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including both old and recent materials .
Karavaeva and Targul'yan
(1963) suggest that there is a certain amount of migration of
mobile humus substances into the deeper part of the soil, toward the
frozen layer, in the spring . This is the season when the soil thaws
and the level of surface water subsides .
In the summer, however,
migration of solutions
toward the permafrost table occurs along the
thermal gradient . Appendix I : Table 22 shows the increase not only
of the organic matter but also of the calcium in an Ayhz horizon which
has developed on top of the permafrost table . Karavaeva (1963)
suggests also that the high organic matter content of the surface
mineral horizon is due to the fact that the ratio of the surface to
underground biomass weights of tundra vegetation is 1 :6 . The bulk
of the underground biomass is found in the 0 to 18 cm surface layer .
Most of the soils examined in the arctic region show very weak
profile development . This is probably the result of : (1) a cold,
harsh climate which provides very little opportunity for either chemical
weathering, removal and addition of materials (Fedorova et al ., 1972)
and (2) the action of cryoturbation which tends to dislocate and
intermix materials which are produced by the other pedological processes .
Thus,
these soil forming processes give rise to new soil types which
are typical of the subarctic and arctic regions .