|Athro, Limited Gubik Field Trip Section 20 or Section 65 Tundra|
Large expanses of northern North America and Eurasia are cold, have permafrost, and are occupied by a set of plants and animals marking the tundra biome. Arctic tundra can be clasified into wet and dry types.
|Tundra at top of Skull Cliff|
The area in this part of Northern Alaska is Wet Tundra. In the brief arctic summer from a distance it appears as a flat plain with many lakes, but seen close up is not flat. There are meter scale hummocks and hollows, often with standing water and boggy patches in the low areas. All of this, including the bogs and lakes is underlain by permafrost. The ground remains frozen solid all year round.
|Variation in vegitation|
An astounding feature of wet tundra is the variation in plant types over very short distances. In low areas of the tundra there is lush green vegetation, while only a meter or so higher in elevation, and a few meters away, high points are very dry, covered with lichen. In temperate regions this is the sort of change in vegetation that would be seen over a mile or so of relief, going from lowland valleys up into dry mountain tops. Wet tundra is marked by extreem moisture gradients over tiny differences in elevation.
|Oriented lakes South of Barrow|
In summer, wet tundra is marked by large shallow lakes. Here, seen from the air in the approach to Barrow, are lakes that are elongated perpendicular to the prevailing winds. These lakes are on the order of a kilometer in length and just a few meters deep. During the winter (most of the year), the lakes freeze and the area is covered with snow.
Colorised digital shaded-relief map of the region around
Barrow, Alaska. Modified from Riehle et al., 1996
There are many such lakes in the wet tundra on the North Slope of Alaska. It is about 45km from Barrow to Skull cliff, and the tundra in this area is covered with these large shallow lakes. Travel over wet tundra is slow and difficult during the brief arctic summer. Large shallow lakes melted into the permafrost of the tundra like these are refered to as thermokarst lakes.
On a smaller scale, polygonal features are common arctic tundra landforms. These polygons are about 10 meters across. They are separated by ice wedges that drive into the permafrost.
|Ice wedge at edge of polygon|
These polygons are bounded by ice wedges. The polygons are visible from the air, but on the ground appear as variation in the topgraphy over several meters.