My last official day on expedition was spent doing the thing that got me interested in permafrost in the first place – we got to visit the Army Corp of Engineers Permafrost Tunnel. Tours of the tunnel have only been opened up to the general public once in its 50+ year history.
Tunnel Entrance.
Heading in.
This research facility dates back to the Cold War but is now primarily used for research. This is especially helpful when doing research about building on top of permafrost. All sorts of experiments can be done in this tunnel because you are actually in the permafrost. It makes accessing the permafrost and conceptualizing it much easier. Ice core samples are many of the holes you see in the walls.
The tunnel was made with excavators and special drills that can cut through the frozen ground. The walls display many different features – early in the tunnel there are bones from Ice Age bison and mammoths. As you go deeper in, ice wedges, silt, and gravel are visible. 25,000 year old grass is preserved and hanging from the ceiling.
25,000 year-old grass.
In some places, the tunnel can get very low.
Going into the tunnel helped me conceptualize what I had been seeing on the North Slope landscape in three dimensions. Ice wedge polygons make a lot more sense when you've seen the feature from above and below.
Ice Wedges!
The Army Corp of Engineers has been working on extending the tunnel into new sections. These new sections are bigger, wider, and show ice wedges in even greater detail.
Large ice wedges in new section.
Unique ice through silt.
Tunnel exit.
Further Reading
Want to know more? Check out this NPR report on the permafrost tunnel.
360 Tour of the Permafrost Tunnel
Best viewed on a smartphone through YouTube app.
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