The EGRIP DEP transition that is also associated with changes in ice crystal sizes. Each colored filed represent an ice crystal. A clear change in ice crystal sized can be seen at the transition.

Saturday the borehole was logged. After spending a night in the borehole the logger measured the bottom temperature to be -3.1 C. The planned flight on Saturday was quickly cancelled as we had terrible weather with high winds, snowfall, drifting snow, low visibility and poor contrast. Sunday the weather improved and we received the Skier over lunch. Unfortunately, the skiway was not in the best condition due to Saturday’s storm, so the skier had to leave some of the retro cargo behind. But we had the crew exchange and received cargo, fresh food and some fuel.
The other day we identified an abrupt jump in the EGRIP DEP profile at around 2618 m depth suggesting we have a disturbance of the ice core stratigraphy. Now Nico has measured the ice crystal sizes across that transition and it confirms the suspicion that the jump is associated with folding of the ice. Above the transition we have large crystals that are found in ice from climatically warm periods, below there are smaller crystals that are normally associated with colder climate conditions and higher impurity concentrations of the ice. In 2010, we came across a very similar transition in the deep NEEM ice core at 2442 m depth that we now know is associated with folding.

Weather: Saturday, we had strong wind from the opposite direction of normal. Usually, the wind is from SW, but now we had more than 20 kt from the NE and gusts up to 28 kt. The weather station reported ‘Hold on to your hat’. We were sitting in the middle of a white cloud with drift snow rising 5-10 m above ground and heavy snowfall lowering the visibility to a few hundred meters at the peak.

A very similar transition in the deep NEEM ice. The color scales applied in the two figures for the crystals are different and can not be compared, but the ice crystal sizes can. Also shown is the ice core line scan that show evidence of more impurities (white spots) in the ice from the cold climatic period.

Another sign of disturbed ice from ice crystal measurements