NOVEMBER, 1908. MONTHLY WEATBXR REVIEW. 359
SPECIAL ARTIOLES, NOTES, AND EXTRAOTS.
THE ULIMATE OF T m HISTORIU PAST. -7-strnct has been set forth with full details in the author’s “The
By ELLSWORTH HUNTINOTON. Dated I.& University, New Haven, Conn., November 10,
INTRODUCTION.
isoa
Among the factors that have influenced human development
an important place must be accorded to climatic changes of all
types, from the great fluctuations of the geological past down
to the small fluctuations in temperature, rainfall, and other ele-
meuts,.which now take place from year to year.
The complex series of climatic changes grouped collectively
uuder the title of the Glacial Period caused world-wide and
profound ccrepressive evolution.” Under the stress of repeated
trrrusitions from cold, damp glacial epochs to warm, dry inter-
glacial epochs, thousands of species of plants and animals were
extinguished, while those which survived were forced to de-
velop with phenomenal rapidity in order to adapt themselves
to new conditions. The excessive changes of environment,
both animate and inanimate, to which early man was then
clubjected are considered by evolutionists to have exerted a
most marked influence upon the growth of his intelligence.
Even the small fluctuations of climate which now occur from
ycar to year and decade to decade produce noteworthy results.
An exceptionally rainy season may flood the Ohio River and
cause the loss of millions of dollars’ worth of property. Such
floods inevitably give rise to want and misery, and perchance
to crime, among the hundreds of families whose means of liveli-
hood are destroyed. I n India and China a scarcity or even a
postponement of the monsoon rains often subjects millions of
people to the horrors of famine. Similar scarcity of waterin
Arabia has more than once so impoverished the Arabs that
they have risen in desperate revolt against the Turks, their
nominal masters.
Between the climatic changes of the glacial period and the
temporary changes which now occur within the observation
of a single generation there is a large gap. I t has often been
assumed that the two types of change are unconnected, the
one being due to some vast cosmic cause whose nature is still
in dispute, the other to local irregularities in the circulation
of the earth’s atmosphere. A study of the climatic history of
Asia seems to require a modification of this view, and to
give ground for the hypothesis that during historic times
there have been changes of climate whose characteristics were
intermediate between those of the glacial period and those
which now occur within the limits of contemporary observa-
tion. The effects of such historic changes must, it would seem,
have been intermediate between the epoch-making results of
the Glacial Period and the slighter, but by no means unimpor-
tant results of the floods, droughts, unseasonable frosts and
similar phenomena of to-day.
Meteorologists have not as a rule accepted the hypothesis
of important historic changes of climate. They have held
that while small changes may have occurred, the general course
of climate has been uniform and that a slight fluctuation in
one direction during a period of a few years has always been
compensated by a slight fluctuation in the other direction at a
succeeding time. In proof of this they point to the unques-
tioned fact that the meteorological records of the past two hun-
dred years or less either indicate no permauent change whnt-
ever or one so small that i t is less than the uncertainty of the
numerical averages that describe the climate. Being accus-
tomed to appeal to the absolute evidence of figures, technical
meteorologists have given too little weight to other less exact,
but no less conclusive lines of evidence, which alone are avnil-
able in determining the nature of the climate of past times.
The present article is written for the purpose of setting forth
some of these lines of evidence. It is impossible here to give
more than the briefest outline; but a full presentation is the less
necessary as practically all the evidence here presented in ab-
Pulse of Asia,”l and in various inagazine articles. If the follow-
ing pages appear to contain a large amount of conclusion and a
small amount of fact, it must be borne in mind that for every
fact here set forth in evidence of climatic change during his-
toric times a dozen have been set forth elsewhere.
Clinintic cycIes.-At the dawn of human history the climates
of the main portion of Asia, and apparently of all continental
regions between the twentieth and fiftieth parallels of latitude,
appear to have been decidedly moister and, presumably,
cooler than is now the case. The change from the climates of
that time to the warmer and drier conditions of the present ap-
parently took place irregularly in a pulsatory fashion. A com-
parison of the state of affairs two thousand years ago, or more,
with that of to-day, suggests that the slow swing from the cold,
moist climate of the last glacial epoch to the warm, dry climate
of the present post-glacial epoch is as yet scarcely completed.
A fuller study of the data for intermediate periods suggests
that the swing is taking place in waves or pulsations. Ap- parently climatic cycles of all sizes are now in progress. The
shortest are those of three, eleven, and thirty-five, or thirty-
six years, whose existence is maintained by Lockyer, Blandford,
Bigelow, Briickner, and others. Nest come cycles measured
in hundreds of years. In studying the 35-year cycles of
Briickner,’ Clough8 concludes that certain data suggest a
cycle of three hundred years. Evidence from Asia, which is
set forth in outline below, indicates that cycles lasting con-
siderably more than three hundred years, possibly a thousand
or more, have occurred during historic times. The series of
cycles is completed so far as recent geological time is con-
cerned, by glacial epochs and glacial periods that appear to
have lasted thousands and tens of thousands of years. The
auiount of the change of climate during a given cycle appears
to vary roughly as the length of the period. Changes of every
degree may be in progrem at once, the small being superposed
upon the larger, and these in turn upon those of still greater
dimensions. All seem to produce results of the same kind,
altho of extremely diverse magnitude; which suggests, tho it
by no means proves, that all the changes inay be due to the
same cause.
PABT I. THE OLD WORLD.
N d m ; aid location qf wideme .ita Asia.-The chief evidence
which has given rise to the preceding hypothesis comes from
western and central Asia. Here the writer has investigated
the subject in various parts of an area as large as the United
States. The area extends from longitude 36’ E. in Asiatic
Turkey to No E. in Chinese Turkestan east of the famous
lake Lop Nor, and from latitude 30’ N. in eastern Persia
and northwestern India to 46’ N. on the border between
Siberia and China. The evidence inay be grouped under three
heads: (1) Physical phenomena such as changes in the lengths
of rivers which disappear in deserts; the appearance or dis-
appearance of springs; changes in the salinity of springs and
rivers; fluctuations in the levels of lakes which have no outlets;
the deposition of alluvium or the formation of terraces by the
dissection of such alluvium. (2) Phenomena relating to the
distribution of plants and animals. (3) Human phenomena
iucluiling (a) ruins and other proofs of man’s permanent pres-
ence in regions now climatically unfit for occupation; and (b)
legends, traditions, and historic records. As a rule all three
kinds of evidence are found associated together. A brief de-
scription of eight distinct basins in various parts of the region
defined above will show the basis upon which the conclusions
’Ellswoith Huntington: The Pulse of Asla. Boston and New York.
1907. 8vo. 415 p.
2 E. Briickner: Klimasohwankungeii seit 1700. Vienna. 1890.
* H. W. Clough. nomena. Astrophysical Journal, 1905, 22: 43-75.
_____-- __
Synchronous Variations in Solar and Terreetrial Phe-
360 MONTHLY WEA!mFa REVIEW. Novlcaw~a. 1908
of this article are based. The basins are selected not because
of the strength of the evidence which they present, but be-
cause they happen to be the eight localities in which the writer
studied the subject most carefully. Five of them, namely,
the basins of Pangong in Tibet, of Lop and Turfan in Chinese
Turkestan, of Seyistan in Persia, and of the Caspian Sea, are
occupied by salt lakes whose rise and fall afford an accurate
index of variations of climate. One of the others, that of
Gyul-jiik in Turkey, contains a slightly brackish lake which
sometimes overflows and sometimes is without an outlet. The
periods when ikis without an outlet appear to be times of ex-
ceptional aridity. The other two basins, those of Kashmir in
India, and Son Bul in Russian Turkestan, contain normal lakes
which overflow at all times. Their evidence is of a different
type from that of the others.
(1) The Vale of Kashmir.-The famous Vale of Kashmir is
blest with a climate very different from that of India in
general. Lying in latitude 34O N., at an elevation of 'over
6,000 feet above the sea, the Vale, which is really a basin
floored with an alluvial plain, has long, cold winters, with an
abundant fall of snow which often remains on the ground well
iuto March. The summers are warm; but in the autumn snow
sometimes comes so early as to ruin part of the rice crop. Mo-
raines and other signs of glaciation in the mountains, and river
terraces in the valleys, indicate that the climatic history of
Kashmir has been as complex as that of other parts of Asia
or Europe or America. A circumstantial tradition relates
that when man first inhabited thevale the climate was so cold
as to make agriculture impossible. The inhabitants, so it is
a d , were pastoral nomads. They spent the summers in Kash-
mir, but in winter evil demons caused so much snow and such
low temperature that it was impossible to remain. The no-
mads were obliged to cross the southern range of the Him-
ala! as to the warm, low plain of India. An appeal to the gods
caused the country to become warmer and less snowy, where-
upon the nomads changed their habits and settled permanently
in Kashmir to practise agriculture.
The tradition is recorded in the work of the Kashmiri his-
torian Kalhana', 114849 A. D., and is also mentioned by the
Chinese pilgrim, Huien Tsianga, who visited the country in the
seventh century of our era. Its details, apart from the calling
in of the gods, are so reasonable and so unlike what the story-
teller would invent, and they agree so perfectly with the phe-
nomena in other parts of Asia, that they possess a high degree
of probability. At the time of Huien Tsiang Kashmir appears
to have been as populous as now, and to have contained a
highly prosperous agricultural population which lived much
as the Hashrniris do to-day. Historic accounts of the block-
ing of the gorge of the Jhelum River by detritus from the
mountains, cauRing a rise in the level of Lake Wular soon
after the time of Huien Tsiang, confirm the legend. They seem
to indicate that the amount of vegetation upon the mountains
had decreased so far under the influence of diminished rain-
fall that the soil and loose rock upon the slopes were no longer
held in place and were washed into the rivers. Various rec-
ords. of early snow and of the freezing of the river in the
middle ages suggest, but do not prove, that the climate may
once more have become slightly cooler or moister than it was
in the days of Huien Tsiang or is now. The evidence of Bash-
mir alone would be of slight weight, but its agreement with
that from remote regions where climatic conditions are very
different gives it a high degree of value.6
(2) Lake Pangong.-Two hundred miles east of Kashmir on
'See M. A. Stein: The Ancient Geography of Kashmir. Journal of
'See Samuel Bed: SI-Yu-Ki. An account of the journeys of Huien
OFor an account of the evidence of rhanpes of elements in Kashmir For a fuller discussion eee Bul.
of the Asiatic gociety of Bengal, 1899. 68 : 65.
Teiang. London. 1884. 2 vola. vol. 1, p. 149.
Fee
Am. Geog. SOC, 1906, 38:667-686. The Pulse of Asia." pp. 36-46.
the farther side of the Himalaya Mountains the salt lake of
Pangong' lies, at an altitude of 14,000 feet, on the western
border of Tibet. The lake owes its origin to glaciers which
scoured out a long valley, forming a series of basins with a
length of over a 100 miles and an average width of only 2
miles. Since the retreat of the last great glacier the level of
the lake has fallen markedly. At first it overflowed to the
Indue River, but later the water fell below the level of the
outlet. J u s t when this happened we can not tell, but it was
certainly long after the retreat of the ice. Since that time
the diminution of the lake has proceeded until now its surface
is at least 60 feet below the level of the former outlet. Some-
times, as is shown in the article referred to above, the water
has risen for a time, as appears from lake deposits lying over
those of streams. Again it has fallen or been almost stationary
for considerable periods. Thus six well-marked strands have
been formed at successive levels from 60 feet down. The up-
per strands are marked by large beaches and high clifi which
could only have been produced by long periods of wave action.
The lower and younger strands are lees strongly marked.
They are so well preserved, however, that i t seems improbable
that they can be more than a few hundred years old.
The length of time since the climax of the last great glacial
epoch has been very variously estimated. From a compre-
hensive study of all the available data in America, Chamberlin
and Salisbury' state that the estimates of the time elapsed
since the beginning of the last ice-retreat range from twenty
thousand to fifty-sis thousand years. The formation of the
uppermost of the six strands of Pangong can not have begun
until a much later date; for before its inoeption the ice must
have retreated from the lake, and the climate become so far
ameliorated that. the water ceased to overflow. The forma-
tion of the strands can scarcely have occupied more than half
of post-glacial time, or from ten thousand to thirty thousand
years. Authentic human history goes back fully six thousand
years in Egypt and Babylonia. I f the ice age in Asia was
coincident with the ice age in America, i t is hard to avoid the
conclusion that at least one and perhaps several of the six
strands of Pangong must have been formed during the period
covered by human history. If this is so, it means that during
that period there have been one or more changes of climate.
The changes appear to have been suficient to exert an influence
upon the habitability of regions which are on the verge of
gred aridity on the one hand, or of unduly low temperature
on the other.
(3) me Lop Baaiti of Chiuese Turke&an.-North of Kashmir and Pangong, on the other side of the great central plateam of
Tibet the Lop or Tarim basin lies with its floor from 2,500 to
5,0110 feet above the sea. The basin occupies the very heart
of Asia. It forms the major part of Chinese Turkestan. Its
length is 1,400 miles and its maximum width from north to
south 400 miles, embracing an area as large as the portion
of the United States east of Lake Michigan and north of
Tennessee. Except on the northeast it is surrounded by lofty
snow-capped mountains, those of Nan Shan on the east, Kwen
Lun on the south, the Pamirs on the west, and Tian Shan on
the north. On every side mountain torrentsflow swiftly down
to the great plain which forms the floor of the basin. A few
which combine to form the Tarim River reach the salt lake
of Lop Nor in greatly diminished volume. The rest wither to
nothing in sand and gravel. Most of the basin is desert. At
the foot of the mountains lies a broad strip of gravel from 5
to 40 miles wide, like an enormous naked beach. This has
been nroduced bv the denosita of countless mountain streams.
many- of which "are theLselves lost in its thirsty depths:
' Panaong: A glacial lake. Jour. of Geol.. 1906.14 :599-617. em. 614 ff. 'Geology,. Vol:III, p. 420. In The Falls of Niagara, 1907, p: 3cet Gq, J. W. W. Spencer gives various estimates of the age of the Nlagara gorge, on which are based the most reliable estimates of the length d the period elapsed since the last glacial epoch.
NOVEMBEU, 1908. MONTHLY WEATHER REVIEW. 361
Within this strip of gravel lies a zone of vegetation from 1 to
20 miles wide, This is the only part of the basin where vege-
tation is abundant. Most of the oases of the country are
located here. Within the ring of vegetation lies the desert of
Taklamakan, one of the great sand deserts of the world, 200
or 300 miles wide and 900 miles long from east to west. At
ita eastern end sand gives place to lifeless clay and salt in the
midst of which the shallow, marshy, saline lake of Lop Nor
occupies an almost imperceptible depression.
The Lop basin contains abundant evidences of climatic
changes, and has been discussed in detail by the writer in
ccThe Pulse of Asia.” Thruout the basin the amount of vege-
tation has greatly decreased in recent times without the inter-
vmtion of man. On the lower slopes of the Kuenlun moun-
tains the dissected condition of numerous deposits of loess
shows that a cover of grass prevailed’ at no remote date, but
has now disappeared. In the zone of Vegetation plants of all
kinds show signs of a process of drying up which has been in
progress for centuries. Tamarisk bushes stand upon mounds
from 5 to 60 feet high, a sure sign of the lowering of the level
of ground-water; poplar forests which once extended for
scores of miles now form wastes of branchless dead trunks
like gaunt gray skeletons; and beds of dead reeds cover hun-
lreds of square miles. It has often been asserted that the de-
struction of forests has been the cause of the dimunition of
rainfall, I n the Lop basin the opposite appears to be the
case; the supply of water has diminished and therefore the
forests have died. Rainfall unquestionably controls foresta-
tion, but neither in the Lop basin nor in other parts of central
and western Asia is there any good evidence that forests have
an appreciable effect upon rainfall.
Another important line of evidence is found in the relation
of rivers to the desert of Taklamakan and to ruins of ancient
dwellings. On the,south side of the Lop basin, from Rhotan
eastward to Lop Nor, the writer examined seventeen streams
which are worthy of notice, because of their size or because they
support oases. All but four come to an end in the zone of vege-
tation, where they spread out and disappear either naturally
or because used for irrigation. Hence it is impossible to de-
termine whether or not they have decreased in length. At the
lower ends of the other four, old channels are found lined with
dead forests which prove that the streams ,once extended from
8 to 25 miles farther than is now the case before finally be-
coming swallowed up in the sand. One of the four rivers, the
Keriya, may have been shortened by the withdrawal of its
water by man for irrigation, but the other three, the Niya,
Yartungaz, and Endereh, had diminished in size before the
few present inhabitants came to the region, and at a time
when their waters were entirely unused.
On the lower portions of thirteen rivers, out of the seven-
teen, one finds the ruins of Buddhist towns dating back a
thousand years or more. In almost every case the ancient
towns were much larger than their successors, and, with three
possible exceptions, the older ruins are situated so far out in
the desert, or upon rivers so small and saline, that it would be
impossible again to locate towns of equal size in the same
places, unless a far better system of irrigation were intro-
duced. The old system, of which portions remain in three
places, was precisely the same as that of to-day; that is, it
was the simplest of all systems of open canals dug in any kind
of soil, with nothing to prevent leakage. The ruins are in
some cases buried in sand, but this can not have been the
cause of their abandonment; for others lie in regions quite
devoid of sand. In some cases it appears that the old towns
were abandoned for lack of water; in others, for instance at
Endereh, there is still a fair supply of water but it is now so
saline that it can not poasibly be used for irrigation, altho
there is abundant evidence of former cultivation on a large
scale. Numerous springs have grown saline in similar fashion.
In addition to the dead vegetation, the shortened rivers, the
increased salinity of the streams and springs, and the water-
less ruins, there are other facts in the Lop basin which point
to desiccation. Ancient Chinese accounts and traditions tell
of much-frequented roads which are now unused and unusable.
One such went northward from Heriya thru 200 miles of sand,
where no native dare go in modern times for lack of water,
and no foreigner has gone except the intrepid Sven Hedin.
In the desert east of Lop Nor, Hedin discovered the milestones
and waymarks of another caravan route located in a region
which is now so dry that his camels merit eleven days without
water.
The lake of Lop Nor lies about 100 miles to the southeast
of the place where Hedin found his second old road. Around
the lake a number of elevated strands, most of which are more
ancient than those of Pangong, indicate that during suc-
cessive epochs the lake expanded enormously. According to
universally accepted geological methods of interpretation,
these expansions must have taken place during the Glacial
Period. Old Chinese maps and records indicate that within
historic times the lake was at one period much larger than
now, and the evidence of ruins and vegetation confirms the
conclusion. On every side of the lake a vast salt plain indi-
cates the extent of the mater not many centuries ago. The
south shore of the plain is skirted bye road which is used by
two or three caravans every year,’in spite of the absolutely
uninhabited desert which it traverses for 300 miles. At a salt
spring called Chindelik the road leaves the edge of the plain,
which here forms a deep embayment to the south, and runs
straight across the bed of the old lake. Thinking that if the
lake had ever covered the salt plain during historic times there
must be an old road skirting the former shore line, the writer
searched for such a road and to his surprise found two. One
follows the lowest of the old strands, 12 feet above the present
water level, and the other runs along the top of the high bluffs
of gravel which mark the second, or 30-foot strand. The up-
per road traverses a plain of sand.and gravel, and is marked
at intervals by cairns of stones, one large and the others small.
For two days the writer zigzagged between the two old roads,
and at various points saw that they always bear the same rela-
tion to one auother and to the strands. The present road runs
direct from Chindelik, where there are fairly good springs, to
Sachgan Sai, the next source of water, where the springs are
very saline. The distance is about 24 miles, a long day’s
journey for loaded oxen, donkeys, and camels, even tho the
track is level and easy. By way of the old road, along the
12-foot strand, the distance between the same points is about
32 miles, too much for one day’s journey, tho the track is per-
fectly level and almost ideal in texture. By way of the higher
road, above the 30-foot strand, the distance is a mile or more
greater than by the other old road, and the track runs thru
heavy sand in some places and up and down across valleys in
others. Along both of the ancient roads, as well as along the
modern road, the country is absolute depert, with neither
water, wood, nor forage from Chinclelik to Sachgan Sai. There
is absolutely no reason for the existence of either of the old
roads unless the present route was impracticable because cov-
ered with water, and there is equally little reason for the road
above the 30-foot strand unless the road on the 12-foot strand
was impracticable for the same reason.
Previous to the writer’s visit the natives of Lop Nor had
apparently never heard of the road above the 30-foot strand.
They knew all about the other, however. Two or three hun-
dred years ago, according to their account, the lake of Lop
mas larger than it is now, and fish were more abundant.
Their ancestors used to bring fish in canoes to a place near
the spring of Lachin where to-day there is nothing but a plain
of dry salt. Thence they carried the fish on donkeys to Sa-
chow, the most western town of China proper. The salt plain
362 MONTHLY WEATHER REVIEW. NOVE~~BEB, 1908
between Chindelik and Sachgan Sai was at that time so wet
as to be impassable, and the road along the 12-foot strand
was used. It seems safe to infer that the older road along
the 30-foot strand was used at a time when Lop Nor stood so
high that the easier route along the younger strand was still
covered with water. A careful study of the phenomena of all
parts of the great Lop basin leads to the conclusion that des-
sication has been the general rule, but that it has not pro-
gressed uniformly. About 300 A. D. it appears to have pro-
gressed with extraordinary rapidity, for a large number of
ruins in the Taklamakan desert were abandoned at that time.
From the descriptions of the country by Chinese travelers i t
seems probable that in the sixth century of our era, or there-
about,.the climate was as dry or drier than it now is? Half
a millenium later, during the middle ages, towns were again
located in places such as Lachinata near Chira, or Yingpen in
the far northeast, where the water supply is now wholly in-
adequate. Apparently, at this time, there was an epoch of
some centuries during which the climate again became some-
what moister than is now the case. It is not possible to
speak with certainty, but it seems as if the road along the
12-foot strand might belong to the mediaeval epoch of more
abundant water supply, and the older road along the 30-foot
Mtrand to the earlier period of more propitious climate some
two thousand years ago.'O
(4) The b a s h of Tuifan.-Many of the peculiar features of
the Lop basin are repeated in the small basin of Turfan which
lies below sea-level about 200 miles north of the eastern part
of the Lop basin. To-day every available drop of water from
above ground is used for irrigation, and about 30,000 people
are thereby supported. I n addition to this, a vast number of
K c kariz " or undergronnd channels have been dug to take ad-
vantage of the water which flows far beneath the surface.
By this means about 20,000 additional persons are supported.
Nevertheless only a small part of the basin floor is cultivated.
In ancient times the system of irrigation by underground tun-
nels did not prevail, but the population amounted to many
times that of to-day. Ruins are found everywhere. The
most noteworthy are naturally located near the present maiu
sources of water close to the foot of the surrounding nioun-
tains. A large number of others are located in a zone farther
removed from the mountains. Here the present density of
population is less than that of earlier times, in spite of the
fact that now a large part of the water used for irrigation
comes from tunnels, while in the past all of it was derived
from the surface. Finally, a third zone lies within both the
others. It is now uninhabited and uninhabitable for lack of
water, or else because the very slight supply of water is too
saline for use. In mediaeval times a large number of villages,
whose ruins still remain, were located in this area, deriving
their water from the same surface streams which supplied the
cities nearer the mountains. The history of Turfan, previous
to about 800 A. D., is not known with sufficient exactness to
warrant any conclusions as to early conditions. There seems
to be little room for doubt that since 800 A. D. the climate
has changed greatly for the worse."
(6) me irrigalion canah of Son Ktil.--h Kashmir and in the
Lop basin,thereis,as we have seen,& shadowing forth of a period
of great aridity about five or six hundred years after Christ.
The little basin of Son Xu1 at an elevation of 10,000 feet on
the Tian Shan plateau, northwest of the Lop basin, furnishes
strong evidence of such a period. No means of dating i t
definitely have been found, but it is probable that it belongs
9899 The Pulse of Asia, p. 270; also, S. Beal: Si-Yu-Ki. London. 1884; ant1 the same author's translation of the life of Huien Tsiang.. London
1888.
1OFor a full discussion of the varied phenomena of Lop Nor and the Lop basin see The Pulse of Asia, Chapters VI-X, XII-SIV. IISee The Pulse of Asia, Chap. XV.
to the Bame period as the dry time of Kashmir and Lop. On
the mountains surrounding the small lake of Son Hul a num-
ber of old irrigation canals may be seen. At present the cli-
mate is so cold that mow falls during every month of the
year. In July, 1903, the writer saw ice on the edges of the
brooks. The only inhabitants are a few Khirghiz nomads who
bring their flocks up to the mountains about the first of July
to feed on the rich grass for a few weeks. Agriculture i b
utterly out of the question; yet the nature of the canals, their
size and length, and the fact that they occur not in one place
only, but several, prove that they must have been made for the
purpose of irrigating fields on the smooth gentle slopes to
which they lead. The age of the canals is so great that they have
been a good deal filled and smoothed away by the movement
of waste on the hillsides. Nevertheless they are still perfectly
distinct and unmistakable, and therefore can scarcely be more
than a few thoulland years old at most."
(6) S;?yislatL and Persia-The basin of Seyistan," in eastern
Persia furnishes evidence much like that of Lop Nor. Dis-
tinct elevated beaches, which the writer has described at length
in Exploration in Turkestan, here surround a large swampy
lake which has D.O outlet except an occasional overflow to an
adjoining body of salt water at practically the same level.
The locations of ruins indicate that during the time when the
region was most densely populated, the lake stood at a high
level. Tradition says that the lake once covered the whole
country. King Solomon, i t is averred, saw that i f the water
were removed the lake bottom would make excellent land for
melons, wheat, and other good things. Therefore he set his
genii to work to fill it. At the same time the springs dried up
when trodden upon by a legendary hero. Ruins are reported
in the middle of what is now one of the ohief bays of the lake.
If the report is true, the ruins probably bear witness to a dry
period similar to that of which me have already found evidence
elsewhere. Tradition, historic record, and the location of
ruins all indicate that during the middle ages the lake was for
a second time larger than now. Abundant evidence in other
parts of Persia suggests desiccation. The time of occurrence
of the early and medizeval cool, moist, epochs and of the inter-
mediate dry epochs agree with those in the other basink"
(7) The Turkish Lake r?fGyul,jiik.-The little Lake of Gyul-jiik,
lying 4,000 feet above the sea among the Taurus mountains
in Armenia, furnishes an interesting suggestion of the effect
which the inferred dry epoch in the early part of the Chris-
tian era may have had even in a fairly well watered land like
Turkey. At present the lske overflows in moist seasons and
has no outlet in times of drought. I n the middle of the lake
lies an island surrounded by water at least 30 feet deep.
Local tradition asserts that this island was once part of the
main land, and that .the western portion of the lake occupies
what was formerly a plain with a brook flowing thru it. There
must be a considerable amount of truth in the tradition, for
the island is covered with the ruins of an ancient Armenian
monastery, and in the surrounding water numerous ruins of
houses or other buildings can be seen submerged to a depth
of perhaps 15 feet. According to the native Armenians of this
region an account of the monastery was preserved in a book
which was destroyed during the sad massacres of 1896-96.
The monastery is surely a thousand years old, and probably
twelve or thirteen hundred. It seems to have been built upon
the dry bed of the lake at a time when all Asia suffered from
a few centuries of drought some five or six hundred years
after Christ.15
19 See W. M. Davis: Exploration8 in Turkestan (Purnpeily Expedition of 1903). Washington. 1905. p. 115; and The Pulse of Asia, p. 351-3. 'YOften apelled Seistan and Sistan, but pronounced Seyistan.
'+See Explorations in Turkestan." Washington. 1905. p. 302-315. IsSee The Pulse of Asia, p. 353-6.
NOVEYIBBB, 1908. MONTHLY WEATHER REVIEW. 363
(8) The C q ’ a n Sea.-The Caspian Sea offers an epitome of
the climatic history of Asia. Here, as in so many other cases,
an expansion of this sea indicates either an increased supply
of water or a lowering of temperature with a consequent dimi-
nution in the rate of evaporation. A study of the beaches
and deposits of the sea itself, and of numerous ancient
accounts by Herodotus, Pliny, and others indicates that at the
time of Christ and earlier the level of the sea was so high that
a long bay reached eastward toward the Sea of Aml. Ships
passed from the Caspian Sea into the Oxus river, apparently
by way of the Sea of Aral, which at that time must have been
so full as to overflow, altho now it has no outlet. During the
fifth or sixth century of our era conditions were very different.
At Aboskun on the southeast side of the Caspian, at Derbent
on the west, and at other points the remains of walls, forts,
and other structures indicate that what is now the bottom of
the sea was then dry land. Warping or other movements of
the earth’s crust do not offer an adequate explanation of the
phenomena, since the waterspread of the lake appears to have
diminished, which would not be the case if there had been no
change of climate. If the climate had remained uniform the
amount of surface exposed to evaporation would also have
remained uniform.
I n the middle ages the surface of thesea again stood higher
for many hundred years than it now does, as appears from the
data furnished by numerous Arab writers who speak of the
water as standing at the level of a tomb in Baku, or a wall at
Derbent, or at other still recognizable points at specified times.
Altogether there seems to be very clear evidence that the Cas-
pian Sea has past thru fluctuations corresponding exactly
to the changes of climate which we heve inferred elsewhere.
Their course is illustrated in the accompanying diagram. It
is not to be supposed that the mediaeval period of compara-
tively moist conditions was notable in moist regions. In such
regions its effects would probably be too small to be noticed,
altho in very dry regions they might be important.
’ Rnria? I+ch
w - (AREten8)
0 ’ ---..*. B.C
W O #N 0 200 M G W 800 l O 0 0 l i W l l E l D ~
FIG. 1.-Approximate changes in level of the Caspian Sea. (Befeered to Briickner’s datum-level, 86 f feet below sea-level.) From “The Pulse of Asia.” p. 349.
The most notable fact in connection with the climatic his-
tory of the basins desoribed above is that the same sort of
changes appear to have taken place in all of them simultane-
ously so far as dates can be obtained. An epoch of compara-
tively cool, moist climate seems to have prevailed previous to
the beginning of our era and for a short time thereafter. Then
there was a somewhat rapid dessication culminating about the
sixth century, and characterized by a climate even drier than
that of to-day. I n the middle ages conditions again improved
from the point of view of arid countries, altho there is a little
evidence of a dry time in the eleventh or twelfth century.
Since about 1300 A. D. there has been a general tendency.
toward drier or.warmer conditions, altho durily the present
century there has been little or no change.
Wge distribution of evidence in both latitilde nnd longitude.-
Changes of climate appear to have been by no means limited
to the central parts of Asia. In the far southeast the lake
of Yunan, in southern China, has no outlet. A tradition is
preserved among the Chinese to the effect that it was once
muah more extensive. In Mongolia, to the north, there are
numerous ruins and lakes which seem to be of the same sort
as those described above, altho they have not been critically
examined. On the other side of the continent Arabia is full
of ruins in places which are now almost waterless, and ancient
writers on the country almost universally speak of it in terms
which imply an abundance of water far in excess of that which
now exists. For instance, Ptolemy gives the location of the
sources of five rivers and of the mouths of three, altho now
not a single stream deserves to be called a river. He locates
another river near Palmyra, where vast ruins indicate that the
ancient city must have had a population of one hundred thou-
sand or two hundred thousand people, altho now the water
supply is scarcely sufficient for a thousand.
In Roman times Palmyra was famous for the excellence of
its water; to-day the water from the same sources is so sulfur-
ous that the guide-books advise people to take drinking water
with them from springs one or two days’ journey to the west.
Earthquakes, war, the destruction of ancient irrigation works,
and the inroads of an uncultured nomadic population have all
been assigned as the cause of the decay of Palmyra and of the
decrease in its water supply. It is a significant fact, however,
that travelers who visited the ruins in 1889, at the end of a
series of years of unusually heavy rainfall, found that the water
was not only more abundant than at other times but also much
sweeter. This seems to indicate that if the mean rainfall were
to become permanently larger than it now is, or if the tem-
perature were to become lower so that evaporation were dimin-
ished, the supply of water at Palmyra would become corre-
spondingly larger, and conditions like those of ancient times
would once more prevail.
South of Palmyra the great Syrian Desert WAS formerly
traversed by large caravans of merchants who past from Bosra
or Petra to the Persian Gulf. To-day the routes which they
followed are utterly impracticable for lack of water. War or
the raids of nomads might cause such routes to be abandoned
temporarily for scores or possibly hundreds of years, but no
war or raid could cause the total disappearance of the springs
or oases upon which the travelers of ancient times relied.”I
In Africa and Europe the subject of changes of climate has
not been studied exhaustively. On the whole it seems to the
writer that the evidence indicates quite clearly that North
Africa has suffered changes like those of Asia. In Europe the
evidence seems to be inconclusive.
North Africa is full of ruins and other phenomena which,
like those in Asia, seem to be most reasonably explained on the
assumption of a change of climate. Herodotus, for instance,
tells of traveling with oxen over routes where the ox could
not possibly be used at present. Numerous writers have ex-
prest the belief that, as Lahache” puts it, there are many places
L‘where it would to-day be absolutely impossible to obtain,
even from very far, the quantities of water whioh the Romans
there utilized.’’ This statement is important because Lahache
feels obliged to make it in spite of the fact that he is trying
to show that at the present time the climate of North Africa
is not changing and that France need not fear that increasing
aridity will add to her other colonial difficulties. It should
be stated that many writers do not agree with Lahache as to
the climate of past times. They hold that ancient Roman
accounts of the country prove it to have been then, as now, a
land of scanty rainfall bordering a desert, and fit for agricul-
ture only in places where water is available for irrigation.
Their arguments lack the quantitative element which alone
can lead to certainty.
The possibility of changes of climate in Europe has not been
much discust. Gibbon concluded that the climate has changed
16See The Climate of Ancient Palestine. Bul. Amer. geog. BOO , 1908,
40: September, October, and November;
17 Lahache: Le des6chement de 1’Afrique franaiee esbil demontd?
Bul. BOC. de geog. de Marseille,:1907, 81 :_182.
--
NOVEMBER, iwa 364 MONTHLY W E A m REVIEW.
notably during the last two thousand years. In the days of
the Teutonic barbarians both the reindeer and the elk, he
says, roamed in the forests of Germany and Poland. To-day
the reindeer can not subsist in regions so far south. At the
same remote period, according to Qibbon, our barbarian ances-
tors crost the Rhine and the Rhone upon bridges of ice, altho
in modern times these rivers never freeze sufficiently to allow
of this. On the other hand Eginitis,I8 in the annales of the
Observatory of Athens, sets forth various reasons for believing
that there has been' no change. He bases his arguments
chiefly upon botanical evidence such as the kind of crops
grown in certain regions, dates of flowering, time of harvest,
and so forth. The great variability of plants, and the degree
to which they are affected by cultivation, and the ease with
which they accommodate themselves to a new environment ren-
ders any conclusions drawn from vegetation uncertain unless
supported by other evidence. The same is doubtless true of
animals. I f Gibbon is right about the ice, however, the climate
of Europe must have suffered a change similar to that which
seems to have taken place in Asia
The geographical location of the evidences of changes of
climate is a subject in regard to which there is much mis-
conception. In his recent excellent work entitled Climate,"
Ward," who opposes the idea of any important climatic
changes during historic times, expresses himself thus: "It is a
very striking fact that the districts from which comes most of
the evidence of changes of climate within historical times are
subtropical or Subequatorial, i. e., they are in just those lati-
tudes in which a slight13 greater or a slightly less migration
of the rain-bringing conditions easily produces a very con-
siderable increase or decrease in the annual rainfall." Such
an assertion is true for Africa, to which Ward has chiefly
confined his attention. Of
the eight basins discust above, none is subequatorial. One,
that of Seyistan in latitude 30' N. is distinctly subtropical,
and Qyul-juk, 38' N., lies on the edge of subtropical regions.
Kashmir, in latitude 34' N., may also be regarded as subtropi-
cal, altho its position north of the first great range of the
Himaiayas subjects it to conditions different from those of
ordinary regions in the subtropical zone. Pangong (in western
Thibet) lies in the same latitude as Kashmir, but its location
beyond or northeast of the whole body of the Himalayas gives
its climate little resemblance to that of other subtropical
countries. The rest of the basins lie well beyond the limits
of what are usually called subtropical regions. The huge
basin of Lop extends from latitude 36' N. to 43' N. Turfan lies
entirely between 42' N. and 44' N., and SonKul likewise. The
limits of the Caspian basin extended from 35' N. to 60' N. The
northern parts of this basin may fairly be omitted from con-
sideration, but Russian observers have recorded a good deal
of evidence which indicates that numerous small lakes in
latitude 46' N. to 60' N., northeast of the Caspian, are, on the
whole, decreasing in size, altho they fluctuate more or less.
The same is true of Lake Balkash farther east in latitude 45' N.
These regions, like Son Kul and Turfan and much of the Lop
basin, receive summer rains, and have a climate of a distinctly
temperate continental type. The fact seems tobe that evidences
of changes of climate have been reported in large numbers from
subtropical regions, not merely because those regions are on
the borders of diverse climatic zones, but also because they are
dry enough to be sensibly affected by changes of climate which
are not noticeable in moister parts of the world. The evidence
of change seems to be found in all dry regions wherever they
are located. It would be rash to conclude that climate has
not changed even in Europe. I n that continent a moderate
change in either direction would produce few results which
T3ee a fuller summery of Eginitis' work in the Monthly Weather Re- view. December. 1898. 26 :564.-C. A.
It is by no means true for Asia.
could be recognized after a lapse of hundreds of years except
in countries such as Spain and Greece which are a t present
suflering from aridity, or in countries such as northern Ruseia
which would be greatly infllenced by a decrease in the length
of summer.
[ To be continued. ]
NOTES ON THE ULIMATE OF EASTERN ASIA.
By Prof. ALFRED J. HENRY. Dated Washlugton, D. C., July 24, 1907.
In point of magnitude and diversity of physical features, the
Continent of. Asia stands preeminent among the grand divi-
sions of the earth. Its greatest length is about 7,000 miles,
and its width from Northeast Cape to the southern extremity
of the Malay Peninsula is about 5,300 miles. It contains the
greatest unbroken land mass on the globe, and ita eastern
shore is washt by an equally great water surface, thus afford-
ing an opportunity for the creation of two highly developed
climates of directly opposite types.
Each of these great surfaces, the land and the water, has
its own distinctive atmosphere each of which differs from the
other in point of temperature, density, and moisture. These
differences arise chiefly because water, on account of its high
specific heat, warms more slowly and to aless degree than land.
Likewise the loss of heat by radiation is much smaller from a
water than from a land surface. As a consequence of the
operation of those two processes, the atmosphere overlying
the great plains of Asia becomes very much warmer in summer
and decidedly colder in winter than that which overlies the
oceans to the east and aouth. When the continent becomes
warmer than the ocean, there is an inflow of air from the sea
toward the interior, and conversely, when the temperature of
the interior falls below that of the adjacent oceans, the flow is
from the interior outward toward the ocean&.
I n winter, the continental influence is the dominating fac-
tor. As the sun recedes from northern latitudes, intense
radiation of heat from the vast Siberian plains sets in and soon
the amount of heat thus lost exceeds the amount received.
The lower layers of the atmosphere are also cooled by oontact
with the frozen ground and doubtless by the slow descent of
the cold air from aloft.. There is thus gradually built up over
these Siberian plains s semipermanent area of cold air of such
proportions that it almost completely dominates4he weather
of eastern and central Asia. This mass of cold air, or the
Siberian high, as it is commonly called, is the seat of the great-
est known cold on the globe; cold north winds proceed out of
it and sweep to the southward over Manchuria, Mongolia,
Cores, and northern China.
It is important to note in this connection that, byreason of the
modifying influence of the rotation of the earth on its aes, a
body set in motion in the Northern Hemisphere is constantly
deflected to the right, hence, the northerly winds which issue
from the Siberian high become northeast some distance south
of their origin as on the central and northern Chinese coast,
and become east winds still farther south in the vicinity of
Hongkong. The north and northwest winds in coming from a
cold interior are dry winds, hence, there is very little precipi-
tation in Siberia, Manchuria, Korea, and northern China in the
cold season.
In summer, the oceanic influence is the controlling factor.
.As the meridian altitude of the sun increases, the cold air of
the interior ir gradually replaced by warm and consequently
light air. The balance of pressure is then shifted from the
interior to the surrounding oceans, hence a change in the
winds, viz, from a northerly to a southerly quarter. Northerly
winds are cold and dry; southerly warm and moist. The rain-
fall of eastern Asia comes with southerly winds.
The above brief sketch Dresents the broad features of the
]@a. DeC. Wakl: Cliiate. New York. 1908. p. 351. general circulation of the aimosphere in its relation to clima6.