Cryogenic Soil Processes - Cryopedology - page 50

Chapter 5
Cryogenic Soil Processes

5.1 Introduction

Although soil-forming processes, such as humifi cation, paludifi cation, podzoliza-
tion, and gleization operate in cryosols, the dominant processes are of cryogenic
origin. A key misinterpretation regarding cryosols is that these cryogenic processes
are geologic rather than pedogenic and belong only to the realm of geocryology
(Tedrow 1966 ; Sokolov et al. 1980 ). Bockheim et al. ( 2006 ) argued that cryogenic
processes involve inputs, outputs, transfers, and transformations of energy, water,
and soil material and, therefore, according to classical defi nitions of soil-forming
processes (Simonson 1959 ), are pedogenic (i.e., cryopedogenic).
Another misinterpretation regarding cryosols is that cryogenic processes destroy
soil horizons and are “infl icted” upon “natural” soil-forming processes (Douglas
and Tedrow 1960 ; Gerasimov 1973 ; Sokolov et al. 1997 ). In fact, Sokolov and oth-
ers ( 1997 ) claimed that “cryogenic processes … do not result in soil formation”
(p. 7) and cryosols are characterized by the “absence of well developed pedogenic
horizons and features” (p. 4). Tedrow ( 1968 ) identifi ed two sets of processes acting
contemporaneously on polar soils: a pedologic process that gives rise to a “genetic”
morphology and a geologic process that tends to disrupt any acquired morphology
(Douglas and Tedrow 1960 ; Tedrow 1968 ). Tedrow ( 1968 ) referred to these destruc-
tive elements as “cannibalization” and viewed the so-called “natural” soil-forming
processes as resulting in soil horizons more or less parallel to the ground surface,
and geologic processes as resulting in irregular and broken horizons refl ective of a
“negative” process contrary to soil formation.
Bockheim et al. ( 2006 ) posited that cryopedogenic processes are “natural” and
characteristic of permafrost-affected soils. An analogous situation is the “vertization”
process leading to the development of vertisols. The irregular and broken horizons
that are common to cryosols are the natural product of cryopedogenic processes,
such as cryoturbation, freeze-thaw, frost heaving, cryogenic sorting, thermal cracking,
and ice segregation (Bockheim and Tarnocai 1998 ). These processes are characteristic