9 June, 1999


I haven't had a chance to tell you much about the permafrost tunnel that

I had the opportunity to visit last week - it was only mentioned in the June

8th journal.

CRREL's (Cold Regions Research and Engineering Laboratory) Permafrost

Tunnel is located 10 miles north of Fairbanks in Fox, Alaska. Permafrost is

ground that has been frozen for 2 or more years. Although Fairbanks and the

surrounding areas have areas without permafrost (discontinuous permafrost),

where the tunnel has been dug is completely frozen.

To get into the tunnel, you must first go through a wooden door at the

entrance to keep the cold air in during the summer. It is refrigerated during

the summer, and during the winter it is cooled by natural CONVECTION - cold

air passes through the inside and out a ventilation shaft at the end of the

360ft long tunnel. They also use fans to move the cold air as far back into

the tunnel as possible. Lights are strung up throughout the entire tunnel,

but they are used as little as possible because of the heat that RADIATES from


The first thing that I noticed upon entering the tunnel (besides the

cold!) is the SMELL! There is a musty, decaying type of smell that comes from

all of the organic matter in the ceiling, floors, and walls, which dates back

to 40,000 years ago.

The tunnel is a very unique place. It was first made to try out

different types of mining in frozen ground. Within the walls are frozen

ponds, ice wedges, and bison bones. As we walked through the tunnel, we

created a little dust storm by stirring up the LOESS, which is a very fine

sediment which is blown by the wind and collects everywhere in that area.


Ice wedges are just what they sound like. They are formed when the ground

contracts in cold weather, forming a network of cracks which are polygon

shaped (many sided). They form polygons, from my understanding, just because

it is a natural shape to fracture under stress - it is the shape of least

resistance. The tundra is covered with these polygon shapes, bordered by ice

wedges, which collect more water during the summer melt of snow and thus grow

bigger and deeper. They start as small ice veins, but over thousands of years

grow to form large wedges. I think that polygon shapes are seen on Mars as

well, which is evidence of past climate and weathering of the terrain there.

(I don't know this for sure, though! Someone could tell me more about it!) In

Antarctica, an area called Dry Valleys shows the same polygon shapes on the

ground, as well.


In areas where there is permafrost, there is normally some thawing

that happens near the surface, at varying depths. This layer that thaws is

called the "active" layer, and causes some problems for people who are

building structures upon permafrost. Often, surface structures sink; in

Barrow, houses are built on stilts, to reduce the surface area that is on the

ground. At the permafrost tunnel, parts of the tunnel are beginning to close

themselves off. I think Matthew Sturm, who was our guide through the tunnel,

called the slow sinking of the ceiling "permafrost creep". Alaska must spend

quite a bit of money repairing roads in the spring when this active layer

begins to thaw!

If you have any questions about permafrost or the permafrost tunnel,

be sure to email me, and I will do my best to find out the answer for you!

Michele Hauschulz (Teacher Experiencing the Arctic Program)

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Branching corridors within the tunnel make fans necessary to help circula= te the cold air down to the end. Lights strung up throughout the tunnel are= used sparingly to prevent further thaw, which would speed tunnel closure. ____________________________________________________________________ Get your own FREE, personal Netscape WebMail account today at http://webm= ail.netscape.com.

Close up (although not very good one!) of a wall within CRREL's Permafros= t Tunnel. A bison bone is protuding from the wall near the bottom of the picture. ____________________________________________________________________ Get your own FREE, personal Netscape WebMail account today at http://webm= ail.netscape.com.

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