She had long, black hair, set off by colourful clothing woven

in the finest alpaca wool, a slender, graceful neck, and well-

muscled arms. She was sacrificed to the god of Mount Ampato,

a 6,300-metre volcano in the Peruvian Andes, by a group of

Inca priests. Over the space of five centuries, successive

layers of freezing snow buried her in a deep blanket of ice.

But dark grey ash from a neighbouring volcano had, over time,

caused the ice to melt and a nearby ridge to collapse, freeing

the young Inca girl from her centuries' old resting place.

In September 1995, Johan Reinhard ascended Ampato where, on the summit, he and his Peruvian climbing companion sighted a bright red feather headdress normally found on Inca ceremonial statuettes. For an expert in high-altitude sacred archaeology such as Reinhard, this was a clear sign that he was on the verge of making a red-hot discovery.

Sure enough, not so far away, he found the mummy herself, a bundle cocooned in textiles and perched atop a pedestal of ice. Remarkably, she was still entirely frozen. Strewn around the frozen body were figurines made of gold, silver and rare spondylus shell as well as corn, coca leaves, llama bones, and pottery fragments.

Of his more recent discoveries, possibly the most spectacular is his excavation, in 1999, of three frozen Inca mummies on the peak of Llullaillaco in Argentina, which, at 6,739 metres, is the highest archaeological site in the world. So well preserved that their facial expressions were still intact, as was the fine hair on their arms, it was as if they had only just been buried. Their hearts and lungs still contained blood. With this quality of information, researchers may determine whether they were genetically related, and even whether they have any living relatives, thus providing a rare opportunity to trace their line of descent to the present day.

Children were favoured over adults for sacrifice, as it was thought that their purity would make them more effective messengers to the divine world. Indeed, a sacrificed child was believed to have been so honoured as to have, in effect, become deified - a direct representative of the people, living with the gods forever after.

Why did the Incas go to such lengths to offer sacrifices to the mountains? Perhaps because they saw them, not just as places where gods lived, but as actual gods whose generosity was as unpredictable as their wrath. The Andes were the backbone of the powerful Inca Empire which stretched 2,500 miles between Chile and the equator. It came to an end in 1533 with the assassination by the conquistadores of the monarch Atahualpa.

Reinhard's discoveries are startling not only for what they tell us about the sacred mysteries of Inca culture, of which so many records were destroyed - but also for the extreme conditions in which they were carried out. Seventy mile-per-hour winds, fierce storms, frostbite and altitude sickness… all of these have been overcome as Dr Reinhard continues to fit key pieces into the rich jigsaw of Inca mountain mythology and provides the world with new instalments of his remarkable adventure.