Welcome to the oft frozen tundra (and no, not the Green Bay Packer Kind).
The tundra is a very unique landscape, with freezing and thawing creating unique patterns in the ground. During the summer, water can accumulate underground, then freeze, which drives the soil upward into a small hill call a Pingo.
Climate of the Tundra
Tundra soils are formed at high latitudes. It is usually very cold in the tundra. Tundra soils are generally frozen, and are classifed as Gelisols (think Gelato!).
In order to be a Gelisol, permafrost needs to be within 100 cm of the soil surface. These soils freeze and thaw a lot, making the soil heave and buckle (cryoturbation), like a mixter does to cookie dough. This creates trees at funny angles (shown above), and can generate a lot of building issues.
Did you know that the largest portion of soil organic matter in the world is located in the tundra? This makes it vital to the carbon cycle. Though this seems contradictory to most, how can soils hold so much organic matter if they are so cold? Well, these regions are too cold for the decomposition of organic matter, so all of the living things stay trapped in the soil. There are many different varieties of mosses, lichens, shrubs and trees, and animals that call the tundra home.
Relief and Parent Material
Most of the soils in the tundra were formed with mixed rock fragments and sediments left behind by the glaciers when they receded. Sometimes, wind blown loess also accumulated over the top of the rocks and other sediments. Organic matter (and bogs) can also be a parent material to these soils.
Most of these soils are very young, and were covered by glaciers until 10,000 years ago.
Special Issues in the Tundra
Because the soils of the tundra freeze, thaw, and stir, there are many unique building problems that can occur. This includes the sinking of housing foundations, and major cracks that form in roads (which also happens in most areas that freeze, as roads are shallow in depth. In Alaska, replacing 1 km of road can cost up to $1.5 million! Read more about it in the Engineering and Urban Soils Page.
Where can I find Gelisols in the US?
There are three main types of Gelisols, but all of them occur in Alaska.
For More Information
A slideshow about Tundra Soils, as well as curriculum links and example assessment questions can be found in the Scoop! Teachers Guide.