Antarctic marine life and the origin of fossils

In the basement of the Crary lab where we work are several large tanks filled with water. In the water are animals that were collected by biologists from the sea floor and the waters of the McMurdo Sound. The temperature of the ocean here is only 28 F (-2 C) , which means it is below the freezing mark of fresh water. Nevertheless the ocean is teeming with life and has a quite elaborate food chain, with top predators, such as killer whales, and leopard seals and the Antarctic krill at the bottom. All these life forms have special adaptations to the cold. For example, fish, such as the Antarctic Cod, have a type of natural antifreeze in their blood which keeps it from freezing. In the photos you can see several strange-looking arthropods, star fish, bivalves and sponges.

There is a marked difference between the fossils we find in the cores and the biota of the modern McMurdo Sound. The difference is primarily caused by the fact that only skeletal body parts are preserved in the rock record. When animals die, their soft tissue decays, and only skeletal parts accumulate on the sea floor. A fossil assemblage therefore only represents a small portions of the actual fauna of the sea floor in the past. Paleontologists are aware of that and are specialists at knowing what is missing.

The last sampling party

Yesterday was the day of the last sampling party. Drilling is still progressing with a narrower bit and we do get to log it during the day, but the sampling will be done off-ice during a workshop in Florida next year. Note the little flags: they look quite used after more than a 1000 meters of core. I have collected ca. 300 samples, which will be processed in the lab at Montclair State University and measured on the laser particle sizer.
Peter Webb, my former PhD advisor is here too and you can see him in the picture below. He is being interviewed for a NOVA documentary and serves as a general advisor and guide to the project. You can watch a video about his early research in this area in the late 1950s on the website of ANDRILL. More videos about Antarctica today and Antarctic Geology can be found there as well. The link is here....

Logged 1011 m of core on the night shift!

A few hours ago we finished logging the first batch of core down to 1011 meters below sea floor. We have been logging for 5 weeks now, 12 hours a day, 7 days a week, so that is why we look so tired. The photo was taking soon after we finished logging and Chris is holding the last core section. The picture was taken by a radio journalist, who joined us this night. The core of last night was magnificent! The last part of it consisted of ripple-laminated sandstones. The ripples are made by currents and the dark mud layers between the ripples indicate that currents were periodically going faster and slower. This is very typical of a tidal environment. You can also see a bit of pyrite ("fools gold") at 85 cm and 93 cm, that formed as crystals in the sand after it was deposited. The minute we finished logging the message came in from the drill site that drilling had started again and that core had come up. We are going to have a one day break now, however, because we are transitioning to day shift.

The Turkey Trot

Yesterday was the day of the traditional McMurdo Turkey Trot. It takes place on the morning of the Thanksgiving meal and it is a 5 km running event on the sea ice. I participated 9 years ago, but this time I didn't feel up to it, but that gave me an opportunity to cheer my colleagues on and take some pictures. Here you see my nightshift buddies Phill, Josh and Chris at the start of the race. (Never mind Phill's outfit.) There was a mean cold wind coming across the peninsula, but it took them less than half hour to get back in: great job guys!

Later that night after we tried to sleep (it was very noisy in the dorm) we had our Thanksgiving dinner at midnight. The food was superb: of course with Turkey, stuffing, fresh fruit, salad, and desert. We also logged 36 meters of core. We have one more night of core logging to go and then we will revert back to the dayshift.

Happy Thanksgiving from Antarctica!

Happy Thankgiving from Antarctica. We will have our Thanksgiving dinner tonight at midnight with the nightshift from the drill site. They will come in from their little camp on the sea ice to celebrate with us: we have a lot to give thanks for with such a great core! We also need to work tonight, so perhaps a glass of wine will be okay, but not too much. Drilling will start again on Sunday. Our drill hole is now the second deepest on the continent (the deepest is the other ANDRILL drill hole of last year) and since we still have time in our schedule, an attempt is going to be made to go deeper than the 1011 m we have now. For us it means we have to keep logging.

After long sequences of mudstones, with very little evidence of ice close to this area, we saw evidence of ice sheets in the core last night. Once again: we see the ice-sheets come and go and the core tells us it continues back in time for more than 17 million years!

No helo trip, but core with calcite veins

The weather turned bad with snow across the sound so we did not get out on our helo trip. Instead, we logged more core (we still have 111 m to go to complete the 1011 m that were drilled). The core had multiple fractures and faults last night, evidence of brittle deformation associated with tectonics. The Earth's crust is spreading apart in this area: we call this a rift and that causes the fracturing and faulting in the rock, as well as the volcanism in this area. One calcite vein fill was truely spectacular: so here is the photograph. Calcite precipitates from the fluids that circulate through the rock.

Helo trip to the Dry Valleys scheduled

This is 08H or zero-eight-hotel. We received the helo schedule last night and a few of the night shift scientists are signed up for a trip with 08H to Taylor Valley in the Transantarctic Mountains this evening. The purpose of the trip is to survey the regional geology so we get a better understanding of the composition of the sediments in the core we are investigating. The plan is to be dropped off at a high point in the Dry Valleys and then walk down the valley walls of Taylor Valley to the valley floor. We will then pass through several rock units, which were eroded by outlet glaciers of the East Antarctic ice sheet. It is likely that some of that eroded rock material is what makes up the sediments in the ANDRILL SMS core. All is scheduled, of course as always weather permitting. Right now it is not looking great with more snow in the forecast.....we will have to wait and see if they let us go out.

A 1000 meters below the sea floor on the night shift!

Last night the night shift at the drill site reached 1000 meters below sea floor, our target depth. We, the core loggers in McMurdo are also on night shift and we celebrated a little bit with them. It is quite hard work, from 10 pm until 10 am every night, 12 hours a day, 7 days a week, but now with the celebrations of the project and the end in sight we are getting new energy. Last night was amazing because we logged meters and meters of core without any evidence for large ice sheets at all. There were a few rocks (clasts) that probably fell out of icebergs, but really only few. That was quite unexpected, but I like surprises better than getting what is predicted: it is the exploring that makes doing this type of research so enjoyable. We also found some fossil scallops, such as these here in the photo: the original fossil is still there, but also a mold, an imprint of the shell. These discoveries make the work worthwhile and interesting. What you see here is the half core: so the drill bit drilled partially through the scallop and then the drill core was split in half.Drilling at the drillsite has stopped and now a new team will step into action. After the drillstring has been removed from the hole, the down-hole logging team will bring their tools to the bottom of the hole and then pull them up slowly. While the tools are pulled up, they will measure the physical properties of the layers of rock and also take images of the walls of the borehole. In the mean time we will continue to describe the core until we have gone through all 1011 meters of it. There will be another phase of drilling with a narrower drillbit after the down-hole logging is completed, but we will describe that core on the dayshift towards the end of the season. The plan is that we will also take a helo trip to the Transantarctic Mountains to survey the geology there, because many of the sediments in the core are eroded by glaciers from that region. Stay tuned for a report of that trip.

Back in time and almost where we would like to be: 1000 meters below the sea floor!

This is an interesting phase of our project. The drill bit is more than 940 meters below the seafloor. The rock is getting really hard and the sediment is impregnated with hard, sometimes black, cement. So deep below the surface the pressure and the temperature are much higher than at the surface and that turns sediment (like beach sand) into rock. We are drilling such a deep hole because we would like to take a journey back in time and observe what Antarctica looked like in the past. We are also trying to find out when and how Antarctica got so cold and whether it is likely to stay that way in times of future global warming. Today, Antarctica is a frigid place, as you may have seen on this blog , but we know from previous drilling that it was not always like that. The arrow points to where I am on the image made by NASA. More than 90% of the continent is covered in ice, with only some mountain ranges sticking out above the ice surface. The photo to the right is of a biodiversity study here close to the station, but as you can see there are no plants growing here now. Previous drillholes have indicated that plants were once present in Antarctica. We are finding coaly plant debris in the core for some time now. We have been sending samples to scientists off the ice in New Zealand and the U.S. who are trying to find out what type of plant the material represents. Today we found some more coaly bits in the dark grey rock to the right. The question now is whether this material represents the vegetation on the Antarctic coast at the time of the deposition of the sediments or some older coal material. We will find out later! We know that aprox. 35 million years ago Antarctica looked very much like the coast of New Zealand (see image by I. Woodward), but when did it change? That is what we are trying to find out.

On the sea ice of the Southern McMurdo

The drill rig is situated on multi-year ice (shore-fast ice) adjacent to the Transantarctic Mountains. In the image you can just make out the drill rig in the distance. Those blue ice areas in the front are frozen meltwater pools, which developed during the last summer season and froze again during the winter (remember that the seasons are opposite here to those of the Northern Hemisphere). The surface of the sea ice can be dirty from dust and rock particles blown onto it by storms or material carried by small meltwater streams. Fresh snow gives the surface a bright and white color, but the sea ice surface is never smooth: the wind sculpts and erodes the snow into sastrugi. Most of the sea ice travel is on flagged routes, where the sastrugi have been plained off.

The sea ice is the habitat of penguins and seals. I didn't see any penguins this year, only footprints so far. I did see a seal flapping around in the distance. Most of the seals we see here are Weddell seals, who are endemic to the Antarctic region. Weddell seals primarily feed on fish. There is also a predatory seal here: the Leopard seal. Divers and biologists studying the seal and fish populations are always on the lookout for Leopard seals. They are solitary hunters and can follow their prey for a long distance without being noticed. Some close encounters have occurred, but no major injuries have been reported.

A visit to the drill site out on the sea ice

Last night we had a day off and we had a chance to visit the drill site. We were picked up by the staff scientist and he drove us per Mattrack vehicle out on the sea ice. We followed the procedures for sea ice travel: checked out with Macops by radio and delivered our estimated time of arrival at drill camp, picked up an extra survival bag, because we had one person more in the vehicle than normally, and off we went. After about two hours we arrived at the drillsite. The drillrig is covered in a white fabric to keep the rig and the people on it away from the wind. The rig is situated on 7-8 m thick multi-year sea ice (frozen ocean) and there are around 380 meters of water below it until the drill pipe reaches the sea floor. The small blue building attached to the rig is the mud room. In the mud room the drilling fluid is prepared and recovered. Drilling fluid keeps the drill hole open and lubricates the drill string. The drillers on the rig floor keep and eye on the pressure of the drill bit on the formation it is drillling. Once a core section of 6 meters is completed, the core comes up from the drill hole and is further processed and cut into one-meter long sections at the drillsite lab. The fractures and physical properties of the cores are studied and measured there too. The whole-round core sections are transported to McMurdo Station by helicopter. There the core sections get split and imaged, before we get to describe the core. Check back later for a blog on the core process here in McMurdo. Lastly: some penguin feet we discovered out on the sea ice, but unfortunately the penguins had left. There was a group of them at the drillsite not long ago and the people there enjoyed the entertainment. They have very little entertainment there so I am glad they had a chance to enjoy themselves.

A busy week for the science team and 800 meters down!

The current depth of drilling is at more than 800 meters below the sea floor. The sedimentology team has logged and decribed more than 700 meters of core and we are starting to feel a bit worn down. We are getting beautiful rocks though, like the ones in the photos below. We still see diamictites but the last few days they alternate with mudstones that are laminated or layered. In the photo the layers are at an angle, tilting, which is a sign of disturbance of the original beds. Sediments are always laid down horizontally, so if we see these tilted layers, we know that something happened to the layers after deposition. Details like these are recorded by us, the sedimentologists, in the core descriptions. We also found very flat-laminated rocks. You can see us at work in the photo above (photo by Tracy Frank). These mudstones are important to the science team because they potentially indicate conditions away from an ice sheet, although some mudstones may accumulate very close to a glacier. We will find out by analyzing their composition and the microfossils they enclose. For example: if there was vegetation on land with formation of soils, we would find pollen of plants and clay particles indicative of chemical weathering in soils in the mudstones. The pollen and soil materials were washed into the ocean from land and the particles accumulated as mudstones. So: we can analyze the composition of the mudstones and reconstruct what the environment was like on land in the past.

Yesterday I took some time to take a walk around the peninsula. The weather was very calm and I enjoyed the view across the sound and the presence of Mount Erebus, the active volcano. I also encountered two skuas, who totally ignored me so I decided to take a picture of one of them.

A forest of wormtubes and the UNDRILL 500

Last night we logged another 30 m of core and a large proportion of it consisted of mudstones with abundant fossil worm tubes made of carbonate. We are having a unique view here on an Antarctic seafloor more than 15 million years back in time. Between the worm tubes we found fragments of moss animals (bryozoa), and foraminifera, microscopic single-celled organisms that live either at the surface or at the bottom of the ocean. Serpulate worms and bryozoa make up part of the present Antarctic benthic community and were recently discovered to be living underneath a floating glacier or ice shelf (see link here). Paleontologists will now investigate the specific species and try to determine in what type of an environment these organisms were living: in open water without ice or near the ice.

The presence of foraminifera, these microscopic creatures, is good news. Diatoms (see a few blogs earlier) are apparently not really flourishing in this environment, so instead of the diatoms, the foraminifera may help us to obtain an age for these rocks. Different species of foraminifera are characterized by different shell or test morphologies and through evolution one species followed another in the past. In other words: different shell morphologies are characteristic of different times in the past. So, these microfossils can help us to find out how old these rocks are.

Yesterday we celebrated the fact that we reached 500 meters below sea floor with the UNDRILL 500. The drillbit is currently already more than 700 meters below seafloor, but we didn't have time to celebrate earlier. The traditional Antarctic way of celebration (going back to Scott's and Shackleton's times) is that you dress up with elements of underwear (or sometimes men wear womens clothes and make-up, yeah really!). We were marching around the station dressed up, with the national flags of the team, a tuba and a trombone, good fun!

The Hut of the Discovery expedition 1902-1903

Yesterday one of my New Zealand colleagues, Greg Browne, gave a presentation about the early expeditions in the Ross Sea area. The first one with a ship called the Discovery went as far South as the sea ice would let it and laid anchor at what is now Hut Point peninsula. It is about 0.5 mile outside McMurdo Station and last week our janitor invited us to accompany him to the hut to take a look inside (he has access to a key). The Discovery expedition in 1902-1903 was lead by british navy captain Robert Falcon Scott. Their accomplishment was that the team made it to 82 degrees South, a place no man had gone before. Later the Nimrod expedition, led by Shackleton, in 1907-1908, made it to within 180 miles of the South Pole. You probably know about the tragic story of 1911, when the Norwegian Roald Amundson, beat Scott and his men in the race for the South Pole. None of the 1911 team members made it home alive. Here they are at South Pole after they discovered the Norwegian flag was already there.

The Discovery Hut was built in 1902 on what is now Hut Point peninsula. It is a prefab Australian outback hut, and it is actually not very suitable for Antarctic conditions. The field party stayed here for 2 winters. In the hut you can still find the fur mittens and the wool sweaters they wore and there is still food on the stove in the kitchen. The clothes are lying near the stove, presumably left there to dry. Boxes of food are scattered through the hut. It is interesting to see that Cocoa is in one of them; it is still a favorite drink here today! Besides a kitchen area, there is a food storage area, a meat storage area and there are stables for the ponies they used. Some seal carcases are lying near the entrance.

Several other expeditions have used this hut after the Scott party, but it is now off limits, unless you are accompanied by a hut guide (there are several on station, such as our dorm janitor). The huts are valuable part of the Antarctic exploration history and we are all trying to keep it that way. I have been in the Discovery hut twice now (the first time 10 years ago), but the second time was as good as the first.

Skies are clearing and more core

The skies are clearing and the weather is improving. Two planes came in in the past 24 hours. One brought our Italian co-chief scientist and a large supply of drilling mud. The decision has been made that we will continue drilling now that it is going so well and skip geophysical logging of the hole until later: that is when logging scientists send instrumentation and a camera down the borehole to make measurements and images of the formations. We are working 12 hours a night now and are describing 30-40 meters of core per shift. We are still about 100 meters behind the drill bit which is currently sitting at 635 mbsf. Today we saw mudstones with hundreds of Serpulid worm tubes and another possible piece of plant debris. We also encountered a beautiful dropstone: a rock which fell out of an iceberg into te ocean and depressed the laminated (or layered) sediments. It is a Ferrar Dolerite clast, which is a group of igneous rocks cropping out in the Transantarctic Mountains. They form hundreds of meters thick sills (the chocolat brown layers in the photo), which are eroded by outlet glaciers feeding from the ice sheet behind the mountains. We are finding many clasts of this type in the core lately. Overall we can see the ice sheets come and go and they leave their signature in the rocks we log. It is a pretty nice job we have!

More than 500 meters below sea floor!

Drilling is proceeding very well at the moment. We are already at 600 meters below seafloor, before we had time to celebrate that we have passed the landmark depth of 500 meters below sea floor. We don't know exactly where we are in time, because the paleontologists are behind in analyzing their samples due to the speed of drilling and the flow of samples coming in. We sedimentologists have seen some very interesting changes in the core over the past 2 days. We encountered several meter thick intervals of what we call mudstones. These are rocks made of very small rock particles. They often appear laminated with distinct layering. The rocks are now also more cemented and they dry out quickly, so we spray water on the surfaces to observe the textures. Also important is the absence of large rock fragments or clasts in the mudstones: it indicates there was not much ice around during the time of deposition. Interestingly, between the mudstones are beds with very large clasts: the record clast so far we found today is at least 42 cm in diameter, which means I am out of the competition .... my entry was 38 cm for the biggest clast contest.

While drilling is going well, the weather is not entirely cooperating. We haven't seen a plane come in from Chrischurch for the past 5 days as a large depression has the Ross Sea area in its grip. We have had a couple of snow storms and travel is permitted only in the very short pauzes between storms. The helo with core has come in from the drillsite, but the windows of fair weather are too short for trips further away, or trips that require sea ice travel. We haven't gotten any fresh fruit or vegetables for a while now and people and cargo are backed-up in Christchurch. Ha: the new weather forecast just got posted and it says inprovement will come in the next two days. Despite the snow and wind, it is actually quite warm. The -12C/+10F minimum windchill is nothing compared to what we had previously and it feels extremely pleasant now that we can expose our faces to the wind. Also: the first Skuas have arrived (Photo: C.B. Gunn). They typically arrive in early November. Skuas are scavenger birds that feed on anything from penguin eggs, dead penguin chicks, afterbirths of seals, and unfortunately the trash cans at McMurdo Station. They are also known to snatch food from peoples hands if they carry it outside. Still: it is quite nice to see some birds flying around. It is a sign of spring after all!
Another great experience was that the janitor in our dorm took us to the Discovery Hut and let us take a look inside yesterday. He is part of a select group of people with access to the keys of the huts. I have no time to post pictures now, but I promise to do that later. The Discovery Hut is in the picture posted previously here.. Check back in a few days for photos from inside the hut.

Another snow storm and more to come

The weather forecast that was just posted reads: "The region continues to be under the influence of a large low pressure system to the east-northeast. Intermittent gusty winds, snow and blowing snow will impact the station until the full brunt of the system moves in." We had a "Condition 1" situation last night, which was lifted just before Midrats. Condition 1 means you cannot leave the building you are in. It is more severe than Condition 2, which means you have to stay on station, or Condition 3, which means that all travel is permitted. Our Midrats meal was in another building, so we were glad to hear that Condition 1 was lifted just before midnight. Here in the picture are some people walking to Midrats, like us. It was still pretty gusty with a lot of blowing snow. It is looking fine now (see picture to the right), but there is more to come. Snow is plastered on the walls of the buildings and the windows. There is a large cloud on Minna Bluf in the distance, which is a bad sign. Luckily a helicopter was able to make a trip to the drillsite before the storm to get us some core, so we can work. Another perhaps comicle fact is that Ann Curry of the Today Show is now stuck here with us. Her Live broadcast was yesterday in front of the Chalet with the flags. Last night at Midrats she was in the lobby and was talking very loudly and came obviously out of one of the bars. She seems to have a good time here. We have not seen the show, so we can only hope that the science we do here was featured to some extent. She called off a trip to our drillsite...

So, yes what about the science? It is becoming increasingly more interesting. We are finding fossils every day now: yesterday a possible plant fossil, today a couple of shell beds with what look like large clam shells. There is still the intermittent presence of glaciers, so it looks like ice ages came and went, but there were some intervals of time with balmier climate conditions than today.

Fossils in the core

The drill bit is now more than 400 meters below sea floor and we are logging core from deeper and deeper layers. It has also been confirmed by the diatom paleontologists that we are currently in middle Miocene rocks. The middle Miocene is the geological period around 15 million years ago, when Antarctica may have experienced extensive ice expansion and cooling, and may have progressed into its current deep freeze state. That hypothesis is debated, however, because of evidence that certain plants and animals survived in Antarctica through this transition. The middle Miocene is also the time of a climate optimum with balmier conditions than today. We are trying to understand what big changes were taking place in Antarctica around 15 million years ago. Before the present drilling program we had no complete rock record of these changes in Antarctica, but we did see the effects on the climate in the rest of the world.

The siginificant find of the last couple of days is that we are encountering more fossil beds in the core. The fossils represent the remains of worms, snails and barnacles that were living on the ancient sea floor at the site where we are drilling. The macropaleontologists are busy to uncover exactly what these fossils can tell us about the water depth and the temperatures of the sea water. Some organisms prefer a certain set of conditions, so when we find them we can use them to reconstruct the environment during that time. In the photo you can see some light-colored circular rings, which are cross-sections of worm tubes and a nice conical shell of a snail. Notice also that there are some rock fragments in the sediment. We can only explain the latter with the presence of icebergs or sea ice. So apparently these snails and worms were living in relatively cold conditions, but perhaps not as cold as today: we will find that out through further research, which will continue when we get back to our home institutions.