After spending five days along Baker River and collecting nearly 40 meters of sediment, our beloved Russian corer deserved a good rest. So did our backs. Before hitting the road to Tortel to start the second chapter of our expedition, we decided to explore proglacial lake Calluqueo, one of Loic’s study sites. Reaching the lake wasn’t easy. It required bringing all of the equipment, including an inflatable boat with engine, along a narrow path winding down the steep lake shore. Half a day and liters of sweat later, Seb and Loic finally took off with the zodiac and echosounder to map the lake’s bathymetry.
Mapping lake Calluqueo gave Loic a first glimpse of the fieldwork that is awaiting him in the coming years. For his PhD, he will study how glacier variability is recorded in lake and fjord sediments. Exploring lake Calluqueo also trained him for the next site on his to do list: proglacial lake Steffen. While Elke, Eleonora, Helena (our British guest), and Seb, were going to spend their time sampling Baker and Steffen fjords, Loic was going to explore the sediments of Lago Steffen, in collaboration with a team of scientists from the University of Bristol, UK.
Our first day in Tortel was spent assembling the many mooring parts that arrived in Chile during the last twelve months. After months of preparation, the mooring was finally ready to be dropped at the bottom of the fjord. It was exciting to see this series of instruments including a sequential sediment trap and a turbidity logger, safely hanging on a 300 m long rope in the middle of Baker fjord. For the coming year, it will continuously collect sediment and record suspended sediment concentrations, providing us with crucial information on how Glacial Lake Outburst Floods are recorded in fjord sediments.
Although most research cruises generally quickly turn into a sampling routine, ours did not. Our only real routine is hitting the alarm clock at 5 am (or earlier when Elke forgets she is on a different time zone) to get up early and be on our way by 6 am. We have so many different types of samples to gather that every single day is different: everyday, we collect a different mixture of water samples, CTD data, sediment cores, grab sediment samples etc, in the framework of the Paleo-GLOFs and HYDROPROX projects. Our team is so well coordinated that in a single day in Steffen fjord for example, we obtained about 2 km of CTD data, dropped supplies along Rio Steffen for our British collaborators, and collected 360 liters of water that Eleonora will spend the coming days filtering to retrieve enough suspended sediments for analysis.
Eleonora is not the only one collecting sediments from the water column. A second sediment trap, which we just deployed in Steffen fjord, will hopefully do the same job for us for an entire year. Thanks to the brilliant splicing skills of our captain Rodrigo, this second mooring was built and deployed within less than one hour! For the coming year, 350 kg of scrap metal is what will keep our two moorings anchored at the bottom of the fjords.
As real geologists, we can’t cruise along a fjord without digging some mud. Whether it’s in a flat prodelta plain, an active channel, or a proglacial river delta, we always enjoy getting dirty! In this part of the world, mud mostly consists of glacial flour. Seb prefers comparing it to dulce de leche, the typical Chilean caramel-flavoured equivalent of Nutella, also called manjar, which is nearly as sticky and has the same consistency as our beloved fjord mud. For Elke, Eleonora and Loic, however, Patagonian mud is much better than manjar … it contains precious information that they will study in details for their PhD theses once back in Ghent.