Martin visits Nome

26 March 2004

Give an ice auger to a group of energetic students and you never know what they might discover. The Anvil City Science Academy (ACSA) students thought it might be easier and quicker to drill through the ice that contains many bubbles that are concentrated in vertical plumes above gas sources at the bottom of ACSA Pond. The students learned that if you drilled into the bubbles, the gas they contained was pressurized and would blow the ice cuttings out of the drill hole when the drill penetrated a bubble. This proved to be a source of much amusement and valuable new knowledge. I had never seen such a thing before. We also learned that the gas smelled of sulphur, probably hydrogen sulphide.

Drilling into huge bubbles in the ice at ACSA Pond to release the entrapped gas.

Todd Hindman and I spent a large part of the day at ACSA Pond with his students. Todd had divided the students into four small groups and we took one group at a time to work at the pond: two groups in the morning, two groups in the afternoon. Parents helped to drive each group to and from the pond. The weather was perfect for being outside for extended periods: yet another clear sky day with bright sunshine and moderate to calm winds.

The ACSA Pond ice is like the Puvragik Lake ice at Wales: it is cold because it doesn’t enjoy the benefits of a well-insulating snow cover. Consequently, the ACSA Pond ice thickness gauge doesn’t always work. Today we had an alternative: my ice thickness auger, which the students enjoyed using so that we could measure the ice thickness (mean of four measurements, one by each group, = 0.95 m) and they could release sulphurous gas from air bubbles in the ice.

Another consequence of not having a good insulating blanket of snow, indeed having large bare ice patches that have been stripped of snow by the wind, is that the ice is subject to significant thermal stress and the formation of many fractures. The ice at ACSA Pond is riddled with fractures that form beautiful patterns. Todd and I are fairly certain that one of the fractures we saw had formed only today, perhaps the result of me slipping and falling flat on my back with a thud that released the tensile stress that had built up in the ice. Ouch, the ice is hard.

Intersecting fractures create beautiful patterns in the ice at ACSA Pond, Nome.