Final blog, 2013 expedition

On 16th January a Twin Otter arrived at our airstrip. John and Malcolm flew immediately to the site of the subglacial Lake Ellsworth project to see if the radar could pinpoint problems associated with the cavity and the decision to abandon the drilling to the subglacial lake at the end of last year. It seemed a good opportunity to use the appropriate radar while it was so close. Late in the day the plane returned and flew the rocks samples plus David and Stuart to Sky Blu. After one night in a much warmer tent than on the outward flight, we took the DASH-7 to Rothera and the glory of a shave, shower, salad to eat, and a beer in the bar. The remaining members of our party came in during the next two days, all experiencing the same delights at Rothera. We have left a depot of everything possible at the camp site for next season, including food, three skidoos and fuel.

Life at Rothera is full. To see wild life is a delight and reminds us of how much we missed it in the interior. We are surrounded by Weddell and Crabeater seals, Adelie penguins and see Minke and Humpback whales and fur seals. The rock boxes were stored in our science cubicle and the first surprise was to find them standing in pools of water the next day. The small cracks had allowed them to fill with snow while in the field and we had to empty and dry them all out, repack them with Bills of Lading etc. ready for transport by ship in March.

A highlight for us on Monday was our science presentation to a packed room. We covered the rationale for the project and each of us spoke about what we actually did in the field. Scott and Malcolm ended with their video of the project – a fine light-hearted slant on the science. It was good to have the opportunity to talk of our work and the discussions afterwards over beer showed that many were interested to hear of our experiences. It was a good way to remember a field season in which, as a result of good support and fine weather, we achieved more than we had hoped. The flight home via Punta Arenas will give us the chance to fine tune our plans to analyse and publish our results.

So, finally we would like to thanks everyone who has supported the project, both in the early days of conception and preparation, but also our families, NERC, colleagues and especially all those in Antarctica who have helped make it possible.

And did the West Antarctic Ice Sheet disappear in the last interglacial? Probably not.

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Ellsworth Blue-ice Project Blog 11

11th January, 2013 and it is two months to the day since we left home in the UK.  It is also the last week-end before uplift and we have spent the last week finishing the science programme and preparing to leave.  The weather has reverted to bright sunny days with gusty winds of 25-30 km per hour blowing drifting snow around the tents. The highest temperature each day is around -10 C so, bearing in mind the wind, we are wearing a lot of clothes.

Talk is increasingly of what we are looking forward to when we get back to Rothera base. Top of the list is a hot shower. I think we are all shocked to realise that we have not washed our hair since 22nd November and that we have relied on a few wet wipes for all ablutions since then.  The thought of shampoo in a shower of hot water is almost a fantasy.  Next on our list is a beer in the bar, fresh fruit, food that you can chew, standing up straight indoors, and a flush toilet instead of a pee-bottle inside and pee-flag (bamboo stick) outside.  A final item on the wish list is a new pair of socks for Scott!  Socks excepted, it is strange how we have reached an equilibrium and that we no longer notice our state of hygiene.

The final week of science has been used to fill gaps, such as securing cosmogenic samples from high-elevation bedrock, installing a micro weather station to run for a year, measuring the altitude along the blue-ice margin, and re-surveying all the 90 stakes recording ice flow in order to see if there are any trends after two months.  We also excavated a trench across a moraine ridge to check that there was a debris band there.  There was!

A highlight of the week occurred on the day the weather changed to give us strong winds.  Cirrus clouds formed as the winds blew over the mountains producing constantly changing patterns of waves, stacks of lenticular discs and funnel shapes like chanterelles, all brought to life by opalescent patterns around the sun.

Over dinner of our usual packet of Pack ‘n’ Go, we estimated that each skidoo has gone about 1200 km, making a total for the four of nearly 5,000 km, mostly commuting to and between the mountain groups.  We have collected 280 cosmogenic samples, each weighing an average of 1.5 kilos, and aimed at dating a particular event.  They now require two years’ work to process.  We have run Differential Global Positioning Surveys (DGPS), accurate to cm, for some 50 km. We have installed 90 stakes in order to measure glacier flow that will be re-surveyed next season.  We have over 15 km of Ground Penetrating Radar (GPR) over the ice and moraines, each one measured with a 3-second stop every 10 or 20 cm!  We have high-resolution laser scanned maps of the main moraine system as well as of mountain fronts in six different locations.  The successful flight of the remote-controlled plane has given us vertical photographs of the vital details of the surface structures in the main moraine system. 

So what does it all mean? In a nutshell we can now begin to answer two main questions of process and evolution that underlie much of science, namely: What’s happening now? and What happened in the past?  Applied to our project the questions are: What processes form blue-ice moraines? and How do they evolve over time?   The link between moraine forms on the surface, structures in the underlying ice, and measurement of changes over the course of a year helps reveal the process of formation.  The geomorphic mapping linked to cosmogenic dating will allow us to track the evolution of the moraines over Ice Age cycles and indeed over millions of years. 

What are the implications for the Antarctic Ice Sheet?  Well, blue-ice moraines certainly provide new insights into ice-sheet history and there is a lot to be gained from their study.  So, now our thoughts have returned to the original question: Did the West Antarctic Ice Sheet disappear in the Last Interglacial?  We are confident that we will be able to answer this convincingly.  We have our hunch but must wait for the dating before we go public.

Ellsworth Blog 10

5th January and time to take down the tinsel and Christmas decorations! The New Year continues to bring clear weather with temperatures generally around -10 C and lots of sunshine. One recent day was exceptionally warm and actually saw us pulling the radar while stripped to our base thermals, a rare occurrence at 80 degrees South.
Work continued over the festive break and now our attention is on the more distant massifs of the Independence Hills and Marble Hills. Each involves a commute of over an hour and the journey is very different. In the case of the Independence Hills two people travel on backward-facing seats on a Komatic, a sledge based on a Greenlandic Inuit sledge. We go over a long snowdrift via a pass in the Patriot Hills. Two skidoos pull the sledge up and the backward-facing view is special. It is like taking off in a plane and seeing the horizon widen and spread out in front of you. At first there is a view of an ice slope, then of the glacier surface, then nearby mountains and finally the whole vista of the southern Ellsworth Mountains – all in a minute or two. Skidoos are then attached to the front and back for the descent onto the next glacier. Since the journey to the Independence Hills is into the prevailing wind the skidoos travel parallel to the alignment of the sastrugi. The journey to the Marble Hills is across the alignment of the sastrugi and is slow and bumpy; we tend to ride with driver and pillion for comfort and security.
The Independence Hills are partly volcanic and we work on a complex of moraines overlooked by magnificent cliffs towering some 500 m above us. We have discovered that the flow of the glacier in front of the cliffs changes direction as the overall ice thickness changes during glacial cycles in response to sea-level changes. The radar work shows that some of the moraine is trapped in an embayment as the ice moves first one way and then in the opposite direction. So we are hopeful of being able to date the oldest material to see if it survived the last interglacial warm period.
Marble Hills continue to impress. At a new site the initial surprise is a hole. You step off the skidoo at the main ice margin and then walk DOWNHILL for a vertical distance of 140 m. The shape of the topography and the winds are able to keep the basin clear of ice. Anywhere else in the world and a hole like this would contain a lake or be filled in with gravel. The climb back to the skidoos at the end of the day with rucsacs full of rock samples was hard. We have made good discoveries in the Marble Hills. We have found buried glacier ice beneath deposits at altitudes about 300 m above the present ice and at higher altitudes are some of the oldest deposits in the region. It will be interesting to find out how long a history we are unravelling. Our instinct is that the ice sheet has changed in thickness to a certain degree but that it has persisted for a long time even by Antarctic standards. The cosmogenic dating should help enlighten us.
Today there is little wind and Stuart was about to fly his remote control plane with a camera to take vertical photographs, the whole flight being pre-planned with GPS. Andy and I had just installed a small met station on a pole drilled into the blue ice and we saw a plane in the distance. At first we thought Stuart had had great success but it morphed into a Chilean Hercules plane, probably checking out their abandoned base which is now largely beneath snow. Inspired by the Hercules, Stuart got his plane airborne and has successfully got vertical photos of our detailed test site. Great news!

Our uplift date back to Rothera is 14th January so we are busy tying up loose ends in the science programme. Malcolm and Scott are beginning to prepare for our departure and plan the storage of camping equipment, skidoos, etc so that the latter survive the winter and can be re-discovered next year. The suspension of one of the skidoos gave out today and Malcolm and Andy are replacing a major part just now. We do not want to ship ou t a heavy skidoo if we can avoid it.
A few more days of good weather?