3587 meters above sea level
Today was our second day here at Site 91, and we were again fortunate to have excellent weather to continue with our work. The drilling progressed nicely, reaching 59 meters by the end of the day, while Atsu coordinated the shallow drilling and recovered two more 7 meter cores.
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At sites with very little snowfall (less than 10 cm of snowfall each year) and very low annual temperature (mean annual temperature ~ -50 °C) drilling can be a challenge, particularly in the upper 5 meters. Close to the surface, snow grains metamorphose from very small crystals that accumulate at the snow surface into large and fragile depth hoar forms. The resulting snow structures are extremely fragile and tend to fall apart if disturbed. Attempting to drill through these layers tends to destroy them, which causes breaks and gaps in the resulting ice core. In order to recover the top few meters here at Site 91, we excavated a 2 meter deep snow pit to collect samples from these fragile layers by hand. This allows us to get a continuous record from the youngest layers at the surface to the older layers at depth.
This contribution is from the log of the Norwegian-US Scientific Traverse Team, who are en route from Troll Station to the South Pole Station. Much more information can be found here.
Photo caption: Jan-Gunnar and Atsu log a section of well excellent quality core. Photo: Tom Neumann.