Terry and Darek extract some clear ice on a nice day. Click on the panorama and drag to look around, press Shift to zoom in, Command (Mac) or Control (PC) to zoom out.
We knew that the ice here would be warm relative to the mean annual air temperature, but none of us suspected that there would be liquid water within the ice. After our first encounter with water at about 70 meters depth, we’ve been tracking water level in the hole over time. Every time we drill deeper, the water level drops. But after a few hours, the water level comes back up again. This implies that there is a larger body of water that is re-filling our hole, but that the connection is not so good because it is so slow. So it’s probably a thin crack. Last night, however, we reached 93 meters depth with drilling, and in the morning the water level popped up to 48 meters below the surface. This indicates that we probably penetrated another crack or conduit that extends into a larger water body that is under higher pressure. Though this sort of thing has been found many times on temperate glaciers further south, this is pretty exciting stuff for an arctic glacier, especially at the highest location on the glacier where melting is at its minimum.
The story gets even more interesting, as this morning we actually cored through a conduit! Since about 90 meters depth, we had been encountering sections of clear ice – that is, ice that seems formed by the refreezing of water, not true glacial ice that had been compressed by snow. Today in one of these sections we actually found a hole that extended completely through the core. Surrounding it were veins of bubbles within the clear ice, as if the hole had migrated and resealed over time. I’m not aware of anyone finding a water conduit within ice core before, though it may have happened. But in any case, it’s pretty exciting and interesting stuff.
The ice core with the conduit running through it. Note the ice fabrics extending from the hole through the rest of the core.
Another view of the core with the conduit in it.
During the next core run, the thermal drill shorted out again, so we had some time to lower the borehole camera. We could see the location where the rest of the conduit we intersected was, but we couldn’t detect any water flow through it. The water is exceptionally clear, containing no sediment, implying that perhaps it was never in contact with the rock underneath the glacier. Perhaps it is coming through crevasses at the surface? In any case, this puts a new twist on the internal accumulation of ice. Previously we had only been considering the refreezing of meltwater within the upper few meters, but our cores suggest that there may be much more significant accumulation of ice near the bottom of the glacier too. So we have a lot to think about.
Some of my best work has been done while I’m half in bag…