Yesterday had been largely a bust in terms of drilling, as well as most other things. The weather continued to remain snowy and windy, and conditions on the glacier were poor for travel as the snow was deep, the trail drifted over, and visibility was frequently zero. I used one break in the weather to pack down the skiway, but that was the extent of my travel away from camp. The drill team tried to make the thermal drill do their bidding, but it was largely being uncooperative. Apparently slush at the bottom of the hole continued to form, and they were worried that they were starting multiple holes, where the 3” diameter thermal drill took over from the 6” diameter hole left behind by the mechanical drill. Some progress was made, but by the end of the day their bag of tricks was exhausted and the last hope was to poor a bunch of ethanol in the hole and let it sit over night, hoping to de-slush the hole and make the drilling easier in the morning. Most of the morning was similarly frustrating, but just before lunch they were able to pull up another meter of core. It was cold, clear ice, like from regelation at the bottom, with bubbles in small layers. So given that progress was continuing to be made, Jason and I headed downglacier to get our GPS station set up before summer began, probably tomorrow.
Grooming the skiway. Today would not be a good day for a flight.
As it turns out, the lower 4-5 meters of ice was colder than the pressure-melting pont at that depth. At 200m depth, the melting point should be something like -0.1C or so (from memory), and that’s what it was for much of lower 30 meters or more. What I had hoped was that perhaps we would hit a cold layer near the bottom, but I would have expected it to be much thicker if it existed. This layer would have formed during the peak of the Little Ice Age when there was perhaps no surface melting of snow to warm the ice beneath. But to only find 3 or 4 meters worth of colder ice near the bottom makes me think it’s more likely to be due to some local subglacial process. For example, if there were a boulder nearby by, the higher pressures caused by the ice trying to flow past it would depress the freezing point of the ice further, creating supercooled water which would flow around the boulder and then refreeze when it feels the pressure drop on the lee side of the boulder. Perhaps we intercepted this water before it had a chance to refreeze, and that’s why the hole was freezing so quickly? Unfortunately I don’t have a book with the necessary charts with melting point as a function of pressure, so I don’t know whether its reasonably to be creating ice at -2.0C down there. That seems colder than I would have expected based on the the boulder theory, but perhaps the steep bedrock gradient here is adding to that. Or perhaps the warmer ice is overriding the colder ice (which formed cold at the surface 200 years ago)? Does this colder ice exist just here, or is it pervasive in this region? These are the sorts of questions that are easy to ask but hard to answer late at night in a tent in a storm in the arctic.
The last posed shot of lowering a thermistor string down the hole, in a small blizzard.
The drilling is finished, the thermistor string has been lowered, and Terry is already beginning to dig out his tent in preparation of leaving. (Click on the panorama and drag to look around, press Shift to zoom in, Command (Mac) or Control (PC) to zoom out.) Enlarge this panorama
Sun sets on the drilling camp and the drilling operations for the season, during a brief break in the weather.