Happy New Year! We had a great little holiday break here on Ross Island as we welcomed in 2020. We marked the occasion with the 31st annual Icestock music festival OUTSIDE at McMurdo Station. The day was full of sun but a tad windy. The good tunes and high spirits made for a great time with new and old friends. It’s incredible to see the hidden talents and creativity of the lovely people here on the ice!
After a few weather delays, we started off 2020 right by making our first trip to sites along the Byrd Glacier. Along the way from Scott Base, we had incredible views along the Transantarctic Mountains. While a scenic ~2 hour flight, we had a chance to see a few sites we plan to visit in the near future…this opportunity allows our first look at sites we know very little about except from high altitude aerial or satellite imagery.
The main sites we are interested for this visit are called the Lonewolf Nunataks…its pretty clear why they are named as such. They are situated on the edge of the East Antarctic Ice Sheet plateau with no bedrock exposed further upstream. Again, as with Fishtail Point, we know lots about this site since the POLENET project had a continusly operating GPS installed here. Last year, when they pulled out the site after more than 10 years of collecting data, a couple friends went for a walk up the mountains and spotted some glacial erratics for us. This critical ground truthing gave us high confidence that the site contained the rocks we were interested in! And as you can see in the wee video, this site delivered…Thanks POLENET!
The whole reason we want to get to these sites is to tell the story of the ancient glaciers of Antarctica and what those stories can tell us about the modern and future behaviour of this massive expanse of ice. For this project, we are primarily interested in collecting glacial erratics. These special rocks were plucked from the bedrock at the base of the glacier and were entrained as the it flowed toward the sea. At its maximum in the distant past, the glacier was much thicker and has since thinned to its current position. During thinning, the glacial erratics are delicately dropped off on mountains flanking the glacier. We glacial geologist come along and collect those erratics along a mountain, from the tippity top to the tippity bottom, usually right down near the glacier.
Back in the chemistry lab, we crush the rocks to sand size grains and extract a rare ‘cosmogenic nuclide’. These nuclides are produced by high energy particles from far off exploding stars(!), a fact that still blows my mind. We have a good handle on how fast these nuclides are produced so if we can isolate and count them up, we can say with confidence when the rocks were dropped off. Taking samples along the entire mountain range and along the glacier allows us to reconstruct the glacier surface through time, similar to how scientists have done using satellites over the past 40 years.
For now, we don’t know the exact story these samples have to tell but we have come a long way in telling that story but observing and collecting them in the field. Further, we’ll plan to visit the Lonewolf Nunataks at least one more time to gather more information about a larger site just downstream. Stay tuned for more and send us any questions you may have.