A Visit to the Snow Pit

WAIS Divide Camp at 79.47°S latitude, 112.06°W longitude – high on the West
Antarctic Ice Sheet Plateau.

The snow pit is quiet, still and very calming. I wish I had one at home!

The snow pit is quiet, still and very calming. I wish I had one at home!

Today I went out the snow pit made earlier in the season by John Fegyveresi. He and Anais Orsi were going to dig it out from the last storm and I hitched a ride. Ice scientists make snow pits to assess the snow pack for a variety of characteristics. John was measuring the physical properties of the snow layers to determine their accumulation rates, variation in storms, annual layers and frost layers. He also took samples to determine their densities.
Back in his lab he will test the ratio of oxygen 18 to oxygen 16 to determine temperatures when the snow fell. There is very little climate information from this part of Antarctica, so all of these measurements help to develop a model for recent, as well as past climate conditions. It took about a half hour to dig out the entrance covered by the last storm, alternating shoveling and cutting out blocks to move the snow. This snow pit has a main room, about 2 meters cubic with secondary pits behind two of the walls. The ceiling of the main room is covered in plywood while the others are kept open to the sky, so that the ice walls are back-lit. The result,
even on a cloudy day, is blue tinted glowing walls, layered with darker and lighter strata showing summer and winter seasons. Snow falling in the summer is less dense (warm temperatures favor larger crystals) so creates a lighter
stratum, winter snow is more dense and darker. Individual storm events are often marked by thin, wind formed crusts that show hard and white.

John and Anais looking at the seasonal layers

John and Anais looking at the seasonal layers

I stood gawking while Anais and John discussed the layers and speculated about particular phenomena they observed, informed by their specialty. It was surprisingly difficult to get a good exposure with my limited photography experience, darn it. We kicked in the snow a bit, and then I walked back to camp. The light was particularly flat, so I had one of many experiences of feeling detached from the ground, trusting my feet to find sure footing over the sculpted terrain.

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