A more extended Investigation regarding the Earth’s Surface.
It is the province of Hydrography to deal with the oceanic world;
Geography proper concerns itself simply with solid forms. The Hydrography
of the globe we must pass over, however. Aside from the fact that it
would lead us into studies of the most protracted nature, it forms
strictly one department of nautical science. Besides, there is the less
occasion to speak of it here at length, that works of great excellence
have been published, relating to that branch. We turn therefore to the
land, and shall study the world of waters only so far as it exerts
influence on the land.
By land we mean the islands as well as the continents, for, as remarked
before, the difference between them is merely relative. To the land
division of the globe, however, belong all rivers and the internal fresh
water lakes, however large. The basis of difference does not lie in the
fact that one part of the globe is water, the other part land, but in the
fact that one is a tract of uniform evenness, the other of constantly
varying surface, the internal rivers and lakes only being frills, so to
speak, to the elevated region, and not sharing the sea level of the great
oceanic mass. Uniformity of surface is then the chief characteristic of
the sea; a lack of it, of the land. A mathematical level is a thing
unknown on extended districts, and an approximation to it is very rare.
Even the basins of former seas do not display a perfectly level bed. The
plains of North Germany are characterized by this billowy rolling. The
flats along the Danube, in Hungary, and along the Po, in North Italy,
have really important deviations from a true level, though the eye is
not able to discern them. Milan is four hundred feet above the Adriatic;
but the eye does not discern that it is not at the center of a plain as
perfect as the surface of the sea itself, and yet that plain does shelve
gradually away till the Adriatic checks and defines it. Pesth is two
hundred and fifteen feet above the ocean level, yet the gradual decline
to the Black Sea is undiscernible to the eye. The immense plains along
the Amazon, even the celebrated llanos on the Orinoco, which Alexander
von Humboldt likens to inland seas of verdure, have a not insignificant
slope from west to east. The middle point of these llanos near the City
of Calabozo, about 100 geographical miles from the sea, he found to be
180 feet above the sea level; far lower indeed than Milan or Pesth,
relatively, yet at a perceptible elevation. All of these plains were
once the bottom of the sea; the Adriatic laved the base of the Apennines
and the Cottian Alps, and the Atlantic swept westward over the llanos
of the Orinoco and the Essequibo, having the Sierra de Venezuela on the
north and the Sierra Parima on the south, till it was checked by the
Cordilleras of Merida and Pamplona.
Depression and elevation, then, are the characteristics of the land. They
are both measured from the level of the sea; their absolute altitude is
reckoned from the imaginary sea level, extended over the whole globe.
Their mutual relations to each other are determined from their relative
heights. The absolute elevation above the level of the ocean can be
determined in a number of ways. If the heights to be measured are in
the immediate vicinity of the sea, a simple system of triangulation
will effect it. If they are removed from the sea, the difficulties are
greater, and increase according to the distance from the sea. The heights
of great inland mountains are determined by complicated operations with
the spirit-level, protracted trigonometrical calculations, the unwearied
and skillful use of the barometer, and constant appeal to the boiling
point of water. The description of these methods falls within the
province of Physics.
As the determination of the heights of the loftiest mountains could not
be made before the appointments of scientific explorers have attained
to a certain degree of accuracy and delicacy, the knowledge of them in
former times was almost wholly relative. The inquiries of La Condamine,
Saussure, and de Luc, in the Andes and the Swiss Alps, are almost
the only ones to be trusted among those of the older observers. All
unscientific travelers without accurate instruments confounded absolute
heights with relative heights, and innumerable errors crept therefore
into the earlier text-books. It is only within the most recent times that
Hypsometry has attained to the dignity of a science.
To meet and counteract the errors alluded to above, and current in
the loose language of popular speech, we shall use a new and indeed
arbitrary terminology,—arbitrary because the data which mensuration
will sometimes furnish are now, in part, wanting. We will divide the
earth not relatively, but absolutely, into highlands and lowlands. The
great districts often met, whose elevations are very moderate, we call
lowlands. They are, for the most part, immense plains, varied but little
above the level of the sea. The great districts which inclose mountain
ranges we call highlands, and sometimes plateaus. True highlands can
often embrace very extended and elevated plains, and these plains again
may include hills and mountains. This does not affect their character
as highlands, which lies in the fact of elevation rather than in more
or less modified variation of surface. There may be vast variety in the
physical manifestations of a great plateau district, entirely independent
of the relative effects produced by the distribution of its surface into
plains, rolling land, hills, and mountains.
In the lowlands there may exist hills to some extent, and these may even
be combined in ranges, provided only that they do not violate the uniform
characteristics of the district in which they are found.
The highlands are generally met with in the interior of the continents;
the lowlands at the coasts. Yet there are exceptions to this.
In the transitions from lowlands to highlands there is great diversity.
We can speak of three distinct bases of discrimination: a sudden
and abrupt ascent; a rise in elevation so gradual as scarcely to be
perceived; and a terrace formation. Yet in these there is a blending of
one variety with another; there is no place sharply marked, where we can
say that one form ends and another begins. There are constantly found
modifications of these three transitional phases. The plains along the
Indus and the Ganges rise sharply to the plateaus of Thibet The flat
Pacific coast of South America is exchanged with equal abruptness for
the highlands of Peru. The transition is a gradual one from the lowlands
of North Germany, along the Baltic and the North Sea, through Saxony
and Bohemia to the Bavarian highlands, north of the Alps. The Spanish
highlands form a series of terraces, increasing in height from south to
north. The immense plateaus of central Asia are also terrace formations,
of diminishing elevation, as they advance to Siberia; so, too, are the
eastern plateaus of Peru, falling off in altitude toward the plains of
the Amazon.
Just as varied are the heights taken from the sea level of the leading
plateaus. Yet they never rise to a point of elevation comparable
with those of isolated mountain peaks or ranges. These attain, in no
insignificant numbers, the height of 24,000 feet, while some ascend
thousands of feet beyond that. In Mount Everest, of the Himalaya chain,
the loftiest summit yet measured (29,000 feet) is found; although it may
be that future investigations more to the south will disclose yet greater
heights.
Highlands.
Continuous highlands or plateaus seldom attain an elevation greater
than a half or a third of the loftiest mountains; the most elevated
range in altitude, from 8000 to 12,000 feet above the sea level. On an
average, they lie about 4000 to 5000 feet above the sea. We take the last
height as a convenient point of demarkation between the two classes of
highlands—those of the first and those of the second magnitude. It is an
arbitrary point, of course, and the division there must remain, without
a natural base to rest upon, till more results in Hypsometry shall have
determined the real point of average between the combined lowlands and
the combined highlands of the earth’s surface. Meantime this division
will be of great service to us in enabling us to bring into a definite
and appreciable classification many facts which would otherwise not be so
well understood in their relations.
_Highlands or Plateaus of the First Class._
By plateaus of the first class, we mean those high, continuous plains
which lie at the elevation of more than from 4000 to 5000 feet above
the sea level. The extreme height to which such plateaus rise is a fact
yet to be ascertained. At an elevation of from 4000 to 5000 feet the
highlands of the first class merge into those of the second. The point of
transition is, of course, very difficult to fix with precision.
The high plateaus of Asia rise more than 14,000 feet. They inclose the
head-waters of the Ganges and the Indus. All central Asia is a vast
congeries of highlands; but, as a body, they by no means belong to
the most elevated of the globe. They are colossal in their length and
breadth, but not in their uniform altitude. In the latter respect, they
are far more varied than is generally supposed.
The plateau of Thibet attains, in its whole great extent of 1800 miles
in length and 500 miles in breadth, an average elevation of 10,800
feet above the sea level. In some cases it rises, of course, much
higher, as, near the holy lake Manasarowar, for instance, where it is
14,000 feet above the sea. Others sink, as at Ladakh, in Little Thibet,
to an altitude of about 9000 feet; so, too, Gertope, in the region
remarkable for its goats and the rich shawls manufactured there, and
Shiffke, are about 9804 feet above the sea. The plateau of Great Thibet,
east of Lassa, the capital, and north of the Upper Brahmapootra or
Yam-Dzangbotscha, is 9000 feet in elevation. There are also districts
filled with mountain groups of great heights, but where the depressions
sink to the level of the valleys of the Indus, Sutlej, Brahmapootra, as
low indeed as 5460 feet, as at Cashmere, so that there is no lack of
diversity in the great plateau of Thibet.
The plateau of Mongolia, or more exactly the desert of Gobi, can be
ranked only on its lower edges, where it touches the Chinese frontier, as
of the first class, although in extent it is twice as large as the great
plateau of Thibet. Only near the north bend of the Hoang-Ho and near
Peking does it reach an altitude of 8000 feet, and gradually sinks away
as it advances toward the northern frontier of the Chinese territory,
to 5100 feet, and farther north to 4000 feet; in the middle portions of
the great table-land it is depressed to a height of 2400 to 3600 feet;
it rises again at the head-waters of the Orkhon and the Toola to an
elevation of 4620 feet, and falls off in terraces toward Kiakhta, near
the northern boundary, where it is 1330 feet high, Selenghinsk, on the
Selenga, where it is 1632 feet high, and Berch-Udaisk, where it is 1458
feet high, till it reaches Lake Baikal, 1332 feet above the sea level
according to Humboldt, though Erman makes it greater.
Western Mongolia, (west of the meridian of Lassa, and west of the
point where the Tarine flows into Lake Lop,) upper Bokhara, and upper
Toorkistan were formerly considered to be a highland district; this is
now subject to doubt. We shall discuss this further on.
Africa, too, has highlands of the first class, which, however, do not
rise to the extreme height of the plateau of Thibet. As in Asia, so in
central Africa, the old supposition of the existence of a plateau of
colossal extent has been very much done away with by the more exact and
critical modern investigations. The strip of territory lying between 4°
and 10° north latitude has been demonstrated by Barth and Vogel to be
destitute of highlands. The range of mountains announced as discovered
by Mungo Park, and called the Kong Mountains, is proved to have no real
existence, and of course his statement fails of verification that that
range is the northern limit of an elevated central plateau. The peaks
which really do rise in the Kong territory form no continuous ridge; they
are mere isolated groups of moderate height. Between these groups the
lowlands continue toward the south, in an unbroken level, for an immense
distance. How far south of the equator the central African plateau
begins, is yet unascertained, for the snow-tipped peaks of Kilimandjaro
and Kenia, discovered by Rebmann and Krapf, in the parallel of Mombas,
1° to 3° south latitude, are of immense height, it is true, but they do
not demonstrate the existence of a plateau of the first class there. They
rise out of table-land about 2000 feet above the sea level, which Krapf
explored in the year 1849.
The Abyssinian plateau, on the contrary, takes rank among the most
elevated on the globe. At 10° north latitude, south of the sources of
the Blue Nile, lies Upper Abyssinia, or the kingdom of Shoa, with its
capitals, Ankobar and Angolalla, 10,000 feet above the sea. Still farther
to the north, in the ancient kingdom of Gondar, the German naturalist
Rüppel ascertained the level of Lake Tzana to be 7000 feet above the
ocean; to the southward of that the land rises to a still greater height,
and northward of Gondar the plateau ascends to an elevation of 8000 feet,
and mountains are met with 14,000 feet high. The terrace of Axaw on the
east is 6650 feet above the Red Sea, which lies along its border.
To the south of Shoa lie the highlands of Kaffa and Enarea. All
travelers agree in the statement that the inhabitants of that region are
light-complexioned; and Johnson draws from this the conclusion that the
central plateau must rise to a height of over 10,000 feet to harbor
people of a whiter hue than the dwellers of the less elevated localities.
He saw a number of men of light complexion who came as far as from the
fifth degree south latitude, not from mountain homes, but from high
table-lands.
The plateau of South Africa rises at Lattakoo, in the country of the
Bechuanas, north of the Orange River, to the height of 6000 feet. To
the east, near the Snow Mountains, where the river has its source, it
ascends to an altitude of over 10,000 feet. To the north, discovery had
made great progress since 1849. There, on a broad plateau, Oswell and
Livingstone brought to the knowledge of the world the existence of Lake
Ngami, whose surface is 2825 feet above the level of the sea. The plateau
which includes this lake at its place of deepest depression cannot be
less than 3000 feet high, and at some localities yet higher. Still more
to the north, at latitude 14° south, on the water-shed between the Zaire
or Congo on the west and the Zambeze in the east, the plateau reaches
an elevation of 5000 feet, according to Livingstone. Yet farther to the
west, it rises still higher and takes undisputed rank among plateaus of
the first class. There, at 18° south latitude, Galtne, on his journey of
discovery in 1850, ascended the table-land of Ovompâ, a region of great
natural productivity. On the way thither, going from south to north, at
21° south latitude, and therefore in the parallel of Lake Ngami, but
about 500 miles westward, he ascended north of the Swakop River, the
table-land of Demara, which he found to be 6000 feet high. From that
plateau mountains, Koniati and Ometako, for instance, rise to a height
of 8800 feet. From the Swakop River to Lake Ngami there is a continuous
plateau.
The high table-land of southern central Africa does not then extend, as
was once supposed, as far north as 9° north latitude, nor even to the
later limit of 4½° north latitude; but at about 4° 10′ the distinction
between lowland and highland seems to be sharply drawn, as the cataracts
which terminate the navigation of the White Nile indicate. Here Father
Knoblecher turned back in 1849, but he ascended the first of the
mountains which there began to rise; his eye reached onward to mountains
very near or on the equator. He says that those high mountains stand
upon an elevated table-land. Thus, here at the source of the White Nile
we have a plateau seemingly of the first rank. From such a plateau it is
probable that the snow-capped mountains, seen by Rebmann and Krapf in the
neighborhood of the equator, rose, which they thought, approaching from
the eastern coast, held the source of the Nile.
At the northwest of Africa, too, at 10° north latitude, the territory
which feeds the springs of the Senegal and the Niger is supposed to be a
plateau of great elevation and of great extent. But at present our lack
of knowledge prevents our attaining certainty regarding it. No thorough
system of measurement has been yet applied there.
America possesses a number of plateaus of the first class. To the
most prominent of these belong the ones which were first thoroughly
studied by Alexander von Humboldt. It is to him that we owe our first
accurate impressions of table-lands which, before his day, had been
indiscriminately confounded with mountains, and had had no place assigned
to them in the department of Geography. Doubtless, too, great prominence
was given to plateaus at the outset; they were pushed into unseemly
proportion to other matters as well worthy of investigation, but they
have come into their true place, and now only wait the development of new
facts regarding the size and height of some, to be properly understood
and appreciated.
The measurements made in North, Central, and South America give the
following results; much more complete, it may be remarked, than the
results yet gained in Asia and Africa.
To the plateaus of the first class belong in America, at latitude 0°, the
plain of Quito, almost 9000 feet above the sea, (Los Pastos in the north
being near 11,000 feet,) and to the south, at 17° south latitude, the
plateau of Upper Peru. Here the great Lake Yiticaca is found, 12,000 feet
above the sea; eastward of the lake, the table-land rises yet higher, and
at Alto de Toleda it is 14,000 feet in elevation, as high as the highest
part of Thibet. At 20° south latitude, south of Lake Yiticaca, is the
City of Potosi, whose streets are 12,822 feet above the Pacific.
In Central America is found, at 20° north latitude, the extended
table-land of Mexico, 500 miles wide, rising to a height of 7000 feet,
and farther to the north, in New Mexico, the plateau of Santa Fé, 35°
north latitude east of the Rocky Mountains, and 7100 feet above the sea.
The table-land on the west side of the mountains, and toward the Great
Salt Lake, is undoubtedly just as elevated.
Europe and Australia are wanting in plateaus of the first rank, and in
general the whole immense flat northern districts of the globe, though we
are not yet quite familiar enough with the extreme north of America to
speak with entire confidence regarding it.
_Plateaus of the Second Class._
Elevated plains which are at once continuous and bounded by a definite
line of demarkation, and which do not attain an altitude of more than
4000 or 5000 feet, are considered plateaus of the second class. They
are far more general over the whole earth than plateaus of the first
class; in every one of the great divisions of the globe they appear in
the utmost possible diversities of elevation, sometimes so gradually
ascending that the lowest limit is hardly to be perceived. This makes it
not only expedient but necessary to assign to plateaus a fixed though
arbitrary system of classification, for without it we could attain to no
thorough view of all their relations. This general system must afterward
be confirmed and justified by protracted special investigations.
That not all the vast plains of Central Asia, from Thibet to the Altai
Mountains, and from the Belur range to the Chinese Gobi, belong to
the first class of plateaus, has been demonstrated by the Russian
measurements, made by Fuss and Bunge in 1832, between Lake Baikal,
Kiakhta, and Peking, and rendered highly probable by the investigations
of Klaproth, Humboldt, and Zimmermann. Toward the northwest the plateaus
generally sink from the moderate elevation of the Middle Gobi, 4000 feet,
to Lake Baikal, 1332 feet above the sea, Lake Zaison, not 1000 feet above
the sea, and the border of the plateau at Choimailocha, the Chinese
frontier post on the Siberian line, 1000 feet above the sea, then to the
lower border of the plateau of Bookhtarminsk (936 feet) and Semipalatinsk
on the Irtish, (708 feet,) where the great Siberian plain begins. In the
valley of the Tarim and of Lake Lop, pomegranates and grapes thrive, and
cotton, which has been raised of an excellent quality in Eelee, is found
at a height of from 1200 to 2000 feet. And in contrast with the great
arctic plain of Northern Asia, not 500 feet above the level of the sea,
this central plateau will take its place as distinctively of the second
rank.
The plateau of Persia lies on the border of both classes; for while the
central portion touches 4000 feet, some parts rise much higher and some
sink much deeper than the normal point. These balance each other, and the
average is about the maximum elevation of plateaus of the second degree.
East of the Persian plateau lies the plateau of Cabool, 6000 feet above
the sea. On the northern edge of Afghanistan is the plateau of Bamain,
7500 feet in elevation. More to the south is the high plain of Candahar,
being 3500 feet, and the City of Candahar, 3264 feet above the sea. The
plateau of Kweltah west of the Bolan Pass is 5220 feet. Still farther to
the south is the great plain of Beloochistan, 7000 feet, with the City of
Kelat, 5418 feet above the sea.
In the central part of the eastern Persian plateau in ancient Gedrosia,
Drangiana, and Parthia, and Lake Zareh, the depression is the lowest.
At Lake Zareh the elevation is 2100 feet; at Herat, more to the north,
2628 feet. In West Persia, on the meridian of the Caspian Sea, it rises
higher; on the northern edge at Teheran it is 3672 feet; at Schabred,
southeast of Astrabad, it is 4000 feet; at Kasbin, west of Teheran, it
is 4000 feet; and at Samegon, 5700 feet. The lowest depression at Com
and Kashan is not 2000 feet above the sea. Toward the northwest Persia
thrusts up a short arm into the adjoining territory of Armenia. This is
the highland of Ayerbaijan, Zoroaster’s “Land of Fire.” This connecting
plateau of 7000 feet elevation belongs to the first class. To the west
of this the plateau of Armenia extends in varying range of elevation,
from that of Lake Van, 5124 feet, to the plain of the Aras, (the
ancient Araxes,) on which the double cone of Ararat rises to a height
of 14,656 feet. But the table-land at the northern base of Ararat, the
site of Erdschmiazin, is only 2860 feet high, Erivan a little higher,
and Erdzeroune, on the plateau of the Taurus, the plain of the Upper
Euphrates, 5730 feet.
The plateaus of Asia Minor embrace wide plains extending through the
whole of the country, at an elevation toward the east, in ancient
Lycaonia and Cappadocia, of 3000 feet, and sinking toward the west to
2000 feet.
To the plateaus of Armenia and Lycaonia, Strabo, whose home was there,
and who carefully studied them, gave the expressive name of ὀροπέδια,
_i.e._ mountain plains, a term which corresponds remarkably with our word
plateau, but which, as Humboldt has remarked, was not of much use among
the ancients. Strabo, however, directed attention also to the Oropedia of
Sicily and India.
In India, Deccan displays similar formations, which rise gradually
from south to north in Mysore, in Poonah of the Mahrattas, and in the
table-land of Vindhya and Malwah, to 2000, 3000, and even 4000 feet.
Deccan enjoys an admirable climate and the richest abundance of all
natural productions. China too must have plateaus, for the Chinese word
_youen_ indicates very clearly a large elevated plain.
In Arabia the plateaus of the second class are largely found, and their
height ascends from north to south, instead of from south to north as in
Deccan. The Syrian Hauran is 2000 feet high, the plateau of Damascus 2200
feet, the plateau of Taif, above Mecca, 3000 feet, the plateau of Sapaa,
in Southern Arabia, 4000 feet.
In North Africa that portion of the great Sahara which has heretofore
been considered a low plain, lying between Tripoli and Lake Tchad, has
been ascertained by the German explorers, Overweg and Vogel, to be
a table-land of the second class, ranging in elevation from 1000 to
2000 feet. It begins at the Chorean plateau (2000 feet) in the south
of Tripoli, and sinks to an elevation of 800 feet in the neighborhood
of Lake Tchad. The average altitude is about 1500 feet. This moderate
elevation of Sahara corresponds with the equally high plateau of
Cyrenaica, 2000 feet.
The Atlas plateau, in the northwest of Africa, rises to a greater
height—2000 to 3000 feet; the upper course of the Draa, near the Sahara,
being 3000 feet; the high, broad table-land on which Timbuctoo lies,
according to Renon’s measurement, is 1500 to 1800 feet above the sea.
In south Africa the low, or rather the moderate plateau, which borders
the district of the Bechuanas on the north, rises, as it advances toward
the lower rim of Africa, at Cape Colony, to an altitude of 3000 feet.
America has many plateaus of the second range of elevation, but her
highlands of the first class are so imposing in extent, as well as
in elevation, that they have been more carefully observed than the
table-lands of the second class.
Along the eastern slope of the Andes, on the same parallel with the
great plains of the Orinoco, the Amazon, and the La Plata, these
plateaus extend, touching the base of the mountains, and appearing
rather as terraces, or vast plains of transition, from the highlands to
the lowlands, than as independent forms. Where Alexander von Humboldt
measured them, west of the low plains of the Amazon, he found their
height, measured from the sea, to range from 1050 to 1200 feet; he
describes them as having the appearance of vast plains, and as differing
from the lowlands of the Amazon only in their greater elevation; their
slope toward the narrowing of the Pongo de Mauseriche being too slight to
be appreciable.
Between the threefold forks of the Northern Andes, Humboldt ascertained
the heights of ten plateaus, extending as far as the plains of Orinoco,
and called by the various names, according to their elevation—Tierras
templadas, or temperate districts, Tierras calientas, or warm districts,
and Tierras frias, or cold districts—varying in height from 1800 to 6600
feet, the highest belonging clearly to the first class of plateaus.
The mountains of Brazil are interspersed among plateaus of the second
class. The Brazilian mountains are not true ranges, but lie in groups,
their height varying from 2700 to 5700 feet, and between them are the
vast elevated plains, called Campas, which are true plateaus of the
second class.
The southern point of South America, south of the Rio Negro, as far as
the Straits of Magellan, known as the plateau of Patagonia, is a true
table-land of from 1200 to 1400 feet in height. It is composed of ragged
strata of porphyry or of vast lava-masses, and has been explored by
Captain Fitz Roy, in 1837, from the mouth of the Santa Cruz River to
the snow-capped Andes in the west. The plateau diminishes gradually in
elevation from west to east, till it touches the sea line.
In North America the broad plateau extending through Northern Texas and
the Indian Territory, and lying on both sides of the Arkansas River,
increases in elevation gradually from St. Louis, on the Mississippi,
less than 500 feet above the sea, to Santa Fé, on the upper course of
the Rio Bravo, 7000 feet above the sea. It ascends so slightly that the
rise is imperceptible to the eye, the broad plains there taking the name
of prairies. St. Louis is 420 feet in absolute elevation; the eastern
Arkansas plateau 1500 to 3000 feet; the high western Arkansas table-land
from 3000 to 7000 feet, where, at the point of greatest altitude, lies
the City of Santa Fé, in the Territory of New Mexico, 7047 feet above
the sea. This broad, sloping tract reaches out to a great extent at the
north, crossing the Missouri, and embracing the colossal North American
lakes. Lake Huron and Lake Michigan, about 578 feet deep, and Lake
Superior, 627 feet deep, lie in vast hollows in that great continuous
plateau, which extends into the British Possessions, rises again to 800
or 1000 feet in elevation, and is rocky and craggy, yet not enough so as
to take the name of a mountain chain, but simply to form a clearly-marked
water-shed, which Fremont and Nicollet have measured.
In Australia and Europe plateaus of the second grade of elevation are
not wanting. In Australia, however, they are limited to the triangular
district in the southeast, which has become the place of settlement
for the chief English colonies, and which, bearing the name of King’s
Table-land, rises to a height of 2500 feet, and occupies the largest area
of all the Australian table-lands.
In Europe this physical feature is displayed most distinctly in the
Spanish plateaus, which occupy by far the largest proportion of the
entire peninsula. Madrid lies on one of these plateaus, at a height of
2100 feet, five times as high as Paris, on the Seine, and as high as
Innspruck, in the very heart of the Tyrol; Toledo, in the valley of the
Tagus, is 1734 feet above the sea. The average elevation of New Castile,
the central part of Spain, is 2000 feet. Old Castile, which borders
it on the north, separated from it by the Guadarrama ridge, is about a
thousand feet higher. Burgos, in the center, is 2700 feet above the sea;
Segovia, to the south, 3100 feet. The average elevation of Old Castile is
3000 feet.
Then comes in natural order the Bavarian plateau, in southern Germany,
ranging from 1500 to 1600 feet high, a broad table-land, on which lie
Munich and Augsburg. It extends along the course of the Danube from west
to east, from Lower Switzerland to Ratisbon.
According to the mean measurements of Humboldt, the lower plateau of
Auvergne, in southern France, is 1040 feet in elevation; still less in
altitude (840 feet) is the plateau of Burgundy and Lothringia, between
the Vosges and the Ardennes. Limousin, Aveyron, la Forez, Monts, and Côte
d’Or are plateaus.
The plateau of Lothringia, whose mean elevation is 648 feet, lies between
the Rhine and the Moselle. The plateau of Luxemburg extends northward to
the Eifel, where Prum lies, and to the Ardennes, where Malmedy, Eupen,
Namur, Liege, and Aix-la-Chapelle lie.
In Middle Germany, a series of plateaus of the second grade begins in
Upper Hesse, and extends eastward, crossed by mountains and valleys,
traversing Upper Silesia and Galicia, and running along the northern side
of the Carpathian Mountains to Podolia, on the Dnieper, thus embracing a
strip extending through the larger part of central Europe.
A line of plateaus begins still farther to the north, at the low hills
of Jutland, crossing Holstein, Mecklenberg, the whole southern edge
of Pomerania, and extending to Lithuania and the Valdai Hills. It is
characterized by a band of inland lakes, whose basins it incloses, and
is crossed by the valleys of the Oder, Vistula, Niemen, and Duna. It has
been called the Pomerania lake country. In the hollows where the lakes
lie, (whose surfaces are, at the highest, not more than 300 feet above
the sea,) and yet more in the depressions, where rivers break through,
the level descends to as low a point as that of the great plain of
Central Europe; but at other places it rises to an elevation as high as
500 feet, and so touches upon the limits of plateaus of the second range.
Many parts of this broad upland may possibly be formed of shifting sand
dunes which have been gradually piled up along the sea line. The plateau
reaches its highest point at the eastern end, in the Valdai Hills, where
it averages 1000 feet in elevation. The highest point is 1100 feet. East
of the Volga, which rises at the eastern side of these hills, the plateau
falls off by imperceptible steps, till it is lost in the great Russian
plain.
In the peninsulas of Southern Europe, as in the Morea, (2000 feet,) and
in the Crimea, (800 to 1200 feet,) the plateau again appears in not
insignificant proportions.
The lower range of plateaus, it will be seen, is far more frequently met
with through all parts of the earth than the higher, yet both combined
occupy a larger share of the surface of the globe. We can designate them
as sharply defined and broadly massive elevations, in contradistinction
to the long, narrow, and broken masses which have received the name of
mountain chains. The latter have too often been confounded with the
former and have received from geographers a treatment disproportionately
full in relation to their claims. The plateau has been until recently
an almost forgotten geographical element. Humboldt restored it to its
rightful place; by many hundreds of measurements he has accurately
settled its form, its effect on climate, on isothermal lines, on
agriculture, on the physical and moral life of nations, and even on the
course of human history.
In closing this attempt at a general consideration of plateaus, I must
confirm the reproach which Humboldt has cast upon most geographers of
this day for their abuse of the word plateau. And I must at the same
time admit that it is justly due to some parts of my own “Erdkunde,”
where I have considered the plateau systems of Central Asia and Africa.
When I wrote the pages of that work, thirty and more years ago, there
were no scientific measurements then made of those regions, and the
general ignorance led to a premature generalization, in which I used the
ascertained features of the New World as probably in analogy with the
unexplored center of the Old World. This use of really untrue analogies
was carried by others to great lengths, and choratographers went so far
as to depict the country according to the hypothesis of those who had
written at first hand, and after using all the lights then existing, but
who had never supposed that what they had indicated in general terms,
would be afterward made so definite and real to the public eye. Those
untrue statements of my own, I must leave however just as they are,
and rejoice that the great advance of science has led to the accurate
knowledge of the great plateaus of which the civilized world then knew
but little. One word more: I set the lower limit of plateaus of the
second grade at 500 feet, lower therefore than the great master in
Physical Geography set his.
“Elevations of the soil,” says Humboldt, “which do not display a marked
difference in climate and vegetation from the country around them, are
not rightly called plateaus.” His meaning is, that the name does not
relate to absolute height measured from the sea, but harmonious climatic
relations existing between contiguous districts, one of which is more
elevated than the other. Highland and lowland are therefore to him words
of unfixed meaning, if they do not stand in the contrast of height,
climate, relief, and rates of temperature. Humboldt therefore did not
consider the depression of Central Asia, at the Taringol, as a plateau;
and table-lands from 200 to 1200 feet in absolute elevation, _i.e._ from
the sea level, are passed over by him as not worthy of the same name
which he applied to the plains 6000 to 10,000 feet above the sea.
Dealing as I do with the elementary features and the physical contrasts
of countries which for the most part are now thoroughly explored, I
prefer, for the purpose of elucidating the subject of Physical Geography,
to consider the plateau as beginning at 500 feet above the level of the
sea. By comparing the plateaus of both hemispheres it is not difficult to
deal with a variety of features, and to make a number of discriminations
which, without an absolute standard, it would be impossible to make.
We pass to the consideration of the much more varied and more imposing
characteristics of mountains.
Mountains and Mountain Lands.
Mountain lands cannot, in the strict use of language, be compared with
plateaus, except in way of contrast, because they are not uniform, broad,
and sharply defined tracts, but extend in a linear direction, having as
their chief feature the longitudinal axis of the mountain chain. Groups
of mountain ridges may be separated from each other, or may be united in
any coherent way which does not make them continuous, and yet, despite
the want of continuity, form a perfect whole.
Mountains, with their fissures, chasms, abysses, valleys, ravines,
clefts, precipices,—in a word, their varied diversities of feature,
broken through in every direction, the whole chain rent into fragments by
these transverse breaks, are in direct contrast with plateaus. They have
quite often a common range of elevation, which, measured from the sea
level, is not unfrequently much greater than the districts lying at their
base. Yet this relation is only incidental, it is not essential. There
is no necessary connection between the height of the outlying plateau
and the height of the mountain range. In Switzerland the mountains rise
to the altitude of 13,000 or 14,000 feet; the country at the foot of the
Alps is but 1000 to 2000 feet above the sea. Here the distance between
the summit and the plateau at the base suggests no relation between them.
The distinctive characteristic of a mountain land is the height of
isolated groups. Great differences of elevation within small distances
characterize mountain regions; small differences within great distances
characterize plateaus. The plateau depends upon uniform evenness of
surface, or an approximation to it, over a large extent of territory.
The mountain range is the exact opposite, the development of all kinds
of extremes within a limited space, and the consequent individualization
of the locality where it stands. Mountain lands cannot therefore be
identified with the type of the highland and the plateau. The mountain
chain has a character of its own, whether existing in unbroken unity, or
subdivided into subordinate ranges, ridges, and spurs, and whether the
summits are conical or sharply pointed,—whether also of moderate, medium,
or loftiest elevation.
And high as mountains rise, their height is equivalenced by the depth of
the depressions which form their valleys; the higher the mountain, the
deeper the abyss which cleaves to the base. The immensely elevated peaks
of the loftiest chains find their correspondence in the narrow ravines
and the mountain lakes at the foot; the precipitous summits of the great
American chain have their barrancos in the Andes and their cañons in the
Rocky Mountains. The valleys are in natural contrast with the summits.
They have just as little of the uniformity of lowland plains as the
mountain tops have of the uniformity of elevated table-lands. They are
infinite in variety, highly individualized, and always adapt themselves
to the characteristics of the chain which conditions them. The mountain,
too, has no uniformity in its character; it embraces within the smallest
compass the production of all climes, and unites the characteristics of
both highland and lowland. Mountain regions have therefore had a great
influence in history and in the development of humanity, even greater
than the more monotonous plateaus, which in general harbor nomadic
races and give little encouragement to permanently settled people. For
this reason the geographer cannot, like the geologist, classify high
table-lands and mountains together; he cannot draw the same inferences
from the plateau as from the mountain range; to the geographer the
plateau is not a lower type of mountain, but the two, in their relations
to man and to history, suggest entirely different results and condition
entirely different processes.
And yet it must be confessed that mountains do stand in intimate
connection with plateaus of both classes, and that the transitions from
the one form to the other are well worthy of study. Yet the present lack
of correct measurements has made this little understood.
It is not the element of height alone which gives mountains their
significance. There are many other features, which are little studied,
yet of real import. It is, however, not a matter of indifference whether
a chain thrusts up its peaks 1000, 5000, 10,000, or 20,000 feet, and the
height has been made and will continue to be made a subject of careful
investigation. In reference to height, we distinguish what, in a general
sense, we call mountains,[3] into hills, mounts, and mountains of various
degrees of magnitude. Yet the height of the highest range, in comparison
with the diameter of the earth, is insignificant, only about ¹⁄₁₇₀₀, and
the combined mass of mountains are of no more account in comparing them
with the entire mass of the globe, than the roughnesses on the rind of
an apple, or perhaps more exactly still, than those on the shell of an
egg. The combined mountain systems in the world would not suffice, if
transferred to the North and South Pole, to fill out the earth to such an
extent that the polar and equatorial diameters would be equal.
In following out his profound scientific investigations, Alexander von
Humboldt, in order to ascertain the center of the earth’s gravity,
taking into account the existing elevations above the ocean level, was
led to the conclusion that too great importance was formerly assigned to
mountains in their relations not to the course of history, but to the
earth as subject to mathematical laws. Very careful observations revealed
the fact to him that all the mountains of France, if reduced to a level
and spread out, would raise the grade of the whole country to a height
not more than 816 feet above the sea line. All the mountains of Europe,
distributed in like manner, would raise the level to only about 630 feet.
In Asia the same process would make the vast plain only 1080 feet high,
in North America 702 feet, in South America only 1062 feet; while the
mountains of the entire globe would raise the level to only 947 feet
above the level of the sea. So insignificant are the combined mountain
systems of the earth in respect to size, in comparison with the immense
body on which they stand, though their importance is great when we regard
their influence on the localities where they are found. Yet in this last
regard, mountains deserve careful study, for they not only exercise and
have exercised a great influence over nature and man, but they serve as
our best key to open to our view the internal structure of the earth.
Some mountains, though of great height and broad base, like Etna,
Vesuvius, Teneriffe, and many volcanoes, belong to no true mountain
system; and even when they lie near together, and yet have no inner
principle of unity, they are not spoken of as a chain or a range: they
make merely a mountainous district. It is the repetition of the common
type and the existence of a continuous valley which gives a right to use
the names chain and range.
The linear extent and height of mountain ranges vary very much; no
definite limits to these can be assigned. Yet there are few chains which
are less than 25 miles long and 1500 feet high. Other features are
necessary in order to determine the strict application of the word chain
or range; one is a ridge-like or comb-like aspect; (that it should be a
water-shed is not essential, although very common;) another feature is
that the rock composing it should be of the same geological formation.
Sand dunes, although occurring in regular and ridge-like uniformity,
like those in Holland, and looking from a distance like a mountain chain,
are not to be reckoned as mountain chains, though like the tells on the
Syrian steppes and dunes in the Netherlands and along the Baltic coast,
they sometimes rise to the height of a thousand feet. In South Germany
and in the neighborhood of lofty mountains, such elevations are called
mere hills; at the north foot of the Alps, yet greater heights are almost
always called level land. In judging of the fitness with which the word
mountain is used, it must always be remembered whether he who employs
it dwells among the Himalayas or on the lowlands of eastern Europe; and
in order to give any fixedness to the use of the word, it is necessary
to take into account other physical characteristics besides height. By
common usage, however, the Alps have become the standard of comparison
for all the mountains of the world, mainly because, besides having their
imposing height, they are found in the middle of the temperate zone;
they are the most convenient to study of any great system on the globe.
In respect to height, we divide these into four grades: the lowest from
2000 to 5000 feet above the sea; the next from 5000 to 8000; the next
from 8000 to 10,000; and the highest from 10,000 on to the height of Mont
Blanc.
Another standard might be found in the colossal Himalaya chain of Asia,
and the Cordilleras of both Americas, which could easily be brought into
unison with the Alpine chain of Switzerland.
The linear direction of a mountain chain, the axis of elevation as we
might say, (so sharply hinted at in the very word mountain-chain,)
brings out relations which vary not only according to the longitudinal
direction itself, but to the lateral extent, the number of mountains,
the situation, and the ramification of the chain. If the direction be
a straight one, we can rightly speak of an axis of elevation. According
to Humboldt’s measurements, this axis in the Pyrenees is 230 miles in
length; in the Alps, from Mont Blanc to the Hungarian frontier, 515
miles; the Ural Mountains, 550 to 2042 miles; the Scandinavian Mountains,
1100 miles; the Altai Mountains, 9900 miles; the Kuenlun, 1600 miles;
the Thian-Shan, in Inner China, 1700 to 2150 miles; the Himalayas,
1600 miles; the Yablonoi Chrabet, 550 miles; the Aldan, 400 miles; the
Ghauts, 760 miles; the Andes of South America, 4400 miles; and the whole
Cordillera of North America, 9200 miles. There is often much doubt about
the true beginning and ending of a mountain chain, and judgments differ
according as they rest on the fact of elevation or on the geological
traces of upheaval where they begin to be manifest. Geographers are not
agreed, for example, whether the Ural Mountains continue as far north as
Nova Zembla, and whether one or two chains in America are to be spoken of
as traversing the plateau of Mexico.
If there are parallel ranges, it is correct to speak of a transverse
axis, running at right angles with the main axis. There is, it is
apparent, a marked difference between simple chains and the accumulated
parallel chains, where breadth is a prominent element, as in the Vosges,
the Black Forest Mountains, the Fichtel range, the Hartz, the Ardennes.
The parallel rows form a mountain system. Yet all great chains are made
up of smaller ones, of groups at least, and so are mountain systems.
Often the grouping is seemingly irregular, a lawless aggregation, but
only because our knowledge is incomplete, and the law of arrangement
concealed from us. This law is traced in the very geological qualities
of the chain, not in the later form. The outer form is often very
deceptive, the very convulsions which indicate the surer signs having
served to obliterate what we should suppose the most prominent marks. The
present of mountains must often be studied in the light of their past.
Orography must be interpreted by geology. But the geological surveys
of the earth are as yet very imperfect; the outer form has often to be
accepted as the only guide. Orography and geology are two sciences which
now go on hand in hand.
In the simple mountain chain it is easy to discriminate between the parts
which make it up; the base is easily ascertainable and the ascent to
the comb-like ridge is readily traced; the eye does not fail to see the
relation between the special prominent heights and the chain from which
they rise, and to trace the manner in which spurs and outlying mountains
are connected with the main chain. Small isolated collections of
mountains are especially valuable as elementary studies, for they always
have a unity of their own. And all the greater and well-known chains are
made up of smaller, simple chains, whose connection and mutual relations
are, however, sometimes exceedingly difficult to trace. But the character
of the whole is not sometimes ascertainable with this preliminary
knowledge of the parts.
The true base of a mountain chain, the line of periphery, in consequence
of the general unevenness of the adjacent country, must be ascertained
by very exact measurements with the level. The geologist does not
begin with this step, he strikes deeper, and seeks the place where the
structure diverges from that of the more level land lying near; and, in
the search after the basis of structure, he discovers the unity of the
range from the foot to the summit. The whole geological district which
has been upheaved into mountains, Leopold von Buch found to be generally
ellipsoidal in form, the longer axis being far more prominent than the
shorter one. The axis of most mountain chains is, then, the longer axis
of an ellipsoid. The Swiss Alps display about a dozen such ellipsoids,
of different characteristics, and arranged according to no perceptible
law of harmony. Each is developed from its own base, as the trunk of a
tree grows out of its root. These separate bases lie contiguously, but
the peaks which shoot up are widely sundered. The forms of the mountain
groups resulting from this are, of course, various. Some of them I will
briefly characterize.
1. The longer axes of the subordinate chains may run in parallels, as in
one portion of the Swiss Alps, the Jura, the Ural Mountains, the Mexican
Cordilleras, and the Himalayas.
2. The chains may diverge or converge. The Alps diverge at the east, and
the forks run northeast and southeast respectively; the Rocky Mountains,
toward the Arctic regions, divide into from five to seven diverging
chains. Converging ranges may come together at varying angles, and
these can mass themselves into confused mountain knots, the summits of
which soar to amazing heights, as the West and Middle Alps do around
Mont Blanc. Alexander von Humboldt distinguishes five of these mountain
knots in the Andes, Porco, Cuzco, Pasco, Assuay, and Los Pastos, whose
construction, carefully studied, he considered, gives the key to the
structure of the whole chain. Side chains often display this knotted
form, as in Upper Peru around Lake Titicaca, the three branches of the
Ural, at the Irmel Tau, the Himalaya, Kuenlun, and Hindoo Koosh chains,
in upper Afghanistan, and the ranges of Swiss Alps, which converge around
St. Gothard. Yet the convolutions which these mountain chains make at
their point of convergence are never regular, never mathematically exact,
but to be measured in sections, and the traces of a linear direction
to be carefully sought with the compass. The whole has, to the eye, a
labyrinthine appearance, and the law of structure is only ascertained,
with exactness, by the geological features, the direction of the strata,
and the like. The geographer must call in the geologist to help him solve
his problems.[4]
3. If from some high central point the mountain ranges radiate
in the form of a star, they form a new variety of system called,
for convenience, by the name “star-shaped.” In volcanic mountains
this configuration is common, as in Mont d’Or and in Auvergne. The
southwestern Alps, known sometimes as the Sea Alps, the Ural at the
Arctic Ocean, the Quito range of the Andes, are types of this form.
4. The ring-shaped system is in direct contrast with the last. It is
found where mountain chains are arranged in a circle, inclosing a plateau
of larger or smaller extent. There are two marked examples of this form
in Europe: Bohemia and Transylvania. The ring of mountains around the
former is made up of a number of ranges, which dovetail together at the
ends, making a unit, but only a rude circle, speaking with mathematical
exactness. The inclosed basin is only relatively a lowland; it is
rigid with hills and low mountains, yet of such little importance, in
comparison with the rim of peaks, that the common name, the “Bohemian
Kettle,” has begun to have an accredited significance, and is stronger
than the more loosely-used word Basin. Transylvania, too, partakes of
similar characteristics. Its border consists of a number of minor ranges,
of varying heights, up to 1800 feet; and the central hollow, which is
much more strongly marked by hilly land than Bohemia, lies 2200 feet
above the Adriatic. The ring-shaped system is one of the rarest met of
all. They are, however, observed in abundance on the moon.
5. Just as rare is the form where ranges intersect in the form of a
cross, those running, for example, from north to south, meeting those
running east and west. As an instance of this, Humboldt cites the
confluence of the Himalaya, the Kuenlun, the Hindoo Koosh, and the
Belor or Belurtagh Mountains. The belt between 35° and 40° N. lat.
is remarkable for its gridiron-shaped mountain system, the points of
conjunction being marked by knots of peaks of colossal height. The most
remarkable one of these is the lofty Pamir Pass, between 37° 30′ and 40°
5′ N. lat., and 18,000 feet high, known, historically, from the sixth
century, and described by Marco Polo, as well as by the ancient Greek
historians. The Persians dwelling in the neighborhood term it the Roof of
the World. Elsewhere the same feature is observable, though on a scale
of less magnitude. So in the Altai range at Lake Yetzkoi, in the western
Swiss Alps, and in the porphyritic chain of Room-Elee, known to the
ancients as Rhodope, and now as the Despoto Dagh. This gridiron-shape of
some mountain systems seems to be the result of upheavals at different
times, which necessarily occasions the most broken configuration at the
point where a chain of more recent formation has been projected through
one of older date.
The varying relations of length, breadth, direction, connection, and
severance of mountain ranges give great diversity to them, and impart
to every system a character of its own. To the features just indicated
must be added vertical or precipitous descents, for the influences which
they exert upon the possibility of man’s constructing mountain roads, are
very great. The extent of these sudden depressions, or, more exactly,
the relation which the distance from the base to the pass bears to the
distance from the base to the summit, gives a key to the uses of certain
mountains as adjuncts of civilization, and shows how some ranges rather
than others may become the abode of men, and produce marked effects on
human culture and the world’s history.
I have before alluded to the comb-like structure of most mountain
chains. The resemblance is more striking than may appear; for not only
do the peaks correspond in general uniformity of height with the teeth
of the comb, but the equally uniform height of the passes from the base
corresponds with the uniform thickness of the solid part of the comb.
The relation, however, of the distance from the base to the passes, to
the distance from the base to the peaks, is widely various. Humboldt has
estimated it in a few leading chains as follows:—
Himalayas.
Height of chain, 25,000 ft.
” pass, 15,000 ”
” base, 1000 ” (Delhi.)
Alps.
Mont Blanc, 14,500 ft.
Height of pass, 7200 ”
” base, 1200 ”
Andes.
Chimborazo, 21,000 ft.
Height of pass, 10,000 ”
” base, (Sea.)
Pyrenees.
Maladetta, 10,722 ft.
Height of pass, 8000 ”
” base, (Sea.)
In the Alps and Caucasus the relation of the height of the pass to the
height of the chain is as 1 to 2; in the Himalaya, Quito Cordillera,
and Alleghany Mountains, as 1 to 1·8; in the Pyrenees and Cordillera of
Bolivia, as 1 to 1·5. In the Alps, therefore, where the pass is only half
as elevated as the chain, the communication is the most direct, and the
least barrier is put to the purposes of man,—a fact of great import in
relation to human culture. The Pyrenees are in direct contrast in this
respect, the most unapproachable, the most sundering of mountains.
The position of mountain chains is a matter of the first importance in
relation to the welfare of man, and the solution of many of the most
important problems in history. Whether interior ranges like the Ural and
the Atlas, or ranges connecting two seas like the Caucasus, or those
like the Mexican Sierras, lying between two oceans, are most open to
human approach and use, is a question which we will not here stop to
consider; but it may be said that, whether situated in the relations
just indicated, or whether they are meridianal ranges like the Ural, the
Scandinavian chain, the Alleghanies, or the great Cordillera of both
Americas, which extends from the tropical world to both polar zones; or
whether they run in the same direction with the parallels of latitude,
turning one side to the colder north, and another side to the sunnier
south; or whether they assume a diagonal direction like the Swiss Alps,
from southwest to northeast, or like the Caucasus, from northwest to
southeast, is a matter of the first importance to ascertain. Of not less
consequence is it to discover whether the chain is the edge or rim of a
plateau, and can have, therefore, only a one-sided development, like the
Himalayas toward the south, or the Anti-Taurus toward the north, because
the existence of a plateau on the reverse side dwarfs the slant distance,
and gives but a fractional part of what, without the plateau, would be
open and clear.
As plateaus usually display this edge on both sides, the border has
been aptly compared to a double ledge or rim, between the two sides of
which the table-land lies, often tolerably high above the sea level. If
these rims, like mountains, are not contiguous to the plateau; if they
are separated from it by a valley of greater or less width and depth,
running parallel with the edge, they form what Humboldt has called
natural circumvallations. Of such the Altai range, on the north side of
the Asiatic central plateau, is an example. The hollow between the range
and the plateau just mentioned is partly filled with inland seas. The
Caucasus may, in like manner, be regarded as the circumvallation of the
American plateau, separate from it by the Koor and the Aras (ancient
Araxes) rims. Yet in the Caucasus another modification occurs—a partial
linking of the plateau with the range at the west extremity, by the
connecting chain of the Moschic Mountains. In like manner the Pyrenees,
in their eastern half, form a circumvallation around the north side of
the Castilian plateau, separated from it by the basin of the Ebro, and
forming a perfect ring around Upper Castile and the elevated province of
Biscay.
In cases where a mountain chain rests upon a plateau, rising up in the
very heart of it, its summits seem to be not high, although the basis,
the true foot of the chain, may not be at the level of the plateau,
but far lower, and such mountains may, therefore, be of great absolute
height. The name superimposed mountains has been given to them. Such are
the Kuenlun and the Thian-Shan ranges of Central Asia, the Guadarrama
chain between Old and New Castile, and the Rocky Mountains in North
America. These superimposed ranges often run near to and parallel with
the rim or edge of the plateau, and seem to give it more completeness and
breadth.
The geologist employs the word “sutures” to designate such forms, because
they serve to unite those parts of a plateau which are at different
heights above the sea level. He regards the mountains as rising to fill
enormous clefts which great convulsions have rent in the earth, and as
passing up, while in their fluid state, to a height above the level of
the plateau, and bridging over the abyss. In this way our mountains which
rest on plateaus seem to have been formed, as indeed is indicated by
their geological structure.
The smaller plateaus display analogies kindred to those seen in the
larger superimposed mountain ranges. The extinguished volcanic group
of Auvergne rests upon the central plateau of southern France, which,
according to Remond, has an average elevation of 1000 feet. The now
silent volcanic group of the northern Rhine broke through the moderately
elevated gray-wacke formation of that locality, and is, therefore, a
superimposed range.
Mountain chains which diverge from plateaus and their serrated rims seem,
nevertheless, to have some relation to them, even though they cannot be
considered continuations of them. The Lebanon chain, for instance, which
turns away at a right angle from the Taurus range, and runs southward
through Syria and Palestine; the Lutznetskia and the Alatau Mountains,
mineral ranges running from the Altai northward to Tomsk; the Yablonoi
and the Stanovoi Chrabet ranges running to the northeast; the still
unknown or little known range of Farther India, traversing the whole
peninsula of Malacca, come under this head.
Completely unlike the groups thus far considered, are the isolated
mountain systems, with uniform slopes on all sides, and with a roof-like
form, distinguishable to the base. The mountains of Europe are mostly
of this class—the Ural, Carpathian, Scandinavian ranges, the Alps,
Apennines, and, in part, the Pyrenees. They give rise to rivers, not
on one side alone, as do the Himalayas and the Andes; they are rich
in resources of all kinds for the student and the economist, and thus
make up in part for their comparatively unimportant dimensions. Their
double-sidedness gives them a large influence on civilization, since
rivers flow from them in all directions; while from the Himalayas they
only flow to the south, and from the Andes to the east.
Plateaus and mountains, different as they are in appearance and
characteristics, yet constitute, in their mutual action and reaction,
and in their forms of transition from the one to the other, the highland
system of the globe. Their relations are inexhaustible as Nature herself.
We cannot study them without profit; but we can never come to a perfect
knowledge of them all.
The Relations of Plateau Systems.
Like mountain systems, plateaus are not to be estimated in respect to
elevated and superficial area alone, but in respect to form and position
as well.
The American plateaus are elongated from north to south, but are of
disproportionate breadth from east to west. The Asiatic plateaus, on the
contrary, are not only of great length, but also of great breadth. The
Spanish plateau, that of the Atlas system, and that of Asia Minor have
their length and breadth nearly equal.
The surface of plateaus is exceedingly varied. It sometimes assumes
the aspect of elevated plains, sometimes of rolling land, sometimes
of horizontal strata of naked rock, as in Patagonia and the western
Sahara. In one place it displays sand-hills, as in parts of the Gobi
Desert; in others barren steppes, as in portions of Persia. Sometimes we
find a gradual ascent of minor plateaus or terraces; sometimes single
mountains rising out of the plateaus, as does Demavend; sometimes we find
a chain of colossal peaks emerging from the heart of a plateau, like
Thian-Shan and Bogdo-Oola. Sometimes there are plateaus broken up into
crags and patches of level ground, like Persia; sometimes plateaus with
deep valleys or river basins, like the plateau of Yoorkistan and Gobi,
including the River Tarim, and reaching its greatest depression at Lake
Lop, or, like the plateau of Afghanistan, including the River Hirmend
and Lake Zareh; again, we have plateaus traversed by water-courses which
forced their way in times of flood, and leave in the rainless seasons
the traces of the former violence. Such are some of the less elevated
plateaus of France and Bavaria.
Especially important are the combinations and groupings of plateaus, as
well as their relation to adjacent lowlands.
In Africa the plateau form embraces the larger southern half of the
continent. Low plains are, on the contrary, the prevailing form in the
north, broken, however, by the Sahara, and the high coast plateaus of the
Atlas range, and of Barca.
In Asia there is a vast central plateau with gradual declivities toward
the east, toward Yoorkistan and Persia on the west, and toward Lakes
Baikal and Zaisan on the north. On the south the descent is abrupt to the
Indian lowlands.
In Europe there are, for the most part, scattered and disconnected
plateaus of small size and little elevation, often passing by an
imperceptible gradation to the other forms. The Spanish plateau is,
however, a marked exception, and has the sharply-defined character of the
northern African plateaus. In eastern Europe the central situation of the
isolated Valdai plateau, whose elevation is very moderate, but 840 to
1080 feet, is remarkable, and is of very great influence in determining
the hydrographical character of the great Russian lowlands. And in fact,
the hydrographical influence of both mountains and plateaus is so great,
that it is worthy of careful and special study.
The combinating and grouping of plateaus in different continents give
rise to great contrasts, observable most distinctly in Asia and America.
Asia, with all its great internal depression from Cashgar to Lake Lop,
yet displays such immense districts of plateaus, all ranges of elevation,
low, moderate, and very great, that the very grandeur and extent of its
colossal mountain chains are subordinate in comparison. Asia is the land
pre-eminently of plateaus.
America displays, not in its central but on its western coast, the
greatest chain of mountains on the globe, flanked by plateaus of great
elevation, but of superficial area quite out of proportion to the length
of the mountain chain, and to the extent of the lowlands of both the
northern and the southern divisions. And while in Africa the regions of
depression are in the north, and in Asia around the great central plateau
system, in the Americas, both North and South, they are thrown into the
eastern portion.
Australia, in perfect contrast again, is, with the exception of its
southeastern corner, a vast tract of unbroken lowland. No diversity is
possible there, no change in the condition of life, but a ceaseless
uniformity of monotonous but prodigal gifts.
Is not the imposing grandeur of these harmonious, provisional
arrangements for the use of man calculated to fill the soul with admiring
wonder, and to lead us to suspect, above all this display of cause and
effect, above all this working out of a manifestly preconceived plan,
the existence of a great and active Being, who has planned and executed
it all with higher ends and a loftier purpose than to satisfy the mere
earthly life of man?
Primeval Formation of Plateaus and Mountains.
To enter upon a discussion of the manner in which plateaus and mountains
were formed, would make it necessary to resort to such judgments as we
could draw from their external appearance and their internal structure.
The rapid progress of geology does indeed afford us many probabilities
thoroughly grounded. A few of these may have been briefly indicated in
connection with some elevated regions, where the massiveness is striking,
and where the axis of elevation is prolonged to a considerable extent.
In such cases the influence exerted on the world is more evident than it
could be elsewhere.
_Origin of Plateaus._
Alexander von Humboldt has employed the term Intumescence, to indicate
the manner in which plateaus have been upheaved. Plateaus appear as long,
often wide, mostly level, sometimes rolling, sometimes hilly elevations,
presenting an appearance as if the earth had swelled with confined gases,
and with depressions here and there as if, in the casting of the molten
mass within, a natural external subsidence had followed. They have,
therefore, viewed in their internal structure, an unbroken wholeness, and
are free from those vast fissures which characterize mountains, rending
the earth for hundreds of feet down. The utmost want of uniformity is
seen in the gradual depressions which often harbor the large internal
lakes found in great plateaus. Varied as they are in configuration, they
always retain marks enough to indicate that they owe their upheaval to
steady, gentle, and not tumultuous forces within, exerted at the time of
the primeval cooling of the earth’s crust; in contrast, therefore, with
mountains, which were thrust up from beneath, through huge seams made
by the bursting through of pent-up vapor and gases. These elevations
of the earth’s crust, whether in the form of mountain or plateau, must
correspond, in order that the symmetry of the globe may be preserved, to
the depressions found in lowlands and beneath the water of oceans and
seas.
It is observable that the great plateau upheaval of the Old World has
taken the shape of a belt, which runs in a northeasterly direction along
its whole southeastern shore, crossing the equator at an angle of 45°,
broken, however, at some places, but never so much as to destroy the
coherence of the belt. The diagonal of the rhomboidal plateau of eastern
Asia, passing due northeast through the table-land of Thibet, indicates
the direction of the whole band of highlands. This band drops toward the
south in uniformly steep declivities; while toward the north it falls
away with gradual steps of transition, reaching at length the regions of
the greatest depression—Libya, northern Arabia, the Caspian, Siberia,
and, at last, the low regions around the north pole.
In this belt or chaplet of plateaus lie the high table-lands of South
and Northeast Africa, Abyssinia, South Arabia, Persia, Beloochistan,
North Deccan, Afghanistan, Thibet, East Tangut, and eastern Gobi, in
Mantchooria.
Correspondent with this immense plateau belt, in the New World, is the
great American chain, once a wholly volcanic, and though differing so
much in structure, direction, and hydrographical influence, yet giving
the globe a wholeness, a unity in diversity, which is strikingly apparent.
_The Origin of Mountains._
The linear regions of elevations of the earth’s surface, as we may term
them, in contradistinction to the plateaus which are characterized
by breadth rather than by length, have been projected in the form of
mountain chains, as has been already hinted, through huge fissures made
by the rending of the earth’s crust. The upheaval to fill the seam has,
in some cases, been all made at once; in others, in a succession of
periods. The uniform agreement of all the geological strata or their
diversity decides this point. Sometimes the rocky strata are laid bare
and easily investigated. Often, however, the observer is obliged to draw
conclusions from a part to the whole. Yet in all cases the mountain, in
contradistinction to the adjacent plateau, is the tract which has been
thrust through the crust. The frequent steep and lofty precipices show
the immensity of the internal force required to lift the mountains from
their places, while the lines of stratification indicate the direction
of upheaval. The rifting of a seam in the earth’s crust was the first
step in the formation of mountains; the filling up of the seam by
liquid matter, the second step. The upheaval of Asia, from the Persian
plateau to Gobi, in a line 60° N. E., seems to be connected with the
most ancient revolution which the earth’s crust ever experienced. The
mountains there are, therefore, more modern in origin than the plateau
on which they stand. The direction of the chain, in all cases, seems
to have been dependent on the direction of the fissure in the earth’s
crust, which the mountain range afterward fills. The breaking through
the crust necessarily occurred when the pressure beneath the surface was
very great, or when a moderate pressure was exerted beneath a thin crust,
where the resistance was slight.
The latter case seems to have been prevalent in most plateau regions.
Their own gradual upheaval probably thinned the surface, and made it
more liable to fracture. This accounts for the fact that the greatest
mountains of the globe are found contiguous to plateaus. And the broader
the original seam in the crust was, the broader the mountain range
which rose to fill it, either at a single upheaval, or in a series of
convulsive throes projecting successive masses of molten matter from
below. In the latter cases the strata thus formed lie on each other
like the leaves of a book, their constitution changing according as the
more advanced stages of melting in the vast internal caldron throw out
more metamorphosed rocks. These later layers rose to a greater or less
height on the sides of the partially-formed mountain, according to their
specific gravity, their more or less fluid state, and their rapidity
of cooling, as we can now see by examining the layers in their present
permanent condition.
Thus far we can conjecture, with great security, taught by the manifestly
wild and fierce convulsions which once threw up the mountains, since in
them distortion is the rule and regularity of structure the exception,
and also by the equally manifest quiet and sustained process of
upheaval, when the plateaus were formed; their strata being in a state
of regularity and unbroken repose.
When the great vents produced by the outward pressure of internal
volcanic forces occurred beneath the sea, they were filled up in the same
manner as on the dry land, excepting that the summits of the mountains
emerge above the surface in the form of isolated islands, or when there
was a chain or group of mountains upheaved, as an archipelago. When there
was no rifting of the surface, and no forcing up of whole chains of peaks
through a thinned crust, the fierce action of the internal heat appears
to have necessitated the upheaval of solitary volcanoes here and there,
in some cases even rows of them, to give vent to the pent-up steam and
gases, and to convey away the molten tide within. When such volcanic
series rose in parallel ranges, they lifted, or may have lifted up the
whole district between them, as if upon their shoulders, and so formed
the American type of plateaus, of less breadth and greater length than
the Asiatic, and in height corresponding with the volcanic peaks which
form their rim, and to which they are probably indebted for the form of
their structure.
It needs hardly to be added to what has been said above, that the general
direction of existing mountain chains depends upon the direction of the
primitive seams made in the earth’s surface by internal forces. The Ural
Mountains, the Scandinavian chain, the Alleghanies, the Ghauts, run on
meridian lines; others more or less transversely.
The various kinds of rock which have been thrown up in mountains
enlighten us as to the process and results of the internal heat of the
earth; the successive formations display not only the various eruptions
of molten matter, and its discharge in new layers above what had been
thrown out before, but reveal the relative age of the various formations.
We have in a single chain sometimes a whole volume of history, marking
off the epochs of upheaval with the most perfect legibility and
exactness. Many crystallised rocks result evidently from the gradual
process of cooling after the ancient exposure to the intense heat of the
inner portions of the earth—granite, porphyry, gneiss, slates, and the
so-called metamorphosed rocks. These used to be considered the oldest
formations, but the upheaval theory treats them as the latest formed.
Most mountain chains have been uplifted to their present height by a
succession of upheavals. To accomplish this has been labor of uncounted
thousands of years. Only a very few—the main Carpathian range, for
instance—seem to have been upheaved at a single convulsion, and to have
assumed their present appearance at once. Where there were incessant
eruptions accompanied with flames, and masses of molten matter (lava)
have been ejected from the crest or from single summits, these volcanoes
and volcanic ranges have been the result. Elsewhere no such phenomena
have been visible. Possibly, in such cases, the masses cooled so rapidly
as to extinguish or fill up what may have been embryo craters, and the
plutonic acclivities may have been repressed, leaving us the traces of
primeval eruptions, but no vestiges of any dangerous forces remaining
till now. Of mountains formed in this manner, may be mentioned the Puys
de Dome, the Bohemian basaltic peaks, trachyte Transylvania Alps, the
Katak Kaumene, (“Burnt Tract,”) of Asia Minor, and Hauran, Iceland,
parts of the great American chain, parts of the Sunda chain, the South
Sea Islands, and Bagdoola, and its range of extinct volcanoes in the
Thian-Shan chain.
But other forces besides fire were competent to form mountains and
plateaus, to spread layers of clay and sand and various deposits at
the bottom of the sea, afterward to harden into strata of rock. In
contradistinction to plutonic formations, these have been called
neptunic, because formed at the bottom of the sea. The oldest of the
neptunic or stratified rocks have been upheaved by the subterranean
forces, and now are found in the elevated plateaus or mountain ranges,
still having, however, their unbroken irregularity of structure. Also,
after the stratification has been complete, and plutonic acclivities have
opened the seams in the earth of which I have already spoken, and molten
masses have rushed up to fill them, fragments of the primitive stratified
rocks have been caught up and raised, together with the molten masses, to
the very summits of lofty mountains; so that the geologist finds fossils
there more or less perfectly preserved, the stratified rocks which
contain them surrounded by the plutonic rock upheaved from below the
surface. Chalk layers full of mollusca and infusoria have been found by
Humboldt and von Buch on the very summits of the Andes, and corresponding
with those which have been discovered by Ehrenburg in the deposits at the
bottom of the sea.
Other older and more recent oceanic deposits are found in their primitive
condition at the bottom of the sea, or in very low places on the land.
In such localities the surface of the earth is composed of horizontal or
slightly inclined layers or strata, of secondary formation, and whose
origin in deposits from water cannot be denied. These are the beds
of chalk, clay, sand, marl, gypsum, and other common substances; and
these strata again have been overlaid with more recent accumulations,
the result of diluvium or alluvium, continuing even up to the present
time.[5]
Lowlands.
This variety of the earth’s surface stands in the strongest contrast with
mountain regions, or, in one word, with the highland form in all its
modifications. The name lowland we apply to all those broad tracts which
do not rise more than four hundred feet above the level of the sea. The
absolute elevation is determined from a section drawn vertically from the
superior surface to the plane of the sea. Every comparison by numbers
of one lowland plain with its more elevated surroundings gives only a
relative result, as for instance, in comparing the valleys of one chain
of mountains with those of a more lofty chain. Such relative lowlands
may lie at a great elevation above the sea, as the vale of Chamouni, for
example, at the north foot of Mont Blanc, is 3000 feet above the ocean
level. Both conceptions of the word lowland, which is common to elevated
plains as well as those at the sea’s margin, are entirely different, and
should be kept distinct, although they are very often confounded.
We are to deal here only with the absolute, great, and generally diffused
lowlands, in contrast with which the elevated valleys and plains just
referred to may be considered as mountain table-lands and the rims of
plateaus.
We assume, as we did in judging of the two grades of plateaus, an
arbitrary standard of measurement, and limit the rise of real lowlands
to an altitude of 500 feet above the level of the sea. Great tracts of
running plain, rising by so slight a grade as to be almost imperceptible,
can be regarded only relatively as lowland, and, in a strict sense,
belong to those regions of transition which fall more truly within the
domain of highland or plateau. The word plain indicates the opposite of
hill or mountain, but has nothing to do with the greater or less degree
of absolute elevation, although it is often used as if it had.
The lower limits of lowlands are sharply defined enough. They are
the margin of the sea, toward which the slope usually becomes almost
imperceptibly small. Often the expression is used, yet not quite fitly,
that the lowland extends into the sea for some distance, and is found
beneath the surface. Strictly this is the bottom of the sea, and does not
fall under consideration in this connection.
Many lowland plains rise so slightly above the sea level, that they are
not unfrequently submerged, and, in many cases, owe their existence to
repeated overflows. They are the basins of old gulfs, as in the very
slightly elevated plains of Caracas, whose whole shore is open to the
influences of the great Atlantic current flowing from east to west;
or, as in the great Lombardy plain, which slopes at the same almost
imperceptible degree toward the Adriatic. There are also some lowlands
found in the interior of continents, and these, too, sinking below the
level of the sea; but they are altogether exceptional, and only met with
in two or three instances. They are called, by an accommodation of an
algebraic term, _negative_ lowlands. To them belong the region around the
Caspian and the Aral Seas, and the much smaller tract comprising the Dead
Sea, and forming the Jordan valley; besides, there is the Suez steppe,
inclosing the bitter lakes between Asia and Africa; and possibly the
Beled-el-Jereed, in the western part of the Sahara and the central part
of Australia.
To these it might not be incorrect to join those partial lowlands which
have been rescued by human efforts from the sea; the marshes, for
instance, behind the dikes of Holland, Sleswick, East Friesland, and at
the mouths of the Vistula, the Weser, the Nile, the Ganges, and other
rivers.
The most extensive lowlands in the world are probably those which embrace
Siberia, in Asia, and the Canadian and polar region of North America.
Many great tracts, entirely inland, are in those flat districts covered
by sea-water which was once driven in by great storms, and now lies
stagnant, resulting in inapproachable swamps and morasses. Yet, under the
equator, there are immense lowlands, as, for instance, in the eastern
Sahara, although this region is broken by strips of plateau, and is by no
means that uniform lowland plain which it used to be regarded. Northern
Australia belongs to the same category, and also those immense plains
which reach from the Atlantic so far into the interior of Brazil, along
the lower Amazon. By the time, however, that they reach the middle course
of that river, they have acquired, though in such imperceptible steps, a
considerable degree of elevation, according to Humboldt’s barometrical
observations, and not reckoning certain limestone hills found there,
from 1050 to 1200 feet. The plains of the middle Marañon are, therefore,
true plains, but not absolute lowlands, and not to be identified with
the great flat region at the mouth of the river, and in comparison with
the real lowlands of Venezuela, which do not rise over 200 feet above the
sea, and genuine plateau, which, level as it is and broad as it is, is
far more elevated than the Valdai plateau, in Russia.
Almost all great river mouths are true lowlands—the Egyptian delta, the
delta of the Ganges and the Indus, for instance, (the two latter being
separated by the very moderate plateau (100 feet) between Delhi and
Mooltan;) to these we may add the delta of the Euphrates, the east shore
of China, between the Blue and the Yellow Rivers, and Senegambia, between
the Senegal and the Gambia. And in America, the same thing occurs in the
Mississippi, Orinoco, Amazon, and La Plata, where the immense mass of
water which they send to the sea passes through lowlands of very great
extent. In the Mississippi they extend from the mouth as far north as the
confluence of the Missouri and the Mississippi, where stands St. Louis,
not 500 feet above the level of the sea. The prairies west of the lower
course of the river rise rapidly, though imperceptibly to the eye, to the
high terraces of Kansas, at Council Grove, varying from 1500 to 2000 feet
absolute elevation, and then more rapidly toward the west, to mountain
plains or plateaus, from 3000 to 6000 feet high. These, of course, lose
the distinctive character of lowland.
The mouth of the St. Lawrence is, in some respects, analogous. Lowlands
accompany it for a great distance from the sea; at Lake Ontario the
elevation is only 232 feet, at Lake Erie only 565 feet. Yet the level
tract is narrowed down to a mere border, and does not widen into great
lowland plains. The contracted region of low country along the St.
Lawrence is broken up, too, by rocky heights and rib-like ledges, whose
absolute height, however, is not to be confounded with the elevation of
the plain which they traverse.
In entire contrast are the broad plains of South America, which lie
along the course of the Orinoco, La Plata, and Amazon, the so-called
pampas and savannas, which extend a great distance into the interior,
farther, indeed, than investigators have yet thoroughly prosecuted
their researches. In no continent are the distinctions between highland
and lowland so sharply drawn as in America. The lowland plains occupy
four-fifths of all the country east of the Andes, in South America: only
one-fifth is highland; for, notwithstanding the extent of low plateaus
and diminutive mountains scattered through these great plains, yet their
entire amount is inconsiderable, compared with the immense lowland
tracts of that continent. America has fitly been called the region of
the greatest depression on the globe, because this is the prevailing
characteristic of its whole eastern side, lowlands forming two-thirds of
all America, and highlands only one-third.
In Asia, the later hypsometrical observations have shown that the
lowlands are by no means so extensive as they were formerly supposed. The
highland extends, according to von Middendorf, much farther northeast of
the Yenisei, toward the northern limit of Siberia and Tschatschi, than
was formerly supposed; and the Siberian plain extending westward to the
Ural Mountains is narrowed down from 4,079,970 to 2,233,800 square miles.
Yet this lowland comprises, including central Bokhara or Toorkistan,
1,051,200 square miles, and other low Asiatic plains 1,314,000, the
enormous area of 4,599,000, or more than twice the extent of Europe,
leaving 9,636,000 square miles for the highlands.
In Africa there are almost no lowlands to speak of, excepting the
districts around the mouths of the great rivers indicated a few pages
back. To all equatorial Africa this physical feature is entirely wanting.
In the north, where the whole Sahara was formerly thought to be one
vast low plain, there are now known to be the moderate plateaus already
indicated. The area of true lowland is, therefore, sensibly diminished.
Vogel’s barometrical observations have already shown us that the country
around Lake Tchad is about 1200 feet above the sea; the surface of Lake
Tchad is 850 feet above the ocean level, and the lower limit of that
region does not, therefore, come within the range already set as the
point where lowlands become highlands.
In Australia the lowland seems to be the prevailing physical form,
although here and there exceptions to it occur.
In Europe there are three great lowland plains to be specially mentioned.
The greatest, that of middle Europe, embraces the shores of the North
Sea and the Baltic far inland, and extend the farthest to the southeast.
A second, hardly of less extensive proportions, comprises all northern
Russia as far as the White Sea and the Arctic. It embraces but one-third
of the great polar plain, and is really one with the region beyond the
Ural chain. The third is the region around the Black and Caspian Seas.
The Middle European Lowlands.
The Germanic-Sarmatia-Russian plain extends, without a break, from the
mouths of the Rhine, through all central Europe, to the middle Volga
and the Ural. It is pre-eminently a region of lowlands, without any
elevations of importance, and having no change of level, except very
gently undulating swells, and on the north and south margin plateaus
which very seldom rise over 500 feet. It begins with the deltas of the
Rhine and the Scheldt, in Holland, passes through Lower Westphalia, Lower
Saxony, the Marks, Lower Silesia, Lower Gallicia, and Poland, as far as
the upper Dnieper and the middle Volga. It extends up the Rhine as far as
Strasbourg, 474 feet above the sea, up the Weser as far as Cassel, 486
feet, and up the Elbe as far as Dresden, 280 feet.
The true Rhine delta may be defined as lying between Amsterdam, on the
sea, and Dusseldorf, 107 feet above the sea level. Then passing by
the broken and romantic tract lying between Dusseldorf or Cologne and
Mayence, we come to the true Rhenish lowland, 240 feet above the sea.
Munster is 400 feet above the ocean level. East of the Weser is the
Lüneburg Heath, which advances in elevation, as we go toward the Elbe and
the Havel, to 300 or 400 feet. Brunswick lies at an altitude of 200 feet;
Magdeburg, of 128 feet. The height gradually increases; at Wittenburg it
reaches 204 feet; at Dresden 280 feet, where the Elbe issues from the
highlands; and in Lower Silesia we find Breslau, 375 feet above the sea,
and its observatory, standing on the hills around the city, at a height
of 453 feet, which seems to be the highest point in the whole vast tract.
Between the Rhine delta and the now dry basin of Paderborn, from the Ems
to the Weser, Aller, and middle Elbe, is the mountain tract of the Hartz,
(with the Brocken at the north, 3500 feet high,) running up as far as
52½° N. lat. By this natural feature the breadth of the great plain is
considerably curtailed. As it is also more to the east of the Leipsic
basin, from which the Mulde, Elbe, and Elster flow, by the hill country
of Lausatia and North Silesia, with the Riesengeberge, (Giant Mountains,)
5000 feet high, which extends northward as far as 51° N. lat.
A third basin is in the Silesian, from which the Oder flows toward the
northwest, and enters the southern limits of the great plain near Oppeln
and Brieg. A third tract of hill country lies on the east bank of the
Oder, and extends to the middle Vistula, the Tarnowitz Heights, in Upper
Silesia, about 1000 feet in altitude. The plateau north of the Carpathian
range, on which Cracow lies, is 669 feet above the sea; and the most
northern hill group of Kielce, between the Pilica and the Vistula, rises
in the Kreutzberg to a height of 1920 feet, and in St. Catherine to 2000
feet.
The great lowland advances eastward, with always diminishing breadth
from north to south, over the extensive plains of the middle Vistula,
at Warsaw, 330 feet above the sea; over the Lithuanian morasses of the
Bug; over the Sarmatian district of Minsk and Pinsk as far as Kiev, on
the middle Dnieper, at the southeast, and as far as Orsha and Smolensk,
at the northeast. Pinsk, in the middle of this tract, lies about 400
feet above the sea. The north side of the plain is bounded by the very
moderate plateau south of the Valdai hills, at Smolensk, 792 feet high;
at Osmana, southeast of Minsk, 882 feet. On the south side it is bounded
by the equally moderate plateau of Wolhynia and Podolia, whose absolute
altitude is yet undetermined, but which, at the source of the Bug, is
about 1000 feet.
This is the great Lithuan-Sarmatian plain, which, east of the Dnieper,
is transformed into the central Russian lowland, at whose middle point
is Moscow, whose exact elevation above the sea is between 300 and 400
feet; at Kazan, on the Volga, the height above the ocean level is but
270 feet, measuring from the highest point on the banks. Southward, the
plain reaches to Simbeersk, 181 feet in altitude. The maximum breadth of
this whole vast lowland tract is about 500 miles; the distance between
Smolensk and Kiev, and the distance from the central point of the great
Russian section to any sea, is between 500 and 600 miles.
The Origin of the Great Central European Plain.
The slight elevation of the lowland just described, rising but very
little above the sea level, bears, throughout the most of its extent
between the dunes of the north and the hill chains of the south, the
character of a formation rescued from the domain of the sea within the
very latest geological periods. The almost unbroken uniformity of the
surface from the Scheldt to the Volga, about 2500 miles, confirms the
character which its geological structure indicates. The deposition of
disconnected, superimposed layers, running to a great depth, is exactly
similar to that which we know results from the action now going on at the
bottom of shallow seas. And in the great central European plain there is
no sharply-defined geological limit met at the border of the North and
the Baltic Seas. The same features extend beneath the surface of both
of those seas. This whole lowland is, therefore, to be regarded as an
immense basin, now dry, but once the bottom of a great sea,—an extension
of the seas which now form a part of its northern border. The old coasts
are now seen far inland. Wherever this coast-line changed its course, the
whole landscape now alters its appearance; and yet more striking than
the external view is the internal constitution of the soil. Masses of
stone, standing out in full view, reveal the inner structure of what lies
concealed. And these rocky projections are precisely analogous to the
jagged outlines of our present bold sea-shores. The land is not cut up by
inlets hollowed out by the action of waves and currents to a considerable
depth, yet traces of such movements, and of the physical formations
effected by them, are found. Promontories and islands are now found
in plateaus, and hills encompassing dry basins. To the latter belong
the intervale of the Rhine, and the basins of Paderborn, Leipsic, and
Silesia. To the former belong the hills and plateaus of Middle Germany;
of the Westphalian Mark, from Elberfeld to Dortmund, or, as might be
said, from the Ruhr to the Lippe; the Yeutoburg Forest to the Weser; then
the Weser Mountains, and the Hartz to the middle Elbe; the Thuringian
Forest and the Ertz Mountains around the Leipsic basin to the upper Elbe;
the Lausatian Mountains and the Riesengeberge to the Glatz Mountains, on
the upper Oder; the Trebnitz Heights of Silesia, and the lower plateaus
of the Fore Carpathian range, embracing Cracow as far as the hills of
Kielce and the confluence of the Sau with the Vistula. Along the southern
border of the ever-broadening plain are the plateaus of Gallicia, about
1000 feet in height, of Wolhynia and Podolia, and then less elevated
plateaus, till we reach the Dnieper.
The geological character of the border of the sea which once covered
what is now central Europe, is full of interest, because from it can be
deduced all that we can know of the history of those great changes.[6]
But we must pass over this, and only indicate the geographical
configuration of the dry basin as it exists now, and forms the great
Germanic-Sarmatia-Russian plain.
In the course of previous remarks on the lowest range of plateaus, I
have remarked, that along the south coast of the Baltic the moderately
elevated hill chains of Pomerania and of Old Prussia separated the true
coast with its lowland from the great interior plain, forming a barrier,
averaging about 300 feet in height, with here and there a form which runs
hard upon the lower limit of plateaus of the second class; at any rate, a
transition from between the lowland and the plateau.
It may here be remarked that the long, low chains, made up mainly of
loose sand and other mixed and uncombined materials, and running along
the southern border of that long, low band which skirts the Baltic, seem
to be dunes once running along the shore of a sea which has now receded
many miles to the north. In the deep channels and old inlets now dry, as
for instance in the great break through which the Vistula passes below
Thorn, only loose breccia, and no united layers of stone, appear. Yet
this does not seem to be the case everywhere, although in the Cis-Ural
and Baltic depressions dune-like ridges are to be found, some of them
rising to a height much greater than was formerly suspected. These, it
is true, are scattered, and only partially prevalent, but here and there
they ascend to an altitude of nearly 1000 feet. At the eastern end of
the great Pomeranian sea-plain west of Dantzic, and between that city
and Bütow, where the sand ridge, which formed the ancient shore-line,
runs very far to the north, there are a number of villages 400 feet above
the sea. The Lower Mountain, (Thurmberg,) 54° 13′ 29″ N. lat., rises
to a height of 1024 feet; the hill near Upper Buschkau, east of the
Thurmberg, is 814 feet high; the hill near Hulterfeld, 846 feet; and the
Höckerberg, near Schönberg, 902 feet.