Heidi and I left McMurdo Station, known to the locals as Mactown, early in the morning on Friday 7th in an A-star helicopter on a perfect day, flying over the sea ice and Ross Ice Shelf and into the Dry Valleys of the Transantarctic Mountains. Our pilot took us on a scenic route, hovering now and then to point out interesting features and zooming up ice-filled valleys only to swoop over ridges down into the next valley. For a first timer to this area, it was truly majestic and really very difficult to get a true sense of scale. The rocks are mostly granite with dark dolerite intrusions that date from the time when Antarctica separated from Gondwanaland, etched by the wind and cracked by the freezing temperatures into phantasmagorical shapes. Often there appeared to be gargoyles along the ridge lines. It was as though the Elder Ones of the Lovecraft’s Necronomicon had been turned to stone and now stood guarding their icy and forbidden sanctuary. Wonderful stuff in the Mountains of Madness! Our journey culminated in a spectacular flight over Lake Bonney and then Blood Falls before we ascended up the ragged tongue of the Taylor Glacier. Fifteen kilometres from here we spotted the field camp below.
We landed at about 09:00, towards the end of the working day for the field team of ten who were all working night shifts. Morning in the camp begins at 23:30 with breakfast and the workday begins at 00:30. Lunch is sometime around 06:00 or when you feel hungry and dinner is at 12:00, prepared by the camp manager Kathy. People seek out their beds at 15:00 or so. The reason for these crazy hours is the ice drilling: the drill performs much better under cold, dry conditions and the sun disappears behind Kukri Hills at 01:00, leaving the drill site in shadow. At this high latitude and at this time of the year it never gets dark. Heidi and I had to quickly transition to these unusual hours from the more normal hours we had been keeping at Mactown.
The next few days were a real learning experience for me. I was the driller Jayred’s assistant, learning how to take the large 10” diameter ice cores the Blue Ice Drill (BID) produces. As the cores are brought up, the melting team trim them to size, scraping the outside surface clean and loading the ice melter. It takes one day to drill the 10.5 m of ice core, weighing about 380 kg, which fills the melter. After evacuation and flushing, this ice is melted over a large propane burner to liberate the ancient trapped atmospheric gas within which is then pumped into a sample cylinder. This process is repeated on another two days, sometimes three, to yield sufficient gas for the analyses. This herculean ice mining finally produces samples of CO and CH4 containing just tens of micrograms of carbon. Separate ice samples are also collected and returned to the University of Rochester where CO2 is extracted by sublimation. All these samples ultimately find their way to the Australian Nuclear Science and Technology Organisation (ANSTO) in Sydney, Australia, where they are measured by me for radiocarbon (14C) at ANSTO’s Centre for Accelerator Science.
Sunday was a day off and eight of us headed up glacier by skidoos to Cavendish Rocks, a nunatak around which the Taylor Glacier passes on its long 150 km journey from Taylor Dome. It is also joined by a tributary of the Ferrar Glacier at this point. Where we are, the ice is flowing at 10 m per year towards the sea, which is an incredible 3 cm per day. The ice is folded and faulted in complicated ways. It gets older as you travel down glacier, but also as you travel across glacier. We are camped on 50, 000 year (50 ka) old ice, but from one side of the glacier to the other it ranges from 7 ka in the Holocene through the Last Glacial Maximum (LGM) to 60 ka. Because the ice layers are inclined it also gets older with depth in the glacier, a real three dimensional time puzzle which has been painstakingly mapped out over many field seasons. What makes this area so special is that the ice is sublimed (from solid directly to gas phase without melting) as it is lifted, exposing large amounts of ancient ice near the surface, just what is need to study large scale changes in atmospheric methane during past times. Even with the atom-counting technique of accelerator mass spectrometry (AMS) a tonne of ice or more is needed to produce just the one sample.
On Monday four of the team were scheduled to leave camp and return home via Mactown. The weather had been overcast since Sunday afternoon, with an up-glacier wind carrying more humid air from the coast and the clouds were hanging low on the mountains. This didn’t look too good for the helicopters which can cope with wind but not poor visibility. However, as the morning wore on the wind changed to down-glacier and the day fined up, with impressive stream of snow blowing off the high ridges around, lit by the rising sun in a most dramatic way. The light and weather are constantly changing here and conspire to make it a place of unique beauty and grandeur.
Finally the helicopters arrived, one carrying a sling of cargo and the other a load of ice core boxes. We bade farewell to Vas, Ed, Joe and Berni who climbed aboard and were whisked away. Now we are eight. I sensed a certain freedom in the air now that the three PI’s had left!