FUNDAMENTAL LAWS GOVERNING THE DEVELOPMENT OF THE HYDROGRAPHIC NET AND THE MECHANISM OF PENEPLAIN FORMATION
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Fundamental Laws Governing the Development oi' the
H~rdrographic diet and the Mechanism
. of Peneplain Formation
V. D. Dibner. Izvestiya Vsesoyuznogo Geograficheskogo
Obshchestva (Reports of the All-Union Geographical
7, Volume 82, No I. (duly/August 1950), pages
society
_
339-'3~I1.? Leningrad: 1950?
RESTRICTED
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STAT
STAT
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4
9
FUNDAMENTAL LAWS GOVERNING THE DEVELOPMENT OF THE
BYDROGRAPHIC NET AND THE MECHANISM
OF PENEPLAIN FOPJ{kT'IO
(Printed on the basis of the revised and supplemented report
first read at a meeting of the Geomorphological Commission of the
All-Union Geographical Society in March 19Lt.7)
The problem posed in the title of this article involves a
number of central questions concerning geomorphology. Hence one
must not close one1s eyes to the extraordinary complexity and vast
ness of the task posed, the ultimate solution to which does not lie
within the powers of one man. This is especially true in view of
the fact that the author has set for himself the task of analyzing
the fundamental laws which govern the development of river networks
under conditions of complex geological structure rather than under
conditions in which a structural plain has simply risen above sea
level, as was preferred by Davis and his many followers up to
Horton.
At the same time it is impossible not to acknowledge that
only such a statement of the problem makes its over-all solution
possible (a simple geological formation frequently proves to be
complex rather than simple); moreover, practice compels us to
develop [new] starting points for the theory of alluvial deposits.
In Osnkhhroblernakh geornorfologii (Basic Problems of
Geomorpholo~r) K. K. Markov (12) presented a developed criticism
of the W. Davis and W. Penck conceptions, and showed conclusively
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that they no longer correspond to the standards of contemporary
geomorphology and related geological and geographical disciplines.
This is absolutely true as regards the problems examined in
this article. Hence it is not necessary for us to begin with a
criticism of the views of W. Davis and W.'Penck; it is even less
necessary (especially in view of the limitations of space) to dwell
any further on the "history of the problem," since there is in the
literature on the subject no original explanation of the nature of
the processes of peneplain formation which differs in principle
from the generally known "orthodox" theory of W. Davis and W. Penck.
Meantime, the need for a theoretical generalization derived
from the enormous amount of material accumulated in recent years,
on the one hand, and the demands of practice, on the other, do not
permit us to discuss at any greater length conceptions which were
partly developed as far back as the last century, which from the
present day point of view were based on patently inadequate factual
material, and which were not developed according to the Marxist
dialectical method.
In the present article the author takes the liberty of ex-
pressing a number of ideas about the problem formulated in the title
of this article in the hope that this will give impetus to a broad
consideration of related problems.
The space limitations of a journal article compel brevity,
regardless of the great number of problems under consideration, In
particular it was far from everywhere po sw_ble to adduce the full
factual material in the author's possession for the support of this
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or that position. The author hopes to remedy this shortcoming
in the near future by the publication of several articles devoted
to a more detailed review and documentation of the various state-
ments made below.
T. INITIAL STAGES OF THE WATER EROSION PROCESSES.
THE INTERACTION OF WATERCOURSES
On a part of the earth's surface which. as a result of fold
formation and anteclinal upheaval has been isolated as a morpholo?
gically expressed elevated region, destructive forces take an
increasingly large part in the process of contour formation as the
tectonic movements abate, (Land erosion begins long before the
abatement of the tectonic forces, but a's long as the processes of
tectogenesis are vigorous enough to nullify the effect of the
erosional processes, the latter can be ignored and their considera.-
Lion begun at a later time).
Among these processes erosional activity plays the leading
part in a majority of cases. The hydrographic net which begins to
develop under primary contour-formation conditions conforms at
first to the already-present negative structural formations.
this process a special, if not decisive role is played by the re-
peated reorganizations of the hydrographic net which take place as
formation of the pre-erosion contour into an erosion contour.
Further development of the hydrographic net proceeds through trans.-
a result of the constant interaction between separate watercourses
and between whole river systems.
3
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words on the nature of this ?tinteraction." In the
A few
f us designate two watercourses having a commofirst place, let
water divide owing in opposite directions as conjugated"
Con u ated watercourses always =~intexact, t' which
watercourses. J g
interaction finds expression in the generallyP'own phenomenon of
aggressionc- on the part of the watercourse having the greater
tt
exaslonal activity against the watercourse which is less active.
It is also generally known that the watercourse which has
in the region between the source and the
the greater average slaps
of erosion will have the greater regressive
nearest base-level
erosion activity of the two streams.
? ~hould be especially noted that the interaction of cone-
s.
It
ses takes place in the form of a capture of the
jugated watercaur
surface (still) and subsurface waters of that water divide zone
from which both rivers are fed.
This is why the interaction over the course of relatively
long time intervals does not lead to contact of the upper parts of
the watercourses, the water divide between which continues to exist
but gradually is displaced toward the side of the less active water-
course (Drawing 1)?
x
1. The Interaction of Conjugated Str'earns
Drawing
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Such "peaceful" interaction between conjugated streams will
develop at an accelerating tempo so long as the water divide does
not shift to a point of junction of receding watercourse A with
another watercourse B of the same river system. The moment this
junction does take place, Watercourse B is joined to the system of
the aggressor watercourse, and the action of regressive erosion is
by degrees transferred to the vicinity of the sources of stream B
(see Drawing 1).
The phenomenon described above is usually called river inter-
ception, representing a "jump" [of one square ] on the ground where
[the game of] interaction between conjugated streams is beginning..
In nature cases are observed where interception is not pre-
ceded by a "peaceful" interaction stage, but in which the upper
part aggressor river makes a right angle raid on the valley of the
adjacent raver and "wins over" that part of the course of the river
lying above the point of interception ("lateral" interception).
Similar phenomena were recently described by K. S. Gerenchuk for
the confluence of Prut and Seret rivers (10).
The process of interaction between conjugated streams is a
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self-inducing process, the "aggressor" watercourse, which, in turn,
intensifies the further advance of the aggressor, and so on.
On the other hand it must be noted that the diversity of the
spacial distribution of the local base-levels of erosion in some
instances brings about a pulsation of the water divide where
repeated changes take place not only in the rate but the direction
of the interaction of conjugated streams, such changes depending on
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T primary erosional streams conform to the morphologically
expressed negative tectonic structures and are localized in their
bottoms; the orientation of the tectonic elements of the last
orogenic phase here determine the orientation of the incipient
watercourses.
In this stage the water-erosion activity on different parts
of the mountain region develop independently from the base levels
of erosion dispersed around the boundaries of the mountain region.
These base-levels of erosion will appear only on the periphery of
the mountain region as long as the water-erosion streams do not
become too deep to have as local base-levels of erosion only non-
draining lake basins of tectonic origin.
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the extent of the effect of the constantly descending base levels
of erosion. In short, the phenomenon on river interception can,
in some cases, precede not a simple displacement of the water
divide but a pulsation of it. (Drawing 2)
Drawing 2? Figures i'--6 show the successive displacements
of a water divide resulting from the effect of constantly descending
base-levels of erosion.
II. THE FORMATION OF PRIMARY RIVER SYSTEMS
The above applies with equal force to entire river systems;
however, before we turn these considerations to the interaction be-
tween river systems we must touch.. upon a,..few problems concerning
the formation of a river system such as might take place under the
complex geological structural conditions of a mountainous area.
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Exarctples of the formation of this type of tectonic lake
are cited by I. V. Mushketov (see Bibliography, 1L', page 473)
who writes, ttBoth anticlinal and synclinal lines display an
irregular slope as a result of which there appear along the latter
articulated settlings which bring about the formation of tectonic
lakes in these primary depressions; such lakes, as for instance
Remorey and St. Poynt in the Dub River valley (in the Dub
depression in Yura west of Lake Neuchatel), as well as the small
lakes in the Orb River valley in the Neuchatel Lake system repre-
sent distinct extensions in the synclinal direction.
Another example of tectonic lakes conforming not to the
folded but to the disjunctive negative structures is to be found in
Academician V. A. Obruchev (18), who, while characterizing the
contour of the southern part of neighboring Dzhungari.a as "block
mountains, fault blocks or wedgings of the crust.....limited by
fractures and elevated to a different height' goes on to say that
here "rivers or streams ternitinate in lakes or little by little dry
up while within the mountain region..," The interaction of con-
jugated streams leads by degrees to the formation of rivers which
are more extended (than the primary rivers), and also brings about
the joining of river systems which are forming on the elevated
locality under study to the water arteries of adjacent (lower)
territories,
Simultaneously with the process of union between the primary
streams there is beginning and developing a network of subsequent
tributaries enter the main river at right angles. The life of
all other (non-perpendicular) feeders is limited by the fact that
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the subsequent tributaries will take the maximum slopes and will
hence display the greatest erosion activity.
At the same time it must be pointed out from the innrunerable
multitude of perpendicular directions the tributaries select for
themselves the structurally favorable sections. They (the tribu-
taries) adapt themselves either to the remaining unused primary
stream beds of secondary tectonic form,
or to elements of deeper
structures opened as a result of erosion by primary rivers. In the
latter case the role of the deeper ands as a rule, older structure
comes down to the effect of the lithological features, since the
deep structure cannot be shorn to be of direct morphological action.
The presence in the main river of a tributary entering at an
acute or even at an obtuse angle bears witn.ess to the fact that this
tributary was formed comparatively early, while subsequent tribu-
taries developed later and still have not succeeded in intercepting
the course of the oblique tributary (Drawing 3).
Drataing 3. Breakdown of an oblique tributary as a result
of capture of its various sections by subsequent tributaries.
The development of subsequent tributaries leads in turn to
interaction between tributaries of adjacent arteries so that in
the last analysis the mast active arteries pick up the pieces of
the less active arteries parallel to them.
In this manner the formation of related river systems takes
place out of different primary streams, in the process of which the
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primary (we suggest calling it the "fragmentaryn ) h d.ro ra h '
y g p ~.c net
changes into a dendritic, and still later into a lattice-type
network.
TIT. THE INTERACTION OF RIVER SYSTEMS AND THE PERIODIC
REORGANIZATION OF THE HYDROGRAPHIC NET
In the course of the described processes the moment approaches,
of Course, when the tributaries of one river system enter into in-
teraction with the tributaries of another river system,
in the
process of which the more actively developing river system will
join
to itself parts of the adjacent weaker systems. Examples o
of this
"conqueringtt of the rivers of one basin by rivers of another basin
are fairly core non and well known. One of the appro r7.ate ex
p amples
,
is shown in Drawing Li,
Drawing ). Capture of the basin of the Sema River by the
Katunt River. The newest section of the Sena River is crisscrossed
with transverse lines; it is evident that the Sema previously flowed
independently to the north. At present preparation for the inter-
ception of the upper section of the Sema is being made through
. the
rivers Apshiyakhta and Sedlushka.
Interaction between river systems is accompanied by a break-
down of the valley of the less active systems and the formation of
a section of dead, or, as they are commonJ_y called, old va
~ 1.l ey s
(old valleys, i.e., valleys which have been left over from a system
of an active hydrographjc network, have been noted by marry researchers.
9
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A. R. Burachek, for example, writes of the old valleys of the
Patomskiy uplands; "Many of these old valleys are well preserved.
The largest of them are oriented along the course of the geological
structures, that is, from northwest to southeast, and they intersect
the watersheds of the present-day river basins. In many places the
sedimentation of the old rivers was well preserved, at times reach-
ing a thickness of probably 20-30 meters" [3].)
However, the further course of development of the processes
described may lead to a breakdown of the attacking system itself.
This takes place when different elements of a lattice-type system
of rivers are intercepted on the periphery of the mountain area
under study by a river system having a lower base-level of erosion
for the entire region than that base level relative to which the
development of the hydrographic net has taken place so far.
Rivers in this stage of their development display articulated
configurations, governed by the configuration of the preceding
(lattice) stage due to natural. variance in the times of interception
of all the rivers, forming one straight line.
The process of formation of articulated rivers augments the
/iiri
number of dead valleys appear at points of breakdown of a
main valley in the lattice stage.
Further on the articulated rivers straighten their course
through the destruction of their bends by regressive erosion be-tween corresponding tributaries (Drawing S).
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Drawing 5. The straightening of bends in the valley of the
Lobva River (on the eastern slope of North Ural). The Kushva and
Rybnaya rivers are "tryingn to rectify bends in the Lobva River.
The Royka River is trying to rectify a bend formed by the Kushva
and Lobva rivers (in the Vakhrushevka-Talitsa section). The
Krasnoyarka River is trying to join the Lobva River (in the vicinity
of the mouth of the Rybnaya River)- to the Sos ova River. Upon com.-
pletion of all these processes the Lobva River will acquire a
single latitudinal. direction of flow.
These interceptions also are accompanied by the formation of new
sections of dead valleys and a change in.
irection of flow in some
sections. Thus a new cycle in the development of the hydrographic
net begins, marked. with the formation of rivers which we designate
as ?secondaryf rivers. These rivers have a direction of flow which
is perpendicular to the flow of 'tprimaxyu rivers.
Due to the augmented erosionaj activity on the newly formed
straight sections of the valley, tributaries appear. These tribu.-
taries, just as in the original stage of land formation, adapt
themselves to the favorable structures opened by erosion along the
sections of the straight valley.
Thus the normal course of the process of erosionj breakdown
of the primary tectoriic contours inevitably leads to its reversal
(inversion). For example on the eastern slops of the Urals several
tributaries of contemporary latitudinal (or articulated) rivers
-ll-
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: 6. Vt1
j meridional valleys, the water divides between which are
complex, with a 'eiirface of Oligocene'-Niocene alluvial sediment-
ation (2O)
Subsequent development of the hydrographic net is proceeding,
through the formation of secondary "lattice" and 'tarticulatedtt
systems and under definite conditions, toward the formation of
rivers of a third generation, which may have an orientation close
to orientation of the primary rivers, though not spatially congru-
ant with them. The formation of rivers of the third generation is
accompanied, wider .tire proper geological conditions, by the
phenomena known as "contour inversion1t
For a better picture of the causes which bring about periodic
reorganization of the hydrographic net, see Drawing 6.
Drawing 6. Readaption of the hydrographic net from base-
level of erosion No 1 (B. E. 1) to the lower base-level of erosion
No 2 (B. E. 2).
The drawing is a schematic representation of an elevated
mountain locality surrounded on four sides by depressed areas which
serve as its base-levels of erosion. These base-levels of erosion
have varying absolute heights above sea level. Since the :first to
develop was a lattice-.type system built relative to B. E. 1, the
system will later be reorganized under the effect of the lower base-
level of erosion -- B. E. 2 -- in the manner described above.
If the remaining base levels turn out to be still lower,
then sooner or later they will compel the hydrographic net to re-
organize again and again.
-12-
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We must also take into account the fact that at the time
of formation of the hydrographic net the relative importance of the
various base-levels of erosion may periodically change due to
oscillatory movements, each such change bringing about a reorgani'-
zation of the hydrographic net,
Iv. FOHMkTION OF A DENDRITIC ffYDR0GRAFHIC NET.
AUGMENTATION OF THE ROLE OF SURFACE WASHOUTS
The periodic reversals of the river systems in a plane,
accompanied by the spatial incongruities of such systems> lead to a
riddling of the contour, in the process of which each new cycle of
breakdown of the water divides progressively increases
slopes.
the number of
Simultaneously with the increase in the number of slopes, a
leveling of the high points of the positive forms of the contour is
taking place. This is explained by the fact that the highest
sections of the Itprimary-tectonic't contour of erosion, and hence
also the interaction between the different rivers, are developed the
most rapidly.
This explanation may perhaps include the cause for the forma-
tion of mountain peak faces -- a problem which K, K. Markov treats
extensively, but at the same time fails to resolve.
Thus, as the erosion processes develop the "primary, contour
not only lowers (this is known) but is substantially broken down
(diminished in size) and flattened (,in the sense of leveling of the
maximum crests).
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In the final stages of development of this process, the
water-erosion activity, because of the progressive breaking down
of the contour, widens the field of activity for the processes
of physical weathering and surface washouts. 'total destruction of
the land and "tightening" of the slopes and peaks by products of
subaerial denudation result in the elements of the geological
structure affecting the development of the hydrographic net less
and less. The moment approaches when the development of the hydroM
graphic net will forever be regulated solely by the action of the
force of gravity.
At this time the main artery and its tributaries take on the
characteristic dendritic form.
All the watercourses now flow in conformance with the general
angle which the locality adopted at the time of the last recon-
struction of the hydrographic net. In this stage the processes of
water erosion, having completely reorganized the locality, act
entirely independentof the geological structural features.
In its overall direction, the process tries to create uniform
drainage for the area in place of chaotic distribution of drainage
adapting itself to the different tectonic directions of the valleys.
Going ahead a bit, let us assume that such "ideal." drainage
of an area is exhibited on the eve of the disintegration of the
hydrographic net (see below).
Let us bring out a few of the preliminary results deriving
from the preceding exposition.
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1 The development of the hydrographic net from the
fragmentary stage to the dendritic stage is a self-inducing process.
b fragmentary
At the end of each cycle of reorganization of the hydrographic net
river systems are formed, the main arteries of which have an
z4' o/
orientation perpendtcularthe rivers of the preceding cycle.
These changes in the orientation of the main streams come
about because the most active tributaries of the main rivers in
each stage are the perpendicular (subsequent) tributaries (see
the activity of which predetermines the formation of new
above) ,
main rivers.
However, spatial congruance of the erosional forms of
the repeatedly rearranging hydrographic net does not come about,
because development the water, courses t'exhure" deeper and
in their deeper geological structures and once again the tributaries which
evolve are located in the favorable sections for erosion of the
latter i.e. as has been repeatedly stated above, out of the 1n-
possible perpendicular directions the erosion selects the
numerable ~
structurally favorable sections, and in this sense the development
of the hydrographic net is guided by the geological structure.
V. THE DISINTEGRAT1OI OF THE HYDROGRAPHIC NET AND THE
FOR ATION OF THE MELKOSOPOCHNIK [SMALL CRATER]
The formation of a dendritic hydrographic net leads to the
augmentation of a whole series of processes which together bring
about the disruption (disintegration) of the hydrographic net.
These processes are as follows:
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1. progressive increase in the number of slopes leads to
excessive intensification of the processes of surface washout and
eroding of the products of weathering in the valley of the water-
course.
2. progressive increase in the number of streams without a
change in climate (that is, a constant quantity ox precipitation)
resul_ts in a weakening of the erosional energy in each of the s t rems.'
3. The accumulation on the slopes of loose weathering pro-
ducts leads to an increase in the filtration of precipitation which
in turn leads to diminished supply to the watercourses from run-
off waters and consequently the erosion force is still further
lessened.
4. The accumulation of alluvial sedimentation in the
negative forms of the contour leads to an increase in the filtration
of bed waters in the ground, which also serves to weaken the force
of erosion.
It should be noted that factors 3 and Li. naturally bring
about a shortening of the upper parts of the watercourses.
The above processes, together leading to a weakening of the
water-erosion action and to a broadening of the field of activity
for slope-terracing agencies, in the last analysis result in a
damming up of the different sections of the river course. This
initiates the degradation of the river net and the formation of
non-draining craters so characteristic of the low hills
[melkosopochnik] of the Kazakh landscape.
M 16 M
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The same conclusion was reached more than fifteen years
ago by G. Ye. Bykov on the basis of field investigations in which
he noticed the following genetic series in the development of the
crater forms of contour of the Kazakh melkosopochnik: "River bed,
stretch of water, stretch of lake, lake valley, round lake, dry
lake crater" (5)?
In the light of investigations of recent years (, , 6, 7,
8) there remains still less doubt as to the erosional-
denudation-derivation of the Kazakh watershed melkosopochnik. (From the number
of opponents of the erosional-denudational derivation of the Kazakh
watershed melkosopochnik we may cite I. S. Shchukin who believes
that this type of contour "is formed for the most part by and
weathering and wind erosion ?f (23, page 53). It is interesting to
note that where these forms have not been affected by a modern
revival of erosional action and have not been ha] f buried under the
marine sedimentation of a tertiary sea, we have evidence that on
the eve of the melkosopochnik stage the hydrographic net possessed
dendritic character. Such a semi-degradation in which traces of
the dendritic configuration of the hydrographic net are none the
less retained is shown in Drawing ?, referring to the region built
almost entirely of paleozoic complex rock (north of Lake Balkhash).
Further breakdown of the positive forms of the contour take
place through a washing out of the slopes until they acquire
critical angles of equilibrium. (The slopes of the valleys which
the watercourses are developing will have a steepness considerably
exceeding the critical angles of equilibrium. Hence it is quite
evident that these angles begin to form only after the process of
washing of the river net has come into its own right).
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Thus in the development of the erosional-denudational
contour the melkosopochnik stage corresponds to the interval of
time from the formation of short critical slopes to the formation
of slopes having critical inclination angles, which takes place
through filling in of the negative forms of the contour with the
products of the breakdown taking place on the slopes.
At the end of this process there has been formed, instead of
a mountain area, an undulating semi-plain (peneplain) having as its
base complex geological structures covered by no less complex
products of breakdown.
To the number of ttpost-peneplain formationt~ processes must
be added the formation of the old weathering crust "fixing", as
K. K. Markov put it, the old denuded contour.
VI. THE EFFECT OF THE MOVEMENT OF hE CRUST ON THE
COURSE OF THE PENEPLAIN FORMATION PROCESSES
Analyzing the development of the erosional processes, we have
purposely kept away from the role of endogenous forces acting on a
given territory during the period of peneplain formation, believing
that otherwise we might detract from rather than add to a correct
understanding of the importance of erosion in contour formation.
On the other hand the extent of effective action of the tectonics
on the contour can be properly understood only after exhausting all
possibilities of recreating different stages of contour development
with the aid of internal laws of development of the hydrographic
net.
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Now let us examine the influence of the ceaseless motion
rth's crust on the development of the erosional processes.
of the ea
With z this point of view it is advantageous for us to give
the following classification of the motion of the earth t s crust: A. Movements noticeably disturbing the geological structure
of the area. Let us agree to call these defor`raatianal movements.
referring to both plicatiye and disjunctive disloca-
Here we are
taona which appear equally in different sections of the area.
.
Def ormationai movements in turn must be distinguished accord-
ing to the relative speed of their manifestation;
1. VorouslY developing movements as a result of which
~.g
lteT(i and the whole hydrographic
the course of a given section of the river.
b. The newly arising structures grow parallel to
strata of alluvia at points of development of negative structures.
development (growth) of positive structures and anomalously thick
In this case antecedent valleys are formed at the points of
to the course of a given section of the river.
a. The newly arising structures grow transverselY
category, in turn, must be divided into two limiting cases:
b
net is able to adapt itself to the new contours. This
graph/:
Slower movements in the course of which the hydro-
2.
the entire plans of the area Zs a
net, so far in effect, is disrupted.
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In this case !-drif t? occurs, i.e., a displacement of the
course of the river according to the newly emerging slopes toward
the side of the axis of the nearest negative structure (displace-
ment of the course of the latitudinal tributaries of the Yenisey
according to the slopes of the extended growths, and in recent
times the structure of the Taymyr Depression [21]).
B. Movements not disrupting or only imperceptibly dis-
turbing the geological structure of the area. Here we refer to
(1) regional anticlinal upheavals, or (2) general subsidence af-
fecting the entire area under observation.
It has been generally agreed in recent times to call this
type of movement ~toscillatory'l movement.
In distinction to the deformational movements, which at
least to some degree inhibit$ or even reverses the process of
peneplain formation, oscillatory movements, generally speaking,
favor this process. This statement may at first glance seem
(. / f /22i$/ 'ak'f 1-4 t'/
~or75rr~~~~ t.r~f a?,
strange. However,
that the entire
1v A.1~~ : }
positive regional movement of the earth r s crust' '"to inten-
sification of the erosion processes (this is always noted), simul-
taneously facilitatesthe progress of hydrographic net reorganiza-
tion processes relative to the base-levels of erosion which
surround the given locality. Thus after each regional upheaval
the contour of the locality acquires a more and more complex
appearance (i.e., it diminishes in size) since the erosional
activity is guided by the geological structures into continually
new directions (see above). During the period of subsidence this
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process is somewhat retarded so that it can revive again during
the period of upheaval.
The full completion of peneplain formation (degradation of
the hydrographic net) can, however, only take place under conditions
of relative rest (relative to neighboring territories) or subsidence.
In brief, the positive regional movements tend to facilitate
reduction of the contour, this comprising, as we have said above,
the first (and evidently the most prolonged) stage of peneplain
formation, Subsidence also assists in completing the secondary and
final stages, but only under the condition that the preceding
periods of contour upheaval have achieved a critical degree reduction.
:Below is a tabular representation of what we have said above;
~~.
> \f c)
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INFLUENCE OF THE MOVEMENTS OF THE EARTH t S CRUST ON
THE DEVELOPMENT OF THE HYDROGRAPHIC NET AND THE
PROGRESS OF THE PENEPLAIN FORMATION PROCESSES
Type of Movement
Oscillatory Movements
Speed of movement Breakdown of
Positive Negative
Movements Movements
Promote the Promote the
exceeds speed of previous process of
erosional hydrographic contour
processes. net and new reduction.
formation
of the tect-
onic contour.
Speed of move- Adaption
ment slower than of the hydro-
or equal to speed graphic net
of erosion. to the incipa
Tent structures.
process of
wearing down
the contour
where the
latter has
achieved a
critical
degree of
reduction.
For the completeness of this section it is proper to intro-
duce a statement by N. I. Nikolayev (16) who says (after
V. V. i3eolusov [1] and others) that tat the present time there is
to be noted an adequately clear connection between the structure
and character of the manifestation of the most recent movements
of the earth's crust, reflected most of all in the sculpture,
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i.e., the geomorphological features of the area." In other words,
the ttprimary'lstructure may show not only the direct effect on the
development of the hydrographic net (see section I, II and III
of this article) but can also affect it in an indirect way through
young movements.
To illustrate the various statements made in this section
we have found it most instructive to treatvd'ious moments in the
meso-cenozoic history of the Urals.
Characteristic of the mesozoic alluvial deposits in the
Urals is, as is well known, their conformance to the old meridional
depressions. These deposits, in turn, inherited the negative
tectonic structure formed at the time of the varisic orogenesis.
Trougaout the mesozoic era the basic water arteries of the Urals
repeatedly reconformed their courses according to the meridional
depressions. These facts testify to the disruption of the normal
erosional processes, and we are compelled to come to the conclusion
that in the mesozoic era the meridional structures of the Urals
underwent repeated "rejuvenation", which was expressed as a false
"conservativeness" of the hydrographic net of that time. It is
still necessary to add that the presence of mesozoic lake deposits
within the depressions affirm the fact that ''normal'' development
of the hydrographic net in the different epochs of the mesozoic
age was retarded by slow, almost ceaseless subsidences beginning
and repeating at different tames on different sections of the
depressions In other words, due to the prolonged development of
the varisic structures in the mesozoic age the hydrographic net
of the Urals not only was "trampled into place'', but was even at
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times regenerated to the fragmentary stage (formation of non-
draining basins). At the same time the occurrence in the Urals
of variously aged (mesozoic) formations of crust weathering bears
out the fact that in different epochs of the mesozoic age the
contour of the Urals acquired a considerable degree of wear. For
these same epochs there is data on the time of the existence of
the latitudinal arteries which is indicated by the material com-
position and slime-mineralogical composition of several varieties
of loose mesozoic deposits.
Thus for the mesozoic Urals there are to be noted alternating
epochs of revived deformation.ai tectonic movements with. epochs of
comparative rest characterized by the predominance of anticlinal
upheavals of wide radius. Such a relatively "tranquil" epoch was
the time just preceding the upper cretaceouspaleogenic transgression. when the reduction of the contour took place.
The final leveling off of the contour, manifested in the
fonne.tion of the Ural melkosopochnzk, demands that we identify
this event with the epoch of the paleogenic transgression. At
this time, due to the high position of the base-level of erosion
the wearing away of the diluvial material from the slopes finally
"drownedtt the activity of the water arteries which up to this time,
we must assume, had had their own dense net of diminishing streams.
The absence of any data whatsoever on the presence of alluvial
deposits belonging to the epoch of maximum transgression of the
paleogenic sea (paleocene and acene) can serve as evidence of
'1Se
M 21
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Judging from available bibliographic data the same things
took place in the paleogenic era in central Kazakhstan.
In the oligocene, miocene, and on the eastern slope of the
Urals in the piiocene as well, there was a new "rejuvenationt1 of
the mesozoic meridiorial structures (echoes of Alpine folding).
In the Quaternary period, and on the western slopes of the Urals
in the pliocene also, favorable conditions for the reorganization
of the hydrographic net were brought about through the diminishing
of the differentiational movements of the Ural structures. There
appeared articulated, and in places latitudinal rivers, which
developed in conformance with the geographic location of the
general base-levels of erosion, which were, at that time, the
Russian Plain and the West.Siberian Lowland. Thus because the
orographic contrasts within the Urals (i.e., the meridional valleys
and meridional water divides) in the Quaternary period little by
little moved into the background in comparison with. the more stable
contrasts between the entire Ural mountain area as a whole and the
surrounding plains, the internal laws of erosion came more and more
into their own.
The activity of the Quaternary latitudinal valleys is accom-
panied by the antecedent cutting..through. of the meridional zones
of upheaval. and the simultaneous accwnulation of anomalously thick
strata of alluvia, in the meridional zones of sagging (d ressions).
VII. THE RULE OF CLIMATE
With regard to the influence of climate on the progress of
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the development of erosional and denudational processes, it is
believed that this factor affects only the rate of these processes.
It is pertinent for our purposes to point out that in the contour
"riddling" period the process of peneplain formation accelerates
as the climate becomes damper; conversely, in the last stage of
peneplain formation (washing out of the hydrographic net and
eroding of the slopes) the process accelerates as the climate
grows drier. In this connection it may also be noted that an arid
climate has the special role of "canning" the different stages of
contour development. For example, on a great part of the territory
of central Kazakhstan there have been preserved up to our time
sections of the development of the melkosopochnik untouched by
recent erosion, and even an indication of the peneplain formation
I
contour overlapped by lower-Tertiary period crust weathering
(I. P. Gerasimov, [7]). (In the post-pa].eogenic period the territory
of central Kazakhstan unquestionably underwent not only oscillatory
but in places also deforro.ational (13) movements whichshould have
under other climatic conditions promoted marked erosional disinte-
gration of the surface of the paleogenic peneplain).
In estimating the preservative qualities of an arid climate
we are in complete agreement with the opinion of S. Yu. Geller
(b), who believes that the contour of a desert is inherited from
the old erosionaladenundational cycles and is carefully preserved
under contemporary conditions of the desert in which, in comparison
with all other landscape zones, the processes of contour formation
have been specifically diminished.
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t~NGLUSIONS
1. The history of the destruction of a mountain area is
the history of the development of its hydrographic net, Its re-
peated reorganizations accompanied by the formation of new
valleys and washing out of the old, ands of course, the degrada-
tion of the hydrographic net all determine the course of the
destruction of a mountain area from the stage of high ttprimary
tectonic mountainstt to the melkosopochnik and peneplain stage.
2. The struggle of the various watercourses and whole river
systems in the field of underground and slope feed is the fundamental
internal law of the development of the hydrographic net governing
its repeated reorganization even under conditions of comparative
tectonic rest,
In this connection the gradual distribution of the effect
of the constantly descending base-levels of erosion may bring about
:
f
nf
y
t o
,
~Q,
S
fi
e~
Chan
repeated g sin the rate butf.nr the direction of the
process in different sections of the area.
3. The role (passive) of the geological structures, which
determine the concrete forms of the hydrographic net development,
results in each new water artery "conforming tr to the increasingly
deeper structural features uncovered by the preceding stage in
the erosional development.
In the last stages of the development of the hydrographic
net breaking dawn of the contour leads to intensification of the
processes of subaerial denudation. The role of the internal
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structure dwindles down to nothing and the hydrographic net
acquires the characteristic dendritic configuration of flat
countries, and then disintegrates entirely.
4. Peneplain formation is a two stage process; stage T .?..
breaking down of the ttprimaryt' contour by erosion, accoraplished
through repeated reorganization of the hydrographic net; stage II
washing out of the slopes by diluvial processes, acquiring decisive
value for the maximum development of stage one.
;. Movements of the earth's crast which may develop during
the period of peneplain formation are to be divided into:
(1)
oscillatory movements which do not change the structure of
the locality, and (2) deformational movements which change the
structure of the locality (active role of the geological structure).
While deformational movements retard or even reverse the
processes of peneplain formation, oscillatory movements, on the
contrary, encourage this process. This is explained by the fact
that regional upheavals facilitate the breaking down of the contour
while subsidences contribute to its washing out, with the stipula-
tion that the degree of breakdown must have already reached its
limit.
Hence it is our belief that in explaining the process of
peneplain formation there is no necessity to assume the existence
of whole geological periods of complete tectonic rest, whichA`' it
is recognized, is the weakest point in the W. Davis and W. Penck
arguments.
28
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6. On the territory of a region selected for study there
may be simultaneously represented many of the types of hydro-
graphic net described above, genetically related to each other.
Each stage of the development of the hydrographic net produces its
own complex of a11uvia1 accumulations, the study of which has great
practical importance in the search for alluvial mineral products.
Only when we are able to reestablish in detail the history of the
development of the hydrographic net of whole regions will the pro-
blem of finding alluvial placers acquire a stable theoretical.
foundation.
BIBLIOGRAPHY
(1) Belousov, V. V., Oscillatory Movements of the Earth1s
Crust, their Development, Properties, and the Problems of Studying
Them, from Proceedings of the. Conference on Methods of Studying
Deformation of the Crust. Geodesic Press, Noscow 198.
(2) Bilibin, Yu. A., Fundamentals of Placer Geology,
NKGONTI, 1939,
3) Burachek, A. R., Ancient Glaciation of the Patomsk
Highlands' Vo~rosy geografii, Volume 3, Moscow, 1917.
(14) Bykov, G. Ye., Contour Forms in Atbasarskiy Rayon,
I. .s J: - No 1, 1932.
(5) Bykov, G. Ye., The Contour and Reservoir of the
Ters-Askan River in Kazakhstan, Tz~La 00, No 5, 1933.
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(6) Geller, S. Yu., A Few Basic Questions in the Origin
of Desert Contours, Izv Acad Nauk, Geographical and Geophysical
Series, 1937, No ).
(7) Gerasimov, I. P., Development of the Contour of the
Kazakhstan Melkosopochni k, Izv Acad Nauk, Geographical and.
Geophysical Series, 1937, No Li..
(8) Gerasimov, I. P., Structural and Sculptural Features
of the Contour of Kazakhstan. Voprosy geografii, Volume 1, 19L6.
(9) Gerasimov, I. P., Basic Characteristics of the
Geomorphology of the Central and South Urals in the Paleogeographic
Light. Trudy instituta geografii, No L2, 19Li.8.
(10) Gerenchuk, K. M., River Interception in Pricarpathia,
Izv VGO, 197, No 3.
(11) Kassin, N. G., Old Valleys in Central Kazakhstan,
(12) Markov, K. K., Fundamental Problems of Geomorphology,
Geography Press, 19.8.
(13) Markova, N. G., The Tectonics of the Chingizskiy Zone
of Northeast Kazakhstan. Tectonics of the USSR, Volume 1.
Kazakhstan, 1948.
(11t.) Mushketov, I. V., Physical Geology, 2nd Edition,
SPb, 1905.
(15) Nekhoroshev, V. P., The Immature Contour of the Al tay
and the Old Valleys of Kazakhstan. Problemy soy geol, 1936, No 7.
r30..
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(16) Nikolayev, N. I., Contemporary Tectonic Movements
in the Territory of the USSR and Geological Methods of Studying
Them. Proceedings of the Conference on Methods of Studying
Movements and Deformation of the Earth's Crust. Geodesic Press,
1948.
(17) Obruchev, V. A., The Origin of the Melkosopochnik
and the Lakes of the Kirgiz Steppe., Priroda, 1930, No 1.
(18) Obruchev, V. A., Neighboring Dzhungariya, Zemlevedeniye,
Volume II, 1918.
(19) Rengarten, V.P., The Mesozoic and Cenozoic Deposits of
the Urals, Izvestiye Acad. Nauk SSSR, Geological Series, No 2, 19Lt.
(20) Sigov. A. P., Redistribution of the Hydrographic Net
of the Eastern Slope of the Central Urals. Materials on the Geo-morphology of the Urals, State Geology Press, 19118.
(21) Strelkov, S.A., Some Features of the Hydrographic
Net of the Lower Yenisey, Izv VGO, 1949, No ;.
(22) Trifonov, V. P., The Structure of the Strata, the
Meso-Cenozoic Continental Formations on the Eastern Slope of the
Central Urals, Materials on the Geomorphology of the Urals, State
Geology Press, 19)8.
Forms, Vo~ prosy geog~, Volume 1, 1946.
(23) Shchukin, I. S., A Genetical. Classification of Contour
(2)1) Davis, W. M., The Geographical Cycle. Geographical
Journal, XIV, 1899.
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(2~) Horton, R. E., Erosional Development of Streams and
their Drainage Basins, Bulletin of the Geological Society of
America, 19115, March (See review by Armand; Robert E. Horton,
Erosional Development of Streams and their Drainage Basins.
V_ o~prossy geogr , Volume 1i., Moscow, l97.)
(26) Penck, W. Die morphologische Analyse. Stuttgart, 1921.
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