Ushuaia 2017

The recreational airport club overlooking Ushuaia Bay and downtown Ushuaia

 After a bit of a hiatus I return to describe what may be my last trip to Tierra del Fuego. Since I've last updated this blog, quite a bit has happened:

• I've measured more samples (including fish!)
• I've passed my qualifying exam (hooray!)
• I've moved universities from Environmental Systems at UC Merced to Earth Sciences at UC Riverside (possibly invalidating my qualifying exam)
• and, finally, I've returned to Ushuaia for (maybe) the last time

But what opportunity awaits while I'm here! I've got some big plans. Next week I'll be traveling to Harberton Ranch to collect water and kelp samples, which eventually should help me do some forensics on where my fur seals, sea lions, fish and other members of the marine food web spent their time (open ocean or kelp forest? Beagle Channel, Atlantic, or Southern Ocean?) At the same time I'll be helping a fellow grad student who has been collecting rocks in a radial fashion around an archaeological site to identify their availability for making tools. 

In about a week and a half, I'll be leaving for Peninsula Mitre, the easternmost point of the Island of Tierra del Fuego. There are no roads to this place, and my colleagues normally reach this place by helicopter. However, we'll be taking the scenic route by horse which will take 3-4 days each way. Very few scientists use horses in their fieldwork these days, so it'll be harkening back to the days of old adventuring. Some French tourists may be accompanying us for the ride, so it'll surely be an interesting experience. I'll be journaling the experience and sharing with you all when I return!

The primary objective of traveling to this place is to collect fur seal and sea lion remains from industrial seal hunting that occurred during the 20th century. So far I've previously looked at fur seal and sea lion remains produced at indigenous archaeological sites, dating from roughly 6000 years ago to the 1700s. I expect to see significant changes in the diets of these animals as human influences changed from subsistence hunting to wholesale slaughter, but I'll find out when we return with the samples to the lab. I'll also be collecting more water and kelp samples, while my archaeologist colleagues will be digging some test pits to compare cultural differences between ancient sites on the peninsula versus sites to the west in the Beagle Channel. 

An inset historic map from James Cook's expedition, one of the first European explorers to document the area. Note that north is pointing to the right on this map and, that the Beagle Channel has not yet been identified. We'll be riding to the far western edge to the Strait of Marie (Detroit de le Maire). I've analyzed some samples from the area labeled "Baye de Valentin" and "Terre des Etats" already (Valentine's Bay, or Bahia Valentin and Staaten Island, or Isla de los Estados today).

Finally, I've spent a bit of time thinking about my PhD journey over the past several weeks and thought I'd share a bit about the process. I came in starting this degree with an idea for my PhD thesis fairly well formed within the first few months of starting at Merced. Those original ideas have shifted as logistics and preliminary data came into view. The questions I originally set out to ask changed and become more focused since the broader questions turned out to be more difficult to answer than expected. This realization required me to think about different types of methods to be used, the learning of new tools to help answer those questions and the number, and all the while scale and scope of the project increased. But it's this process that I think is probably the core of what a PhD is about: to come up with good questions and find a way to answer them, given limited time and resources. Of course, this sort of thing takes some planning so I made a timeline to illustrate it. Just in case you might considering a PhD, maybe you will find this helpful!

La Campaña: En la Casa

A late afternoon view toward the Southwest from Moat Bay. Isla Picton with Isla Navarino in the background, the opening of the Beagle Channel to the Pacific in the west (right).

Buenas tardes folks,

Now that its been a few weeks and I've settled back into the routine here in Ushuaia, it seems like a good idea to describe in some detail what life was like, what I learned and how I'm moving forward as a result of this fieldwork.

You should know by now I'm interested in studying food webs and ecology using remains of hunted fur seals and sea lions from archaeological sites. While it's possible I could've just gone and asked my colleagues to just send bones to me in the US, that would've been no fun and I'd be missing out on understand how and why these bones showed up in the first place, both in the context of the culture of the peoples who hunted them and in the natural climate and taphonomic processes. Over the month I was in the field, being outside everyday, I not only learned what it was like to live as an Argentine in Tierra del Fuego, but also what weather the Yamana may faced (which was not very much like California).

Rain over the Beagle Channel, looking Southwest. Moat Bay extends to the left, while our ranch and nearby lake are on the right. The dirt highway, Ruta J, continues for about 20km to the east before ending.

From Ushuaia, which is near the middle of the Beagle Channel, we packed up some trucks with nine people and our gear for the month; three professors, three graduate students (including me), two undergraduates working on their senior theses, and a lab assistant. After we piled in we drove 3-4 hours east of Ushuaia, past Estancia Harberton, to Moat Bay. Moat bay is located at opening of the Beagle Channel to the Atlantic Ocean, which provides a stunning view of Islands to the south in Chilean territory; Isla Nuevo, Lennox, Picton, and Navarino.

A rainbow over our ranch house, during our daily afternoon water refill routine.

We arrived at a remote ranch, and luckily for us we had a guest house to stay in. Despite having a kitchen, bathroom with a flushing toilet, and generator for power, there was no running water as the pump had broke. As a result, we carried buckets of water from the nearby lake and drank water from the rain that collected in a barrel off the roof. The lake water had a bit of an algal taste, and was preferred by some of our members to the rain barrel water, which had a distinct "wooden barrel aged" taste, even though the barrel was plastic.

Our fully stocked kitchen at the beginning of the campaign.

Generally, we'd wake up around 8 most mornings, after tough days or celebrations we might sleep until 9. We'd have a light breakfast of coffee and tea, bread and jam or butter, or if lucky facturas (basically donuts) that were brought by visitors or our members who had left and come back. When we ran out of bread, it was a sad day since we were left with crackers and maybe some cookies. But usually that was a short lived experience because someone would show up at the ranch with a fresh resupply of bread and pastries, and maybe even wine or beer!

Lunches were also fairly light, we'd generally eat a mix of bread, cheese, crackers, and dried sausage or salami; some fruits and vegetables, like salad, carrots and apples, followed by cookies and chocolate. Later on we needed to use our leftover pasta, so we'd cook some at our field sites. We generally also snacked on crackers and cookies while working, but careful not to drop any food in the field pits. Lunch is a later than what I'm used to, usually around 1, but sometimes later. We'd spend about an hour on break. And, of course, we wouldn't have survived without Mate, the shared Argentinian tea-like beverage which helps keep you working. We generally drank mate continuously throughout the mornings and afternoons. 

When we returned back to the ranch house and were exhausted, we would go get more water from the lake, maybe take a bath or at least wash our hands and face, and make some more coffee and mate. On more difficult days we'd have fernet and coke, the favorite drink of Cordoba (a province in Argentina) and the Porteños (the residents of Buenos Aires) from which almost everyone in our group shares culturally. 

A fine chicken dish in a big wok!

Dinner in Argentina is late. You might start cooking at 9, and start eating at 10 or later. We'd break open boxes of cheap wine (easier to transport in the field, and easily disposable containers) and have different kinds of meals. Sometimes it was a meat or fish stew (giso), sometimes pasta (with ñoquies, a potato derived noodle), pizza or the famous Asado (steak BBQ). In any case, dinner was always much appreciated and we ate well. Afterward, if we had enough energy, we'd sit to play a game of cards or dice, usually jodete or generala. After that we'd be truly exhausted and hit the sack, meaning a pile of sleeping bags laid out on the floor of the living room in front of the warm pot bellied stove.

Until next time, here's some highlights from the house area:

Starting up the truck in the morning...easier said than done

And starting up the generator in the evening

Practicing the recorder, taking a walk during some downtime while the weather was good. You can see the ranch house in the background. 

Sorting out a knot problem on the living room floor

The hummocky road leading to the beach, facing south from the house.

Another view of that (double) rainbow to the east, showing the length of Moat Bay

Vuelva a Ushuaia

Ushuaia Bay upon landing

Hello once again!

I figure it's a good time to start writing again since it's been several months since I last updated the blog. Quite a bit has happened in the intervening months. I've ran the South American fur seal samples I collected and they've provided some puzzling results. I measured the carbon and nitrogen stable isotope from the bits of processed seal bits (collagen if you recall from my previous posts). Stable isotopic values of various elements will show you varying characteristics of the world based on how they cycle through biogeochemical systems (and an animal's biochemistry). Carbon and nitrogen are particularly useful for measuring ecological characteristics, like finding out one's trophic level (if you are a vegan, vegetarian, or a meat eater.)

When interpreting the results of these isotopic values, there isn't much of a basis for comparison if you have nothing to compare against. In classical studies, you need to know what the values are at the base of the food chain as well as potential dietary components of your study animal. Even without this info, there are some inferences we can make. There are some noticeable differences between male and female fur seals from 6400 BP, but age did not seem to have a large effect. Most of the fur seals seem to cluster together toward a lighter carbon isotopic ratio.

Pulled from the latest version of my proposal

Based on literature values of fur seal dietary components from modern collections, I can see if diet corrected values of my ancient seals fall within expected dietary boundaries of modern fur seals. Essentially, you connect the dots of the most extreme dietary values, creating a diet polygon, and should see your animal's diet corrected values fall within the polygon. From there you can create an isotopic mixing model to see which dietary components contribute the most to the animals diet. For example, I should be able to see if the seals are eating mostly squid or mostly fish.

Alas, this is not what happened when I compared modern diet to ancient animal. There has clearly been some kind of shift over time as none of my seals fell within the diet polygon. Modern dietary components are much lighter in carbon than the more recent seals. Something has changed in the carbon. One might argue "Hey wait a sec, what about the Suess effect?"

The Suess effect is a change in the ratio of the atmospheric concentrations of heavy isotopes of carbon (¹³C and ¹⁴C) by the admixture of large amounts of fossil-fuel derived CO₂, which is depleted in ¹³CO₂ and contains no ¹⁴CO₂.

However, I had already applied a Suess affect correction based on literature values, and not including this correction would have actually made some of the individuals fall within the diet polygon. In any case, I have more work to do grappling with this issue and doing some ANOVAs.

Analysis of variance (ANOVA) is a collection of statistical models used to analyze the differences among group means and their associated procedures (such as "variation" among and between groups), developed by statistician and evolutionary biologist Ronald Fisher.

Ok enough Wikipedia citations. My guess at the moment is that there's been a shift in the base of the food web over the years and seals are probably eating roughly the same things that were 6400 years ago. I won't be able to find out whether that's true or not until I find some way to measure the base of the food web, either by looking directly at animals near the base of the food web (preserved in the archaeological record) or by looking doing compound specific amino acid stable isotope analysis of seals over time. The idea is that certain amino acids do not change in as they move up the food web as they undergo minimal chemical reactions (aka source amino acids). I just got to try out this technique before leaving Merced, and while it's certainly time intensive I plan to do a lot more of it when I return.

Also I will be leaving for fieldwork (ie. doing Indiana Jones style excavation of sites) in two days at a place called Moat Bay for almost a month. I'll be taking lots of pictures, but I won't be able to post them until I return. Expect some lots of photos in the future!

On a boat

I've fallen behind on my posting since a lot has happened in the last week! I left Ushuaia this morning and am now vacationing in Buenos Aires, so I can relax and reflect a bit. Last week I was lucky enough to go on a boat trip to see some of my fur seal and sea lion friends in live form, which was certainly different from seeing them from the perspective of half destroyed skulls. The sea lions down south were similar in many ways to the ones you find on coastal California, but one thing that was different and immediately obvious is that they appear shorter and fatter. They vocalized quite a bit, just like the sea lions to the north, but the way they vocalized was completely different. They sounded mostly like old men yelling, unlike the barking kind of noises you hear to the north.

The Blue Eyed cormorant with many Sea lions (Otaria flavescens). 

Sea lions in the Beagle Channel. The large sea lion in the foreground is an alpha male, guarding his harem

Selfie shot

We traveled a bit further up the channel, circling a mostly abandoned lighthouse except for a few stray cormorants. This was the spot most popular with the tourists, everyone had to get their selfie with the lighthouse (including me). Something that struck me as unique was how calm and tranquil the waters were in the Beagle Channel, surely nice for both the explorers who used the channel to avoid the rough seas of the Southern Ocean and easy fishing and sealing for the Yamana in their little canoes. Even so there are a large number of recorded shipwrecks around this area. As I learned in one of the museums, insurance fraud led to the demise of many of these.

We circled around and stopped by another island on the way back to Ushuaia harbor. This one was much quieter than the one with the sea lions, but had a number of relatively quiet Fur seals on it (Arcophoca australis). There were also a good number rafting in the water, holding there fins up out of the water. This is a common behavior in Otariids, a thermoregulatory technique (something humans are having trouble with) that allow them to either cool down or absorb heat, depending on the conditions.

Rafters on the right!

This concludes my posting for tonight I think, I'll continue typing some business later!

Viviendo

A rainbow rising from the Beagle Channel

Apologies for the late post here, there hasn't been to much new information to report since the last time I updated. However, there is still plenty I can share with you!

Simple but dependable kitchen

Lately I've been living the CADIC life, which has a nice hotel like space for visitors like me and actually has shared apartments for students who study here. It's simple living, but definitely comfortable. The old gas stove heats up my food maybe a little too fast, but it works! Last weekend the power went out, but I managed well enough cooking in the dark. This time of year there aren't very many visitors so I've had the kitchen and dining room to myself. I end up spending most of my spare time in the office since the internet doesn't really make it to my room (short of holding my phone next to the window) and really only venture out into the world when I need to go shopping. I would go out more often, but by the time I'm finished working for the day the sun has long since set, and its too dark and cold to really enjoy sight seeing. At the very least the weekends give me an opportunity to explore the town a bit and to get to know people. This weekend I'm planning on taking a walk across town to check out the maritime museum, located in the old prison. I'll be sure to share more details about that later on. Today I discovered that the shower is actually capable of getting hot and not just lukewarm, it turns out that I wasn't waiting long enough for it to reach temperature. Knowing this will make my life much more comfortable!

The dining room, straight out of a 70s designer catalog

Over the time I've spent here, I've been learning a ton about the species of seals I'm studying. As it turns out, there's still quite a bit unknown about fur seals and their evolutionary relationships, which strikes me as somewhat odd given that they're common large mammals occurring in many different oceans (Pacific, Atlantic, Indian and Southern.) The majority of Fur seals live in the southern hemisphere, except for one species off of California, the Guadalupe Fur seal, very nearly driven to extinction in the 19th century. Pinnipeds (all seals and sea lions) are divided into two groups: Otariids and Phocids. Fur seals are joined by Sea Lions in Otariidae, while true seals are in Phocidae. My Californian friends are probably familiar with the Otariid California Sea lion, which tends to bark very loudly and keep people up at night. You'll notice that Otariids have ears that stick out and can pose upright, supporting themselves on their front flippers. True seals, Phocids, are unable to do this and are also missing those ear flaps, signalling potentially stronger adaptations to the marine environment.

A picture of A. australis I found on the internet

In South America, only Otariids exist today (except for lost or wandering Antarctic or sub-Antarctic Phocids, and a small colony of southern elephant seals hanging out at the very south-eastern edge of the continent).  Phocidae once had a significant presence in South America, however changing sea levels during past ice ages effectively removed the open beaches that they loved so much several million years ago, leaving behind only rocky shorelines. A-ok for Otariids, bad for Phocids. Some Otariids that took over during this time were the Fur seals, which proliferated throughout the whole southern hemisphere, diversifying into at least six different species in South America, Australia, New Zealand, South Africa, and the sub-Antarctic islands. In 2011, researchers proposed re-classification of most of the fur seal species into a new genus: Arctophoca, (formerly Arctocephalus, only Arctocephalus pusillus kept the genus name) based on a review of genetic data.

The taxonomic situation gets even more tricky for my primary target species, Arctophoca (née Arctocephalus) australis, the South American Fur seal. In the mid 20th century, Judith E. King proposed two subspecies based on comparison of two skulls from the Galapagos and the Falkland Islands. This classification never really stuck though since the skull from the Galapagos was deemed to be a separate species completely (the Galapagos Fur seal) and for many years no subspecies were considered, despite the huge geographic range of A. australis, stretching from northern Chile to Uruguay. In the same review of genetic data that reclassified the genus of most Fur seals, the authors found that the South American Fur seal could have as many a four different subspecies, though more data is needed to confirm these distinctions. At the very least there are three different evolutionarily significant units (ESUs) of A. australis, occurring in northern Chile, Tierra del Fuego, and Uruguay. Interestingly, most of our knowledge about the A. australus comes from the huge colony that lives by Uruguay. The seals from here have smaller body sizes than the seals to the south, potentially hinting at a phenotypic indicator of differences between ESUs (and possibly subspecies). 

The uncertainty about some of these evolutionary relationships has intrigued me to the point where I'm getting serious about another type of analysis that will be helpful: Ancient DNA extraction. I plan to bring back some samples to do a test run to extract ancient mitochondrial DNA. If successful, I can use ancient DNA not only to disentangle some of these complicated relationships between the ESUs, but also find out how the population of Fur seals in Tierra del Fuego has changed over time, from 6,000 years ago to present.

Weighing time

In more other science news, I'm starting to get really busy on the isotope side of things. While I'm demineralizing the last set of bones, I've begun weighing pieces of dried collagen to find out how much is actually left after all that chemical treatment. So far, it appears that I've recovered amounts consistent with previous extraction runs, which is excellent. The weighing step is easily the most time consuming and boring, but it does allow me to listen to a lot of music and podcasts. After measuring the collagen yield, I place a small amount of the collagen into very tiny tin boats, which will later be incinerated at around 900 degrees C to measure those carbon and nitrogen isotopes I'm after. I'll write more about what happens next when I'm back in Merced. 

A closer look at the tin capsules

In a future post I intend to talk a bit about the post-European contact history of A. australis and a bit about the Sea lions. which has important implications for my research! Also some Ushuaia (prison) history. Stay tuned!

ácidos y bases

Ushuaia from the oven room window

Today was my Argentine lab-mate Daniella's birthday (Feliz Cumple!) and so the various members of different labs and offices nearby congregated in the kitchen to exchange gifts, eat delicious cake, and pass around bottomless cups of coffee and mate. This is the third birthday that's happened since I've arrived here, and I'm beginning to think that these aren't really birthdays. People just like to have cake every few days. One of the professors joked that I must be thinking along these lines, apparently there's just a high concentration of birthdays this time of year. He continued to say their new hiring criteria here is that your birthday isn't in July, presumable to prevent endless cake eating. In any case it can be nice to have a break every once in awhile from working in the lab and reading papers.

A bone sample in acid solution

Over the last week and a half I've been checking the samples everyday. To measure trustworthy dietary information from bones, there are a few steps that need to take place. Like I mentioned previously, I'm interested in the bone collagen since collagen exclusively records diet. In order to get at that collagen we need to first dissolve the bone mineral around it (bioapatite for short), in a process known as demineralization or acidification. For smaller pieces of bone, like the ones I'm demineralizing, you use a fairly weak concentration of acid, just 0.5 molar (M) Hydrochloric acid (HCl). (For comparison, the concentration of HCl in your stomach is around 0.1 M.) This slowly dissolves the bioapatite so you can prevent it from dissolving the collagen, too. After 24 hours the HCl has completely reacted with bioapatite, releasing carbon dioxide gas, so a new acid solution must be applied until nothing but collagen is left. (Don't screw the caps on completely, that gas will eventually escape catastrophically, blowing those caps off in the middle of the night). Others will use a weaker concentration of HCl, 0.2 M, though this will take longer. I could dissolve the bones in a few minutes with the raw 12 M HCl, but it would likely take the collagen along with it. It took two days with the 0.5 M HCl for my bone samples to be reduced to collagen, which retains the shape of the original hard bone, but is now soft, spongy and rubbery.

Humic material extracted from old seal collagen

Most people tend to wash their hands if they put them in the dirt after a few minutes. What do you do if they've been sitting in dirt for several thousand years? As the soil scientists at UC Merced can attest to, soils are home to quite possibly the most complex and unknown ecosystems on Earth, hosting vastly diverse organisms and an incredible number of species. These microbial communities often vary considerably from place to place, seasonally, and even diurnally (thoughout the day). The most significant byproduct of soil microbes, or the byproducts that can create untrustworthy stable isotope values in any case, are humic acids, a general term that characterizes the extremely complex (and acidic) organic compounds that are excreted by these microbes. Apply a weak base for several days though and you rectify several thousand years of microbial waste. After some rinsing of the remaining collagen with water and application of 0.1 M Sodium hydroxide (NaOH) for several days, your collagen bits are as good as new! Each individual bone varies in how dirty it is, so those with very little humic acid will be ready after 24 hours, others might take up to five days.

Samples about to be dried in the oven

The next step in the process is to dry the collagen samples. Now that the collagen has been sitting in liquids for the past week and half or so, they're quite waterlogged. What better way to dry off than to be cooked at 55⁰ C (135⁰ F) for 24 hours. Afterward, the samples are ready to weighed to account for the collagen percent yield, which tells us how well preserved the bones are (which hopefully will be around 25% for every sample). Then I will weigh a tiny amount (1 mg, from original pieces of 150-250 mg) into 3x5 mm tin boats, ready to be analyzed by the element analyzer and mass spectrometers in the Fogel lab back at UC Merced.
 
So far I've been limited to 82 samples, since that's how many plastic vials I have. Now that those plastic vials are mostly free again, I'll start this process again with the remaining unprocessed 78 seal bones. Hooray!

When not working in the lab, I've been discussing background material and general ecological and archaeological information related to my project with Pancho, and possible directions where I can fill in gaps in our understanding of the evolution of this ecosystem over the last several thousand years. In a future post I plan to talk about the ecology of Tierra del Fuego and some ideas I'm playing around with. Stay tuned!

El Intercambio de Arquelogía y Ecología

Sunrise at CADIC

Today I was lucky enough to visit el Parque Nacional Tierra del Fuego with Pancho and his graduate student Pili to learn a bit more about both the environment and the Yamana (the indigenous people in southern Tierra del Fuego) who have lived here for thousands of years. Pili is studying how the Yamana processed seals after catching them by looking closely at the cut marks and various other human produced scrapes and scratches, carefully noting changes in how the seals were butchered over time. Thus, she is an excellent companion to have around, and with Pancho, provided me much insight about some of the characteristics and practices of the Yamana. Despite the abundance of archaeological sites here, there is still quite a bit of unkown information about these people, especially their ancestors from several thousand years ago.

There are number of ethno-historical accounts describing the culture and lifestyle of the Yamana written by British missionaries from the 18th and 19th centuries, however it can be problematic to extrapolate this information into the deeper past, not only because these first European contacts tended to exaggerate stories about the cultures they encountered, but also due to the fact that culture is constantly evolving and changing. The Yamana of 18th century were certainly very different from the Yamana of 6000 years ago, even if many of their tools and physical patterns of settlement only show subtle differences. We are unable to identify most of those potential differences since we are left with a scant record of artifacts and other archaeological data since the Yamana had no written language.

Nothofagus trees, with lichen that guanacos love to eat in winter

Despite this, we know that the Yamana were extremely mobile marine resource intensive hunter-gatherers, moving in small familial groups from site to site every few weeks. They would fashioning harpoons tips made of whale bone scavenged from beached whales to 3-4 meter long wooden poles from Nothofagus trees (a relative of oaks, for those of you familiar with trees from the northern hemisphere.) The Yamana of the Beagle Channel would paddle out to sea in their canoes (made from Nothofagus bark) and launch their long harpoons into their preferred targets, Arctocephalus australis, the Southern Fur seal. They would follow their targets until they died from their wounds, unable to dive with the large poles keeping them afloat. The fur seals, unlike other marine mammals, were small enough to fit in their canoes to bring to shore.

Once on shore, the Yamana would butcher the seals with bone and rock tools. (Some early stone tools were made of obsidian only found far to the north, evidence that the early peoples may have been more mobile than the more recent Yamana.) After this work was finished, a few remains, broken tools, and various other bits of unneeded materials were thrown to the side. Typically, working and living sites are identified by a circular pattern with the refuse all around the sides, creating pits in the middle. The vast majority of artifacts used to study these cultures come from the sides of these pits.

Bahia de Lapataia, connected to the Beagle Channel in the background

Why am I telling you all this? Today's goal was to go see some of these pit sites in person. Originally we planned to go the Tunel I, where all my seal samples came from. But a snowstorm yesterday made the 40 minute walk to the site impassable. Instead, we went to the national park were there are a number of other sites and things to see. One very popular tourist attraction, the Bahia de Lapataia (Lapataia Bay) has a number of raised boardwalks that prevent people from disturbing the numerous shell middens and pits underneath. (Midden is the archaeological term for "trash pile"). This particular site is so extensive and has so many shells that the soil chemistry has been altered, resulting in grass that grows in a different color. Unfortunately, these sites were all buried in snow so I couldn't see anything underneath the boardwalk, but I should be able to during my next trip south.

El Rio Lapataia, connecting Lago Roca to Bahia Lapataia

Another very cool place with an exciting geological history is the freshwater lake Lago Roca, which feeds a short, shallow and wide river that dumps into Bahia Lapataia and the Beagle Channel. I should state that all of Tierra del Fuego has an extensive glacial history, almost the entirety of the landscape here was influenced by glaciers during the Last Glacial Maximum (often abbreviated LGM, occurring roughly 25,000 years ago.) Glaciers carved not only the valley in which Lago Roca lies, but also the entire Beagle Channel. The lake is only at an elevation of 2-3 meters above sea level, hinting at its history as a fjord connected to the ocean after the glaciers retreated. Geologists believe that the fjord was cut off from the ocean about 6,000 years ago, leading to the formation of the lake. Archaeologists, however, contest this date since they find sites with shell middens (marine shells, mind you) from 4,000 years ago along the lake shores. While early peoples could have transported these shells inland, that would be inconsistent with observations found in other parts of Tierra del Fuego. In any case, it's very pretty and is a popular spot among hikers, canoers and kayakers during the summer months.

Looking toward the north shoreline of Lago Roca, where many shell middens are found

Looking at the south shoreline of Lago Roca, which marks the boundary with Chile

I was planning to write a bit about how the chemistry side of seal analysis was going, but this post seems pretty long and full of info already, so I'll save that for a post later this week. Stay tuned!