After our successful excursion at Duthiers Point, the ARAON sailed north through the Gerlache Strait to Hughes Bay.The Cayley Glacier, among the most rapidly retreating glaciers in the Antarctic Peninsula, drains into Hughes Bay.Spring Point is a rocky embankment that looks over the bay and the glacier, a perfect place to install a triad of glaciological monitoring devices.
Spring Point can be reached by zodiac, but as our team arrived onshore, they soon realized the steep, slick rocks made it quite difficult to move heavy equipment up to higher ground.The helicopters were able to hoist cargo nets from the beach to a landing zone at Spring Point, where a Chilean summer hut stands.While it was not particularly cold outside, a steady drizzle of freezing rain ensured the field party was drenched.
Our colleagues from KOPRI installed a seismic station to monitor the vibrations and shockwaves that glaciers emit as they flow and icebergs calve into the water.These measurements provide a continuous quantitative record of the physical behavior of nearby glaciers.Another device that was installed, a camera from the Extreme Ice Survey, will take time-lapse photographs of the Cayley Glacier.The photographic evidence, in concert with quantitative measurements from the nearby seismic station, will bolster our understanding of the glacier’s behavior.
A GPS station is also present at this location which measures changes in the elevation, as the earth rebounds following deglaciation.The earth’s crust compresses like a sponge when glaciers are present.When the glacier is removed, the land rebounds and rises.By measuring subtle changes in elevation it is possible to estimate how much ice was present in a given area.
Following the field party’s return to the ship, we began our transit north through the Bransfield Strait.As is tradition on the ARAON, our Korean hosts put on a great celebratory dinner as our science concluded.The chefs laid out a wonderful spread of Korean cuisine, and the entire science staff enjoyed each other’s company in the galley.
Following dinner, we traveled through the Croker Passage to the open waters of the Bransfield Strait.While most of journey, including our first crossing of the Drake Passage, was relatively tranquil, this transit through the Bransfield Strait was not.With sustained winds of more than 50 knots and nearly 10-foot swells, the ship rocked back and forth for the entire night.My cabin, which is on the third deck about 35 feet above the water, was constantly being splashed as the ship rolled onto the crests of large waves.While I did not become seasick, even without the aid of Dramamine, I certainly didn’t sleep at all during the overnight journey.
Our destination was King George Island in the South Shetland Islands and King Sejong Station, the Korean research station.The rough seas of the Bransfield caused some delay, and we arrived at the station after dark.King George Island has several research stations built on it, making it the most densely ‘populated’ place in the Antarctic; however, no one actually lives in the Antarctic year-round. The purpose of our visit was to transfer food, supplies and fuel for those spending the winter there.
Due to severe weather conditions and required base operations at the station, the ARAON remained at King George Island for a few days.It was nice to sit still on the vessel following the rough seas in the Bransfield.We left for the Drake Passage on May 11, and much to our surprise, it was a rather calm crossing. We arrived in Punta Arenas on May 14 early in the morning. It was a bittersweet moment to leave the ship. We were eager to be back on land, but we also realized that the trip had come to a close.
Later that day we had our post-cruise celebration at a hotel that overlooks the town.It was a great chance to see everyone from the cruise one final time, relax and reminisce about the voyage.It was a time to celebrate our success and accomplishments.The ARAON proved to be a strong, able vessel capable of enduring the harshest seas and sea ice.We ventured to both the west and east sides of the peninsula, a feat no one anticipated.Furthermore we were able to collect data from the Larsen A, B and C ice shelf areas.The Weddell Sea is truly a frontier on this planet, and this dataset will no doubt break new ground in understanding this region’s climate and geologic history.
The next day, a few of the marine geology students, including me, ventured to Torres del Paine national park in Patagonia.We left early in the morning and arrived in Puerto Natales, the gateway to the park.Puerto Natales is set in a stunning landscape next a large proglacial lake nestled between high snow-covered and glaciated, jagged peaks.The drive to the entrance of the park was long, nearly two hours, but an adventure in and of itself.Packs of guanacos, llamas native to Patagonia, lined the road into the park as the famous torres (towers) loomed in the distance.
The weather on our trip was remarkably clear and warm, especially for one of the harshest, wettest and windiest environments on the planet.This made for absolutely stunning views of everything in the park.The park is truly a geologic wonder in every sense.Many of the lakes in the park are stranded basins, or lakes that have inflows but no outflows.This situation creates unique hypersaline conditions forming special salt crystals along the shoreline and poses interesting hydrogeologic questions as to how the lakes drain via groundwater flow.
The Torres themselves are a geologic enigma.They are composed of a large sequence of marine turbidites (submarine avalanche deposits), overlain by white granite that possibly intruded as a laccolith, and capped by a brown mudstone.How the granite intruded so magnificently between marine sediments is a mystery, and due to the extreme inaccessibility of the peaks, many geologic questions remain.Glaciation and tectonic uplift sculpted the Paine Massif into impressive vertical towers and horns that boggle the mind.For a glacial geologist, this landscape is breathtaking as so many glacial processes are preserved in the park.
The following day we ventured to another part of the region to the Cueva del Milodon, a glacially formed cave where a multitude of paleonotological and archeological artifacts have been recovered.The fossils at the site include many Pleistocene megafauna, large iceage mammals, including horses, llamas, sabertooth tigers, bears and the Milodon, a giant ground sloth.The site also has the remains of the first human inhabitants of Patagonia nearly 12,000 years ago, making it one of the most important and significant anthropologic sites in South America.It’s a humbling, humanizing experience to set foot where brave men and women survived one of the world’s harshest environments.It was great bookend to our long adventure at el fin del mundo.
In the past few days we transited up and down along the Graham Land coast. After successfully recovering sediment cores in Bigo Bay, the ARAON sailed north to Andvord Bay by way of the Gerlache Strait. The plan was to attempt helicopter operations to the east side of the peninsula, but a low ceiling and heavy cloud cover in the east prevented crossing over the Bruce Plateau.
The focus of the day then shifted to installing a short-term mooring in the Gerlache Strait to monitor physical oceanographic properties and glacial behavior. Dr. Erin Pettit, a glaciologist from University of Alaska Fairbanks, installed a hydrophone to the mooring as a way to “listen” to nearby glaciers. Different glaciological behaviors such as melting, basal sliding and outbursts of meltwater emit sound waves at distinct frequencies that can be identified and interpreted. Much of our observations of glaciers rely on observations from the surface, so collecting information from underwater closes a data gap and enhances our understanding of glacial systems in their entirety.
After the mooring was deployed, the ARAON performed a multi-beam survey of the Gerlache Strait to further resolve the glacial marine geomorphology of the region. We collected sediment cores from a relict grounding zone, or where glacial ice was in contact with the earth’s surface, with the hope to date the retreat of the AntarcticPeninsula ice sheet at the end of the last ice age.
We awoke on Friday in Flandres Bay to clearer skies than our first visit. The sun rose and illuminated the majestic peaks and snow- covered sea ice in the fjord. As I stood on the back deck, I saw a group of Adelie penguins swim by and pop their heads out of the water.
With clear conditions in the fjord, the helicopters were able to take off. The grandeur of the fjord distorts any sense of scale until a helicopter leaves the ship and looks like a small toy as it flies next to the towering peaks. The differentiated climate of the peninsula yet again prevented travel to the east as clouds shrouded the top of the Bruce Plateau and east. The helicopters returned as a group of approximately 10 mink whales surrounded the ship, breaching the surface and making courtship displays. It seems they knew everyone on the ship was on deck watching as they put on a show.
With helicopter operations cancelled for the day, we were presented with the incredibly exciting chance to take a scenic helicopter ride in the fjord. All of the science staff was given the opportunity to cruise through Flandres by air. Words cannot describe how amazing it was to rise above the ship, fly between mountainous icebergs and realize the scale of the fjord. I will never forget this experience!
The ship departed Flandres Bay to sail north to Andvord Bay and perform a multi-beam survey of the Gerlache Strait along the way. On the way out of Flandres, the sun set at approximately 3 in the afternoon providing some great views.
We awoke on Saturday morning in Andvord Bay to attempt helicopter operations, but low clouds and poor visibility again prevented flying. Instead the ARAON redirected course to Duthiers Point near the mouth of Andvord Bay.
At Duthiers Point the other students and I were given the chance to depart the ship by a zodiac boat to go ashore. After a short ride, we set foot on the Antarctic landmass and a group of Gentoo penguins greeted us. The penguins definitely preferred our visit to the two hungry seals lurking around the beach at the time. While some students assisted the glaciologists with a seismic monitoring station installed at Duthiers Point, I joined Dr. Jeong Bae Seong, a glacial geologist from Korea University, to search for glacial erratics and glacially sculpted bedrock for cosmogenic radionuclide dating samples.
Cosmogenic radionuclide dating is a geochronological technique, or a method to determine when an event happened in Earth’s history, used to determine when ice retreated from formerly glaciated areas. The Earth is bombarded with cosmic rays, and these rays interact with elements in the atmosphere. This interaction creates isotopes that accumulate in rocks exposed at the earth’s surface. When rocks at the surface are covered, by a glacier for example, these isotopes cannot accumulate. So when a glacier retreats then the rocks are exposed again and the radioisotopes accumulate in the rocks. After quantifying the abundance of the isotopes in the rock, it is possible to determine how long it was exposed at the surface, telling us when ice retreated from a given location.
Glacial erratics are rocks that were transported by a glacier and deposited after the glacier downwasted and retreated. The lithology, or rock type, often does not match its current surroundings, so they can be easy to identify — that is if they can be found! Dr. Seong and I had difficulty finding any erratics to sample, especially with the amount of snow covering the ground. We were able to collect samples of the glacially polished bedrock. These results will further pinpoint when ice retreated from this area at the end of the last ice age. As this method will be the focus of my future graduate studies, I was particularly excited to collect samples—especially in the Antarctic Peninsula.
The ARAON spent April 29 in Flandres Bay completing a comprehensive series of CTD casts. Each cast recorded physical parameters and collected a set of water samples from discrete depths keeping the oceanographers and biologists in our group very busy. Scientists from the Scripps Institute of Oceanography sampled water continuously to analyze the concentration of chlorophyll, an indicator of primary productivity, among other biologic properties of the water. To learn more about that group’s activities, follow the link posted on the left side of the page.
After completing the CTD work, the ARAON departed Flandres Bay for Beascochea Bay to attempt helicopter operations for the glaciologists. Traveling out of the protected fjords into the Bismarck Strait and Grandidier Channel proved to be quite rough, and the night watch crew endured some large rolling waves. We arrived in Beascochea Bay the next morning to seemingly ideal weather conditions. The skies were relatively clear, and the sun slowly rose up and above the mountains, illuminating the glaciated mountains, sea ice and icebergs in the fjord. Both helicopters took off to attempt glaciologic work, but clouds shrouded the eastern side of the peninsula barring them from working there.
With helicopter operations cancelled for the day, the ARAON cruised south to Bigo Bay to expand multibeam survey coverage and collect sediment cores. Bigo Bay is of particular interest to me as it is adjacent to the fjord I studied for my senior thesis, Barilari Bay. After identifying a couple of potential sediment core locations, the KOPRI team successfully recovered a set of sediment cores from Bigo Bay including two gravity cores and two box cores. A box core aims to capture just the very upper interval of sediment and maintain the sediment-water interface. As these cores were brought on deck, we examined the creatures that live on the seafloor including spiders and worms. We sampled the surface of the box core in order to characterize the modern biologic communities and conditions present in Bigo Bay today.
The gravity cores were a great success and both are over seven meters in length. Everyone is excited to open, describe and sample the cores to learn more about the paleoenvironmental history of Bigo Bay and how it compares to other studied locations nearby, namely Barilari Bay. More geologic work is planned in Leroux Bay, the adjacent fjord to the north, to add to the pre-existing data collected from the four fjords along the Grandidier Channel.
Since last Thursday, the ARAON has traveled north out of the Larsen B embayment through the icy Weddell Sea to reach the open waters of the western peninsula. The sliver of open water in the Weddell had begun to close as the temperatures dropped and winds shifted. At the northern end of the Larsen A, massive icebergs choked the sea. The ship squeezed through the ice just around Snow Hill Island into the open Erebus and Terror Gulf and back through the Antarctic Sound to the Bransfield Strait.
The change in itinerary brought by sea ice on the eastern side of the peninsula presented us with the opportunity to visit the majestic fjords of the west again, but this time via the Gerlache Strait. The Gerlache passes between the impressive mountains of Brabant Island and Anvers Island to the west and the Danco Coast to the east. We entered the Gerlache via the Croker Passage at dawn on Saturday morning. The scenery the entire day was spectacular as towering peaks encapsulated in glaciers surrounded us, icebergs with deep blue hues passed by the ARAON, and the sun set between Anvers Island and Brabant Island. We encountered the RVIB Lawrence M. Gould, one of the United States Antarctic Program icebreakers while near Brabant. In transit we continued to collect CTDs (the primary tool for determining essential physical properties of sea water) to further resolve the oceanic circulation around the Antarctic Peninsula and sampled sediment cores collected from the Larsen embayment.
Yesterday morning the ship arrived in Flandres Bay, a large fjord just to the southeast of Anvers Island to attempt helicopter operations. Clouds and snow kept the helicopters grounded again, so the biologists in our group devised an extensive CTD sampling plan for the fjord. While a CTD is cast, a set of instruments measures water properties such as temperature, salinity, density, and chlorophyll. The instruments continuously measure these parameters for the entire depth of the water at a given location. In a fjord setting it is possible to see the influence of different water masses and processes such as the influx of warm, saline modified Circumpolar Deep Water, last year’s winter water, the warm, productive waters from the past summer, and contributions from glacial meltwater. Then water is sampled from discrete depths on the CTD cast, further bolstering the dataset from that location.
The current plan is to stay in or near Flandres Bay for the next few days. We are keeping our fingers crossed that the skies will clear so our glaciology team can complete their work!