Transiting back to Site U1359
Position: 64º 34’S, 140º 30’E
Water Depth: 3700 meters
The scene outside: 2 days of storms and lots of icebergs

ABOARD THE JOIDES RESOLUTION, OFF THE COAST OF WILKES LAND, ANTARCTICA– Our latest drilling target is in an area where sediments that document the transition of Antarctica from the “Hothouse” to the “Icehouse” can be easily reached at shallow depth beneath the seafloor. We drilled for 18 hours and then had to pull the drill pipe up out of the hole and reposition the ship to avoid a large iceberg that was heading straight for us. When the iceberg had passed the weather started to deteriorate. Our forecast was for 60 kt winds and big seas so we headed north out of “iceberg city” to ride the storm out in deep water away from icebergs and sea ice. The forecast was true to its word – we had waves up to 30 feet and winds over 60 kts for more than 24 hours. But we had great iceberg viewing on the way to our WOW (Waiting On Weather) point so I’ll write something about them and how they fit in with our project.

The Antarctic ice sheet is always accumulating new snow that gradually turns to ice. For the ice sheet to remain the same size it must either melt or release ice to the ocean as icebergs. In parts of Antarctica some of the ice is in fact melting but most of the ice loss that maintains the continent at its present state occurs through the calving of icebergs. Most icebergs calve off of ice tongues and ice shelves – areas of concentrated ice flow at the coast. Imagine that the ice is draining off of the high parts of the continent by flowing down small ice drainages to form mighty rivers – but rivers of ice in this case. These vast rivers move slowly, only a few 10’s to 1000’s of meters each year. When they reach the coast, the ice flows out into the ocean where it begins to float wherever the water is deep enough. In some cases, this is where the water is over 500 meters deep and the ice is over 560 meters thick. Floating ice shelves or ice tongues are influenced by winds and ocean currents. They begin to melt if the water is warm enough but they mostly breakup to form icebergs.

Many of the icebergs here off Wilkes Land came from the Ross Ice Shelf – the world’s largest ice shelf. It is over 1500 km away in the Ross Sea but icebergs travel great distances in the Southern Ocean. The water is cold and they drift with the ocean currents, for decades in some cases. As they drift, they melt a bit below the waterline and become rounded. Sometimes they flip over and this rounded part is then visible. Icebergs often collide and gouge away at each other or they list over at an angle and slowly fall apart. This means that icebergs come in all shapes, sizes, and textures.

The biggest iceberg we’ve seen was over 20 km long.

Icebergs come in all colors, from the pure white of fresh snow to the deepest blue of pure crystalline ice from far below the surface of the ice sheet.

Icebergs come in all shapes, sizes, and textures.

A penguin on a growler (a small iceberg).

The ice at the base of the ice sheet often carries sediments: boulders, gravels, cobbles, and sands. When these parts break off and begin to float they form “dirty” bergs with dark rocky layers intermixed with the clear blue ice. The debris that falls from these dirty bergs accumulates in sediments at the seabed. When we see gravels or sands in otherwise fine-grained sediments, we know this debris was transported out over the ocean by ice. In fact, the presence or absence of ice-rafted debris is something we keep close track of in the cores we are collecting on this trip – this tells us whether Antarctica was generating lots of icebergs and therefore had at least some kind of ice sheet in the past. Conversely, when we see sediments that do not contain this debris we know we are looking at a record from a time when Antarctica was much warmer.

In the foreground, a dirty iceberg.

We’ve seen over 400 icebergs in the past 2 days.

As I write, the storm has abated and we are transiting back to our drill site.

Dawn at 4:30.

The core splitter.

The majority of the cores on Expedition 323 are mud cores. They require a straightforward procedure to cut them. The plastic core liners are placed on the splitting table and on a grooved track. The track has an motor controlled cutting tool that consists of two hooked razors that split the core liner, but are set at a depth to cause the least damage to the mud in the core. In addition to these razors, there is a thin wire that is held taught and sliced down the length of the core. It works like a big cheese slicer. After the entire liner and end caps are cut, a good tap on the table next to the splitter usually separates the core cleanly into halves. Stickier sediments may cause the halves to cling together, but a small squirt of water or even manually moving the parts with a spatula will cause them to fall apart. This video gives you a good idea of how the process goes.

We’ve been lucky enough to have some hard rocks recovered at one of our sites as well, so I was able to look at the process for them as well. First the pieces of core are cleaned of debris caused by the drilling. The edges of the core may have residue left over from the very physical nature of the coring. After the pieces are cleaned up, they are compared to one another to find out if they are continuous but broken pieces, or if there are gaps. If there are gaps plastic markers are glued in the casing to let those who observe the cores later know what was together in the ground. Often tool marks on the outside of the core can be matched up to give a definite idea of how the pieces were assembled. If the pieces are present, but might crumble or move during the cutting, a quick application of some plastic shrink wrap does the trick to hold them in place for the cutting.

Next the reassembled core is placed in the same groove as the mud cores, but the splitter blades and wire are replaced with a diamond cutting wheel assembly. The blade is slowly moved down the length of the core slicing through the hard rock. It is a noisy and dusty process. Afterwards the halves are carefully separated and cleaned to remove any dust created during the cutting. Afterwards they are left to dry, and the various pieces are labeled with tags glued onto their surface.

Hopefully you have a really good idea of how all of this works now! Next the cores go to the sampling table.

Dr. Pekar as the helicopter landed at the Offshore New Harbor field camp.

The excitement built when a distant dull hum steadily became a louder roar as the helicopter approached and finally landed at our camp. Eight of us strapped ourselves in for a most memorable ride.

Flying in the helo.

I had only been in a helicopter once before and I couldn’t wait to see the view unfold before my eyes. We were going to be flying over New Harbor, a sight we had seen from afar every day since we had arrived at our field camp. But this time, it would be different. Once over New Harbor, we would fly through the Ferrar Valley, over the Ferrar Glacier and eventually to the Friis Hills field camp to visit with Dr. Allan Ashworth and Dr. Adam Lewis who were looking at 20 million-year-old glacial lake sediments for fossilized plant leaves to better understand Antarctica’s role during that relatively warmer time period of Earth history.

Looking up Ferrar Valley, flying over New Harbor.

Shortly after take-off we were already getting a much closer view of New Harbor and the Ferrar Glacier as we quickly approached Ferrar Valley. As we sped past glaciers seemingly falling off the sides of mountain tops, the vastness of the Transantarctic Mountains opened up. We were in the Dry Valleys.

The banded mountains of the Dry Valleys.

The mountains were huge and banded with different colors, each color a different rock type. As we soared higher and flew deeper into the mountains, the enormity of Antarctica showed itself.

The East Antarctic Ice Sheet.

The largest continental mass of ice on Earth, the East Antarctic Ice Sheet, could now be seen. We were only seeing a very small portion of it, but it extended as far as the eye could see beyond the mountain tops. This is the source of the ice producing the glaciers that we could see all around us.

Friis Hills field camp as the helicopter touched down.

The helicopter landed at the Friis Hills field camp, and the first thing I noticed was how the Dry Valleys got its name. It was dusty and gritty, very different than what I was used to out on the sea ice. The rotor blades of the helicopter blew sand and gravel into the air. Sand and stone were everywhere. But it hasn’t always been that way. We were meeting Dr. Ashworth and Dr. Lewis. They had agreed to take us on a tour of their research site and explain to us what they were studying.

Walking through a former glacial lake.

Dr. Ashworth and Dr. Lewis explained to us that in the past glaciers cut through the surrounding hill tops, and that 20 million years ago it was a relatively warmer time in Earth’s history. And because it was warmer, some of the ice from the glaciers melted to form lakes. By studying how these glacial lakes formed and what kinds of vegetation were in these hills of the Dry Valleys, Dr. Ashworth and Dr. Lewis hope to better understand how Antarctica responded to this warmth.

The most exciting part of their tour was to see the 20 million-year-old leaf fossil impressions that they had dug up at their research site. The leaves themselves are gone, but what is left is the impression that these leaves made in the lake-bottom mud. The leaves of bushes bordering this lake were blown into the water when they fell off the branches. They then sank into the mud on the bottom of the lake. Shortly afterward more mud accumulated on top of the leaves. The leaf material then disintegrated but a mark was fossilized in the rock where the leaves once laid.

20 million-year-old leaf fossil impressions.

We made our way back to our camp. This was the last time that the entire team would be together out on the sea ice. Andrea, Shakira, Joanna, and I were flying back to McMurdo Station on the helicopter that had taken us around during the day. We had a few minutes to gather our belongings, load up the helicopter, and have a group photo taken, by the helo pilot no less (thanks Paul!).

The Offshore New Harbor Team.

I had mixed emotions as the helicopter took off. I could see how tiny our existence on the ice was as camp soon became a little speck on the horizon behind us. The only way to notice it as we got further and further away was by following all of our tracks on the ice surface that we had traveled to get out to the transect lines where we were collecting data. All paths lead back to camp. We were 17 people in the vastness of Antarctica. 17 people working together to accomplish a common goal. We were successful against early setbacks and I was proud of what we had done as a team. The data that we collected will be used to identify a drilling location to obtain sediments to study our past climate in order to better understand our future changing world. And I was a part of it all. I felt extremely lucky to have been selected to join the Offshore New Harbor Expedition and very honored to have shared that place with every other member of the team.

Offshore New Harbor Field Camp from the air.

This new path with no track in the snow was not going to take me back to camp. I was beginning the long journey home. Back to McMurdo Station, fly to New Zealand, and then make my way back to New York. I am going to miss the Offshore New Harbor Team and the many good friends I’ve made at McMurdo. But thoughts of family and friends I haven’t seen in many months flooded my mind. I have missed them immensely. I am ready to leave. I am ready to return home. My work here is done, for now.

McMurdo Station from the air.

At sea, it looks like black ice, shiny and dark.

Black ice.

Today we sampled such an iceberg. A party of 5 (Tim Shaw, Ken Smith, Rachelle Pagtalunan, Stian Alessandrini and Rolly Rogando) went on a boat a few hundred meters away from the ship carrying picks and buckets to chip the ice and bring it on board.

Taking rock samples from the ice last season. While we usually take zodiacs (small rubber boats) to sample ice and rocks, occasionally we can do it from the side of the boat.