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to northeast, extending in that direction for a distance of
nearly six thousand miles, there has been a counter series of
elevations nearly at right angles with the main line, making
an echelon of the whole. The succession of the strata show,
also, according to MushketoflF, that the elevations running
northwest and southeast are subsequent in origin to the main
line from southwest to northeast.

Early Geological Periods

This rapid glance at the framework of the geological system
of Asiatic Russia prepares the way for an intelligent compre-
hension both of the general history of the great geological
movements, and at the same time of s<Hne later minor move-
ments which have had much to do in determining the history
of the region.

It would seem that early in the geological history of the
Asiatic continent there was a series of long parallel elevations
of the earth's crust running in the main from the southwest
to the northeast, and separated by depressions which were oc-
cupied by the beds of shallow seas having free access to the

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ocean. During all the earlier geological ages the detritus irom
the mountain elevations partially filled up these sea beds, fur-
nishing material for the older sedimentary rocks. From the
Ural chain, which is now but a bare remnant of the original
mass, this sedimentary material was spread far and wide over
the plains of the Volga to the west and over those of the
Obi Valley on the east ; while from the mountains forming the
Mongolian border, and from the plateau extending northeast
to Bering Strait, great rivers brought down the sediment into
the vast areas now occupied by the Aral-Caspian depression,

the eastern side of the valley of the Obi, the entire valley

of the Yenisei, and the northern portion of tfie Lena Valley.

Impressive evidence of the length of this period of erosion,
as well as of its extent, is found in the deep broad valleys
eroded by the rivers which come down from the mountain
plateau. In some cases the valleys occupied by the streams
are synclinal, that is, formed by a downward flexure in the
crust of the earth which originally determined the course of
the stream. But even in these cases as well as in many others
which were entirely independent of such a movement, the
amount of material removed by the ordinary erosion of the
rivers is ever3rwhere seen to be immense. The main streams
which come down from the Pamir occupy waterwom gorges of
many hundred feet in depth from which the material has been
carried out and spread as sediment over the entire plain inter-
sected by the Amu Daria. Similar gorges appear in the upper
tributaries of the Syr Daria and of the Chu and the Hi, coming
down from the western and northwestern flanks of the Tian-

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Shan range. In the earlier period when the sea covered the
whole area of the Aral-Caspian basin, this process of erosion
had gone on until extensive deposits of carboniferous and Ter-
tiary rocks had taken place; the material in various degrees
of coarseness being spread over the whole area. But all around
the margin of the southwestern, western, and northwestern
base of the Tian-Shan range, there were swamps and lagoons
in which vegetation grew and accumulated, forming in due
time beds of peat, which, during a later period of depression,
were covered with fresh deposits of silt and transformed into
lignite and coal.

In the immense valley of the Obi and the Yenisei a similar
process went on. The upper portions of the Irtysh, of the
Obi, and of the Yenisei River have worn valleys many hun-
dreds of feet in depth, and of great width even when crossing
the strata of hard rock which intersect their courses in the
lower mountain chains. All this material, as well as that
which was removed by superficial erosion and carried away by
the streams, was spread out over the border of the sea into
which it entered, the coarser part being left near the base of
the mountains, and the finer being carried to an indefinite dis-
tance into the gradually deepening water.

The upper tributaries of the Angara River, entering Lake
Baikal from the Vitim Plateau and its extension south into
Mongolia, present very impressive evidence of the eflfect of
long-continued water erosion. For hundreds of miles the
Selenga, the Chikoi, the Khilok,. and the Uda rivers occupy
troughs a mile or more in width and hundreds of feet in depth.

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which they have worn in the rocks in the course of their rapid
descent through the three or four thousand feet which separate
the surface of the plateau from the level of Lake Baikal. All
this waste is now being deposited in Lake Baikal, and it is
one of the striking evidences of the youth of this lake that
it was not long ago filled up by the enormous amount of sedi-
ment brought into it by these streams. The lake, which is now
completely surrounded by mountains, and has a depth near its
south end of 4,186 feet, is the product of those more recent
geological changes of which we shall presently speak. But
at an earlier period before the formation of the lake, the sedi-
ment brought down by the stream was spread out over the
extensive plains now covered with Silurian, Devonian, Jurassic,
and Tertiary rocks which cover the vast area watered by the
Angara and its tributaries below Irkutsk. Here also in Jurassic
times the highlands were bordered by extensive swamps and
lagoons in which peat accumulated, and which, as in the other
places mentioned, was, under subsequent changes, covered over
with fresh sediment and transformed into beds of lignite and

The Lena Valley has passed through a somewhat similar
history. The sections given by Barcm Toll show that much of
the broad low plateau west of the middle portion of the Lena
consists of Silurian and Cambrian strata deeply eroded by the
streams; while almost the entire valley of the Yana is com-
posed of Triassic rocks, and the immediate valley of the Lena
from Yakutsk to its mouth is occupied by rocks intermediate
between the Jurassic and the Cretaceous, all of these being

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composed of sediment washed down from the very ancient
plateau bordering the region on the southeast and limited by
the Yablonoi Mountains.

A similar lesson in river erosion is easily studied along the
Amur, where for hundreds of miles through the Daurian
and the Great Kinghan Mountains the bed of the river lies at
the bottom of an eroded channel several himdred feet in depth ;
while farther down, in crossing the Bureya Mountains, its
channel follows an even gradient, showing that the entire work
of deepening its channel had long since been accomplished.
Here, as in the other rivers, it is easy to see that the material
for the sedimentary rocks over the vast area east of the
Yablonoi Mountains has been transported along the lines of a
drainage system which was essentially the same as that now
in existence.

More Recent Geological Changes

But the entire mountain system of Asiatic Russia was raised
to its present high level at a very recent geological period.
This is shown by the fact already noted that all along the
western border of the Tian-Shan Mountains, marine Tertiary
strata are found at high elevations even up to 10,000 feet;
while, also, the deep river valleys of erosion, already described
as characterizing the basin of the Selenga River and its tribu-
taries coming down from the Vitim Plateau, are lined with
rocks of Tertiary age. They are, to be sure, probably of
fresh water origin, as are the Jurassic rocks in the upper An-
gara basin about Irkutsk, but even so they doubtless indicate

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that a much lower level characterized the geological condi-
tions before the formation of Lake Baikal than that now pre-

To this evidence of great changes of level since the middle
of the Tertiary age may be added the existence of Lake
Baikal itself, which lies in a longitudinal trough formed by
the elevation of a mountain ridge on the western side of the
lake parallel with the Vitim Plateau. Simultaneously with
the elevation of this ridge there was a phenomenal subsidence
of the whole bottom of the lake under its southern end, which,
as already said, is 4,186 feet deep, or nearly 3,000 feet bdow
the sea level. The general facts concerning this lake have been
already given in a preceding chapter, to which the reader is
referred. But in this connection, as evidence of its recent
origin, attention is directed to the single circumstance that the
lake exists at all.

Even as it is, the Selenga River has built up a large delta
where it enters the lake upon the eastern side, but it is easy
to see that, if this depression had existed to catch the sediment
as long ago as the beginning of the Tertiary period, there has
been enough material eroded from the Vitim Plateau to have
filled the south end of the lake full of sediment many times
over. The calculation is of such interest that it is worth while
giving it in brief.

The Selenga with its tributaries drains an area of fully
200,000 square miles. , Everywhere the rivers have a steep
gradient, all of them descending 3,000 feet between their sources
and the level of Lake Baikal, where their sediment is now

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deposited. Considering the magnitude of this gradient, it is
doubtless much below the truth to estimate that the superficial
erosion over the area has amounted to one foot in S,ooo years,
that being the rate which has been ascertained for the Mis-
sissippi River, whose gradient is much less. At that rate 8,000
cubic miles of solid material would have been removed from
this basin by the streams within a period of 1,000,000 years,
which we may provisionally take as a moderate estimate for
the length of the Tertiary period. But reckoning the south
end of the lake to be on the average one half mile deep, (which
is a liberal estimate), 210 miles long and 40 miles broad, 4,200
cubic miles of material (or one half the material actually re-
moved) would have filled the depression with sediment. Five
hundred thousand years, therefore, is all the time that it would
require for these streams to have filled the whole southern
end of the lake. Whereas it has as yet scarcely made a be-
ginning, the present delta covering less than one thirtieth of
the area. After making all allowances for the amount of ma-
terial which may have been carried into the lake where it is
below water level, it would be difficult to stretch the period
under present conditions longer than fifty thousand or even
thirty thousand years. Previous to that time, it must be sup-
posed, the drainage of the Selenga continued across an open
country to the head of the Angara, and carried its material
through that great stream into the Yenisei Valley.

Nor is the direct evidence of recent geological disturbances
in this region altogether wanting. Earthquakes are a frequent
occurrence, вАФ ^an extensive area about the mouth of the Selenga

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having been permanently submerged during a convulsion in
1862 ; while there are numerous warm springs along the shore,
one of which at Turka, near the mouth of the Bargusin River,
has a temperature of 130*, indicating the proximity of sub-
terranean fires.

Another evidence of a rapid elevation of a broad area in
recent geological times is visible in the rock terraces upon the
Amur, Yenisei and Obi rivers. All the way up the Amur River
from Blagovestchensk, rock shelves or terraces are a promi-
nent feature in the scenery as one views it from the deck of a
steamer. B^:inning at an elevation of about 100 feet, they
increase in height to several hundred feet above the river before
Stryetensk is reached. Evidently the river flowed at that level
until it had eroded a trough about twice as wide as it now
has, enlarging ccmsiderably where tributary streams came in to
assist in the erosion. Throughout this entire distance of seven
or eight hundred miles the evidence is clear, that, at the time
of the excavation of the upper rock shelves, there had been a
long halt in the action of the elevatory forces, so that a great
amount of base leveling had been accomplished, and that this
was followed by a comparatively rapid elevation during, or
since, which the river has eroded its inner gorge through
solid rock for a length of several hundred miles and to a depth
of several hundred feet. Similar terraces likewise occur on
the Yenisei River both below and above Krasnoyarsk, and not
only there, but on both sides of the river, for nearly a hundred
miles farther south, where the stream has cut its way through
the intersecting Yeniseisk Mountains below Minusinsk. Such

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terraces are also abundant on the upper tributaries of the Obi
where they emerge from the Altai Mountains.

Evidence of a Post-tertiary Subsidence

But still more impressive evidence of recent changes of level
over this whole area is found in the alluvial deposits which
cover all the inland plain stretching everywhere from the Arctic
Ocean for a considerable distance south, completely enveloping
the entire basin contained between the Yenisei River and the
Ural Mountains, and extending over the whole Aral-Caspian
depression. The region affected by this depression includes
an area of not less than 3,000,000 square miles, and was de-
pressed, in some portions, at any rate, to the extent of 3,000
feet. It was during this submergence that the fertile soil of
the vast prairies of Western Siberia, and the terraces and deltas
of loess around the southern and eastern borders of Turkestan,
were accumulated, together with the great loess-covered areas
which furnish the richest wheat fields of southern Russia.
Increased interest attaches to this depressi<Mi, from the fact
that it probably occurred since the advent of man, and is in
some way connected with the distribution of the mammoth and
the woolly rhinoceros over Northern Siberia and with their ulti-
mate extinction. It will therefore be worth while to present
this evidence scwnewhat in detail, a part of which may well
consist of some of my own recent observations in the region
for the purpose of determining more definitely its condition
during the glacial period.

Starting from Peking early in May 1900, Mr. Frederick B.

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Wright and myself went inward two hundred miles, and as-
cended the eastern border of the great Mongolian plateau near
Kalgan in search of glacial phenomena. We were here in al-
most the same latitude as that of New York City, and in a
mountainous district from 5,000 to 6,000 feet above the sea. But
we found there no signs of the glacial period. We then went
to Port Arthur^ and' made a north-and-south section through
the center of Manchuria to the Amur River, and thence up the
river to about latitude 54* N., being, at Chita, 2,500 feet above
the sea, and at the eastern base of the Vitim Plateau, whose
general level is 5,000 feet. But though we were here sixteen
degrees farther north than the southern point to which the
ice extended in the valley of the Mississippi, we could find
no signs of the glacial period.

We then crossed the Vitim Plateau to Lake Baikal, and,
after crossing the Yenisei River, at about latitude 56**, pro-
ceeded to Omsk, on the Irtysh River, where we turned to the
south, and for one thousand four hundred miles drove in a
Russian tarantass along the northwestern base of the Ala-tau
Mountains to Tashkent, and thence, through Samarkand, Bok-
hara, and Merv, to the Caspian Sea. In reality, this entire trip
frcwn Lake Baikal to the Caspian Sea is at the base of the
mountains which border the great plateau of Central Asia.
The distance traversed at their base was more than four thou-
sand miles. To the southeast of us, mountain peaks from
10,000 to 16,000 feet were constantly in sight, all glistening
with the dazzling brightness of miniature glaciers and extensive
snowfields. To the northwest, however, there stretched a con-

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tinuous plain as far as the Arctic Ocean, except where inter-
rupted by the Ural and some minor mountains. But we found
no indications that glaciers ever extended out from the moun-
tain valleys crossed, like those which deployed over the plains
of Switzerland and Northern Italy from the Alps, which are of
about the same height and in about the same latitude.

On the contrary, throughout this entire regicMi we were con-
fronted with the evidence of a great subsidence of the land
which had taken place in recent geological time, and which, in
date, would correspond roughly with that of the glacial period
in North America. For several hundred miles, while driving
through the region south of Lake Balkash and the Aral Sea,
we were evidently upon a terrace of the fine loam which is
called loess, about 2,500 feet above sea-levd. Indeed, at dif-
ferent elevations this loess extends continuously in a broad shelf
along the base of the mountains, from the Irtysh River to the
Caspian Sea, and is found in extensive level areas over various
portions of the Caucasus and Northern Persia around the base
of Mount Ararat ; while the so-called " black earth " of South-
em Russia is a deposit of the same material, and probably of
the same age, one hundred or more feet in thickness. The dis-
tribution of this loess is the key to the whole situation.

Distribution of the Loess

Persons living in the valley of the Missouri River are fa-
miliar with the deposit in such bluffs as border the valley at
Sioux City, Omaha, and Kansas City, where perpendicular sec-
tions one hundred feet or more in thickness may often be seen

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which have stood for many years without crumbling down. It
is not clay, but a very fine sand through which the water
percolates freely, but which always retains some moisture
through the effect of capillary attraction. Wells penetrating
the loess never obtain water until reaching the bottom of the
deposit. It can be easily cut with the spade, and caverns
excavated in it make comfortable and permanent dwelling-
places. The bluffs at Vicksburg, on the Mississippi River, con-
sist of this deposit, and during the celebrated siege of that
city the people found safety in caverns excavated along its
side. In China millions of people live comfortably in such exca-

Our trip through Eastern China took us through innumer-
able villages thus constructed. In some places in China the
loess is one thousand feet in thickness, and houses may be
seen on the slopes one above another, the roof of one row
of houses serving as the playground for the children who live
at a higher level. All Northeastern China proper is enveloped
in this deposit. It is the sediment gathered from the loess
which renders the great rivers of China so turbid and g^ves
appropriateness to the name of the Yellow Sea. When forty
miles out from land, the traveler upon this sea will meet a
sharply defined line, on one side of which is the clear ocean
water, and on the other side water which is fairly opaque with
the heavy load of sediment brought in by the streams, and
which is constantly increasing the shoals along the border of
the continent, and adding to the margin of dry land which is
rapidly encroaching upon the sea. So rapid is this process

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that it has effected great changes upon the Chinese coast since
the beginning of the historic period In the year 220 b. c
Putai was a seaport; now it is forty miles inland. Daring the
Han dynasty (about 200 b. c.) Tientsin was a seaport; now
it is thirty miles inland.

Twenty-five or thirty years ago Baron Richthof en endeavored
to make out that the loess was a wind deposit; and certainly
he found much in Northeastern China to support this theory.
Upon returning from our trip to the Mongolian frontier, we
were inclined to accept it, for we had seen and experienced,
in the dust-storms encountered, enough to make us ready to
attribute almost anything to the power of wind. For a whole
day we once rode in a cloud of dust so dense that it was
impossible to see objects twenty feet away; while everywhere
in the mountain valleys we saw instances where this loess had
drifted into protected places, as snow does in winter. But there
were constantly appearing other things which were difficult to
explain by the acticm of wind. For example, the loess
was occasionally spread out, even at high levels, in broad,
lakelike basins, as if deposited by water. Also the material
now most blown about by the wind is coarse sand, which is
piled up in dunes quite unlike the ordinary loess deposits. In
one instance we found the high walls of a large Chinese city
completely buried on one side by a wind deposit; but this
was coarse sand, and not loess. In many cases, also, we found
long lines of gravel and pebbles interstratified with loess.
Thus the difficulties of explaining everything by wind so in-
creased that they became well-nigh insuperable.

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But, on ccHning around to the northwestern side of the
great Asiatic Plateau, in Turkestan, which is in almost the
exact center of the continent, the wind hypothesis became en-
tirely incredible, and evidences accumulated that the land had
lately been depressed to such an extent that the water of the
ocean reached the base of the bordering mountains, rising to
a height, certainly, of about 3,000 feet ; for, at this level, south
and southwest of Lake Balkash, we found the loess spread out
in such an extensive terrace that the wind would be entirely
incompetent to produce the results. We were interested to
find, upon visiting St. Petersburg, that the chief Russian geol-
ogists had arrived at substantially the same conclusions which
we had formed. They said that, however successful Richt-
hofen might be in maintaining his wind hypothesis in Northern
China, it could not account for the loess in Southern Russia.

In confirmation of this theory of a recent extensive de-
pression of Central Asia, a number of other most interesting
facts present themselves, prominent among which are those con-
cerning Lake Baikal.

Arctic. Seal in Lake Baikal

As already said. Lake Baikal lies in a longitudinal trough
on the edge of the Central Asiatic Plateau, at an elevation of
1,561 feet above the Arctic Ocean, with which it is connected
by the Yenisei River after flowing across the northern plains
of Siberia for a distance of about 2,000 miles. A most curious
fact, long known to scientific men, is that this lake is occupied
by a species of seal almost identical with those found in the

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Arctic Ocean. The same species with slight variations are also
found in the Caspian Sea, but not anywhere else along the
3,000 or 4,000 miles which separate these bodies of water.
The most probable explanation of this fact, and the one usually-
accepted by scientific men, is, that these species of seal were
thus widely distributed during a continental subsidence in
which the waters of the Arctic Ocean covered all of North-
western Siberia, and extended up to the base of the great
Asiatic Plateau which we followed for such a long distance on
elevated shore lines in Turkestan. When this depressed area
emerged from the sea, it left the seal isolated in the two great
bodies of water which still remain on its former margin. So
lately has this taken place, that there has not been time for
any great changes to be eflFected in the specific characteristics
of these animals.

Freshness of the Internal Seas

Another indubitable evidence of the recent great changes
which have taken place in this central part of Asia is to be
found in the condition of the inclosed seas and lakes which
abound in it, and which have no outlets. The Caspian Sea,
for example, though it receives the drainage, through the Volga
River, of more than one half of Russia, besides that which
comes in from the Caucasus and the valley of the Ural, has its
surface eighty-five feet below the level of the ocean. The

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Online LibraryH[enry] Justin RoddyComplete geography → online text (page 14 of 22)