Date: January 5, 2007
Latitude: 80 degrees, 21 minutes, 34
seconds South
Longitude: 144 degrees, 26 minutes,
39 seconds East
Temperature: −22°C (−8°F)
Wind Speed: 8 knots
Wind Chill: −31°C (−25°F)
Elevation: 2,272 meters (7,454 feet)
Written by: Dan D.
Kilometers Traveled 463
Meters of core drilled: 390
Today’s travel started out very well, our only hindrance was a bit of fog that caused the CAT radiator grilles to clog up with rime. Gordon was our driver; he did a fine job of keeping an eye on the coolant temperature gauge, stopping, hopping out, and brushing the grille off whenever the temperature crept up.
We were moving very smoothly over a surface as flat as that which we experienced yesterday. The wind was still dead calm and we were all set for another excellent travel day. We traveled for approximately 10 km and suddenly found ourselves in an area strewn with firn cracks. Firn cracks are voids that form within the upper layers of the ice sheet surface. They look just like lines on the uppermost snow surface but widen out with depth. The cracks that we witnessed today were quite large and they seemed to be increasing in width as we progressed. It was clear that we were in an area unlike anything that we had experienced before so we proceeded with utmost caution. Just before reaching our 48th waypoint, we received a radio transmission from the Pisten Bully up ahead telling us to stop. Joe, who was operating the crevasse-detecting radar mounted on the front of the Pisten Bully, had detected a firn crack that was very large indeed! Or so we thought
Paul ordered the Pisten Bully to pick up Rick, who was driving the lead train, and regroup back at the rear train. Not wishing to take any chances, Paul and Mike climbed in to their crevasse safety gear and waited for the Pisten Bully. As soon as the Pisten Bully returned, they jumped straight in and headed out to investigate the monster firn crack. The rest of the team, apart from Josh who was driving the Pisten Bully, waited patiently for the return of Paul and Mike.
Upon their return, Paul and Mike informed us that the crack was large enough to constitute a danger to the heavy trains and we were going to have to survey the surrounding area with the radar before we could move again. We started by surveying the area immediately surrounding the train and when we were confident it was safe we set up camp. Next, Brian and Rick went out in the Pisten Bully to scout a safe path back to camp for the lead train. During the scouting mission, Brian discovered several more cracks of similar size to the first. The remainder of the day was filled with team meetings. By the end of the day we all decided that it would be prudent to stop the traverse until we have investigated this area thoroughly.
Date: January 6, 2007
Latitude: 80 degrees, 21 minutes, 34
seconds South
Longitude: 144 degrees, 26 minutes,
39 seconds East
Temperature: −23°C (−9°F)
Wind Speed: 10 knots
Wind Chill: −34°C (−29°F)
Elevation: 2,272 meters (7,454 feet)
Written by: Dan D.
Kilometers Traveled 463
Meters of core drilled: 390
It was another clear, beautiful day out on the ice sheet. There was an air of excitement as we ate our breakfast this morning, everyone was talking about the monster firn–crack feature that we happened upon yesterday. What could it be? How deep is it? Are there many of them in this area? The day's goal was to investigate and characterize the large firn–crack feature and to determine if there are any more of similar size in the area.
After breakfast, Paul, Andrei, Lora and I headed out to the monster firn–crack location in the Pisten Bully. Paul put on his harness, roped up, and proceeded to investigate the crack. After dropping us off, Brian, Gordon, and Josh proceeded to use the crevasse-detecting radar to scan the area between the trains and the crack, marking out several smaller cracks with flags. Meanwhile, while investigating the monster crack from the surface, Paul could see a void extending down at least 10 feet before reaching any kind of visible solid structure. The question then became: is the visible structure at 10 feet a solid surface or just a snow bridge?
Snow bridges form across crevasses and cracks, effectively masking their presence. They are usually composed of wind blown snow that builds up from both edges of the void until the gap is effectively bridged. Once bridged, normal surface deposition can occur making the crack look identical to the surrounding area. Therein lies the danger; snow bridges are notoriously unstable, liable to give way at any moment, and are virtually impossible to see - that is unless you have a handy crevasse-detecting radar.
In order to determine if the structure within the firn–crack was a snow bridge we used the PICO hand–auger to drill down to it. When we reached the structure with the drill we continued drilling for about another 30 cm before hitting another void. The structure was a snow bridge. We added another extension to the drill and lowered it back down the hole. The second void turned out to be about 5 feet deep with another snow structure at the bottom. We added another drill extension and continued to drill. The second structure turned out to be about 50 cm thick. This process continued repeatedly until we reached about 7-8 m depth. At this point we could not detect any more structures with the drill so we used a 100 m tape measure with a heavy weight on the end. We lowered the weight down the hole, and lowered it, and lowered it, and lowered it. We did not detect another structure until 33 m depth!
At this point, Paul decided that what we were dealing with was more than just a monster firn–crack. He used the VHF radio to warn the Pisten Bully not to approach any closer and then we all carefully removed our gear back to the trains. By the time we had carried all the gear back to camp it was lunchtime.
After lunch, Paul, Brian and Gordon put on their harnesses, roped themselves together, and walked back out towards the void with Brian towing the crevasse detecting radar and GPS in a banana sled. They spent a couple of hours walking back and forth over the bridged section of the void. They also walked past the void and scanned around the local area. They discovered that there were several more bridged voids, some of them at least as large as the first.
It seems that the large void we discovered was the first in a series of large bridged voids across our intended traverse path. To thoroughly investigate this area and determine a safe route through would take many more days than we have left in the season. Therefore, at this late stage, we have decided to backtrack to an area well away from these features and prepare the trains for the winter.
It is important to note that we are confident in our ability to detect these void features. They showed up clearly on both Brian’s deep radar and the crevasse detecting radar. Our new wintering site is approximately 10 km back along our route from the first occurrence of the voids. During the upcoming year we will be investigating as many ways as possible of remotely detecting the void features. There are several new types of satellite sensors currently in operation, we are hopeful that these will provide us with the means to re-route the traverse safely.