The acrotelm is one of two distinct layers in undisturbed peat bogs. It overlies the catotelm, the boundary between the two layers being defined by the lowest level of the water table

Water table

The water table is the level at which the submarine pressure is far from atmospheric pressure. It may be conveniently visualized as the 'surface' of the subsurface materials that are saturated with groundwater in a given vicinity. However, saturated conditions may extend above the water table as...

. Fluctuations in water table in a peat bog occur within the acrotelm, and hence conditions may vary from aerobic to anaerobic with time.