Saturday, 26 September 2009

Fairbanks#11 - permafrost tunnel in Fox

On our last day in Fairbanks we had the opportunity to visit the permafrost tunnel in Fox ( Absolutely fascinating to be able to walk through the permafrost and see the ice lenses and wedges in the soil and gravel! It was also a welcome escape from the hot (30 C and very smoky) air outside the tunnel.

Entering the tunnel. The tunnel was built in the 1960's to study both the permafrost itself and mining and construction technology in the Arctic.

Pleistocene fossils of steppe bison n the upper gravel layers.

Ice lenses.

Reticulate-chaotic ice in the middle right of the photo as result of freezing of soils that had been thawed earlier. Ice lenses in the top of the photo.

The end of the tunnel collapsed. There used to be a vertical ventilation shaft out to the surface, but melt water trickling in weakened the permafrost and caused the shaft to collapse.

Another example of reticulate-chaotic ice (frozen soil).

Foliated ice wedge. Melt water seeps into vertical cracks in the soil and freezes.

Tony standing underneath an ice wedge.

Another ice wedge, clearly wider at the top.

Ice lens and reticulate-chaotic ice in the ceiling.

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