SCHOLARSHIP DAY 56: Visit to the Alaskan Permafrost Tunnel

Today I was very lucky to be offered my own individual tour of one of Alaska's most interesting tunnels; the internationally recognised and researched 'Permafrost tunnel' just outside Fairbanks. Hiking over permafrost affected features is all very well, and I have enjoyed my work so far on top of terra firma, but I decided that the time had come to actually get up close to the permafrost.

Margaret Cysewski was my guide; a PHD student, and extremely knowledgeable about permafrost. She very kindly drove me from the university this morning and off we went. It was great to be able to talk about permafrost and permafrost-related sciences to someone a little younger, and it convinced me by the end, that there is an all round interest in the subject, which is good news for the future generation of Alaska's permafrost studies.

We arrived at the tunnel, a little after 11:30am. The whole site is surrounded by wire meshing and two very tall metal gates, but this was no surprise as I had been briefed about the fact that the army owns this area of land. Despite these observations, after we passed the gates, the atmosphere was rather relaxed and I was able to focus my attention on the tunnel and the science. (That was, after I had my very embarrassing difficulties with fitting my hard-hat). The tunnel is very clearly marked from the outside, and before you could say "permafrost" we were in.

The Permafrost Tunnel was built in the 1960s and after various revampments over the last 50 years, it currently stretches 110m, about 15m below the surface. Originally it was used for evaluating excavation techniques in permafrost soils, and how mining could be successfully managed. Over the next twenty years or so, it was to be a great resource for researchers who wanted to study ground ice features up close. For the public, it serves a different purpose. Given that Interior Alaskan engineering is governed mainly by whether there is permafrost or not in the ground, the tunnel allows the public to see just what it looks like, hopefully making them more aware of it, and ultimately to remind them that the Earth is just as diverse underground as on the top.

Bison horn fossils are just one of the many artefacts that are preserved within the permafrost. These are said to be at least 12,000 to 14,000 years old; the dates configure with radio carbon dating tests and match with other fossils found.

 

The tunnel now branched into two separate tunnels and we made our way down each. It was starting to get quite narrow now and whilst Margaret had no difficulty in making her way through, I was a little taller and had to duck at many points. What we eventually walked to was just one of the many examples of ice lenses and ice wedges. Perhaps, for the benefit of those who aren't quite knowledgeable on these features, I should explain each in turn.

Ice lenses are very hard to capture in a photo, due to the fact that they are often localised deep within the soil and can be disguised very easily by a silt layer. As moisture accumulates in the soil (in this case silt loess deposits) ice forms, and produces a disc known as an ice lens, which can force the rock apart. Below ground they aren't significant enough to be able to cause large disturbance on the ground surface above, but they can actually work together to create pingos (tall earthly mound covered in ice) and palsas (lower more oval shaped mounds). In the photo below, the ice lenses cannot be seen clearly, but you can just make out the cracks in the rock, that have been caused by ice lens frost heaving processes.

Ice Wedges are slightly different. They begin as 3m wide cracks just below the ground surface, which extend down into the ground, often getting narrower as they go down. At wintertime, the ice expands and causes cracks in the ground surface. In the Spring, meltwater can accumulate in these cracks and freeze once again, during the fall. Multiple ice wedges working together can create polygon formations on the ground surface, as I saw when I was walking through the Boreal forest in Creamers a couple of weeks ago.

The tunnel is popular with the public, make no mistake about that. Indeed, the last open house event in August attracted 3000 people; some having to be turned away. When it isn't being shown to these very impressive numbers, the tunnel is subject to permafrost researchers and recently it's being used as a freezer for researcher's sediment core samples. After all, the tunnel is kept cooled by refrigerators during the summer and is naturally sub-zero at winter. Plus, despite the risk of seismic activity, I was assured by Margaret that the tunnel is very unlikely to collapse. (The reason why is some quite complicated soil science that I won't go into here).

I enjoyed my tunnel visit, for two reasons. This phase of the scholarship has allowed me to talk to professors about cutting-edge research regarding permafrost, and has given me the opportunity to go out in the field to witness the impacts and pressures that permafrost puts on the state. The Permafrost Tunnel didn't just supplement that, but enhanced my understanding of just why the ground surface looks the way it does. And the other reason? Well, it's once again, a 'diversity' thing. To go underground, is to observe the anatomy of the Earth; to realise the mechanisms that work together to create what we see on top. If you catch your finger in a door (and I have), you'll notice a bruise forming; in other words, you're observing how events below the surface of the skin can affect the outside. In the same way, the permafrost tunnel allowed me to witness just how ice-rich soil below the surface have such an impact on Alaska's rugged surface, ultimately making me realise that the underground world is possibly even more diverse than that which lies on top.