From the Himalayas to the Alps and Rockies, mountain glaciers are rapidly melting. A sign of a warming climate, their retreat may also threaten hydropower and water supplies for cities below. To put current trends in context, scientists at Columbia's Lamont-Doherty Earth Observatory are studying rocks that record the ebb and flow of ice since the last ice age, over the past 20,000 years. They will travel the high peaks of the Peruvian Andes, including Nevado Coropuna, a 22,000 foot volcano. Other scientists will study pre-Columbian remains on the mountains. Geologist Gordon Bromley reports from Peru, while geochemist Gisela Winckler writes from the Lamont campus.
1 August 2011 – Final Dispatch from Arequipa, Peru
Now, after more than six weeks trawling the Peruvian Andes in search of palaeoclimate clues, we’re out of time. More than that, rather exhausted, too. Since we left Ampato, Matt has gone back to Tacoma, leaving Kurt and me to visit potential calibration sites near Coropuna. The objective of that ongoing work is to refine the cosmogenic surface-exposure method for the tropics, thereby improving the precision of new and existing datasets. It’s therefore a very high priority.
Many hours of rough driving over destroyed mining roads brought us finally to an isolated copper mine north of Coropuna. There, having waded through piles of bureaucratic red tape and caught a wretched cold from a forlorn security guard, I spent a few days exploring potentially suitable lava flows, while Kurt went off in search of palaeoindian lithics and rock shelters. It’s a fine spot, with amazing volcanic features and stunning views of Coropuna, and boasting more viscacha (a type of Andean rodent/rabbit/monkey mix) per square meter than anywhere else on Earth. It’s too early to say whether this area will prove useful, but the search itself certainly constituted a worthy adventure.
With our last samples collected and bagged, these last few days have been a whirlwind of tying up loose ends, such as returning the vehicle, shipping 100 kg of stones back to Lamont, and eating as much as possible. Arequipa is a lovely city, and a fine place to call base camp, but with so many chores to be done it was with a great measure of relief that we climbed onto the plane again at the foot of Volcan Misti, bound for Lima and, ultimately, the northern city of Huaraz. I could go on for pages about the splendours of that place, tucked up in the stupendous Cordillera Blanca, but I shall save it for another year. As for now, I shall swap icy peaks, tents, and blue skies for the record-setting heat of urban New York, while Kurt heads back south to Arequipa for a while longer to complete archaeologic lab work there. This has been a fantastic season, our most successful yet – I hope you’ve enjoyed following along from a safe distance.
20th July – Dispatch from Nevado Ampato, Andes
Our camp is at 5045 m on the dusty slopes of Ampato, an extinct, ice-clad volcano in the Western Cordillera. This is the very mountain from which Juanita, the famous Incan ‘ice maiden’, was plucked back in 1995. The tents are clustered in the lee of a large glacial erratic and, now the clouds have cleared, the view is second to none, taking in the dry plains far below and myriad volcanic peaks in every direction. Of these, only distant Ubinas shows any activity, letting slip the occasional cloud of ash. To complete the picture, behind us are the hulking masses of 6380 m-high Ampato and it’s smaller yet more violent brother, Sabancaya.
Yes, it is a fine place to call home as we begin mapping and sampling moraines of late-glacial and Holocene age in this part of the world. For added interest, the landscape here is dominated by sinuous lava flows that extend many kilometres from Sabancaya’s summit to the puna below. These black tongues of rock are both grotesque and strangely beautiful, especially when dusted with snow.
Speaking of dust, or rather sand, recently it has become a bit of a plague. Given the propensity for volcanic activity in this part of the Andes, our peaks camp is located on a surface of black sand, dust, and gravel, much of which becomes airborne during the fierce wind storms we’ve been experiencing. Just yesterday, as we were working on the youngest and highest moraines on Ampato, we happened to be suffering through a particularly bumpy spell of weather.The wind was funnelling down from the peak and pushing around waves of drifting snow. It was truly invigorating! From our high perch, though, we watched as plumes of dust were lifted by the wind from the plateau below, forming a brown blanket that came to obscure all but the highest peaks before spreading south to torment the city of Arequipa. By the time we returned to our camp that afternoon, our world was one of particulate matter. Sand in our food, sand in our tents, sleeping bags, and clothes. Worst of all, there was sand in my tea. But then, they always did say it takes a lot of grit to be a glacial geologist.
14th July – Dispatch from Chivay, Peru
After a busy few weeks in the Cordillera Carabaya, we’ve said goodbye to the snowy, tempestuous climate of the eastern Andes and are moving west to the desert of Arequipa. Here the mountains are massive, isolated volcanoes, many of which exceed 6000 m in elevation. In fact, Coropuna is the third highest mountain in Peru and certainly the most sprawling. It’s a landscape dominated by lava and aridity, and populated only by wild vicuna, condors, and a few hardy llama herders. Our first stop was Chivay, a lovely little town nestled in the upper Colca Canyon under the shadow of the enormous Nevado Ampato. We spent a day there recharging, replenishing our stocks and generally avoiding the blizzard on the plateau above. This being the desert, we had not anticipated that the bad weather would follow us west, but evidently it is possible. There is nothing quite like driving through the night, down the side of a canyon, in a snowstorm to focus the mind!
Our work here involves mapping both the glacial deposits and Holocene lavas on the two volcanoes, Ampato and Sabancaya. Though in sight of Arequipa, the place is actually more remote than Coropuna, accessible only via a two-hour drive down a washed out dirt road. This is a new region for us and so it promises to be a fascinating few days of exploring.
10th July – Dispatch from Nevado Tolqueri, Cordillera Carabaya, Andes
We have acquired a dog, ¨”Mooch”. Walking back to camp yesterday, amid driving snow and fully laden with rock samples, there he was exploring what passes for our kitchen. Unlike most Andean dogs – ferocious beasts trained to keep geologists from harassing the livestock – this one is a cheerful soul, happy to hang around and be fed whatever is going, and always up for affection. Where he came from we don´t know. We´re camping at 4750 m in a shallow valley between moraines that keeps the worst of the wind at bay.
There is nothing to burn here and so the nights are frigid, though the view of the entire Cordillera Carabaya, as far as Bolivia, is superb. There are a few hardy souls farming alpacas up here, so presumably the canine comes from one of those, but nobody seems to be missing him. Last night he cleaned our plates and pans, as the snow fell all around, and this morning he was still there. I awoke to find Mooch curled up by the stoves, tucked up in a snowy ball. He immediately perked up once I arrived and waited with agreeable patience as we made a sort of rice pudding for breakfast. Then, with breakfast done, he followed Matt and me as we went off to collect a few more samples for surface-exposure dating. It will be sad to leave the pup, but we must head west soon to the desert Andes. And as Kurt noted, a high-altitude dog accustomed to sleep in the snow would hardly fare well in subtropical New York!
A word on the weather here. It´s taken a turn for the worse. We´ve been working on LGM moraines beneath Nevado Tolqueri and have made great strides there, collecting tens of samples from a fantastic sequence of moraines. But a drawn out storm has engulfed us from the east, appearing first as enormous thunder clouds and transitioning into incessant snow and high wind. It´s not quite what we´d expected but what can you do? It´s times like these we wish we had a kitchen tent instead of a patch of open mountain for cooking. It will be interesting to see how far west this system goes. In the meantime, we will try to keep our feet dry and the dog fed.
4th July – Dispatch from the Andes
Thanks in large part to Matt, an undergraduate from Pacific Lutheran University in Washington, we now have more than sixty samples for surface-exposure dating. This is no easy feat, for collecting these samples requires a great deal of hammering on granite boulders with nothing more than a hammer and chisel. There are other ways of doing it, such as using small explosive charges, rock saws, or splitting wedges, but we find that good old-fashioned hammering is by far the safest way. I say ‘we’ but really this means Matt. He has a gift for removing large amounts of rock, be it a soft shale or the hardest quartzite. And best of all, he doesn´t complain. So in all, we have sixty four samples from the Aricoma region, from moraines of all ages. In addition to the hammering, the process includes detailed descriptions of each boulder and measurement of location, altitude, and how much of the surrounding sky is obscured by mountains. It can take a while but we have it down to an art now, as the ton or so of granite in the back of our vehicle attests!
We´re also collecting sediment cores from bogs within the moraines, so as to provide radiocarbon ages for the deposits. Just yesterday we extracted a two-meter core from a basin near camp that lies between two long moraine ridges. It was a messy business, taking the three of us to punch the core barrel through the malodorous slime and into the stiff glacial clay, going as and as far as the rocks below. When all was said and done, each of us was fairly bloody and covered with ancient mud, but the core was extracted and the day was ours. Now the core is neatly contained in plastic tubing, sealed from the air and ready for shipment to Lamont where it will be analyzed.
Each morning starts the same in the Andes: the frost is heavy on the insides of our tents and falls with the slightest movement, while the realization that it´s going to be a freezing exit from the sleeping bag is tempered by gratitude that the thirteen hour night is over. Yes, sunrise in the Andes is a momentous occasion each day, one that feels a million miles away from home. Kurt typically is the first up and dutifully begins brewing fine coffee on the camp stove. Matt emerges shortly thereafter. Nobody says a word, we just stand around in the frost like cold lizards – or maybe zombies – until the sun arrives to warm us. By midday it is fearsomely hot in the sun and the down clothing is replaced by sandals and wide-brimmed hats. Then, just as one is getting used to the idea of a nice afternoon siesta, the sun drops behind the skyline and the climate is icy once again.
One thing I am reminded of daily is that here in the Cordillera Carabaya, unlike in the western Andes, we are never alone. The moraines we investigate and the valleys we explore are someone´s backyard. Herds of alpacas swamp our campsite, followed by ferocious dogs, and mining trucks, laden with gold ore from Limbani, compete with our 4 x 4 for road space. We´ve met some interesting folk here, too, such as the toothless, Quechua-speaking alpaca herder high on a moraine, to school children asking us how to pronounce derogatory words in English.
We´ve been at Aricoma a week now and, I am pleased to report, have a lot to show for it. In addition to scratty, dusty beards and admirable tans, we´ve mapped and sampled glacial deposits young and old, from the last glacial maximum right up to the present day. This work has taken us up into the high valleys, where the last remnants of glacier ice are tucked away in shady recesses above 5000 m elevation. Here, we are surrounded by imposing peaks and deep, glacial lakes of indescribable beauty. It truly is a geologist´s dream, if a cold one.
June 22, 2011
After a very cold morning in Crucero, the sun burned off the clouds to reveal the black peaks of the Cordillera Carabaya to the east. There´s not so much snow left on the hills these days, just a few glacier patches clinging to the south faces of the highest summits. Nonetheless, the vista is spectacular and Crucero by day is quite colourful, with fantastically painted buildings spaced around a busy plaza.
We had a stroke of luck today when we ran into a local man by the name of Demitrio. Demitrio was an enormous help back in 2009, helping us gain access to Aricoma and the hills beyond. This year he was all smiles and quickly ushered us into the mayor´s office, where Kurt explained (in his superior spanish) what we were doing and the objectives of our project. Now, with the town´s blessing and a signed, official-looking letter in hand, we´re about to head off to our camp at 4600 m on the shore of Aricoma.
This morning we also made our final gear acquisitions – some plastic piping to transport sediment cores back to the US for analysis. These we had to cut into sections with a small hacksaw and then split in half, a delicate and quite tiring job at this altitude, but necessary. Now, vamos a trabajar!
June 20, 2011
This morning we left Arequipa and the comforts of the tourist trail, driving east across the puna towards the Andes proper. Our route took us along the newly constructed Caraterra Interoceanica – a highway linking the Pacific coast of Peru to ports in Brazil – and up to elevations of 4700 m. Along the way we passed the smoking Volcan Ubinas, Peru’s most active volcano, and the enormous inland sea of Lake Titicaca. As we approached the Cordillera Carabaya, which bounds the puna to the east, the clouds increased and the landscape changed dramatically, from desert to grassland.
In recent weeks, social unrest related to the opening of a gold mine near the city of Puno has resulted in violent protests. Though we were able to avoid Puno as we travelled east, this sort of anti-mining sentiment underlines the importance of obtaining the blessing of locals to carry out our research on their land.
By mid afternoon we arrived in the small town of Crucero, located at 4100 m beneath Laguna Aricoma – our first site. This town is, frankly, a bit grim, consisting of grey concrete houses and rubble streets, and located on a windswept plain below the mountains. Nonetheless, we’ll spend the night here in order to meet with the governor tomorrow. Fingers crossed that he will remember us and grant us permission once again to roam around. To end on a light note, the Cordillera Carabaya happens to be the alpaca centre of the universe, and so there is a high chance that one of these cute fluffy camelids will end up on our dinner plates tonight.
19th June 2011
What a difference a day makes! We’ve said goodbye to the sprawling metropolis of Lima and now are happily settled in Arequipa – the White City. This name refers to the white sillar rock used in the construction of the old colonial city and which is in fact a pyroclastic deposit from the volcanoes towering above us. From our hotel room I can see the massive bell-shaped peak of El Misti (5800 m), the only active volcano of the group, and it’s looking particularly snowy this year. In fact, flying in to Arequipa, I was surprised to see so much cloud. Normally, with this being the dry season, the sky in this desert region is blue and the mountains dry. Perhaps we should prepare for some wet, snowy field work!
Thankfully, nothing has changed at La Casa de Melgar, our Arequipa base, and I dug out my sampling tools from where I’d stashed them last year, a little dusty but in perfect working order. The rest of our gear, due to its incredible weight, is making its way slowly from Lima by road and should be here tomorrow morning. As for Matt, we found him in the airport, looking surprisingly fresh-faced after his red-eye flight, and so our field team is now complete.
We’ll spend the rest of the day organizing our transport and, in the interests of science, sampling the rather incredible local cuisine.
18th June 2011 Lima, Peru
Our 2011 field season is underway. After a full day’s travel from New York, we arrived in Lima, the capital of Peru. This sprawling city perched on the edge of the Pacific Ocean is home to more than nine million people and, after Cairo, is the largest desert city in the world. Being winter in the Southern Hemisphere, the Peruvian coast is swamped by fog rolling in off the cold Humboldt Current and the sky over Lima is grey with smog and cloud. It’s surprisingly cool, too. Only the palm trees, cacti, and spectacular Spanish colonial architecture remind you that this is indeed the tropics.
Since our work will focus on detailed mapping and sampling of glacial deposits, we are heavily reliant on high-resolution aerial photographs of the field sites. Therefore, our first port of call this morning was the Instituto Geografico Nacional, a cartographer’s dream where enormous collections of maps and imagery are stored. It’s a spartan building with a distinct military air – a real throwback to more austere times – but the personnel there were very helpful, dutifully returning from store rooms with stacks of black and white photographs for us to peruse. Incidentally, these photos were taken in the 1960s by the United States Air Force and it never ceases to amaze me just how much the has retreated over the past 50 years. Some of the glaciers have vanished.
With that chore done, we’re currently packing (and repacking) our equipment for the next leg of our journey. Tomorrow we fly to Arequipa, Peru’s second city, located at 2300 m at the foot of the famous Volcan Misti. There we’ll meet up with Matt, who’s on his way from Tacoma as I write. Though we’ve been here only a few hours, it’ll be great to leave the coastal smog for the blue skies of the Andes.