2-3 December 2005

After leaving Hughes late in the morning on Thursday 1 December, I was able to spend the afternoon in the office doing useful things before leaving for Mentasta on Friday 2 December. Shortly before leaving the office I checked my e-mail once more and there was a curious message from Kenna Dubois in Delta Junction. She, Barb and the students had visited their study site that day and found the ice fractured and hummocked and apparently collapsed into the lake.

Since the Delta study site is on the way to Mentasta we decided to investigate. So there we were at about 9:15 before sunrise on Friday morning looking at a very odd ice cover that was all that Kenna had described. What seems to have happened is that the water level in the lake has fallen as the water level in the nearby Delta River has fallen, and much of the ice cover simply subsided as the water level fell. Very peculiar. We haven’t seen that before.

After coffee and doughnuts, and a quick visit to Delta Cyber School to chat with Kenna and Barb, we continued to Mentasta. Not surprisingly, it was windy between Delta Junction and Dot Lake, with snow blowing along the road surface. It was somewhat windy when we arrived in Mentasta, with gently swaying trees, but it wasn’t blowing too hard.

By about 2 pm we were on the ice at Mentasta Lake, where the wind was gusting occasionally very hard but also falling completely calm for a few enjoyable seconds. Since the air temperature was -23°C, the wind chill was an important factor and by the time we finished putting in the study site we were all a bit chilly, particularly Raymond, an 8th grade student, who was able to help us. It was good to have an extra pair of hands in those cold and windy conditions.

The study site was placed in the same location as it has been for the past two winters – just a short distance offshore from Benny Funk’s cabin. The snow on the ice was about 23 cm deep with a respectable wind slab overlying softer snow. Breaking trail to run out the 100 m tape was not fun. The ice where we installed the ice thickness gauge was 0.55 m thick, but the “super saw” quickly cut through it and the ice thickness gauge was installed without any difficulty.

The study site on Mentasta Lake is a short distance offshore from Benny Funk’s cabin. Photograph taken on Friday 2 December 2005 at about 3 pm.

The sun has disappeared behind the mountains, and Kim, carrying the “super-saw” and bundled up against the cold wind, is ready to leave Mentasta Lake on 2 December 2005.

In addition to the ice thickness gauge, an ALISON study site has a line of 21 wooden stakes spaced 5 m apart. After walking backwards and forwards numerous times along that 100 m line in snow with an awkward consistency, and buffetted by the cold wind, we were each tired and ready to return to school. So, at roughly 3:15 pm, with the sun already having disappeared behind the mountains, we plodded back up the trail to the truck and a short drive to school, satisfied in the knowledge that another ALISON site, the 12th this winter, had been set up.

We left Mentasta at 7:30 am on Saturday to return to Fairbanks via the Big Delta pond and its subsided ice. We were there just as the sun was rising and were able to take photographs, and confirm that there is water under the by the ice thickness gauge. We also think that there is water under the ice at most of the wooden stakes. So, the study site is still viable.

(Left) Looking south along the line of stakes it is possible to see how the ice was deformed as it subsided when water drained out of the pond. Saturday 3 December 2005, ~10:45 am.

(Right) A closer look at the hummock in the centre of the photograph at left.