EVERY day Berta Sulca, a goat-herder, wakes up in her stone hut high in the Argentine Andes, packs the youngest of her 13 children off to a distant school, milks 50 animals and makes cheese. It's a hard and fixed regime, except that occasionally something unusual happens.

A smart white van will slow to a halt on her remote mountain track, the door opens and out steps... someone like me. A tourist, come to stay.

It was a peculiar meeting we had that day.

On the one hand, the shy, impoverished Berta in an isolated valley called La Quesera, and on the other, a tiny tourist group crossing the mighty Andes for fun, pausing for a night to sleep in a luxury tent in Berta's yard, and eat wonderful food that a cook had driven two hours to prepare, before showering in sweet fragrances under hot water, in a converted barn.

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• On the wine train through Chile

It was an unusual juxtaposition of cultures, even values. But Berta was pleased enough to see me (she gets rent when foreigners call), and I certainly found my hostess charming, welcoming and natural - she was, in fact, an intriguing centrepoint to our journey, a memory to hold on to at 3,500m (11,500ft) in a landscape where pumas stalk and stream water is the only sound at night.

We had started our trip in Chile, on the western side of the vast 7,000km (4,400 mile) ramble of rock and colour - browns, whites, yellows, blues - that is the high, mythic Andes. Aiming to cross from there to Argentina by van and on foot, we acclimatised first in the Atacama desert, a region I had longed to see for much of my life.

This is the driest place on earth, drier than California's Death Valley - so arid that in some places no rain has fallen, ever. The result of all this scorching heat and night cold is a convoluted landscape so diverse that it seems a poor thing simply to stare.

So we did things. We biked, hiked, staying in a relaxed hotel called Explorer en Atacama on the outskirts of the San Pedro de Atacama, a one-time mining town that offers a pleasingly down-at-heel, mud-walled strangeness to tourists seeking a taste of desert life. Here, 2,400m above sea level, we spent three days testing ourselves at increasing heights in preparation for the journey to come.

Take just one experience. Five of us walked to Moon Valley in the Sal mountains, setting off as the sun slid behind red-rock ridges of clay and eroded gypsum studded with chunks of glinting, volcanic salt. On a mud-flat we sweated in heat, awed by the configurations of rock walls looming over us. Yet within 20 minutes we were up on the heights, blasted by bitter, fierce winds as we looked down on enormous salt flats 30km away, glinting like an ocean of trapped waves. We had at least five experiences like this, all equally strange, all peculiarly unearthly.

Then came the journey itself, piling into a van loaded with wine and food, a witty Chilean guide called Chino offering insights into everything we passed: heading 200km to the Argentine border, then a further 500 to the town of Salta on the other side of the mountains, mostly driving, sometimes walking. They call it a “travesia” - a crossing, a true journey.

The formalities we met were ludicrously low-key - isolated outcrops of officialdom in vast stretches of desert and mountain, bureaucrats with ponderous stamps who were happy to see anyone at all on a lonely day in nowhere. As we left Chile, a guard came out to stand under his national flag to be photographed, waving as we drove past his barrier into the emptiness.

The road was rough and stony, the track always rising. The sun shone brilliantly on occasional lagoons, salt-flats and ice-rims on rare wetlands.

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