The gully, slick with water ice, is different from what has come before. Further down, my crampons had screeched on the shale, but here their fangs hit home with a satisfyingly firm thunk. Glancing up through my sunglasses, I can see the summit cross etched against the Prussian blue of the sky, a rude alpine rood bolted into the granite. The map, waterproofed in Ortlieb plastic and stuffed down my jacket, says "Piz Buin, 3,312m".
As we tramp up the final easy stretch my thoughts turn to the descent. Far below, on the moraine at the end of the glacier, at 2,341m, nestles the Silvrettahütte, our shelter for the night. A scarlet Swiss flag asserts its sovereignty in this high country where the border with Austria is rendered arbitrary by altitude. With any luck, I tell myself, on this, the sixth day of the Silvretta Traverse, we should have the magnificent glacial ski down to the hut to ourselves. After all, that is only fair, as we did ski up the hill as well.
Ski tourers and ski mountaineers use specially adapted bindings that release at the heel to allow them to ski uphill. Before the start of an ascent, "skins" - once genuine sealskin, but now mohair and nylon - are stretched on to the base of the skis. The fabric, like velvet, is smooth one way and rough the other, allowing the ski to slide uphill without slipping back down. Once the climb is completed, skins are stripped off, heels are clipped back into the bindings, and the descent is completed in a conventional manner.
Thus equipped, the ski tourer is freed from the tyranny of mechanical uplift and the mountain world is his or her wintry oyster. Tours range from short climbs from lifts to reach otherwise inaccessible terrain, to backcountry expeditions lasting several days.
Many years ago, Sir Arnold Lunn, founder of the Alpine Ski Club, quipped that "the combination of skiing and mountaineering is the finest of all sports". A century has passed since Lunn's pioneering ski tours, and snug soft-shell jackets have superseded tweeds. But still the allure of earning your turns remains. As the writer Arnie Wilson comments: "Ski touring is the ultimate, and in the end, the most satisfying route to the top of any mountain."
The Alps, garlanded with the invisible safety net of mobile-phone signal, may be the most domesticated major mountain range in the world. But still, nothing kills like fresh snow, and every year ski tourers, venturing far from marked pistes, die in glacier crevasses or get caught in avalanches. Therefore, proper training and equipment are essential. As Richard Targett-Adams, a former army officer who now works in Chamonix for Ski Weekend, says: "You can still be unlucky no matter what your experience level, but you must try to take the necessary precautions."
The possibilities, however, are endless. The Alps are interlaced with touring routes; and high mountain huts, offering simple accommodation and industrial quantities of carbohydrates, negate the need to carry tents or fuel. The Silvretta Traverse is one such celebrated tour, stitching back and forth for 80km across the border between Vorarlberg in Austria and the Swiss canton of Graubünden, in the shadow of the lofty summit of Piz Buin.
To me at least, the Romansch moniker of the mountain conjured images of bronzed, hard-bodied girls advertising tubes of creamy SPF extravagance. But, I discovered, this is only because the chemist Franz Greiter decided to christen the sun protection product he invented after the name of the peak on which he sustained terrible sunburn in 1938.
I skied the Silvretta Traverse as part of a group from the Eagle Ski Club, a venerable institution that organises a busy programme of ski touring. Our party assembled in the deep trench of the Paznauntal Valley, in Ischgl, a ski resort deficient in nothing except vowels.
We warmed up on chic pistes awash with bling new Russians, who had brought their petro-roubles and the monocellular cheekbones of their women with them to Austria. Then, leaving the groomed Slavic slopes behind, we switched our Fritschi bindings to uphill mode and struck out hors piste to the south, staging our multi-day odyssey in the Silvretta's delightful mountain huts.
There is a wonderful rhythm to ski touring, beholden to nothing but the daily weather and avalanche bulletins faxed up from Berne or Vienna. Each day we rose before dawn, and, as the first alpenglow struck the crags, we would be off, skinning steadily towards that day's peak or pass, wrapped in merino wool and comprehensive outdoor activity insurance policies. As one of our party put it, we had found "adventure, tranquillity and escape from the crowds".
All in all, we climbed four Dreitausender, or 3,000-4,000m peaks, including the great sugarloaf of Piz Buin itself. But as we skied out of the range a week later, our satisfaction was tinged with slight sadness. The last stretch of our route ran for two nail-biting kilometres over the tenuously frozen ice of the Silvretta-Stausee. The lake's ice groaned and creaked, as if to protest at the unseasonably mild weather.
I could not help thinking, as we skied up the beach at the far end of the lake by a hydroelectric dam, that in a generation's time the Alps' winter mantle may be a thing of the past. However, I reminded myself, that is all the more reason to enjoy the mountains while they still choose to wear white in winter. And ski touring is certainly a fitting swansong for the snow.