I've just been rewriting this bit in the light of my own experience. My travelling companion read it and says that Burke's trip bore uncanny parallels to ours. (I have to say that we turned back before the pass and spent the night in a stone hut rather than under canvas. But we know exactly how Burke felt.)
Though the trip across the mountains promised to be an adventure, he still found himself reluctant to leave Mendoza. Magnificent as they were, the Andes were unmistakably hostile. The days remained reasonably warm but there was already a nip in the morning air that reminded James that winter was on its way. He put off their departure for one last day of civilised comforts, and then the expedition set out.
As they left the town, they were hardly aware of making any sort of ascent at all. The ground seemed as flat and featureless as it had for days before, but, as their horses trudged onward, Burke was aware of a slight, but steady, gradient. Nothing, though, prepared him for the sudden change from the plains to the mountains. For hours they had moved across the flat, if gently sloping, countryside. Now, suddenly, they were in the hills. The hills, to be fair, were not that high, but the contrast between the plain they had ridden on for so long and this new mountainous terrain was dramatic.
Apala struck out confidently along a valley which twisted and turned until they were surrounded by hills on all sides. There was enough grass for cattle and horses to be grazing but there were cacti too, yellow and red flowers bursting from their green fleshy bodies.
After only half an hour, they were at the head of the valley, and in front of them, they could see the towering heights of the Andes. The track that their guide followed rose more steeply, angling up slopes covered with tumbled rock. For a while, they followed the course of a stream carrying meltwater that would feed Mendoza's irrigation channels, but then they struck off, zigging and zagging up a track that was little more than a dusty trail on the bare rock of the mountain. The Andean peaks closed around them. Facing back down the track, sheer walls of red rock blocked off their view, while ahead they saw the ominous white of the early snows already covering the mountain peaks. The sense of isolation was reinforced by the sight of the condors, circling in the brilliant blue of the sky.
"What do they eat?" asked William.
"They scavenge the dead," Burke told him.
"They're following us."
"We'd best remember not to die, then."
It had been hot in the valley, but, already, Burke was noticing the chill of the air. He called to the guide to stop, so that he could unpack his greatcoat from one of the bundles of baggage hanging precariously from the mules' saddles. Apala, though, insisted that they press on.
"Soon we must stop. We cannot wait for the cold and dark before we make our camp. We will stop in less than an hour. There will be time for you to dress more warmly then."
For another mile, they climbed still more steeply, the track doubling back on itself as they made their way up the mountain. At last it levelled off and, rounding a rocky ridge, they saw a patch of level ground with a shallow stream splashing across the rocky surface.
"Here we will camp," their guide announced. Their porters set to unloading the tents, unused on their travel across the plains. Soon, the sound of mallets on tent pegs was echoing from the rocks as they did their best to secure their guy ropes in the stony soil.
Burke had freed his greatcoat from one of the baggage rolls but, as the sun vanished below the peaks, he felt himself shiver. "We need a fire."
Apala shrugged. "Of course, senor. But first I will have to collect something for us to burn."
Burke looked about him. There were no trees, not even any shrubs. The only greenery in sight was occasional clumps of what looked like moss clinging to some of the rocks.
He watched, astonished, as Apala strode to the nearest of these mossy clumps and tugged at it. Beneath the green coating some straggly wooden stems grew down into cracks in the stone. Burke heard them snap and realised that they were dry and brittle.
"They will not burn for long," said his guide. "We will need a lot. Do you want to come and help me collect it?"
Though he was tired from his day in the saddle, Burke was more than happy to explore the area around their camp. He remounted and set off with Apala, leading one of the pack mules with them. Every time that they saw any of the mossy shrub, they would dismount. The young bushes were no use to them but most had at least some older, dry parts that could be ripped from the ground and roped onto the mule's saddle. Each clump was small, though, and protected by sharp thorns that tore at their hands. It seemed to take forever to collect enough and it was almost dark when they turned back toward their camp, the mule almost hidden under a great pile of brush.
The brushwood needed no kindling, burning fast and brilliantly. For several minutes they all huddled round the fire, enjoying the blaze. But, all too soon, the fierce heat was dying and they threw on more wood to protect themselves against the cold of the night. In less than an hour, what had seemed like a huge pile of fuel was almost exhausted. Reluctantly, they abandoned the fire. They took the sheepskins from their saddles to spread on the ground inside their tents and, wrapping themselves in blankets, lay down to sleep.
James did not sleep well. Several times, he woke and lay shivering in the thin mountain air. At last, the sky began to lighten and he heard the crackle of the flames as porters relit the fire to brew coffee and warm themselves before they started that day's ride.
When he left the tent, it was to find that it had snowed during the night. There was only a thin scattering of white on the ground, but it was a reminder of the dangers of travelling this late in the season.
"We must push on hard," said Apala. "We have to cross the pass before nightfall. It will be too cold to camp up there."
The porters were already packing away the tents while James and William sipped at their coffee. Barely an hour after sunrise, they were back on the horses and pushing on up into the mountains.
There was no snow falling now but, as they climbed, the snow lying on the ground grew thicker. The path rose steeply and, after an hour, the landscape was distinctly wintry. As they neared the pass, the wind, moving through the gap in the mountain range, grew stronger and the snow covering was blown about. In some places reddish or black rock lay bare to the sky while, in others, the snow was banking to the point where the horses would stumble, unable to see their footing beneath the white covering.
"We can't stay on the track," Apala said.
He was right. The snow was drifting off the steeper rocks at the side of the track and banking on the path to the point where there was too much danger of a horse falling and breaking its leg. They urged their reluctant mounts from the apparent smoothness of the path onto the ragged rocks alongside it. Though these were steeper and, under other circumstances, would have made for more difficult riding, the snow lay thinly here and the horses could pick their way in comparative safety. Inevitably, though, leaving the path slowed them down and Burke saw Apala casting increasingly worried eyes upward as the day progressed.
Looking in the same direction, Burke could see nothing. Mist covered the top of the mountains and merged with the snow to make it a blank wilderness of white. He was astonished that their guide could navigate confidently through this emptiness but Apala push them on with no hesitation as to their route. His sole concern was that night might fall while they were still too high on the mountain.
The horses struggled as the snow grew thicker. Sometimes they would stumble in the steeper drifts and everyone would dismount to lead their beasts, which were less likely to fall when relieved of their weight. Climbing through the snow, even for short distances, was exhausting, though. The damp began to leak into Burke's boots and he found himself panting for breath in the thin air. He longed to rest and make a fire to be warm and dry, if only for a few minutes, but Apala drove them on.
Now the mountains closed around them and they were struggling through deeper snow, against a wind that howled through the gap between the peaks ahead of them.
Then the wind fell and Burke was aware that the path was dropping beneath them as steeply as is had been rising before. They were through the pass.