I was roused at daybreak by the most welcome sound a skier could awaken to: the soft poom of distant avalanche guns, which Snowbird ski patrol was using to control the glorious welter of snow the heavens had dumped overnight.

I'd flown into Salt Lake City late the night before, heading into the mountains through a magnificent blizzard that infuriated the van driver and thrilled his passengers in equal measure. And by this mid-March morning, with the week's snow accumulation nearing the four-foot mark, it was clear that Little Cottonwood Canyon was enjoying the kind of extraordinary conditions a casual skier will experience only a handful of times in his life.

Nestled in the Wasatch Mountains, the canyon is a well-known snow trap. As storm systems come in from the west or northwest, they pick up moisture from the Great Salt Lake, travel into the canyon, and run smack into a headwall. Corralled by the mountains, the clouds then seek to escape by rising into colder air, which causes them to drop prodigious loads of powder on 64-year-old Alta, Utah's oldest lift-served ski resort, and Snowbird, a flashier upstart founded in 1971.

Alta and Snowbird have far more in common than otherwise, but a gentle chauvinism nonetheless abides among each area's denizens, making the two resorts seem like a pair of proud nations sharing a border. As the rustic pioneer of Utah powder skiing, Alta prizes its laid-back atmosphere and purist no-snowboarders policy. Snowbirders, meanwhile, boast of their area's varied terrain and the reasonable lines made possible by a base-to-pinnacle aerial tramway and three high-speed quads. Both resorts are renowned for steep, challenging runs and generous snowfall.

For most of their history, Snowbird and Alta did not particularly encourage cross-border contacts. Starting last season, however, the two resorts began offering a kind of alpine visa, the Alta Snowbird Pass, which permits skiers to explore the two areas' combined 4,700 acres. To transport travelers across the frontier, a new high-speed quad was built at Mineral Basin in Snowbird, bridging that lofty bowl with Albion Basin in Alta.

I'd learned to ski as an adult at Snowbird's acclaimed mountain school a dozen years before, and in my seven return visits, never crossed the border into Alta to ski both mountains on the same day. So I was eager to make the high-altitude transit. Accompanied by my old friend G.H., a sometime competitive ski racer, I set out, carried heavenward by two chairlifts, the higher of which, Little Cloud, offered a fine view of red-jacketed ski patrolmen tossing explosive charges to generate controlled avalanches. After reaching the wind-blown top of the lift, 10,830 feet above sea level, we dropped into Mineral Basin, on the back side of the mountain, and descended into a bowl of soupy fog and driving snow. Though the powder underfoot was remarkable, visibility was essentially zero, and when I asked G.H. for pointers on negotiating the tricky black-diamond descent, he suggested I "use the Force." Skirting the Hamilton Cliffs, we safely reached the bottom of the bowl.

The time had come to push beyond Snowbird's outer limits. When you visit one ski area year after year, as I do, the terrain takes on a familiarity that can cause you to take for granted that you are near the summit of a cloud-fringed mountain, nearly two miles above sea level, your only means of descent the pair of skinny high-tech planks strapped to your feet. But as G.H. and I were scooped up by the Baldy Express chair and carried through the fog on a slanting journey over territory unknown to me, the wildness of the snowbound mountains was inescapable, and I had the odd sensation of leaving my homeland and venturing into foreign parts.

Snow-cloaked slopes glided by beneath us, punctuated by clusters of fir and spruce, until the chair reached the top of Mineral Basin and deposited us in a no man's land called Sugarloaf Pass. A short shuffle brought us to the border checkpoint, complete with a wooden shack and a beaming young immigration official named Mark.

"So you're what a citizen of Alta looks like?" I asked him, as he checked our traveling papers. "Yep," he answered with almost a straight face, "I'm an Altoid."

Alta's marvelous terrain -- including steep, tree-lined slopes and addictive egg-carton bump runs -- felt awfully similar to that of Snowbird (though I didn't dare risk deportation by saying so). But in addition to the black-diamond descents, Alta offered lazy runs that allowed me to give my less-than-Olympic-strength legs a break. Descending toward our midmountain lunch stop, Collins Grill, G.H. and I cruised down a slope so lovingly groomed that its ridged surface suggested the wide-wale corduroy of a colossal trouser leg. At the foot of this leg, we bore left and skied right up to Watson Shelter, a rustic building housing both a traditional rough-and-tumble cafeteria and the more upscale Collins Grill.

The name Collins evokes Alta's past as both a rowdy silver-mining community and the cradle of lift-served Utah skiing, for the saloon keeper and sometime ore prospector Charles Collins ran the Alta Lodging House in the 1870's, and when the ski area's first chairlift began operation in 1939 -- just two seasons after the country's first, in Sun Valley -- it was dubbed the Collins lift.

Upstairs from the crowds and cacophony of the cafeteria, Collins Grill offered a serenity unusual for midmountain lunch sports. Jazz fusion music wafted from speakers, and instead of clumping around in our ski boots, G.H. and I sat by a crackling fire and slid our weary toes into slippers. Embracing Collins's rugged swankiness, we ordered bison burgers and Champagne -- the latter a tribute to the canyon's light, airy snow, which some call champagne powder. After imbibing a glass each, G.H. and I gave the rest of the bottle to Nancy, a chatty waitress wearing snowflake earrings, whom we subsequently heard giggling in the kitchen with her colleagues as we sipped espresso by the fire and gorged ourselves on a rich cake called Chocolate Decadence.

A pleasant drowsiness settled over us, and when we finally glanced at the clock we realized that the mountaintop border crossing would be closing at any minute. A dash to the Germania lift, followed by a ride on the Sugarloaf quad and a sprint to the checkpoint, enabled us to slip back into Snowbird just before Mark sealed the border.

It felt good to be "home." Once the Mineral Basin Express chair had taken us back to Snowbird's north-facing side, we made a sinuous descent through the Gad Valley, sampling the range of runs, from advanced (Shireen) to novice (Big Emma), that makes Snowbird such a hospitable mountain. Light snow was still falling, dusting the slopes like confectioner's sugar, as we made a final hairpin turn and skied into the base at Snowbird Center.

It was hard to imagine a more convenient end to our day, for a five-minute walk took us to our small but comfortable Snowbird rental condo at the Inn. Before the hour was out, we were luxuriating in the lodge's bubbling outdoor hot tub, gazing up at the mountain we had just descended and sipping a Utah microbrew called Polygamy Porter. Why Have Just One? asks the label, and considering the manifold pleasures of a day split between Snowbird and Alta, the same might be said of ski resorts.

If you go

Getting There

Snowbird Ski and Summer Resort is in Little Cottonwood Canyon, 45 minutes' drive from Salt Lake International Airport and 30 minutes from downtown Salt Lake City. Canyon Transportation, (800) 255-1841 or (801) 255-1841, runs a van service between the airport and Snowbird's lodges for $50 a person round trip, or $44 if you pay by credit card over the phone.

Places to Stay

You can also get the $44 rate if you book the van ride through Snowbird Central Reservations, (800) 453-3000, www.snowbird.com, when you book a room at any of Snowbird's four lodges: Cliff Lodge, the Lodge at Snowbird, the Inn or Iron Blosam (named for an old mining claim). The lodges range from the Inn ($249 a night for a balcony room with two queen-size beds and full bath, in peak season) up to the Cliff ($319 for the same type of room).

Skiing

A Snowbird all-area (chairlifts and tram) pass costs $56 for one day ($47 for chair only); $47 a day for three out of four days; and $43 a day for five days out of seven. Children 12 and younger ski free if staying at any Snowbird lodge (two children per paying adult); children who are not Snowbird lodge guests get a free chairlift-only pass.

The Alta Snowbird Pass costs $64 a day; $56 a day for three of four days; and $52 for five or more days. Collins Grill, (801) 799-2297, is in Watson Shelter, midmountain at Alta. Reservations are recommended. Salads start at $8, entrees are $12.50 to $15, and all desserts are $5.