Pieces of wood, such as buried tree branches, roots, or whole trees, can make up 5 to 15 percent of the soil. The water level in muskeg is usually at or near the surface. Stepping on muskeg is like stepping on a sponge, and walking across it involves avoiding the multitude of open ponds that range in size from potholes to small lakes. Despite their innocuous appearance, muskeg holes can be more than just messy - they can be dangerous. Some are quite deep and offer no toeholds to help the unwary climb back out.
Sphagnum moss is the mainstay of muskeg.
It soaks up and holds 15 to 30 times its own weight in water. In the process, it keeps water from draining through the soil. So muskegs can form even on relatively steep slopes, especially in Southeast Alaska's cold wet climate. These may grow only 5 to 15 feet high and less than 10 inches around in 300 to 400 years. A dead plant that falls on dry soil is attacked by bacteria and fungi and quickly rots.