One of the core objectives of our project is to image the part of the plate tectonic boundary that locks up and then ruptures to produce great earthquakes. In the Aleutian subduction zone, the Pacific plate is being thrust northwards underneath the North American plate. To examine deep parts of the interface between these plates, we need to go as far north (and as close to the coast) as possible. This is easier said than done. We are towing a lot of scientific equipment behind the ship, including two 8-km-long cables (streamers) filled with pressure sensors, so approaching the coast and making turns is complicated and requires special attention to safeguard our gear. The southern edge of the Alaska Peninsula is rugged and flanked by lots of small jagged islands and shallow features just below the surface of the ocean. Currents and water density can vary locally near the coast, which could affect the positions and depths of our streamers behind the ship. And there is more fishing activity close to the coast, and thus increased risk of tangling seismic gear with fishing lines and nets. To reduce the risk, we scouted all of the trickiest parts of our survey ahead of time before we deployed the streamers, and we monitor the currents and fishing as we approach the coast. Captain Jim O’Loughlin, Chief Science Officer Robert Steinhaus, and the Langseth’s other crew and technical staff have a tremendous amount of experience and skill in maneuvering in tight spots while towing seismic equipment.
We recently completed one of our closest approaches to land near Unga, one of the Shumagin islands. At the apex of the turn, our 8-km-long (5-mile-long) streamers came within less than a mile of the coast. Due to some early difficulties with our equipment and an abundance of marine mammals, we had to make several attempts to collect data on the landward part of the line (and thus several passes near the shoreline). I held my breath and watched our third (and final) pass from the bridge. After the ship and gear passed safely through the most harrowing part of the turn, the captain turned to me and asked, “We’re not going to do this again, are we?” Thankfully not! At least not here. But there are several other important parts of our survey ahead that will require close approaches to the coast to image critical parts of the plate tectonic boundary. As with this near-shore encounter, we will rely on the skill and experience of the mates and the technical staff, as well as a little luck.
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.
On July 11, we marked the successful completion of the first phase of our project and embarked on the second. Part 1 involved deploying ocean bottom seismometers and recording air-gun-generated sound waves. We successfully retrieved all of the OBS’s, and the data that they recorded look very exciting at first blush (and contain some surprises!). Part 2 involves towing two 8-km-long cables (or streamers) filled with pressure sensors behind the R/V Langseth, which will also record sound waves from the Langseth’s airgun array. Changing gears in terms of scientific activities also involved changes to our science party; we swapped personnel in Sand Point on a beautiful sunny evening. The excellent OBS team from Scripps departed on the Langseth‘s zodiak, and we were joined by new reinforcements. The newcomers included five undergraduate students from Columbia University, who are also blogging about their experiences at sea.
Just two hours after taking on our new personnel, we started deploying seismic gear – a very quick transition! Our seismic streamers are stored on gigantic spools, which unreel cable off the back of the ship into the ocean. A large buoy is affixed to the end of the streamer, and ‘birds’ are attached along its length, which can be used to control the depth of the streamer. Large paravanes hold the streamers apart; these are like large kites flying in the water off the back corners of the ship.
Deploying miles of streamer and the other attending gear is an impressively long and complicated undertaking. We started over two days ago, and have been working around the clock in shifts ever since. Many repairs and adjustments are made to the gear as it’s deployed. The streamer is divided into 150-m-long sections connected by modules; both sections and modules can fail and need to be replaced. Replacing a 150-m-long section of cable is an arduous task involving major manual labor by teams of ~5-6 people. But we are nearing the finish line; as I write, the last kilometer of the second streamer is going over the back of the boat. Fingers crossed that the deployment will soon be complete and the data collecting can begin!
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.
After leaving our seismometers on the seafloor offshore Alaska for a few days to record sound waves generated by the air guns of the R/V Langseth, we returned to collect them. The recovery of OBS always involves a certain amount of suspense. Despite all of the advanced engineering and planning that goes into these instruments, it is an endeavor with inherent risk, and things can and do go wrong sometimes: one or more of the glass balls that make the OBS float could implode; the acoustic communication with the instrument could fail; it might be stuck on the seafloor for one reason or another; it could have been accidentally dragged off by trawlers. All of these thoughts ran through my mind at each site as we waited for the instrument to come to the surface.
To recover the OBS, we return to the place where we deployed it and communicate with it acoustically. We send it a command to release from its anchor and float back to the surface. The OBS rises through the water at 45 meters per minute, so the wait can be long if the water is deep. Some of ours were 5500 m below the surface! The instruments can also drift away from their original deployment location on the way down or the way back up due to ocean currents. When they arrive at the surface, we can spot their orange flags and strobe lights; they also send out radio signals.
Despite all the technology required to place a seismometer many miles below the ocean on the seafloor and summon it back to the surface, many aspects of actually plucking an OBS out of the ocean and pulling it on deck are remarkably low tech (yet still very impressive). Once we have spotted the OBS floating on the surface, the ship drives alongside. It is akin to driving your car up next to a ping-pong ball. People lean over the starboard side of the Langseth and attempt to attach a hook with rope to the bars on top of the OBS using a long pole. Its not always easy since the OBS is bobbing up and down in the waves. Once we hook it, we can attach a rope to the winch and haul the OBS onboard. Sometimes, OBS’s bring back surprises – an octopus returned with one of our OBS’s! He was alive and healthy, so we returned him to the sea (though some lobbied to keep him for lunch…)
Happily, we recovered 100% of our OBS’s and have started to (briefly!) pore over the data they recorded while they were on the seafloor. We can see the arrivals of sound waves from our air guns as well as lots of earthquakes, some very close and others far away. It would be delightful to dig into the analysis of these data immediately, but it must wait – there is more data to collect! We’re currently deploying OBS’s along our second profile.
On July 2, we finished deploying over twenty ocean-bottom seismometers as a part of our marine expedition to study a major tectonic boundary offshore Alaska. Ocean bottom seismometers (OBS’s) are autonomous instruments that sit on the seafloor and record sound waves traveling through the earth and the water. Floats made from glass balls and syntactic foam make each OBS buoyant, but an anchor holds it on the seafloor during the study. We communicate with each OBS acoustically, allowing us to send it a command to release from its anchor when we are ready to recover it.
For our project, we are placing OBS’s from Scripps Institution of Oceanography on the seafloor along two lines that span the major offshore fault zone. Immediately prior to deployment, we assemble the main components of each OBS on deck while the ship transits between sites. When we arrive at the deployment site, the ship slows down, and the OBS is lifted over the side of the vessel and into the water with a large crane. We release it, and it sinks to the sea floor. Thanks to the skill and hard work of the Scripps OBS team and the ship’s crew, we were able to deploy one OBS every hour, which is very efficient!
The larger the distance between the sound source (earthquakes or air guns) and the seismometer, the deeper into the earth the recorded sound waves travel. OBS are very sensitive and not attached to the vessel, so they can record sound waves generated very far away by earthquakes or air guns (commonly >200 km). Because we want to examine deep fault zones that cause large earthquakes off Alaska, OBS are a critical part of our effort.
In a few days, after we steam back over the OBS’s generating sound waves with our air guns, we will return to retrieve them. Even after ten years of working with ocean-bottom seismometers, it never ceases to amaze me that we can throw a bundle of very sophisticated electronics over the side of the ship and hope to pick it up and retrieve useful information from it. We are very excited about the new insights that will be provided by the data recorded on these instruments…
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.
Yesterday evening, we left Kodiak aboard the R/V Marcus G. Langseth and began our 38-day-long research cruise offshore Alaska. As we left port, we were treated to clear skies, calm seas and spectacular views of Kodiak – dark grey mountains tipped with snow emerging from the lush green landscape.
Although Kodiak offered beautiful sights and delicious seafood (like locally caught halibut and scallops), our science party was eager to leave for sea. We have been waiting for the opportunity to collect these data for a long time. Our expedition was originally planned for September 2010, but there were delays in the Langseth’s schedule that would have required us to conduct our offshore study later in the fall, when the weather deteriorates. Rough seas make some marine operations more dangerous and can also reduce the quality of the data. We opted to postpone until the summer of 2011 to secure a better part of the limited weather window in this remote and northerly region.
But for some members of our science party, the wait has been much longer. In 2003, my colleagues Mladen Nedimović, Spahr Webb and the late, great John Diebold first conceived the idea for this study. Although many other scientists in our community and the National Science Foundation were very supportive of this project, it was scuppered by limited science funding and the temporary lack of a US academic seismic vessel between retiring the R/V Ewing and acquiring the R/V Langseth. But sometimes good things come to those who wait, and at long last we are setting out…
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!
Seven days and eleven flights after we arrived in Alaska, we finished deploying our seismic stations onshore. Our final constellation of stations differs a little from our original plan (as always happens with field work), but achieves our main goal of instrumenting the part of the Alaska Peninsula that is nearest to our planned offshore work on the R/V Langseth. We installed our final seismic station yesterday in aptly named Cold Bay. This town sits next to a large bay with the same name and is famous for its wind. The most common damages sustained by cars and trucks here are jack-knifed doors from the wind (as I learned the hard way!).
As luck would have it, we finished deploying our seismometers just in time to catch a large earthquake (magnitude 7.2) that occurred farther west in the Aleutians around the Fox Islands. Of course we would love to immediately look at the recordings of this event on our stations, but we must wait patiently until August when we return to recover them. Many permanent seismic stations are telemetered, so data are transmitted back to scientists in near real time. But for temporary deployments like ours, the data are just written to a local disk and thus must be downloaded in person at the station.
We did have the chance to take a sneak peak at some of the data recorded at our station in Nelson Lagoon during the first few days of our deployment. Reassuringly, we saw evidence for several local earthquakes in these data, including a magnitude 3.1 near Sand Point.
Now that the onshore deployment is finished, Katie and Guy departed for home, and I soaked in some sunshine in Anchorage and started looking ahead to our upcoming research cruise. Tonight I fly to Kodiak to await the arrival of the R/V Langseth and our shipboard science party…
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.
Every field location comes with logistical hurdles, and the Alaska Peninsula is no exception. Weather, wildlife and modes of transport pose the greatest challenges. We are hardly the first scientists to encounter these: Lamont-Doherty Earth Observatory has a long, rich history of collecting seismic data in this region (e.g., Shumagin Seismic Network, which ran for >20 years), and many groups continue to collect geophysical data here today.
The Alaska Peninsula is too rugged and wild for a network of roads, so planes, helicopters or boats are the only transportation options. We opted for planes, which immediately imposed a restriction on the locations of our seismic stations: they must be near airstrips. Happily, the Peninsula is sprinkled with small communities and lodges with airstrips, most of which lie close to the Pacific or Bering coasts rather than in the remote interior. Back in the office before our deployment, we chose the most ideally located airstrips for our stations and connected the dots between them with the most efficient possible flight plans. But, our plans quickly changed once we were in the field. The weather dictates when and where you can fly each day, and it varies dramatically. We have been lucky enough to have several clear days (even saw some blue skies and sunshine!), but other days we have been grounded by weather and wiled away the time indoors at the inn in Nelson Lagoon.
Once we arrive in each location, we need a quiet, safe place to install our equipment and a ride from the airstrip. On both counts, local communities have been unwaveringly helpful and friendly. The two school districts here kindly granted us permission to install our seismic stations at any of their schools, and we also obtained permission to place equipment at various lodges and village offices. Residents volunteered to take our gear and us from the airstrip to our sites. In one town, our pilot made a general plea over the radio: “Is anyone listening on Channel 3? I’m here at the airstrip with scientists who need a ride to the school”. Someone answered immediately and picked us up 5 minutes later.
Many of our sites are in spectacular places near remote lodges or in towns nestled between mountains and the ocean. All of them are home to impressive wild life that poses a risk to our equipment, particularly bears. We can protect the equipment against curious small animals but fully bear-proofing a station for a short (two-month-long) deployment is not feasible. Instead, we hope that placing our stations in villages (rather than in the wild) will provide some protection, but we will also need good luck. Fingers crossed…
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.
May 22: The 2011 field season has been a very very successful year, in fact the most successful one we have ever had. The weather has been great, the equipment proved to be mostly reliable, the people have been great and the samples are plenty. In the month to come, we will analyze the water samples and eventually end up with a tremendous amount of very exciting data. Thanks to everyone who made this happen.
We left Alert yesterday and are on our way back home. We are stranded in Kangerlussuaq, Greenland, for a couple of days until the Air National Guard can take us and our valuable freight back to the U.S.
The Switchyard Team.
We decide today is the last day for our camp, and we pack up and drive back to our base camp, the Central Transantarctic Mountain camp (CTAM). A sadness in a way, because it was our cozy home for a week. We ate, slept, and joked around here night after night. Also, we realize that packing up camp represents the end of the field season, except for one more day. For the last day of work we will fly by helicopter to the Achernar area from the CTAM camp.
The last day at Mount Achernar. We use the helicopter to go near the southernmost part of the area, near the Lewis ice tongue, which comes off the East Antarctic ice sheet. After a long day, we collect our last samples, and wait for the helo to pick us up – the end of the field work for this season. We realize we had a very successful field season. Not one day of work was lost at either Mt Howe or Mt Achernar (a very rare experience for Antarctica). We think about how we accomplished our goals in terms of getting to both remote sites and collecting samples.
Back at CTAM camp, we scramble to get all our stuff packed up ready to be shipped back to McMurdo. They are closing the CTAM camp for scientific work in a week because they need to take everything down by the middle of February. The middle of February represents the end of the field work for everyone in Antarctica. It starts to get too cold, and the sun starts setting in some areas farther north. People start to go home then and McMurdo gets ready for the winter.
We all fly back to McMurdo. A bed and running toilets (!) for the first time since we left for our camping trips. Also, the dorms have dark curtains that go over the windows. So, darkness, a bed, and a toilet – who would have known life can get so good!
Mike Kaplan (Lamont)
We set out on the snowmobiles with all the sleds to Mount Achernar with all our stuff. After about three hours we reach the site (crossing the flagged crevasse zone with no problem). We are joined by a fifth team member, Tim Flood, a Professor at St. Norbert College in Wisconsin. Tim has expertise in petrology or rock composition. So, we will have one additional person for the Achernar part of the trip.
At first we only find ‘blue ice’ to set up camp. Blue ice gets its name mainly because – in contrast to the typical situation of having a layer of snow on top of the ice sheet – there is only ice. The snow layer that normally covers the top of the ice sheet is blown away where the winds blow pretty fast and consistently. This means there is no good place for camp right in the Achernar area because all the blue ice is a sign of strong winds. We decide to back up a few miles to where the snow starts again and camp a little but away from Mount Achernar. This means we will have a ‘daily commute’ to get to where we want to work, but at least we have a nice place to live for the week. It is less windy where we decide to set up camp and a nice layer of snow in which to pitch the tents and walk around. Blue ice is very difficult to walk on – it is just what it sounds like – walking on ice!
We set up camp. Unlike at Mount Howe, here each person will have their own tent. In addition, we set up the bathroom tent and a huge kitchen tent, named the ‘Arctic oven.’ The arctic oven will act as a kitchen and dining area. It is about 25 feet long, enough to be comfortable. And, when we have two stoves going inside, the temperature gets up to a comfortable 60 degrees or even higher (hence, its name); comfortable enough to start peeling off all our jackets while eating. Two little speakers that Tim picked up in an airport, attached to ipods, means we even have a stereo system in the arctic oven cook tent.
The first day we drive out to where we want to work. It takes about an hour and a half each way by snowmobile. This is quite a bit of time. In addition, the glacier deposits we want to study are much larger in area compared to at our first site at Mount Howe. It is not practical for us to drive everywhere and get to all the places by walking. We realize we will need to utilize the helicopter from nearby CTAM. So, the next week or so we alternate: a “snowmobile day” when we commute by snowmobile from camp to the field site and “helo days”. On the helo days, the helicopter flies out to our camp (a short flight by helicopter from the CTAM camp) picks us up, takes us exactly where we want to go around Mount Achernar, and then at the end of the day, comes back out to bring us back to our camp. All these trips only take the helicopter folks about 75 minutes in total each day, given how fast they go.
We spend the next 8 days or so doing the same sort of work as at our first site Mount Howe. We map the glacier deposits (how red or oxidized are they – how do their elevations changes? How do the deposits themselves change in terms of shape and composition and other characteristics?). Mike K and Mike R (with occasional assistance from others) collect samples for the surface exposure dating, so they can eventually figure out how old all the deposits are. Kathy, Nicole and Tim study the composition and types of glacier rocks and sediments left behind.
Similar to our finding at Mt Howe, we find pronounced changes in the glacier moraine deposits around Mt Achernar. This indicates there are likely deposits of different ages, left behind at different times by the ice sheet when it was bigger. All the team members continue to collect samples that will be analyzed later in the lab.
Mike K, Kathy, Mike R, Nicole and Tim
We are back at the CTAM (Central Trans Antarctic Mountain) camp.
Over the last several days we take stock in that we accomplished the first major goal of our trip. That is, to study the glacier deposits at Mount Howe, the southernmost rock outcrop on Earth. We found (what we think are) deposits left behind by the ice sheet when it was bigger, at several different time periods in recent Earth’s history. We can tell in a preliminary way, before we have carried out the laboratory work back home, that the glacier deposits must be of different ages because they are different ‘colors’ – red for more oxidized (rusted). They also show other signs of varying in age such as the weathering of the rocks and landforms, which increases away from the ice sheet (=older). This means that there will be a record of the glacier leaving behind different types of rocks over a period of time, likely well before the last ice age. It was an important goal to find such deposits for our sampling.
We quickly regroup our stuff over the next few days at the CTAM camp and start to get ready for the next major camp move, to Mount Achernar. For this stage of our trip, which is only about 25 kilometers from the CTAM camp, we are hoping to get there by snowmobile. We will use 4 snowmobiles pulling 6 sleds (two snowmobiles will pull two sleds each). This will allow us to move our entire camp, set it up for more than a week near the site, work, and then come back to CTAM after 8 days or so. However, there is a small problem. There is a crevasse shear zone in the ice sheet between the CTAM camp and Mount Achernar. So, we must figure out where to cross the crevasse zone. We do this two ways. First, we take a helicopter trip from CTAM for an hour (they are quick) to scope out or reconnaissance the area (a “reconn”). On the helicopter, we think we figure out where we might be able to cross the crevasse zone. The helicopter trip also allows us to see the whole area of Mt Achernar and where we want to camp. Camp ideally has to be on a snow patch so we can stake the tents down and in a spot not too windy.
The second way we figure out how to cross the crevasse zone is to go to it, by snowmobile on just a day trip from CTAM (another “reconn”). Mike R (Roberts), our mountain guide, shows us how to link the snowmobiles by ropes, in case one falls into a crevasse. We also put on climbing harnesses and rope ourselves to a second set of ropes between the snowmobiles. This is so that if we fall in, we can either climb out or be pulled out by others.
We get to the crevasse zone which starts at about 15 miles from the CTAM camp. The first few crevasses seem quite bad – each about 2 to 5 feet cross. Although they all seem to have natural ‘snow bridges’ that cross the top of the crevasse, which we can drive across, we need to be confident that they will not collapse due to the weight of the machine. Mike R slowly investigates each crevasse we cross to see how strong the overlying snow bridges are and how wide each crevasse is. After about an hour, we start thinking maybe there are just too many crevasses (every few hundred feet we are finding another one) and it would take too long to figure out how to get across the entire crevasse zone. Mike R suggests we park and get off the snowmobiles, link up with ropes and slowly walk for a while to see how much longer the bad crevasses continue. This seems easier at the moment then stopping and starting the snowmobiles every time we reach another crevasse. To our surprise, the crevasses quickly get smaller and disappear just as we start walking! We did it ! We found a reasonable and quick way to get across the crevasse zone which is less than a 1 mile wide at its bad part. We put flags next to each one so that we can easily see where they are when we come back through on the way to Mount Achernar site to do our work.
Mike Kaplan, Kathy Licht, Nicole Bader and Mike Roberts
The first day of geologic work at our Mt Howe field camp. We start walking on the moraines (piles of debris left by a glacier, just like around NY, Indiana, Wisconsin, where we are from) and we have to put on crampons. These are spikes that go on the bottom of our boots. This is because the moraines are really hummocky to walk on and right under just a few inches of dirt is ice, making us slip and slide and do more leg splits than we can remember!
But, we quickly identify roughly where we think the ice was during the last ice age. We can do this because the deposits are ‘grey’ in color as they do not have time to oxidize (like rust on a car). The stuff left behind by older ice ages is red in color – because it has had time to oxidize. We start collecting our first samples. Kathy and Nicole collect material to figure out the type and chemistry of the glacier deposits left behind, which will help tell them which way the ice must have been moving in the past and what kind of rocks it brought up from below. Mike K and Mike R start measuring the elevations of all the glacial deposits and more important start collecting samples from the tops of large boulders. These samples will help us figure out the time at which they were left behind. Once back home, we will use a method called cosmogenic surface exposure dating. We will use our lab facilities at Lamont-Doherty Earth Obsservatory to date the rocks, using the cosmogenic nuclides Beryllium-10 as well as Helium-3.
Over the next 6 days or so, both teams just systematically collect samples from each set of ridges or moraines that the ice sheet left behind in the past. The idea is that each distinct moraine ridge represents a different time period or glacial period when the ice sheet was bigger. The weather holds up well, an important fact when you are only a couple hundred miles from the South Pole. The temperature remains about -10 to 0 during the day. Anytime the wind picks up thought, the wind chills causes it to get colder fast. Often exposed skin has to be covered quickly. Only a few days are cloudy, otherwise the sun adds a little bit more warmth. Fortunately, the tents are warmer, especially when we run the coleman stoves. So, eating dinner is way more comfortable than being outside.
Mike K., Mike R., Kathy and Nicole