Cent. Eur. J. Geosci. • 4(4) • 2012 • 623-640
DOI: 10.2478/s13533-012-0109-8
Central European Journal of Geosciences
The Cryosphere and Glacial Permafrost as Its Integral
Component
Review Article
Wojciech Dobiński∗
Department of Geomorphology, Faculty of Earth Sciences, University of Silesia, Będzińska st. 60, 41-200 Sosnowiec, Poland
Received 7 September 2012; accepted 12 November 2012
Abstract: Since Earth sciences have undertaken studies of other celestial bodies, its various fields have moved beyond the
scope of study assigned to them by name. Interest in space makes it necessary to abandon research geocentrism
and reverse relations when comparing the structure of the Earth with other celestial bodies. As an exceptional
place in the universe, it should not be the Earth which constitutes a reference point, especially in cryospheric
research, but rather the other celestial bodies of our planetary system. This approach, referred to as “Spatial
Uniformitarianism,” is the basis for determining the place of ice in the environment and for assigning it to the
lithosphere. Ice can be penetrated by frost just as other minerals and rocks, so the occurrence of permafrost may
yet be attributed to glaciers and ice-caps. In the article, the occurrence of glacial permafrost has been worked out
on the basis of a thermal classification of glaciers with a thorough understanding of the phenomenon. This allows
us to specify permafrost’s presence beneath glaciers and ice-caps, a concept which had been needlessly vague.
Further, by considering rock glaciers as a mixture of two types of rocks, and by understanding the importance
of movement in their evolution, we are now closer to fruitfully determining their role in the environment, their
geomorphological significance.
Keywords: Glacial permafrost • ice • rock glaciers • spatial uniformitarianism
© Versita sp. z o.o.
1.
Introduction
The communicative integration of science disciplines, as
well as interdisciplinary research, plus more and more
accurate measuring instruments, and constant studies of
regions of the Earth which until recently seemed to be
inaccessible, these four provide a huge amount of data. It
is not possible to analyse them without computers, which
are usually programmed to create a test model of phenomena on the basis of such data. Taking into account
∗
E-mail: [email protected]
a time factor makes understanding even more uncertain.
Such scepticism has always characterized scientific research, but has also created a useful cognitive distance.
The increasing ease in obtaining measurement data and
analysing them contributes to the fact that, in this, mainly,
many scientists seem to recognize an opportunity for scientific progress. In addition, issues of such importance and
currency as environmental protection, climate change, etc.
absorb scientific circles to a predominant degree, directing them towards the more practical issues such as finding
solutions to specific environmental problems, which may
also become social problems. Therefore, in a way out of
necessity, scientific activity results in a disproportion between the application of oriented research, and research
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which arises solely out of curiosity, and leads to a greater
recognition of the surrounding reality. This article is a
step into this second, less popular side of science. It is
a continuation and development of the author’s previous
considerations, and it aims to link some achievements of
seemingly distant disciplines. When applying this new
methodological approach, which can be called “Spatial
Uniformitarianism,” it seems possible to understand, more
deeply, some of the spatial relations in Earth sciences, and
to solve some scientific problems which have remained at
a standstill for many years.
The main objective of the paper is, therefore, to present
a concept of glacial permafrost on a basis of this principle of Spatial Uniformitarianism, which should allow one
to gain a new, unified understanding of the cryosphere,
treating, in the same way, glaciology and periglaciology,
and permafrost science. This framework also allows for a
better understanding of rock glaciers as a phenomenon,
and integrates both the disciplines and environments to
which they belong.
2.
Spatial Uniformitarianism
In the Earth sciences, there are a few concepts which
do seem to be so obvious that, for centuries, they have
remained beyond the range of researchers’ interests, although the volume of knowledge about our planet, other
planets, and even about distant cosmic space makes us
now reflect upon the terms which, so far, have seemed to
be obvious. In a natural way, the only starting point and,
at the same time, the reference point in Earth sciences, is
our planet. However, “Earth sciences” has become somewhat of a misnomer, since scientific attention has “left the
Earth” and the subject of its research is now extended to
the other planets of our solar system, their satellites, as
well as to comets and to other celestial bodies. Study of
the cosmos implied a long time ago that the Earth is a special exception in space, especially in regards to its surface.
The lithosphere, hydrosphere, atmosphere and biosphere,
all notable for the presence of liquid water, life, and their
resulting manifestations, are combined on the surface in
a manner unusual elsewhere. This division represents a
natural reference point for “Earth sciences” which are also
carried out beyond the Earth, and, despite this fact, under
sciences which have not changed their names. Geo-logy
and geo-graphy are disciplines whose research methods
are being used on the Moon, Mars and the other planets, without changing their nomenclature (geo-), and the
knowledge of geology, petrography and all the other properties of the Earth constitutes points of reference there.
This alone shows the specifically “geocentric approach”
that scientists adopt when studying other celestial bodies. Yet, it is a known fact that it is not the other celestial
bodies, but the Earth that is an exception in space. Thus,
to understand well the relations between the basic components of the Earth’s surface, consistent with studying
all the other celestial bodies, it is necessary to dispense
with a geocentric attitude and reverse the direction of the
comparison. The point of reference for Earth sciences conducted on the Earth should be constituted on the findings
referring to the planets [1, 2], since the rule is how, in
terms of geology, they are built, and not how the Earth is
built. Water is present on many celestial bodies, but usually in the form of ice, rather than in a three-phase form,
as on the Earth. Solid water forms the surface of certain
celestial bodies, and might be called the lithosphere, by
analogy to Earth’s lithosphere, because it performs the
same role and is subject to similar processes. This regularity can and should be transferred to the conditions on
Earth, and not vice versa. So I would call such a formulated principle “Spatial Uniformitarianism,” because it
relates to the analogies existing in space, and is complementary to the Hutton - Lyell uniformitarianism, which
can be called “Time Uniformitarianism” (temporal), itself
designed for geological research on the Earth, where the
same natural laws and processes that operate nowadays
have always operated in the past [2].
The principle of Spatial Uniformitarism can be formulated
as follows: The Earth should not be the reference point in
analogous studies of the geological structure of celestial
bodies, as it has a unique status in the cosmos, in this
regard. It is the cosmos and celestial bodies that constitute the reference area for the Earth, and for its geological
structure.
The practical application of this principle should also facilitate a more coherent understanding of nature, and clarify a number of related concepts. The concept of “Snowball Earth” and, connected with it, the term “sea glacier”
are, for example, more important because of their global
and universal importance [3–5]. One of the latest results
is the new concept of “krio-conditioning” which underscores the interconnected roles of periglacial, glacial and
azonal processes in the development of cold region landscapes [6, 7]. Of other concepts, periglacial, paraglacial
and proglacial are essential for a comprehensive understanding of glaciated environments, and reframing them
has been undertaken recently by O. Slaymaker [8].
Such a cognitive repolarization, consisting essentially in
reviewing past geocentric perception, of the processes
and forms occurring on the surface of the Earth in accordance with the available knowledge of other celestial
bodies [1, 2], enables easy clarification of concepts which,
in this context, i.e. out of the need for making precise
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scientific statements, means simply that the present conceptualization will be a bit different from the usual.
A stand on geomorphology, as complementary to the proposed rule of Spatial Uniformitarianism, such as has been
formulated for planetary landscape systems, is presented
by Victor R. Baker in his impressive work [9]. I will take
the liberty of quoting one of the conclusions: “The study of
extraterrestrial landscapes is not just a means for bringing excitement to geomorphology. It is integral to the
logic of systems thinking that geomorphological systems
of landforms and landscapes cannot be restricted solely
to the subset of those features that just happen to reside
on the terrestrial land surface. To the degree that extraterrestrial landscapes are consistent with the components of the landscape system defined for analysis, then
they comprise essential parts of the relevant system for
geomorphological inquiry. In short, their exclusion is not
merely unproductive; from a systems viewpoint, it is illogical.”
3. Imprecision in Delineating Permafrost Extent on the Earth
The separation of glaciology from geological sciences may
partly result from a difficulty in treating ice as a component of the hydrosphere, notably, in reconciling issues
related to ice freezing, and to the presence of permafrost,
as associated with the lithosphere when understood in a
traditional way.
In Greenland, 84% of the surface is covered with ice, i.e.,
nearly 1.84×106 km2 . In the Antarctic, an ice cap covers
13.3×106 km2 . [10] According to the two maps presented
(Fig. 1), it is not clear to what extent these more than
15×106 km2 are underlain by permafrost. As stated by
French [11], the Antarctic as a whole is subject to the occurrence of permafrost. On the other hand, Bockheim and
Hall [12] limit its occurrence under the Antarctic ice-sheet
to relatively small areas of ice frozen to the bed. The same
difference of opinion applies to Greenland. To be clear, it
is difficult to find justification for the lack of permafrost
beneath this ice sheet in some cartographic studies, especially when the permafrost ends directly under the ice
sheet, despite the overlying ice being presented as continuous (Fig. 1). The artifice of such a separation is blatant.
It is also in contradiction to the principle that permafrost
disappears spatially, through a transition from the continuous zone via the zone of discontinuous permafrost, finally
to the zone of sporadic permafrost occurrence. It is essential to reach a settlement over this issue as it relates to
areas with a surface of more than 15×106 km2 , and in a
fundamental way this affects any precise determination of
Figure 1.
Two well-known cartographic representations of permafrost occurrence within Greenland. According to the
International Permafrost Association logo (upper), and the
map of permafrost extent of the National Snow and Ice
Data Center (lower) from the http://ipa.arcticportal.org (access: Sept. 19. 2011), permafrost spreads either over the
whole island, or, only over its portion which is not frozen.
The criterion for the two divisions is not clear. On the
bottom map, continuous permafrost is arbitrarily limited to
the coastal strip and ends up in an unnatural way under
the glacier without transition zones (as discontinuous and
sporadic), and such zones are obviously characteristic of
it in the periglacial environment. See also [97].
the extent of permafrost in the world, as well as an understanding of glacier-permafrost interactions. On a smaller
scale, the same conundrum applies to all the other glaciers
in the world.
It is quite obvious that glaciers are frozen, as they are
composed of ice. It is also widely recognized that permafrost does not occur in the substrate of polythermal
glaciers, because there is water there, except at its frontal
part, usually as permafrost frozen to the bed. Permafrost is
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commonly associated with frozen ground, and this does not
always exist in the substrate of polythermal glaciers [13].
Such a position, however, is in error. It is not the physical state (frozen vs. unfrozen, solid vs. liquid) but the
temperature, that ought to determine what is or is not
permafrost. Everywhere underneath a glacier there is a
constant temperature of 0◦ C or lower, which satisfies a
reasonable condition for defining this state as permafrost.
Note that lack of freezing is usually caused by increased
pressure attributed to the presence of a thick layer of ice,
and also to frictional heating and geothermal flux [14].
Introducing the concept of glacial permafrost to the scientific community can resolve the above inconsistency,
which significantly affect the process of permafrost research. Correct understanding of ice and permafrost also,
by extending this concept to glaciology, clarifies the concept of the cryosphere and resolves some problems, such
as the question of rock glaciers, a topic whose terminology
and taxonomy have remained at an impasse for years.
4.
Permafrost Perception
Siberian studies show that, during an initial research period, permafrost was associated with the presence of underground ice [13]. Glaciation occurring on the surface of
the Earth was simply massive ice, present on the ground.
An analogy justified the applied nomenclature: Permafrost
was associated with term “underground glaciation” [15],
juxtaposed, as it were, with “surface glaciation” which resulted in glaciers and ice sheets. Treating permafrost in
such a way clearly indicates that an attempt at a holistic
approach to the ice present in and on the lithosphere was
made during those years.
Detailed studies then began to show that the presence of
permafrost does not have to be linked with the presence of
water or ground ice. Noticing the freezing of rocks other
than sedimentary, though sedimentary may contain much
more water than metamorphic or igneous rocks, in a significant way redefined our views on permafrost occurrence
and significantly influenced its definition. The introduction of the concept of dry permafrost may have eventually
oriented thinking about permafrost towards extant physical conditions, and away from things [16].
Not trivial, with reference to permafrost, is the statement
that its definition is based on temperature and time [17].
This statement is entirely consistent with the findings
generally accepted in permafrost science. Several experts
claim the same. R.F. Black [18] writes that “permafrost is
defined on the basis of temperature and thus may consist
of any type of natural or artificial material, whether consolidated by ice or not.” In 1976, the same author [19]
claims that “the definition is based exclusively on temperature, irrespective of texture, degree of induration, water
content, or lithologic character.” H.M. French [11] writes:
“Permafrost is defined on the basis of temperature: it is
ground (i.e. soil and/or rock) that remains at or below 0◦ C
for at least two consecutive years. (...) Furthermore, permafrost may not necessarily be frozen since the freezing
point of included water may be depressed several degrees
below 0◦ C.” Haeberli et al. [20] argue that permafrost is
a “specific ground thermal condition” (p. 191). On this
basis it can be concluded that permafrost is not a thing
but a state, an invisible phenomenon of a concealed, as it
were, nature.
This view is valid nowadays, i.e. permafrost is considered
to be the state of rock or soil (as the physical presence of
water is less relevant), remaining at a temperature equal
to or lower than 0◦ C. This means that, in fact, permafrost
is invisible.
It is very important to consider here this sharp boundary
which is determined by the temperature 0◦ C. This value
was probably accepted because it defines the boundary
between what is and what is not permafrost in a totally
unambiguous way. In the Earth sciences, there are few
such clearly defined boundaries. It can be admitted that
this situation is invaluable in research and, in a way, directs it towards more general methods of (geo)physics.
The only universal and yet very simple method of gathering data which meets the requirements of the definition
is the measurement (two-year monitoring) of soil temperature.
A temperature of 0◦ C determines the boundary of the
phase transition between the solid and liquid state of water, yet under specific conditions. A boundary temperature of 0◦ C was accepted, probably, because of a common belief that it separates what is frozen from what is
not frozen in the lithosphere. In this sense the temperature 0◦ C is perfectly associated with the term “perennially
frozen ground.”
In nature, however, such cases are rare. Dissolved mineral
content and pressure are the main factors that influence
reductions to the temperature of water’s phase transition.
It is worth remembering that 70% of the Earth is covered
with the oceans, the salinity of which causes a temperature
of 0◦ C, as the limit for water’s phase transition, to be
completely inappropriate here.
Progress in research on permafrost ultimately led to a
crisis based on the shortcoming of taking the temperature
0◦ C as the limit to what is and what is not frozen in the
Earth’s lithosphere [17] (Fig. 2). There was then created a
challenge over what would constitute a decisive criterion
for what is and what is not permafrost: whether it should
be the temperature (≤0◦ C) or the solid state of water
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fine the area of permafrost occurrence it was eventually
defined as a feature of long-term frost, which, in practice,
boils down to two consecutive years, and, as such, was
included in this newer definition [13, 15, 17].
4.2. Water and Ice and Their Relationship to
the Lithosphere
Figure 2.
Simplified diagram of a geophysical model of permafrost
after [16]. Due to the inadequacy of the temperature 0◦ C
as the limit for the transition solid / liquid phase transition, permafrost comprises both liquid and solid phases
of water in sub-zero temperatures (after [24] with minor
changes).
which might be present within. It was an introduction of
the concept of “kriotic ground” (kriotic state) which eventually shattered the older understanding of permafrost as
permanently frozen (in solid state) ground. Since then,
permanently frozen ground is considered only a part of
the permafrost layer, as has been depicted in Figure 1
in [17], and as is better illustrated by the drawing here
(Fig. 2).
4.1. Permanence: Permanent vs. Perennial
By definition, the basic features of permafrost are its temperature and durability. It is worth showing how, fundamentally, the perception of its durability has been changing. Observations made in Siberia which indicated its stability enforced an assumption that its durability is “eternal” (Russian: viechnaya merzlota). Further observations
in areas of less frequent, especially discontinuous, occurrence of permafrost demonstrated temporal variability in
its presence. This discovery demanded that the term be
adjusted, and apply, at first, to permanently, and, later,
to perennially frozen ground. “Frozen” refers to its durability, but “permafrost” no longer meant an eternity. This
name is somewhat valid today. In order to explicitly de-
Water occurs under natural conditions on the Earth as
forms of solid, liquid and vapor. The location of H2 O is
divided into two spheres. To the hydrosphere should be
assigned water as a liquid and vapor phase because both
these states of matter are recognized by physicists as fluids [21], and there is no reason why Earth sciences would
deal with this issue in a different way, if we want to maintain a reasonable unity of science. Ice as a mineral and
rock (also in the form of sediment - snow) belongs to the
lithosphere [1, 22]. Only such a classification allows the
inclusion of the Antarctic to the group of continents. It
would be otherwise if ice were regarded as a component
of the hydrosphere, since the name “continent” can only be
applied to a part of the lithosphere. Therefore, in such a
traditional approach, with no ice cap, the Antarctic would
be only an archipelago of islands [2]. A similar reasoning
applies when determining the height of the highest mountain peaks, usually permanently covered with snow or ice.
The layer of snow ought not be added to the height if it
is a component of the hydrosphere.
Also, the act of considering the location of ice in permafrost means that, to begin with, the essence of ice must
be reconsidered. A starting point for this may be its definition. It is one of those commonly accepted definitions
which seems so obvious, but which has probably never
been discussed [1]. For general use, it is, indeed, somewhat satisfactory, and, perhaps, that is why there is no
need to change it. Ice is commonly defined as frozen water. It should be noted that a problem only arises when we
begin to consider it in its scientific, more precise context.
The definition of ice describes it as water that has undergone the process of freezing, i.e. it is in the solid form. It
must be understood so by default, because the definitions
in a number of encyclopedias and textbooks usually do
not comment on the subject. But we know that the most
common definition of water, which is also as evident in
widespread use as the definition of ice, tells us, however,
that water is understood as a liquid. So if you do not
want it to be a contradiction here, in scientific terms the
ice is not water because it is not liquid. It also does not
have the basic characteristics of water: water is wet and
ice is dry. For this reason, there is a need to redefine water, and add to the definition that water is a three-phase
substance.
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This important distinction seems to be understood well by
geologists and especially by petrographers, who rate ice
to the category of minerals [22], and therefore its greater
accumulation must be called rock. Indeed, ice has all the
mineralogical features which are used to describe other
minerals [1].To ice, science has attributed fairly common
characteristics which make it fundamentally distinguishable from the other components of the lithosphere. The
main ones are:
1. Ice, in comparison to other rocks, melts easily,
which causes it become wet and associated with
water as a liquid. The temperature of ice melting
is very low in comparison with other rocks and minerals, as it can be melted even in a human hand.
In fact, ice melts easily only in those places on
the Earth that are favourable for being inhabited
by man, i.e. in lower latitudes, because a warmer
climate favours both; hence such is a common human experience. But at other places of Earth’s surface, ice can be long-lasting, and is much older,
and much more stable, than quaternary sediments
or contemporary, volcanic eruptions.
2. It is seemingly transitory. In view of the fact that
ice melts easily, it is regarded as a very transitory
phenomenon. Indeed, the easy phase variation of
water in low and medium latitudes, and at not high
altitudes, initiates and is responsible for many geomorphologic processes. But it is not so everywhere.
Suffice it to say, the glaciation of the Antarctic has
lasted for about 40 million years [23]. This is not
synonymous with the age of the ice located there
because of its movement.
3. It floats on water. Ice is not the only rock, the
physical properties of which (low density) allow its
floating on water; another one is pumice, a volcanic
rock, which is not as common as ice.
4. It is a common belief that ice is a water reservoir.
The above-mentioned features of ice make it considerable as a reservoir of freshwater. This statement is justified to a very limited degree. Due to
the following characteristic, it is a kind of presumption that the basic form of the ice is water in a liquid
form. Ice, or rather a glacier, or ice sheet, may be a
reservoir of water in its liquid phase when, during
the ablation season, it can accumulate the water of
snowmelt and rain in specific ponds and lakes located on the glacier surface. Glaciers as such, are
therefore reservoirs of ice, not water (liquid).
The proposed above rule of Spatial Uniformitarianism may
be very helpful to understand correctly the place and role
of ice on the Earth. It allows one’s perceiving ice on the
Earth in the same way as ice present on other celestial
bodies is perceived, i.e. as the icy lithosphere [1, 2, 24].
These findings show that ice ought to be considered a
component of the lithosphere just like any other rock or
mineral. This approach is helpful but not historically
necessary, as many have acknowledged that ice existing in nature may solidify as any other rock. Freezing
in glaciers and ice sheets is an obvious and long-studied
process [14, 25]. However, oddly, their study does not fall
into the category of permafrost sciences, as permafrost
sciences are reserved exclusively for the periglacial environment.
4.2.1.
Glacial Ice
Quite commonly, a glacier is not recognized as a ’permafrost body’, although the idea of a division into cold ice
and temperate ice has, for a long time, led to such a perception for a great number of glaciers [26–28]. Presenting
the differences between some basic forms of ice occurring
in nature, and in glaciers, ought to allow enough preparation of the framework for a working thesis on permafrost
occurrence in glaciers and ice sheets.
According to the “Glossary of glacier mass balance and
related terms,” prepared by the Working Group on Massbalance Terminology and Methods of the International
Association of Cryospheric Sciences (IACS), IHP-VII [29],
glacial ice is defined in two ways:
1. “Ice that is part of a glacier, as opposed to other
forms of frozen water such as ground dry ice and
sea ice.
2. Ice that is part of a glacier, having been formed
by the compaction and recrystallization of snow to
a point at which few of the remaining voids are
connected, and having survived at least one ablation season. In this more restricted sense, the
term refers to the body of the glacier, excluding
not only snow and firn but also superimposed ice,
accreted ice and marine ice. The density at which
voids cease to form a connected network, that is, the
density at which firn becomes glacier ice, is conventionally taken to be near to 830 kg m−3 ” [29].
The first definition describes a locative state. This definition can also be called a geomorphologic definition. It
is a fact that a glacier may consist of, for example, many
types of ice in the genetic sense, but, according to this
definition, it is not the origin, but the place of ice within
the form of a glacier, that determines that ice is glacial.
The latter definition is much more precise because it
brings up the question of ice’s origin. Taking genesis into
consideration in the definition is essential, to the extent
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that a glacier may come into existence, and, then, develop in the initial phase only through the accumulation
of snow, followed by its compaction, metamorphism, and
finally by the movement of ice. Only such a process allows
the creation of a glacier or ice sheet. Other types of ice
appearing within a glacier are not able to create a glacier
independently, and they are secondary to the first type
- the initial one. In this genetic meaning, only one type
of ice may be considered as glacial ice, the one which is
formed from snowfall.
4.2.2.
Non-glacial Types of Ice in Glaciers
In glaciers, there are commonly also other types of ice,
which, in terms of genesis, are different from the ice which
may initiate glacier formation (Fig. 3). As they are not
able to initiate the development of the glacier on their
own, they cannot be called glacial ice in terms of genesis.
The most important among them are:
1. Ice formed in the process of so-called internal accumulation, that is, the refreezing of water within the
glacier, between the summer surface and the bed,
which goes undetected. Internal accumulation proceeds by the freezing of water that has percolated
early in the ablation.
2. Superimposed ice – Ice accumulated on the current
summer surface, during the current mass-balance
year, by the freezing, there, of rain or meltwater.
Superimposed ice is not the same thing as internal
accumulation, which represents refreezing.
3. Accreted ice – Ice formed by the freezing of water
at the base of an ice body [29].
The types of ice listed above might constitute a significant part of the structure of a glacier or ice sheet. Internal
accumulation may constitute up to 64% of the annual accumulation of a glacier [30]. Further, recent discoveries
in the Antarctic reveal a new feature referencing the role
of accreted ice present in the ice-sheet. In some places,
beneath Dome A ice stream, for example, up to half of
the ice thickness has been added from below [31]. Note
that, because basally-accreted ice does not develop from
surface snow, it does not contain direct records of past
climates [32].
In fact, it may be concluded that a significant portion of
some glaciers and ice sheets is not built from glacial ice
in the genetic sense. Especially the ice formed in the
process of internal accumulation can be classified as the
ice associated with the periglacial environment, because
it may be partly rainwater from rainfall. In this light, there
appears a kind of merging of glacial processes with nonglacial ones, which indicates a specific interpenetration
Figure 3.
Different types of ice that builds a polythermal glacier.
Hansbreen, Spitsbergen. A - Ice on the surface of the
glacier B - Regelation ice occurring in the crevasse.
of glacial and periglacial fields. This issue needs further
consideration.
5.
Glacial Permafrost
The inclusion of glaciers in the category of lithosphere,
in accordance with the principle of Spatial Uniformitarianism mentioned above, allows their updated systemati-
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Figure 4.
Thermal structure of glaciers by Blatter [50], after [46], supplemented with the cold and temperate glacier ideas of the
author.
zation in other conceptual categories also. The approach
facilitates a preserving consistency between science disciplines, and a cohesion within geological sciences. This
taxonomic scenario also holds true for the application of
the term permafrost to glaciers and ice sheets.
First of all, it should be stressed, that freezing of glaciers
is obvious, and excluding them, as a category of forms
covering permafrost, is completely artificial and countermanded a priori, as already stated by A.L. Washburn [28]. This allows rejecting, easily, such a limited
research approach, where permafrost is attributed only to
the periglacial environment. It is important to remember
that ice, as well as permafrost, are assumed to exist also
on the other celestial bodies (e.g. Mars) [33].
T. Hughes [34] was probably the first one who used the
term glacial permafrost. He defined it in terms of physical
categories, referring to permafrost as “a physical condition,” which could include a center built exclusively of ice,
just as well as a center devoid of ice. J. Menzies [35]
presents hypotheses on the migration of frost at the base
of glaciers, and also indicates an important role for this
process in the interaction of the glacier with the ground.
Other researchers have also used the term “permafrost” in
relation to the glacial environment, to a greater or lesser
extent [36, 37].
The relation between permafrost and glacier is an important one, although it is still not a fully recognized issue, as
it is relatively new: “Glaciers and permafrost have commonly been viewed as mutually exclusive” [38]. Scientific
work on glacier-permafrost interactions is now predomi-
nantly identified as research on materials and processes,
e.g. as ice formation with glacier-permafrost contacts, as
landforms, as rock glaciers and glacitectonically deformed
moraines, or as glacier beds [38–40], or within research on
massive ground ice inherited from last glaciation, together
with its subsequent evolution and modification [41, 42].
As a geophysical condition – the temperature of the lithosphere – permafrost may be only a host for two processes:
aggradation and degradation, by means of the change to
its temperature. In these processes freezing and thawing
may also occur, but this is constricted to material that
contains water. Note that the presence of water is not
necessary for the occurrence of permafrost. Theoretically,
its content in permafrost (regardless of the phase state)
can vary from 100% in glaciers to almost 0% in solid crystalline rocks.
Sometimes subglacial permafrost is limited exclusively to
cold-based ice, where the temperature of the basal ice
is below the pressure melting point [38]. Under current
thought, a cryotic state is equivalent and synonymous to
permafrost, and similarly a temperature of 0◦ C constitutes
its boundary condition. Without a clear justification for
this new position, perhaps, for some, it cannot be accepted,
since, under past usage, it is contradictory to the definition
of permafrost to take cryotic state as a synonym. Looking
at this issue is very important for two reasons:
1. Taking the classic understanding of cryotic state
as a synonym of permafrost allows one to maintain
the same boundary condition of 0◦ C for both of the
terms.
2. Maintaining the value of 0◦ C as the permafrost
boundary condition is of a fundamental, practical
importance. It ultimately enables science’s resolving the issue of the presence of permafrost beneath
glaciers: It occurs then everywhere, under every
glacier and ice sheet, regardless of their thermal
states (cold or temperate), because, under a glacier,
the temperature is always below 0◦ C, as expressed
in the term “pressure melting point” [2] (pp.19-20).
These reasons, especially the latter, as it was stated earlier, make it necessary to revise again the incidence of
permafrost occurrence throughout the Earth, as the opinions on the quantity of the Earth’s surface covered by
permafrost may vary by up to 15 000 000 km2 (!), when
we take into account the ice sheets of the Antarctica and
Greenland (regardless of their being frozen or temperate).
The second issue refers to attributed material characteristics, in various forms, of permafrost, and some authors
are not yet respectful of this current (updated) definition
of permafrost, as in the following: “Permafrost frequently
contains water, either as a liquid or a solid (ice)” and
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“subglacial permafrost can be physically indistinguishable
from debris-rich ice within the basal layers of glaciers
and ice sheets, especially polythermal glaciers with coldbased margins.” [38] (p. 2) Waller, Murton, and Kristensen, thereby, are still treating it as a thing.
Given the current definition, permafrost cannot hold attributes or features referred to as “rheology” and therefore, justly, ought not be described as anything that some
authors, e.g. [38], associate with it, such as, “deforms by
creep and ductile behavior.” For the same reason particle
size is not now thought to be a function of permafrost, just
as the statement that “permafrost is partially frozen and
comprises a mixture of sediment, ice and liquid water” (p.
3) is not correct. “Glacially-deformed permafrost” (p. 4)
does not exist as only a thing (moraine, substrate) can be
deformed, not a state. When regarding permafrost degradation, some authors may use the term “thaw” [38] (p. 5),
which refers to the phase change of water (solid / liquid).
Thus it can be concluded that the authors cognize permafrost as something that is frozen and contains frozen
water. In the context of this old definition, the answer to
the question, “How can permafrost persists beneath thick
ice masses? ” [38] (p. 5) is very simple: The lack of permafrost under glaciers is not possible. It is a fact that
“the distribution of contemporary subglacial permafrost,
especially beneath ice sheets, is poorly understood.” But
with the knowledge that the temperature beneath glaciers
is always lower than or equal to 0◦ C, there is no need
for additional research to state with certainty that permafrost is always present under all the glaciers of the
world. Worry about “cold-based conditions and therefore
subglacial permafrost” [38] (p. 6) is an erroneous position,
and, truly, the division of permafrost occurrence into three
zones beneath large ice masses does not reflect the state
of permafrost. Of course, when referring to some hydrological or glacial process itself, the distinction between
“dry-bed and wet-bed systems” is necessary, though permafrost is a term that does not affect this distinction. In
the past, it did indeed affect so-called subglacial thermal
organization.
To be sure, unification of contrasting ice-classification
schemes employed by glaciologists and permafrost scientists, however possible [43], is not an ultimate solution
for communicative unification of these two sciences.
As glacial permafrost, they consider either a cold layer
of a polythermal glacier, or a totally frozen glacier along
with the ground. Dobiński [1] assumes a thermophysical
point of view, i.e. he refers to the thermal state of the
lithosphere as permafrost, considers “cold” glacial ice, that
is frozen, existing in the temperature below 0◦ C, as glacial
permafrost, and includes in the range of the lithosphere
also any form of ice occurring in nature. However, he takes
it as a problem that is associated with the term “kriotic.”
The issue of glacial permafrost was raised by the author also elsewhere [24], where it was dealt with in reference to permafrost in general. This is the first time that
someone had presented a geophysical model of glacial
permafrost. A permafrost body is limited from above
and below by the thermal surface of 0◦ C. In the case of
periglacial permafrost, the upper surface constitutes its
active layer, that is, the near-surface layer of the lithosphere, where in summer the temperature rises above 0◦ C.
Due to the nature of ice, the active layer will not occur
in any form within a glacial permafrost, as the ice polymorph Ih does not occur at a temperature above 0◦ C (See:
http://www.Isbu.ac.uk/water/). At a temperature above 0◦ C
other types of ice (ice VII, X, XI) may occur, however under
much greater pressure [1, 14], also improbable in natural
conditions prevailing on the Earth. An active layer does
appear in the summer, as ice turns into another state of
matter, and it is removed from the surface of the glacier
by the force of gravity. In this case, and in mountain
periglacial permafrost, which occurs at high altitude in
equatorial areas, permafrost starts at the surface of a
glacier and is devoid of its active layer [24]. Determining
the bottom of glacial permafrost in a totally frozen cold
glacier is simple and comes down to determining the run
of the surface of 0◦ C, which means, rather, the surface of
the pressure melting point under a glacier, whereas determining the bottom of the permafrost layer in a polythermal
glacier is a bit more complicated. In fact, for a polythermal
glacier, the entire glacier body has a temperature below,
or equal to 0◦ C, so it is in a frozen or cryotic state. The
entire polythermal glacier is in state of permafrost, and
not, as stated previously by other authors, only to the
cold-temperate transition surface (CTS) [24]. For a better
understanding of the concept of permafrost here is a brief
characteristic of the glacier thermal regime.
5.1.
The Thermic Characteristics of Glaciers
The thermal state of a glacier is the result of the coexistence of several processes, both glacial and non-glacial.
The temperature of an ice mass is a function (1) of the
rate of geothermal heat influx at the sole, (2) thermal fluxes
across the atmosphere/glacier interface, (3) horizontal and
vertical components of velocity (4) internal and basal ice
friction at the glacier bed [14, 44]. Just as in traditional
permafrost, the temperature of the upper 10-20 m of ice
is formed under the influence of seasonal changes to the
surface energy balance and similar changes in thermal
conductivity. Since, in the winter, ice has a temperature
higher than the air above it, there occurs a temperature
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gradient which causes the flow of heat. Heat dispersion
causes the ice’s temperature to drop, which is called the
propagation of a cold wave inside the glacier. Such thermal anomalies as cold waves and percolation zone layers
are preserved within the ice, resulting in the development
of distinct paleo-thermal layers [44]. According to Paterson [25], a minimum temperature at the depth of 10 m
occurs with a delay of 5.5 months compared to a minimum
on the surface. He concludes that, at this depth, the amplitude of seasonal changes is not greater than 1◦ C, and
seasonal changes disappear at a depth of 15-20 m. The
freezing process is thus analogous to what one sees in
traditional permafrost.
In those parts of the glacier where melt water percolates
throughout the snow, large amounts of heat can be released, notably, in the areas where water encounters a
sub-zero temperature and freezes [25]. This process (internal accumulation) is particularly important in the upper layers of a glacier’s accumulation zone, as it eliminates winter cooling down, definitely, faster than under
conditions when thermal conductivity operates alone [45].
In the summer, when a glacier surface reaches its melting temperature, any occurring melt water flows down the
surface. Here, seasonal heating of the cold layer is slow,
as the temperature cannot rise above 0◦ C, and most of
the energy is absorbed by phase transition [46]. Other
words: During winter, the glacier surface is cooled below
the pressure melting point, as a winter cold wave penetrates down from the surface, due to consistently cool air
temperatures. During the spring and summer, the release
of latent heat, as meltwater refreezes at the ice surface,
and progressively higher air temperatures, driving ablation, ensure that the seasonally cold surface layer initially approaches and, then, remains at the pressure melting point. The depth of this surface temperate ice zone is
limited by latent heat release, solar energy receipt, and
by the poor thermal conductivity of glacier ice [47]. This
surface ice in the ablation zone of a glacier is called a
transient thermal layer and is visible also in Figs. 5- 8.
The processes presented here are quite diverse, and depend on the geographical environment in which a glacier is
present. This also causes enough variation that, in terms
of thermal regime, existing glaciers can be divided into:
(1) cold glaciers, (2) polythermal glaciers, and (3) temperate glaciers (Fig. 4). In temperate, wet-based glaciers,
basal temperatures are found at ca. –1 to –3◦ C and in
polar, cold-based, frozen-to-the-bed glaciers, basal temperatures reach –13 to –18◦ C [25].
According to Paterson [25] the thermal classification of
glaciers is as follows:
1. All the ice is below the melting point.
Figure 5.
Geophysical model of glacial permafrost of a cold glacier
frozen to the bed. Due to its thickness the seasonal and
long-term temperature changes go deeper than in other
types of glacial permafrost. All the ice is below the melting point, and, therefore, glacial permafrost in this case is
marked as ‘A’. Beneath the glacier there is a layer of “traditional” permafrost, to a depth of occurrence of the 0◦ C
surface.
Figure 6.
Geophysical model of glacial permafrost of a cold glacier
not frozen to the bed. Seasonal and long-term temperature changes get less deep. The melting point is reached
only at the bed. Glacial permafrost is also marked as type
‘A’. Beneath the glacier the formation of the cryotic state
takes place – melting of the ice – because the pressure
melting point has been reached. This change affects the
movement of the glacier, allowing bottom slide. As the
temperature is still below 0◦ C under the glacier, traditional
permafrost is also present to a certain depth.
2. The melting point is reached only at the bed.
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Figure 9.
Figure 7.
Figure 8.
Geophysical model of glacial permafrost of a polythermal
glacier. The upper part of the glacier constitutes active
permafrost, where seasonal changes in temperature take
place, as in the previous cases. Permanent freezing, however, penetrates into a layer thicker than active permafrost,
so this part of permafrost is marked as ‘A’ permafrost. A
basal layer of finite thickness is at melting point. Within this
layer there is a cryotic state under pressure. This layer is
defined as ‘B’ permafrost.
Geophysical model of glacial permafrost of a temperate
glacier. All the ice is at the melting point except for a surface layer, about 15 m thick, that is subject to seasonal
variations in temperature. Permafrost of this type is defined as ‘B’ permafrost.
The photograph shows a conglomerate whose structure
may resemble the internal structure of some rock glaciers
cemented with internal ice. This conglomerate occurs
in Holy Cross Mts., Poland. It consists of poorly coated
clasts of Devonian limestones and dolostones cemented
with iron-carbonate and calcite. Later cracks are bound
with calcite. The analogy between the calcite and ice cement in rock glaciers is clearly visible, although the plasticity of ice at 0◦ C is much higher than of calcite, which
does result in creep and its symptoms, visible in the forms
of rock glaciers.
3. A basal layer of finite thickness is at melting point.
4. All the ice is at the melting point except for a surface layer, about 15 m thick, that is subject to seasonal variations in temperature.
As the glacial ice may contain impurities such as water,
air, CO2 , salts, the term “pressure melting point” does not
mean that it is solely dependent on pressure. Impurities,
indeed, depress the melting point in a glacier [25].
Cold glaciers, in the context of the occurrence of glacial
permafrost, are forms which cast no doubt, because in all of
their volume, they contain ice, the temperature of which is
lower than the temperature of the pressure melting point,
which is well below 0◦ C. The liquid phase in such a glacier
is very limited and occurs only in summer, and the glacier
is frozen to its base. Diagrams of the glacial permafrost of
a cold glacier, both frozen and not refrozen to its substrate,
are shown in Figures 5 and 6.
Polythermal glaciers can be also divided according to
Baranowski [48] and Blatter [49], into several specific
types (Fig. 4). With the exception of one, all the types
have a layer of cold ice localized over a layer of temperate ice. Though a more detailed thermal classification is
possible [47, 49, 50], it is not necessary for introducing
the concept of glacier permafrost. The polythermal type
of glacier has a small layer of temperate ice on its surface,
in the zone of percolation, in the author’s opinion, which
corresponds to the term “zero curtain” in traditional permafrost, and results from the dissipation of the latent heat
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of fusion of water during freezing or thawing of the ground
(ice, snow). This layer can persist for several hours or
several weeks, depending largely on the total water content of the ground snowcover, and on air temperatures.
A geophysical model of glacial permafrost in polythermal
glaciers (Fig. 7) applies to that portion of their bodies
where there is warm and cold ice.
Temperate glaciers are those which contain ice at the
pressure melting point in their entire volume. This means
that in fact, to a little extent, the liquid phase of water
contributes to the construction of such a glacier. A geophysical model of glacial permafrost in temperate glaciers
is shown in Fig 8.
Out of the existing types of thermal glaciers [49, 50], the
polythermal glacier was chosen as a preliminary model
to present glacier permafrost, due to the details of its
thermal structure [24]. Initially, the upper layer of cold ice,
in a strong interaction with the climate, was recognized
as a layer of permafrost. Therefore, the limit for a suchdefined glacial permafrost was the CTS surface. Clearly,
it was doubtful whether the ice present at the pressure
melting point could be considered as perennially frozen.
In another publication [51] the authors refer to a layer of
such ice as basal cryopeg.
However, a reading of both the permafrost definition and
of Fig. 2 demand that one recognize as permafrost any
kind of soil or rock which is charted at a temperature
equal to or lower than 0◦ C. It is also a well-known fact
that, especially in fine-grained materials, not all water
freezes at 0◦ C, and a liquid phase may be present in permafrost even if it is at a temperature far below 0◦ C [17].
A holistic approach demands that one treat ice as a mineral and as a rock. In the most well-known and widely
accepted geophysical presentation of permafrost, namely,
Figure 1 in [17], permafrost is presented as the portion
of the graph on the right, “unfrozen” side of the chart,
along with the cryopeg, or Figure 2, in this work. The
reason for the assessment is, again, that the layer of permafrost comprises material that is perennially cryotic, not
perennially frozen. In light of this analysis, the term permafrost should also refer to temperate ice which occurs in
glaciers and glacierets [52]. Therefore, when taking into
account the thermal classification of polythermal glaciers
along with the concept of glacial permafrost, there must
be distinguished a glacial permafrost of Type A, which can
be called cold, which is directly related to the impact of
climate, and Type B, which can be called warm, located
at the melting point under pressure. This terminology is
convenient enough to be also used when relating to traditional permafrost, because it always includes a material
at a temperature equal to or lower than 0◦ C. This solution
facilitates consistency for the whole concept in relation to
both occurrences of permafrost: glacial and periglacial.
This division is also so very important, because it preserves the division of glaciers due to their thermic qualities, and because the second layer is not as much affected
by the climate change as the first one. This second layer,
i.e. temperate ice, although it is at the melting point, has a
temperature below 0◦ C. In a glacier about 200 m thick, for
example, where the pressure at the bottom is 1.80 MPa,
the melting point is –0.1◦ C, whereas, at a thickness of
5000 m, when the underglacier pressure is 44.98 MPa,
the melting point is at –3.3◦ C [29]. Therefore, there is
no doubt that, all the time, one is dealing with rock which
meets the requirements of the definition of permafrost, this,
due to the fact that the second layer is, to a much lesser
extent, susceptible to the effect of climatic impact, while
quite dominant here are various glacial processes. The
geophysical models of glacial permafrost, founded on the
thermal classification of glaciers [25, 49, 50], have an initial character. As they are a component common to both
glaciology and permafrost science, the author believes
that the contribution of scientists from both the disciplines
will significantly improve under the proposed models contained herein (Figures 5- 8).
6.
Rock Glaciers
The problem of elucidating the origin of rock glaciers
has been intensively discussed for more than 30 years.
For geomorphologists, rock glaciers are probably one of
the most intriguing forms in the periglacial environment.
Since the time the term was created, the views expressed,
on forms, genesis, evolution, internal structure, movement,
age and the significance of rock glaciers in the geographical environment, these have been presented in hundreds
of articles. The most influential are the first scientific
papers [53, 54], which are still the basis for the development of new viewpoints, especially, the ones which are
most characteristic for the development of this field of research [55–64]. The number of interesting polemics in
which sharp differences of opinion emerge also indicate
scientists’ engagement, and are essential for understanding the development of this field of knowledge [65–75].
Many of the articles contain a classification scheme for
rock glaciers [76–80]. Listed in the references are papers
essential in understanding the long-lasting discussion devoted to rock glaciers. A particularly peculiar concept has
recently appeared in permafrost studies, as well as in the
context of research on rock glaciers: numerical modeling of
the four-phase interaction between solids, water, ice and
air [81–83]. Although ice is a phenomenon in some ways
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peculiar, there is no reason to treat it as a fourth phase
and thus exclude it from the set of solid bodies. Otherwise, this will lead to breaking off the working relationship between permafrost studies, geology (petrography),
and physics.
Recently, a significant input of new ideas, data, and
increasingly detailed observations have been added to
rock glacier study by a relatively large number of scientists [83–87].
Also, nowadays, there is no classification model yet in the
literature describing a rock glacier in a way that would
satisfy, to a minimum degree at least, all the research.
Quite often the classifications overlap, making the synthetic presentation of the knowledge of the forms difficult;
adopted terminology has also been discussed [59, 60, 62].
The review articles summarizing the status of research on
glaciers that have been published recently are the works
of Burger et al., [80], Haeberli et al., [20] and Berthling [6].
Among the host of views and classifications, two mainstreams are dominant: The most important, a genetic one,
where the genesis of rock glaciers is associated with the
processes of the glacial and/or periglacial environment,
and a geomorphological one, which divides rock glaciers
into subslope and valley glaciers; the first is believed to
be of periglacial origin and the latter – of glacial origin.
Disagreements have always resulted from this classification: in perceiving rock glaciers as a part of the glacial or
periglacial environment.
It is worth emphasizing that probably only one process,
the so-called “Balch Ventilation” [88, 89] cannot be interpreted in glacial terms, as, according to this process, the
formation of ice in a rock glacier is an effect of the circulation of underground air in microclimatic conditions. There
is also one form, the Kunlunshan type (ice-cap shaped)
rock glacier [90] that cannot be interpreted as genetically
connected with a classic glacier, although the ice accumulation in this rock glacier is similar to the accumulation
zone of an ordinary glacier.
These dominant, extant, divergent views can be summarized as follows:
1. Rock glaciers are exclusively of glacial origin.
2. Rock glaciers can form in the glacial and in the
periglacial environment.
3. Rock glaciers are forms of exclusively periglacial
origin.
4. Rock glaciers constitute an “ablation complex,” or
“landscape continuum” between the glacial and the
periglacial environment.
This approach is also a subjective generalization, and
classification can be more extensive since Barsch [see [60]
indicates, in his classification, more than 500 possibilities. However, none of the classifications hitherto has
fully recognized the role of rock glaciers in the geographical environment.
The different opinions on the origin of rock glaciers result directly from the separation of glacial research from
the periglacial, and the creation of a separate range of
terms for the two fields. Periglacial research began to develop in opposition to the glacial, and occurred because
the periglacial environment was initially defined as a peripheral area of the glacial zone, that is, as a strip of
land adjacent to an ice cap. Hence, the separation of
those two zones was done on a spatial, rather than on a
climatic basis [91, 92]. The view has evolved over time,
which specifically allowed the periglacial environment to
be extended from the areas adjacent to ice caps, into those
covered by permafrost, and into ones where frost action is
a dominant factor [92, 93]. In the meantime, ice has ceased
to be perceived as a bridge, an element shared by both
environments, such as is now happily visible in the permafrost definition. Presenting the glacial and periglacial
environments as opposing concepts in the discussion on
the genesis of rock glaciers has made a consensus difficult to reach. This might have led to the rejection of such
concepts as “continuum” [64] or “ablation complex,” [61] although both of them might have been good starting points
for the synthesis of views about rock glaciers. An attempt
to return to unity in cryospheric sciences was made by
the author [94], who proposed the reinclusion of ice into
the term “lithosphere,” and such would enable considering the components of rock glacier (ice and debris) as two
different rocks. One of the most interesting publications
attempting to resolve the issue of glacial debris in recent
years is a publication by I. Berthling [6]. It acknowledges
the ambiguity of the term which excludes glaciers from the
permafrost realm. He proposes a new genetic definition
of “rock glacier,” where active rock glaciers are considered as a visible expression of cumulative deformation by
the long-term creep of an ice / debris mixture under permafrost conditions. This author attributes them neither to
the glacial nor periglacial environments, describing them,
instead, as krio-conditioned landforms. In a traditional,
interdiscipline-centered view, they may be, however, considered as an integrating phenomenon of the glacial and
periglacial / permafrost environments. The proposed principle of the Spatial Uniformitarianism may be helpful in
further research and consideration here.
6.1.
Movement
In the periglacial environment there are many structures
containing ice. Also, most permafrost which occurs in the
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world usually contains some form of ice. Rock glaciers,
however, are the only geomorphological forms which may
be associated with the presence of permafrost, and which,
in addition to ice, show downslope movement. It is, justly,
this specific movement that facilitates such a geomorphological formation which resembles a glacier’s, and that
causes it to have a similar name. Aside from its material composition, that is, an ice – rubble mixture, motion
is the fundamental process leading to its creation. Understanding its motion is therefore essential for a proper
understanding of the entire form. Fundamental to all theoretical treatments of glacier movement and deformation
in other materials is a formula relating the amount and
rate of deformation to the applied stress. In a Newtonian
viscous material the rate of deformation is proportional to
the stress, whereas in an elastic material deformation and
stress are not proportional. In glaciers, this deformation
relation depends on loading conditions, confining pressure, state of stress, and other factors. Ice responds elastically to high-frequency sound waves (seismic method),
and ice may fracture if a large stress is applied rapidly.
If stress is applied slowly, ice becomes permanently deformed in a way that is intermediate between Newtonian
viscous and perfectly plastic behavior. [25]. This motion,
however, being the movement of the solid body, should not
be called “flow,” since this term applies to fluids, which
include liquids and gases. As regards plastic solids, which
include ice and glaciers, the term “creep” should be applied widely. And most often this is so, but sometimes it
happens that the terms “flow” and “creep” are used as synonyms in glaciology. Such an establishment as is outlined
above enables a proper determination of the same point
of reference for the movement both of ordinary glaciers
and and of rock glaciers. There is no doubt that the "primary process responsible for the creeping motion of rock
glaciers is relatively well understood to be due to creep
deformation of ice," [20]. However, if permafrost is considered as a ground thermal condition i.e. a state of the
lithosphere, it cannot be assigned movement as a “thermal condition” [20] cannot creep. That is why permafrost
cannot be seen, and the only processes that may occur in
permafrost are aggradation and degradation. Therefore,
describing the movement of a rock glacier boils down to
applying the equation for the secondary creep of polycrystalline ice [6, 20, 95], which also has been adapted for
glaciers by [96]. The description of the motion of the two
forms, of ordinary glaciers, and of rock glaciers, is based
generally on the same principle. Creeping is a kind of
deformation which is caused by movement within or between single crystals of ice, and which slightly resembles
the deformation of metals at temperatures near their melting point [96]. Creep in rock glaciers is smaller than the
creep rate of pure ice by at least one to two orders of
magnitude [59]. Yet, there should not be applied different
terms in naming this movement: “flow” for glaciers and
“creep” for rock glaciers. This could open another discussion as to whether the process of permafrost creep is
essentially different from that for glacial movement [6].
Understanding this relationship is of fundamental importance for a useful cognitive framework for rock glaciers,
especially when the occurrence of glacial and non-glacial
ice can be observed in both environments: glacial and
periglacial. Hence, this as an alternative to that past distinction, which, indeed, loses its decisive role in a proper
understanding of rock glaciers.
7.
Conclusions
The concept of glacial permafrost introduced above has
an preliminary character and, because of its novelty, it
probably needs further development and refinement. The
present analysis, however, allows for a better understanding of, variously, permafrost, glaciers, and ice sheets, in
the context of a cryosphere consistently understood as being part of the lithosphere, the primary criterion of which is
the solid state of the elements that constitute it. Such an
order allows further synthetic development of both glaciology and permafrost science.
Just as, within ordinary glaciers that are in the glacial
environment, there can be distinguished ice of periglacial
genesis, so, too, within the periglacial environment, there
can be distinguished ice of glacial origin. The volume of
ice may be significant. This means that, in certain climatic and geological conditions, both environments permeate, so, treating them separately, in the way it is being
done currently, makes it impossible to understand some
elements of the Earth’s surface, such as, notably, rock
glaciers.
A holistic approach to ice in Earth sciences, treating it as a
rock, and including it in the lithosphere, together with the
concept of glacial permafrost, as well as an understanding of the principles of its motion, allows the resolution
of the problem of rock glaciers. In light of these findings,
they are a mixture of two types of rocks: weathered rock
and ice, that, as the elements of two different spheres –
the lithosphere and hydrosphere – are not in opposition
to each other. The genesis and the amount of ice in a rock
glacier are of secondary importance in terms of its polygenetic origin both in glacial and periglacial environments.
The special property of ice, that is, its visco-plastic creep
at a temperature much lower than of other rocks, facilitates movement and the creation of landform sculptures
such as rock glaciers. Its specificity allows its recognition
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W. Dobiński
as a form of the cryosphere, which is an element shared
between the glacial and periglacial environments.
The inclusion of all the components of the cryosphere into
the lithosphere, and the application of the principle of
Spatial Uniformitarianizm makes it feasible to adopt a
new, unified approach to scientific studies of the presence
of ice not only on our planet but in the entire cosmos. The
floating ice of the Arctic, ice-sheets, and permafrost areas
can be considered an analog of extraterrestrial landscapes
like those on Mars or Titan, and vice versa.
Acknowledgements
I would like to express my thanks to two anonymous reviewers for their comments which allowed me to improve
the text, and to Prof. Jonathan M. Harbor, for all his kindness, help and understanding with my publications in the
Earth Sciences Review. AMDG.
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