A muskeg is an area of boggy ground found in northern tundra regions. Most of the ground in such regions, such as the tundra of northern Canada and Russia, is permafrost. But in the summer the top few centimeters of soil thaw, and the meltwater, unable to run away, forms muskegs. The bogs support lichens and mosses (notably sphagnum moss), which are important food for herds of reindeer (caribou).