Development of peat land and types of peat - Geotechnics of Organic Soils and Peat - page 26

Figure 2.8 Lake fill process.
Figure 2.9 Paludification process.
Blanket bogs are associated with wet upland areas. The peat develops where slopes
are not excessive and drainage is impeded. The process is often one of paludification,
or swamping, and it may start in shallow waterlogged depressions. The bog extends
down-slope if poorly drained surface water gives rise to waterlogging. In fact, high
rainfall in such cool upland areas gives rise to leaching, which leads to the accumulation
of impervious humus colloid and iron pan at small distances below the surface, usually
between 0.3m and 1.0m. Such an impermeable layer gives rise to waterlogging, which
represents the ideal condition for the development of ombrotropic peat. Soft sand
and clays generally do not underlie blanket bog, as vegetation grows directly on the
ground beneath. Generally these peats are thinner at higher altitude and on steeper
slopes. Significant thickness is attained only in large deep depressions in the flat surface
topography. A noteworthy example of this type of peat land is the Red Lake peat land
in northern Minnesota (Figure 2.9). It began with the onset of a cooler and wetter