick layers of their fallen needles to soften our footsteps through the woods. Nothing but the wind and the occasional call of the cuckoo disturbed the silence.

We had passed no one since leaving Prelles and felt free to imagine ourselves the first passers-by in these lonesome hills. At times we were ringed about by butterflies: multicolored swarms of them careened down the hills intercepting the warm shafts of sunlight that filtered through the shade of the pine boughs. Later bumblebees in search of nectar bumped drunkenly against us as we plowed our way through a meadow waist-deep in flowers. Seeing the first rooftops of Ratiere behind a gentle hill, we quickened our pace.

We rested our packs on the steps of a tiny 17th-century chapel dedicated to St. Anne. The chapel and a stumpy turret of a building grandly named "La Citadelle" sit atop a scattering of cottages--summer dwellings used in the past by families who kept cattle in these parts. It had been practical and common for residents in the valley to move up to Ratiere with their herds for the entire summer, but those herds have dwindled as the younger generations have drifted away from the farms to jobs in Brianc,on. These days even the old-timers hesitate to move their animals up, much less open their houses, so that most of the little stone cottages have become summer retreats for relatives in from the cities.

After a short snack, we looked for the path leading to the lakes. The air was cooler here as we passed in sight of summer snowdrifts. The pines began to thin out at the top of the tree line and then gave way to mountain shrubs. Eventually even the shrubs fell behind us as our path curled upward across patches of snow. But the flowers stayed with us, intensifying in color and number at that cool and windy altitude: yellow and purple pansies, violets and the mysterious "amourette" seemed to run ahead and wait for us as we toiled up the slopes.

The lakes are something of a misnomer. From the top of our last hill we saw two almond-shaped pools, each at most 50 yards across. No less striking for their diminutive size, the "lakes" are free of algae, light blue in color and completely transparent. In the sunlight they glittered like pale sapphires.

We kicked off our boots and set up a picnic. Our simple fare: baguette, goat cheese and Camembert, saucisson, Corsican figatelli, black olives sprinkled with thyme and mountain spring water to wash it all down. Finishing with apricots and a hunk of dark chocolate, we stretched out in the grass. The air was sweet here at the top of the world; we drank it down and dozed off. But too soon a chill wind came rippling across a ravine, setting the lakes astir. The warmth of the sun suddenly scattered in the freezing wind, forcing us back into our sweaters and jackets. It was time to go anyway.

During the remainder of our stay in Prelles, we hiked other trails, picked the mushrooms that abound after a summer rain, rounded up escargots, and visited some of the neighboring villages. Brianc,on was close enough for us to go in on a couple of mornings. Several times a year vendors set up their wares outside the moated entrance to the town. On these days, in addition to offering the usual abundance of fresh produce, certain vendors specializing in products for sheep and cow herders sell cowbells, saddle packs, shears, rope, bedding and dried provisions to pastoralists preparing for a summer in the mountains.

After touring the market, we crossed the moat to stroll in the old town. Brianc,on has remained essentially unchanged since Louis XIV sent Vauban to rebuild the town's fortifications. We sauntered down the Grande Rue--known locally as the Grande Gargouille--Briancon's main artery. A road reserved for pedestrians, the Gargouille follows the course of a man-made stream that bubbles from one end of town to the other. Our tour was a simple matter of following the stream which took us past the town's distinctive old houses with their wooden balconies and their ornamented facades.

Like all pleasant experiences, our week-long visit was too short. As we said good-bye to Mamie and boarded the train to Marseille, we were already concocting plans for next summer. Next time we'd fish for trout, cross into Italy, hike the glacier trails of the Ecrins. Mamie had walked to the edge of the platform to wave us off. She had a way of waving that seemed to say "come back" instead of "farewell." She needn't have worried. We'd be back.