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Eng‘?- by Erhard. Dram by A.Vuillemin
% HARPER & BROTHERS, NEW YQRK


f/ /
THE EARTH
A DESCRIPTIVE HISTORY OF THE


PHENOMENA OF THE LIFE OF THE GLOBE.
BY ELISEE EECLUS,
TRANSLATED BY THE LATE B. B. WOODWARD, M.A.,'
AND
EDITED BY " HENRY WOODWARD, BRITISH MUSEUM.
[LLUSTRA TED
BY.
TWO HUNDRED AND THIRTY MAPS INSERTED IN THE TEXT,
AND TWENTY-THREE PAGE MAPS PRINTED IN COLORS.


NEW YORK:
HARPER & BROTHERS, PUBLISHERS,
FRANKLIN SQUARE.
187m
CONTENTS.
PARTI.
THE EARTH As A PLANET.
CHAPTER L-omallness of the Earth as compared with the Sun and Fixed Stars; Grand-
eur of its Phenomena—Form of the Terrestrial Globe; its Dimensions . . . . . . . . . . . . . .
CHAPTER II. —Motion of the Planet. —Diurnal Rotation and Annual Revolution.-—Si-
dereal and Solar Day. -—Succession of Days and Seasons. ——Diﬁ"erence of Duration of
the Seasons in the Two Hemispheres. -Precession of the Eqninoxes. —Nutation. ——
Planetary Perturbations. ——Movement of the Earth towards the Constellation Her—
cules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - . . . . . . . . . .
CHAPTER III.——Various Opinions as to the Formation of the Earth—Laplace's Hypoth-
esis; grave Objections raised to it. -—Theory of a Central Fire; Objections to it . . . . . ..
CHAPTER IV.—-Geological Strata—Conglomerates.—-Sandstones.—Clays.-——Limestones.
——Fossiliferous Beds—Sequence of Organic Beings—General Classiﬁcation of Strata.
——Duration of Geological Periods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
CHAPTER V.——Incessant Modiﬁcation in the Shape of Continents—Attempts made to
learn the former Distribution of Soils and Climates. ——Object of Geology—Province
of Physical Geography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

P A R T I I.
THE LAND.
CHAPTER VI. —Regular Distribution of Continents. —Ideas of Ancient Nations on this
Point. —Hindoo Legends—Atlas and the Giant Chibchacum. —-Homer’s Shield. —-
Strabo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .- . . . . . . . . . . . . . . . . . . . . ..
CHAPTER VIL—Inequality of Land and Water.—The Oceanic Hemisphere—The Sem-
icircle of Land. ——Distribution of the highest Plateaux and loftiest Mountain Chains
round the Indian and Southern Oceans. —Polar Circle. —Circle of Lakes and Deserts.
-—-Coasts arranged in Arcs of a Circle . . . . . . . . . . . . . . . . . ., . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
CHAPTER VIII.—Division of the Land into the Old and New Worlds.—Double American
Continent—Double Continent of Europe and Africa. ——Double Continent of Asia and
Australia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHAPTER IX. —Principal Analogies between Continents.—Pyramid Form of Portions of
the World. —Slopes and Declivities. —Closed Basins of each Continent. —Southern
Peninsulas in each Group of Continents—Hypothesis of Periodical Deluges.—Rhyth-
mical Arrangements of Peninsulas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
' CHAPTER X.——Numerous Indentations of the Northern Continent. —Heaviness of Form
in the Southern Continents—Inequality of Size in the Continents of the Old VVorld.-—-
Extent of Coast-line in Inverse Ratio to the Area of Land. —Contrasts between the
Old World and the New. —The Transverse Position of the Axes of America and the
Old World—Contrasts of Climate in the various Continents; North and South, East
and West . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Page
13
16
24
39
46
50
64
(39
iv CONTENTS.
CHAPTER XI.-—Harmony of Shape in Oceans—The two Basins of the Paciﬁc.—The two
Basins of the Atlantic. —The Arctic Frozen Ocean and the Antarctic Continent. ——Con-
trasts, an Essential Condition of Planetary Vitality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHAPTER XII. — General Aspect of Plains—Alluvial Plains. -——Cultivated Plains. —Uni-
formity in Uncultivated Plains—Varieties in Appearance produced by Climates and
different Physical Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHAPTER XIIL—The French Landes—The Brandes and the Alios.—The Campine.—
The Heaths of Holland and Northern Germany. —The Puszta of Hungary. —The
Grassy Steppes of Russia.—The Salt Steppes of the Caspian and the Aral.——The Tun-
dras...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 . . . . . . . . . . . ..
CHAPTER XIV. —-Semicircle of Deserts parallel to the Semicircle ofLandes and Steppes.—
The Sahara—Sands, Rocks, Oases.—-The Deserts of Arabia—The Nefoud.—Deserts
of Iran and the Indus.—The Desert of Cobi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHAPTER XV. —Plains and Deserts of the New World. —-Humidity of the American
Continents. —- Distribution of Savannahs and sterile Tracts. —The Prairies of North
America—The Llanos and Pampas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHAPTER XVI. —American Deserts—The Great Basin of Utah.—The Desert of Colo-
rado.—The Atacama and the Pampa of TamarugaL—Deposits of Salt, Saltpetre, and
Guano . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHAPTER XVIL—Diﬂ'erence between Plateaux and Plains. ——Material Importance of
Plateaux in the Economy of the Globe—Distribution of elevated Regions on the Sur-
face of Continents ....................... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHAPTER XVIII. -—The Great Plateaux of Central Asia and the Gate of the Hindoo
Kntch. ——Plateaux of Europe. -——Their symmetrical Arrangement. --Plateaux of the
two Americas. —Similarity between the closed Basin of Bolivia and the District of
Utah.—Plateaux of Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHAPTER XIX—Isolated Mountains.-—Mountains in Groups—Chains and Systems of
Mountains. -—The Beauty of Mountain Peaks. —— Sacred Mountains. — Pleasures of
Mountain Climbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHAPTER XX. —Various Forms of Mountains. —Poverty of polished Languages in de-
scribing their Appearance. —-Richness in this respect of the Spanish Language and
the Alpine and Pyrenean Pat0is.——The numerous Provincial Terms employed for va-
rious Shapes of Hills and Mountains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHAPTER XXL—Inequalities and Depressions in the Vertical Outline of Mountains. —
Origin of Valleys, Gorges, and other Depressions.—-Longitudinal Valleys. —Transverse
Valleys—Winding Valleys with Parallel Sides.——Valleys with Deﬁles and Gradations
of Levels.—Cluses and Caﬁons._—Gcneral Arrangement of Valleys. ——Amphitheatres.
——The ()ules of the Pyrenees.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHAPTER XXII. —Depressions in Mountain Ridges. —-Diversity in the Form of Passes
(Cols).~—Relation between the respective Altitudes of Summits and Passes.——Law of
Debouchments. —Real and Ideal Slopes of Mountains. —Estimated Solid Contents of
Mountain Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .'
CHAPTER XXIII. —-Hypotheses as to the General Laws of Mountain Chains. ——M. Elie
\de Beanmont’s Theory of Parallel Upheavals. ——Chain of the Pyrenees taken as a Type
of the Cordilleras or Longitudinal Chaim—Various Irregularities in the Chaim—The
Pyrenees as an Ethnological Barrier . . . . . .. .
Page
81
90
97
102
107
111
117
122
139
a o n o a ‘IOJSOIOQ'IOOOI'Il'II‘IUIIOOOOIO".
CHAPTER XXIV.—Mountains of Central Europe—Contrast between the Alps and the
Jura.—The J ura as a Type of a System of Mountains with Parallel Chains—Appar-
ent Chaos of the Alps—Central Group of St. Gothard.—Groups of Monte Rosa and
Mont Blane—The Alps considered as a Frontier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
144:
CONTENTS.
CHAPTER XXV.—-Mountain Chains of Central Asia.—The Kouen-Lun, the Karakorum,
the Himalaya—The South American Andes, a Type of the Bifurcated Chain . . . . . . . .
CHAPTER XXVI. —G radual Cooling of the Air on Mountain Sides.——Diﬂiculty of Ascents.
—-Limits of Man’s Habitation.—Illness felt by Mountain Travelers . . . . . . . . . . . . . . . . . . .
CHAPTER XXVIL—Gradual Subsidence of Mountains during the Lapse of Ages—Sud-
den Downfalls and Chaos—The Fall at Felsberg.—Slow Action of Meteoric Agencies

P A R T I I I.
TIIE CIRCULATION OF WATER.
CHAPTER XXVIII. —Snow-fall on Mountains. —Lower Limit of Snow. —Zone of Per-
petual or Permanent Snow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHAPTER XXIX. ——Inﬂuence of the Sun and Meteoric Agents on the Snow. —Avalanches.
-—Protecting Forests.——Defensive Works against Downfalls of Avalanches . . . . . . . . . . . .
CHAPTER XXX. —-Gradual Transformation of Snow into Ice.—Néve's, or Glacier-reser-
voirs—Phenomenon of Regelation.—Crystals of Ice. —Glaciers of the First and Second
Order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHAPTER XXXL—Movement of Glaciers—Experiments and Theories.—-Convexity of
the Central Part of a Glacier.—Its successive VVindingsr—Friction of the Ice against
the Bottom and Sides of the Bed—The Glacier Gauge. -—-Inclination of the‘ Glacier Bed
CHAPTER XXXII. —Marginal, Transversal, and Longitudinal Crevasses. -—Se'racs. '—
Moulins. —-Bridges of Snow. —Veins of fresh Ice. —Surface-streams on Glaciers.—
Gouilles.-—Lakes and Inundations.-—-Discharging Channels . . . . . . . . . . . . . . . . . . . . . . . . . .
CHAPTER XXXIIL—Débris lying on the Surface of the Glacier.—Holes in the Surface.
— Glacial Tables. —Moraines; Lateral, Medial, and Frontal. —Ribbons of Mud. —-
Measurement of the Speed of Glaciers—Ablation.—Sub-g1aciary Streams.——Terminal
Arches. —Contrast between the Glacier Ice and the surrounding Vegetation . . . . . . . . . .
CHAPTER XXXIV. —Progress and Retirement of Glaciers. --Appearance of the Bed
when abandoned by-the Ice. —Roches Moutonnées.—Parallel Furrows . . . . . . . . . . .
CHAPTER XXXV.——-Distribution of Glaciers over the Surface of the Earth . . . . . . . . . . . . .
CHAPTER XXXVI. —-The Glacial Period—Ancient Glaciers of Europe. —Dispersion of
Rocks and Boulders from Scandinavia and in North America. —-Ancient Glaciers in
Tropical Regions . . . . . . . . . . . . . . . .; . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHAPTER XXXVIL—Secondary Part taken by Glaciers in the Circulation of Water.—
Mountain Flood-waters. —-Absorption of Rain and melted Snow by the Earth, Peat-
mosses, and Rocks. —Springs and their Nymphs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHAPTER XXXVIIL—Variation in the Discharge of Springs.——Estavelles.—Equaliza-
tion of the Supply in Springs with deep Sources.—Intermittent Springs . . . . . . . . . . . . . .
CHAPTER XXXIX. —-Ascending Springs. —Artesian \Vells. — Temperature of J etting
Springs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHAPTER XL. —Cold and Thermal Springs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHAPTER XLL—Mineral Springs.-—Incrusting Springs.—Metallic Veins. -—Salt Springs
CHAPTER XLII. —Subterranean Rivers. —-The Spring of Vaucluse, the Touvre. —Sub-
marine Aﬁ’iuents.—'I‘he Rios of Yucatan.—The “ Mud-lumps” of the Mississippi. . . . .
CHAPTER XLIIL—System of Subterranean Streams.--Joints and Fissuresof Rocks.—
Stalactites.—-The Inhabitants of Caves.—The Mammoth Cara—Caverns of Carniola
and Istria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Page
183
192
201
206
‘216
222
997
NJ
31
IO IO
co 0::
on s-
245
251
Vi CONTENTS.
. . . , Page
CHAPTER XLIV.—Rivers.—Various Denominations ofWater-courses.——Determ1nation
of the principal Branch among the Afﬂuents of a River. 4—River Basins and Water-
sheds.—Forks of certain Rivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
CHAPTER XLV.——The Hydrographical Systems of various Parts of the \Vorld . . . . . . . . . 271
CHAPTER XLVI. —The River of the Amazons. —Diversity in the Character of Water-
courses. -—Unity of the Law which governs them. —Equalization of their Slopes. ——
Upper, Middle, and Lower Courses of Rivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
CHAPTER XLVII. —Mountain Torrents—Inequalities of their Beds and of their Dis-
charge of Water. —Temporary Streams—Filling up of Lakes.—Erosions, Gorges, and
Slopes.—T0rrents of the French Alps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284
CHAPTER XLVIIL—Erosion of Lacustrine Dikes.—Cataracts and Rapids . . . . . . . . . . . . . 296
CHAPTER XLIX.—Formation of Islands—Reciprocity of Curves—\Vindings and Cut-
tings.-—Shifting of the Courses of Aﬁluents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306
CHAPTER L.—Periodical Rising of Streams. —“ Embarras" of Floating Trees.—Ice_
ﬂoods in the Northern Rivers—Inundations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
CHAPTER LI.——Means of Preventing Floods—Natural and Artiﬁcial Reservoirs—Irri-
gation Channels-—Ernbankments, and Cracks in them . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325
CHAPTER LII. —The Mouths of Rivers.——Estuaries.—Long Banks of Sand—Deltas.—
N et- work of Branches of Rivers in Alluvial Plains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 339
CHAPTER LIII.—-'I‘he Channels of the Mississippi.— “ Working Rivers.”—Shifting of
the Point of Bifurcation—Raising of the River-bed above the Delta.——Alteration in
the Situation of the Mouths of Rivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349
CHAPTER LIV. ——Bars of Rivers. --Operations undertaken for Deepening the Mouths of
Rivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 363
CHAPTER LV.-—Alteration in the Position of Water-courses in Consequence of the R0-
tation of the Earth—Masses of Water brought down to the Sea by Rivers. —General

Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 372
CHAPTER LVI.—Lakes.——Formation of Lakes—Their Increase and Diminution.—Their
Form and their Depth—Lakes lying in Successive Gradation of Elevation . . . . . . . . . .. 383
CHAPTER LVII.——Various Phenomena in Lakes—Color of their “Taters—Seiches—
Currents and Tides.——-Formation of Ice in Lakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 39%
CHAPTER LVIIL—Lakes acting as Regulators of the Rivers which pass through them,
-—-Fresh-water and Salt-water Lakes—The Caspian Sea . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399
CHAPTER LIX—The Dead Sea. —The Salt Lakes of Asia Minor and the Russian Steppes.
—The Great Salt Lake. —The Melr’ir . . . . .., . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407
CHAPTER LX.—-—Marshes.—Swamps of North America.—Peat-bogs.-Unhea1thiness of
Marshes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 413
P A R T I V. ’
SUBTERRANEAN FORCES.
CHAPTER LXI. —Eruptions of Etna in the Year 1865.—Mutual Dependence of all Ter-
restrial Phenomena . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 419
CHAPTER LXIL—Sea-coast Line of Volcanoes—The Paciﬁc “ Circle of Fire."-——Vol-
canoes of the Indian Ocean; of the Atlantic; of the Mediterranean; of the Caspian;
of Central Asia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 426
CHAPTER LXIII. —Torrents of Steam escaping from Craters. —-Gases produced by the
Decomposition of Sea-water.——Hypotheses as to the Origin of Eruptions.—Independ-
ence of the several Volcanic Outlets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . 433
CONTENTS. vii
Pa
CHAPTER LXIV.—-Growth of Volcanoes—Theories of Humboldt and Leopold von Buch g8
as to the Upheaval of Craters.——Disagrcement of these Theories with the Facts observed 440
CHAPTER LXV. —Number and Arrangement of Volcanic Outlets—Form of Volcanic
Cones and Craters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 445
CHAPTER LXVI. —-Composition of Lavas; Trachytes: Pumice-stone; Obsidian; Ba-
salts; Basaltic Co’lonnades . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .r . . . . . . . .. 453
CHAPTER LXVIL—Sources of Lava; Stromboli; Masaya; Isalco; Kilauea—Lateral
Crevices in Volcanoes.-—Eruption and Motion of Lava . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 458
CHAPTER LXVIIL—Volcanic Projectiles.-—Explosions' of Ashes. -Subordinate Volca-
noes.—Mountains reduced to Dust.—Flashes and Flames proceeding from Volcanoes 468
CHAPTER LXIX.—Streams of Mud ejected by Craters—Mud Volcanoes . . . . . . . . . . . . . . . 475
CHAPTER LXX. -— Volcanic Thermal Springs.—— Geysers.— Spring in New Zealand.—
Fumerolles.—-Solfataras.—-Craters of Carbonic Acid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 480
CHAPTER LXXI.-—Submarine Volcanoes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 489
CHAPTER LXXII. —-Periodicity of Eruptions.—Inﬂuence of Temperature on Volcanic
Phenomena. -—Extinction of Furnaces of Lava . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 497
CHAPTER LXXIII.-—-Earthquakes.—Vibrations of the Ground—Various Hypotheses . . 500
CHAPTER LXXIV.—Earthquakes of‘ Volcanic Origin. —Subterranean Downfalls.—-Ex-
plosions of Mines and Powder-mills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 503
CHAPTER LXXV. — Great Catastrophes. —-Earthquake at Lisbon. —- Area of Disturb-
ance—Earthquakes at Sea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 507
CHAPTER LXXVI. -—-Movement of Terrestrial WVaves. —Variations caused by the In-
equality of Vertical Outline and the Diversity of Rocks. —Areas of Disturbance. —
Noise of Earthquakes—Fright of Men and Animals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 511
CHAPTER LXXVIL—Secondary Effects of Shocks.—Springs.—Jets of Gas.—Fissures.
-—Depressions and Elevations of the Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 519
CHAPTER LXXVIII. ——Periodicity of Earthquakes. -—The Maximum in Winter. —The
Maximum at Night. — Coincidence with Hurricanes. --Inﬂuence of the Heavenly
Bodies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 523
CHAPTER LXXIX. --Slow Oscillations of the Ground. ——Diﬂiculties presented in the
Observation of these Phenomena—Causes of Error: Erosion of Shores, Swelling and
Sinking of Peaty Soils.——Inﬂuence of Temperature. -—Local Upheavals . . . . . . . . . . . . . . . 527
CHAPTER LXXX. ——Upheaval of the Scandinavian Peninsula; of Spitzbergen; of the
Coasts of Siberia; of Scotland; of Wales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 531
CHAPTER LXXXI.-—Upheaval of the Mediterranean Regions.—Former Libyan Strait.
—Coasts of Tunis, Sardinia, Corsica, Italy, and Western France ..... . . _. . . . . . . . . . . . . . 538
CHAPTER LXXXIL—Coasts of Asia lV[inor.—Ancient Ocean of Hyrcania.-—-Coasts of
Palestine and Egypt. —The Adriatic Gulf . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 542
CHAPTER LXXXIIL—Subsidence of the Shore of the Channel, of Holland, of Schleswig,
of Prussia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 546
CHAPTER LXXXIV.—Upheaval of the Coasts of Chili and Perm—Probable Depression
of the Coasts of La Plata and Brazil—Coasts of North America and Greenland . . . . . 550
CHAPTER LXXXV. -—Reefs of the South Sea. —-Darwin’s Theory as to Upheavals and
Depressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 556
CHAPTER LXXXVL—The Great Areas of Upheaval and Depression—Mobility of the
so-called Rigid Crust of the Earth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 562
ILLUSTRATIONS.
[The Illustrations I. to XXIIL, the titles of which are in capital letters, are printed in
colors, their place being opposite to the pages indicated. The other cats, designated as F ig-
ares 1 to 234, are inserted in the pages as given.]


NUMBER PACE NUMBER PAGE
I. MAP OF THE WORLD ................. .. . 1 31. The Mountains of Gavarnie... 126
II. GEOLOGICAL CHART OF THE WORLD 13 32. Pene: Piz a Lun de Guscha ........ .. 127
1. Solar and Sidereal Day .............. .. 18 33. Tete: Wallenstock deWolfenschiessen 127
2. Orbit of the Earth around the Sun“, 20 34. Channel of the Bosphorus ............ .. 131
3. The Pyramid Mountain .............. .. 33 35. Circular Valley of Ourdinse ......... .. 134
III. GEoLoCICAL MAP OF ENGLAND. . 37 36. The Pyrenees ........................... .. 141
4. Paradoxides Harlani ........ ..'. ...... .. 37 37. Luchon and Val d’Aran .............. .. 142
5. The Weald of Kent ................... .. 41 38. The Sierra de Marcadau ............. .. 143
6. The World, according to Homer..... 49 39. The J ura ................................. .. 145
' 7. Proportions of Land and Water .... .. 50 40. Valleys and Combes of the Jura .... .. 147
8. The Oceanic Hemisphere ............ .. 51 X. THE ALPs.
9. The Continental Hemisphere ....... .. 52 41. Proﬁle of Monte Rosa ................ .. 149
IV. NORTH AMERICA ..................... .. 52 42. Valley of Cashmere ................... .. 152
10. Basin of the Paciﬁc ................... .. 53 43. Great Landslip of Goldau ............ .. 161
11. Circumpolar Ocean .................... .. 54 44. Limit of Permanent Snow ........... .. 165
12. Circle of Inland Lakes and Seas... .. 55 45. Cornice of Snow ........................ .. 17 3
13. Semicircle of Deserts .................. .. 56 46. Internal Banded Structure of Ice... . 175
14. Western Shores of the Mediterranean 57 XI. THE MER-DE-GLACE ................ .. 17 8
V. SOUTH AMERICA ....................... .. 58 47. Windings of a Glacier ................ .. 180
15. Terra Quadriﬁda ....................... .. 61 48. Cascade of Glacier ..................... .. 180
16. Mundus Tripartitus .................... .. 62 49. Slope of the Mer-de~Glace ........... .. 181
VI. EUROPE ................................. .. 64 50. Marginal Crevasses in a Glacier .... .. 182
17. Circle of Junction of Continents .... .. 66 51. Intersecting Crevasses ................ .. 183
VII. AFRICA ............................... .., 67 52. Transverse Crevasses, in Proﬁle.... . 184
VIII. ASIA .................................. .. 71 53. Transverse Crevasses, in Plane. .... .. 184
IX. AUSTRALIA AND ARCHIPELACo .... .. 73 54. Longitudinal Crevasses, in Plane. 185
18. The “Landes” of Gascony .......... .. 82 55. Longitudinal Crevasses, in Proﬁle. .. 185
19. Extent of Heath—Smoke in 1857 .. 84 56. Longitudinal or Terminal Crevasses. 186
20. The Black Lands of Russia...... . . 86 57. Superﬁcial Torrents of a Glacier... . . 187
21. Oueld-R’ir ............................... .. 94 58. Chasms in Glacier, ﬁlled with Snow. . 188
22. The Pampas ............................ .. 100 59. The Glacier of Giétroz, in 1818..... . 190
23. The Caussade .......................... .. 113 60. Glacier Table ........ ................ .. 193
24. Indented Plateau of Nantua ......... .. 114 61. Lateral Moraines ...................... .. 194
25. Section of Africa ....................... .. 115 XII. GLACIERs 0P GEIsBERa .......... .. . 194
26. Crest of Monte Viso ................... .. 123 62. Frontal or Terminal Moraines... . 195
27. The Pie du Midi d’Ossau ............ .. 124 63. Frontal or Terminal Moraines... . . .. 195
28. Einshorn de Splugen .................. .. 125 64. Frontal or Terminal Moraines. 195
29. The Gross-Glockner ................... .. 126 65. Frontal or Terminal Moraines. 195
30. L’Esquerra des Eaux-Bonnes ....... .. 126 66. Valley of Avoca, New Zealand. .... .. 195
X
EL US TBA TI 0N8.
NUMBER PAGE
67. Ribbons of Mud, Mer-de-Glace..... 196
68. Sources of the Arveiron ............. .. 199
XIII. GLAciERs OF LANGTHAL .......... .. 201
XIV. GLACIER OF VERNAGT ............. .. 204
69. Glaciers of the Alps .................. .. 207
70. The Glacier d'Aletsch ............... .. 208
XV. GLAoIERs on THE ADIGE .......... .. 211
71. Ancient Glaciers of the Aar ........ .. 217
72. Ancient Moraine falling down ..... .. 218
73. Ancient Glacier in the Himalayas.. 220
74. Estavelles of Porrentruy ............ .. 228
75. Section of an Intermittent Spring... 230
76. Artesian System of Oued R'ir .... .. . 233
77. N atnral Bridge of Panbouk-Kelessi 240
78. Saline Springs of Tonzla...... . 243
79. Vaucluse and the Sorgues .......... .. 245
80. Course of the Touvre ................ .. 246
81. Mud Island in Course of Formation 249
82. Mud-Lump on Mississippi .......... .. 250
83. Chasms of Carniola .................. .. 254
84. Grotto of Lueg, Illyria .............. .. 255
85. Grotto of Adelsberg .................. .. 257
86. Grotto of Planina ..................... .. 259
87. Cut of Riﬁihue, Chilian Andes .... .. 264
88. Bifurcation of the Orinoco ......... .. 265
89. Bifurcation of Valleys of the Rhine 267
90. Threshold of Sargans ................ .. 268
91. Marshes of-Pinsk ..................... .. 269
92. The Ponto-Caspian Isthmus ....... .. 270
93. Sources of the Garonne ............. .. 274
94. Basins of the Amazon and La Plata 277
95., Inclination of the Nile .............. . . 282
96. Slope of the Po, Tessin, and Oglio. 282
97. Circle of the Valley of Lys ......... .. 286
98. The Igharghar ....................... .. 288
99. Valley of Cogne ...................... .. 289
100. Quadrangular Basin of Erosion... . . 289
101. Erosion of the Bourgogne .......... .. 291
102. Talus of Debris, Valley of Adige . . 293
103. Talus formed by Torrents ......... .. . 293
104. Ancient Lakes and Deﬁles of Alnta 294
105. Lakes of Thun and Brienz...., .... .. 294
106. Filling up of a Lake Basin ......... .. 296
107. Deposits of the Rhone and Dranse. 297
108. Course of the Niagara .......... 298
109. The Falls of the Zambesi ........... .. 299
110. Rapids of Maypures, on the Orinoco 300
111. Cataract of Felon, Senegal ......... .. 302
112. Proﬁle of Cataract of Niagara. 303
113. Islands in the Western Scheldt .... .. 307
114. Meandering of the Mense ........... .. 308
115. Meandering of the Seine ............ .. 309
116. Meandering at'Luzechnu... . 310

NUMBER PAGE
XVI. CoURsE 0P THE MISSISSIPPI .... .. 311
117. Old Channels of the Mississippi.... . 311
118. Old Meanderings of the Rhine .... .. 312
119. Channel of Vicksburg ............... .. 314
120. Diagram to show Guiding Banks... 315
121. Middle Course of the Rhine ....... .. 316
122. Floods, Basin of the Amazon .... .. . 318
123. Limits of Inundation of the Rhone. 323
124. Growth by Floods ........ ..\ .......... .. 326
125. Subsidences of the Waters .......... .. 326
126. Map of Fayoum ...................... .. 330
127. Section across Fayoum .............. .. 331
128. Dikes along the Rhine near Seltz... 333
129. Mean Heights of the Isere ......... .. 335
130. Dikes by the Po ...................... .. 336
131. Golenas by the Po ................... .. 337
132. Gap formed near New Orleans....;. 338
133. Belts of the Senegal .................. .. 342
134. Old Course of the Adour ............ .. 345
135. Mouths of the Mississippi ........... .. 350
136. Channel of Loutre .................... .. 351
137. Depths of Gulf of Mexico .......... .. 352
138. Depths of Gulf of Mexico ........... .. 352
XVII. DELTA OF THE GANeEs ......... .. 353
139. Delta of the Nile ..................... .. 354
140. Mouths of the Po .................... .. 356
141. Delta of the Rhone .................. .. 357
142. Height of Layers in Delta .......... .. 359
143. The Mississippi at Plaquemine. . 361
144. Ancient Course of the Amou-Daria 362
145. Section of Bar of the Mississippi. 364
146. Mouths of the Danube .............. .. 370
147. Jetties of Soulina ..................... .. 371
148. Middle Course of the Volga ........ .. 374
149. Left and Right River Banks ....... .. 375
150. Radiation of the Gaves .............. .. 376
151. Comparative Discharge of Rivers... 378
152. Lakes of Finland ..................... .. 385
153. The Dombes ........................... .. 386
154. Altitudes of Lakes, Italy ........... .. 387
155. Altitudes of Lakes, Switzerland“... 388
156. Lake Maggiore ....................... .. 388
XVIII. LAKE GARDA ..................... .. 388
157. Lake of Neuchatel ................... .. 389
158. Valley ................................... .. 390
159. Cluse ................................... 390
160. Combe...... ............................ .. 390
161. Stages of Lakes in Valley of 00.... 391
162. Lakes of Nors Elf .................... .. 392
163. Lake Stages of Estom Soubiran..... 393
164. Caspian Sea ............................ .. 401
XIX. THE BUGORS OF THE CAsPIAH.... 405
165. The Dead Sea and the Jordan.... .. 408
ILL USTRA TI ONS.
NUMBER PAGE
166. Section of’ Palestine ................. .. 409
167. Lakes of Huiduck .................... .. 412
168. Salt Marshes of Paraguay .......... .. 414
169. Marshes of Corrientes ............... .. 415
170. Coulee of Monte Frumento ........ .. 421
XX. ERUPTIONS OF ETNA .............. .. . 425
171. Curve of Volcanic Islands .......... .. 428
172. Equatorial Volcanoes ................ .. 429
XXI. VOLCANOES .......................... .. 433
173. Fracture, Etna and Vesuvius. ...... ..437
174. Section of the Island of Hawaii... . . 438
175. Isle of Palma .......................... .. 441
176. Section of the Island of Palma .... .. 442
177. Volcano of Jorulla, Mexico ........ .. 443
178. Series of Craters, Hawaii ........... .. 445
179. Auckland and its Volcanoes ....... .. 446
180. Cone of Tuﬂ' ......................... 447
181. Cone of Tuﬁ, and Crater of Scoriae 447
182. Volcano of Rangitoto ................ .. 447
183. Mount Vesuvius ................ .... .. 448
184. Section of Vesuvius ................ .. . 449
185. Section of Etna ....................... .. 449
186. Mount Orizaba ...................... .. . 449
187. Proﬁle of Orizaba .................... .. 450
188. Volcanoes of Java .................... .. 451
189. Flow of Lava at Mauna-Loa ....... .. 455
190. Crater of Kilauea . ................... .. 461
191. Crater of Mauna-Loa. ............. 461
192. Section across Craters of Kilauea. . 462
193. Nevado de Chillan ................. 466
194. Regular Cone of Ashes .............. .. 469
195. Cone of Ashes modiﬁed by the wind 469
196. Cone of Etna and Val del Bove. 469
197. Eruption of Coseguina ............. .. . 471
198. Eruption of Timboro ................ .. 472
199. Crater of Sete Cidades .............. .. 476
200. Crater of Demavend....... .......... .. 480
\
xi
NUMBER PAGE
201. Volcanic Region of New Zealand... 484
202. Section across Basins of Tetarata... 485
203. Island of Volcano .................... .. 487
204. Isle of St. Paul ...................... .. . 490
205. Volcano of Taal ...................... .. 491
206. Santorin ................................ .. 492
207. Ka'imeni Group. ...................... .. 494
208. Graham's Island, or Isle of Julia 495
209. Coule'e of Puy dc Pariou ............ .. 499
210. Area of Explosion at Mentz ....... .. 506
211. Chart of Earthquake, Sept. 14, 1866 509
212. Transmission of Earth-waves ..... .. . 512
213. Area of Earthquake of Viége, 1855 514
214. The Runn of Catch .................. .. 521
215. Distribution of Earthquakes ....... .. 523
216. Distribution of Earthquakes ....... .. 524
217. Distribution of Earthquakes ....... .. 524
218. Distribution of Earthquakes ....... .. 525
219. Distribution of Earthquakes ....... .. 525
220. Distribution of Earthquakes ....... .. 526
XXII. MAP OF UPHEAvALs AND DE-
PRESSIONS ....................... .. 527
221. Elevation of Bed of Gulf of Bothnia 534
222. Bank of Altenﬁord ................... .. 535
223. Biesbosch ............................... .. 547 .
224. Coast of Fricsland. ................. .. . 548
225. Coasts of Puerto San Jorge ........ .. 550
226. Coasts of Coquimbo ................. .. 551
227. Valley of Rio Santa Cruz ........... .. 552
228. Keeling Atoll .......................... .. 557
229. Atoll of Ehon .......................... .. 558
280. Isle of Vanikoro ...................... .. 559
231. Section of Isle Vanikoro .......... .. . 560
XXIII. AToLL ARI ....................... .. 560
232. Growth of Coral ...................... .. 560
233. Great Bank of Chagos ............... .. 561
234. Bridge of Adam, or Rama...... . . 563


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THE EARTH.

PARTI.
THE EARTH AS A PLANET.

CHAPTER I.
SMALLNESS OF THE EARTH AS‘ COMPARED WITH THE SUN AND FIXED STARS;
GRANDEUR OF ITS PHENOMENA.—FORM OF THE TERRESTRIAL GLOBE; ITS
DIMENSIONS.
THE earth on which we dwell is one of the lowest in rank among the
heavenly bodies. If an astronomer in some other planet were exploring
the immensity of space, our earth, owing to its small size, might readily
elude his intelligent view. A mere satellite of the sun, the volume of
which is 1,255,000 times greater, the earth is but a point as compared
with the immense tract of ether traversed by the planets in their courses
round their central globe. The sun itself is only a spark, which seems
lost amid the eighteen millions of stars which Herschel’s telescope dis-
cerned in the Milky Way; the latter, an immense agglomeration of suns
and planets, which looks to us like a broad streak of light round the whole
universe, is in reality nothing but a nebula; that is, a cloud of stars re-
sembling a mist, which would be as nothing in inﬁnite space. Beyond
our own sky, other skies stretch far away into inﬁnity, and others beyond
these, so that light, notwithstanding its prodigious rapidity, takes eterni-
ties to cross them. How small the earth seems in this fathomless abyss
of stars ! Individually, it may seem immense to us; all too vast for our
littleness, we have not yet succeeded in investigating the whole of its sur-
face; but, as compared with the whole sidereal cosmos, it is less than a
grain of sand by the side of a mass of mountains, or an atmospheric par-
ticle compared with aerial space.
True enough that the earth is nothing but an almost impalpable grain
of dust to the vision of the astronomer scanning the nebulae in the ﬁeld
of his telescope, but it is, nevertheless, quite as much worthy of study as
any other of the heavenly bodies. If it does not possess magnitude of di-
mensions, it presents an inﬁnite variety in all its details. Whole genera-
tions, living one after the other upon its face, might pass their lives in
14 THE EARTH AS A PLANET
studying its phenomena without comprehending all their full beauty.
There is not even any special science, having for its aim some portion of
the terrestrial surface or some particular series of its products, which does
not present to our scwcmz‘s an inexhaustible ﬁeld of inquiry. Moreover, is
not our little globe, as well as the sky, a real cosmos, both by the admira-
ble arrangement of its parts, and by its supreme harmony as a whole ‘3 In
a certain point of view, is not our almost imperceptible planet as great as
the universe, in that it is the expression of the same laws? In the form
of its orbit, in its movements round the sun and on its own axis, in the
succession of days and seasons, and in all the phenomena governed by the
great law of’ attraction, the earth becomes the representative of all the
other planets; in studying it, we study all the heavenly bodies.
Our planet is a spheroid; that is, a sphere ﬂattened at the two poles
and enlarged at the equator, so that all the circles passing through the
extremity of the polar axis form ellipses. The presumed depression of
each pole is about thirteen miles, nearly a three-hundredth part of the ra-
dius of the earth ;* but it is not altogether certain that the two poles are
equally ﬂattened. Perhaps a contrast exists between the two hemispheres,
not only in the features of their continents and the distribution of seas,
but also in their geometrical shape. Be this‘ as it may, it appears to be
proved that the curvature is not exactly the same at all points of the
earth at an equal distance from the poles; the meridians appear without
exception to be irregular ellipses. The recent measurement of degrees
carried out by astronomers, and especially the great trigonometrieal sur-
vey made between 1816 and 1852, under the direction of Struvc, from the
coasts of the Frozen ()cean to the banks of the Danube, have disclosed
some singular deviations in the form of the earth, caused either by the
geological nature of the crust or by the vicinity of considerable mountain‘
chains. Thus, among the countries of Europe, the surfaces of England
and Italy are sensibly depressed in comparison with adjacent countries.
These inequalities of curvation, which are doubtless variable, and cor-
respond to the changes in the position of the earth’s centre of gravity, are
cognizable only by the astronomer, and nowhere interrupt the apparent
horizontal character of the surface of plains and seas. As far as man is
concerned, the roughness and hollows forming our plains, mountains, and
valleys, are more important than any inequalities in the roundness of the
globe. According to Von Schubert, the academician, an enlargement,
perpendicular to the equator, and therefore parallel to the meridian, bulges
out all round the globe, passing through Europe and Africa; this hypoth-
esis is not, however, made good by the measurements of an arc of the me-
ridian recently made in India.'
The dimensions of the earth, as we have already seen, are almost as
nothing compared with the larger celestial bodies, and especially with
the extent of space which can be explored by the telescope. If light, the
* According to Bessel, the astronomer, 2991528. All possible errors are embraced be-
tween 302'301 and 296'005.
THE EARTH AS A PLANET. 15
speed of which has been adopted in astronomy as a term of comparison,
could be diffused in a curved line, it would travel seven times round the
globe in a second of time; this standard of measurement, therefore, the
only one suited to the stellary ﬁeld, is completely inapplicable to the sur-
face of our globe. Man, small as he is in comparison with the planet on
which he lives, in the ﬁrst instance chose out for the measurement of his
domain either parts of his own body, such as the foot, cztbit, or fat/tom,
or the distance traveled during a certain period of time, as the parasang,
stadium, mile, or league. It was not until the end of the last century that
the savants who then adorned France conceived the idea of dividing the
circumference of the earth into equal parts, which for the future should
serve as a standard of measure for all terrestrial distances. This measure,
or metre, which, with the aid of its multiples and divisions, enables us to
estimate, with equal ease, the circumference of the globe or that of an al-
most invisible molecule, is the ten-millionth part of the are described from
the equator to one of the poles. Owing to errors which the diﬂiculties
of actual measurements rendered inevitable, the ideal metre exceeds the
customary one by nearly the eleventh part of a millimetre ,' but this very
triﬂing difference, which is imperceptible to the naked eye, may be disre-
garded in practice without any inconvenience. A line, therefore, going
round the earth, and passing through the two poles,.would be of the length
of about 40 millions of metres, or 40,000 kilometres. Thus, as Schubert’i‘
remarks, it is about the distance which the usual pace of a man would
travel over in a year—that is, if he did not stop for a single instant. The
superﬁcies of the globe, as calculated by Wolfers, according to the most
recent measurements which astronomers have made of the arcs of the lon-
gitude and latitude in various countries, is 197,124,000 square miles. Ac-
cording to Encke, the astronomer, it amounts to 197,108,580 square miles,
and the planetary mass would attain to a bulk of 256,000 millions of cubic
miles. ‘
* Geschichte der Seele.
16 THE EARTH.
CHAPTER II.
MOTION OF THE PLANET.-—DIURNAL ROTATION AND ANNUAL REVOLUTION.—
SIDEREAL AND SOLAR DAY.--SUCCESSION OF DAYS AND SEASONS.—DIF-
FERENCE OF DURATION OF THE SEASONS IN THE TWO HEMISPHERES.-—
PRECESSION OF THE EQUINOXES.——NUTATION.—-PLANETARY PERTURBA-
TIONS.'—MOVEMENT OF THE EARTH TOWARD THE CONSTELLATION HER-
CULES.
TIIE isolated globule in the immensity of space which we call the earth
is not motionless, as the ancients necessarily supposed, looking upon it, as
they did, as the immovable base of the ﬁrmament of heaven. Hurried on
in the vortex of universal vitality, our globe is ever actuated by ceaseless
motion, describing in ether a series of elliptic spirals so complicated that
astronomers have not yet been able to calculate their various curves. Be-
sides rotating on its own axis, the earth describes an ellipse round the sun,
and, under the inﬂuence of this body, is drawn along from one heaven to
another toward distant constellations. It also oscillates and rocks on its
axis, and deviates more or less from its path, to salute, as it were, every
heavenly body which meets it. It is probable that it never passes a sec-
ond time through the same regions of the air; yet, if it has again to trav-
erse the spiral line of ellipses it has already described, it would be after a
cycle of so many thousands of millionsof years, that the earth itself, com—
pletely transformed, would be no longer the same planet. Nature, immu-
table in its laws, but forever variable in its phenomena, never repeats itself.
The motion of the earth, the immediate effects of which are the most
obvious to the notice of men, is the daily rotation which takes place round
an ideal axis passing through the two poles. The globe turns from right
to 1eft,101; from west to east—that is, in a contrary direction to the appa-
rent motion of the sun and stars, which seem to rise in the east and to set
in the west. As the earth’s axis terminates at each pole, there is least
surface-motion at those points, and the motion is the more rapid in any
part of the surface of the globe the farther it is from the central axis. At
_ St. Petersburg, in 60° latitude, the speed of rotation is about nine miles a
minute; in Paris, it exceeds eleven and a half miles during the same brief
time; on the equatorial line, which may be looked upon as the ring of an
immense wheel, the speed of the earth is twice as great as it is at 60° of
latitude—that is, about eighteen miles a minute, or 528 yards a second—
a rapidity equal to the ﬂight of a 26-pound cannon-ball impelled by thir-
teen pounds of powder. By means of this rotatory motion, the earth pre-
sents toward the sun each of its faces alternately, and each also in turn
toward the comparatively darker regions of space; the succession of day
MOTION OF THE PLANET. 17
and night is thus constituted. In addition to this, the rotation of the
earth is an important fact which must always be taken into account in
determining the direction of ﬂuids in motion on the surface of the globe,
such as streams and rivers, also marine and atmospheric currents.*
The annual revolution which the earth performs round the sun follows
the line of an‘ ellipse, one of the foci of which is occupied by the central
star; the eccentricity of the ellipse is nearly equal to T53, of the great
axis. The distance between the sun and the earth always varies accord
ing to the particular point of its orbit which the latter is traveling over.
At its aphelzon, that is,-at its greatest remoteness, this distance is about
98%- millions of miles; at the period of its perihelion, when the two heav-
enly bodies are nearest to each other, it is approximately 90,259,000 miles.
The mean distance, as estimated by astronomers since the corrections of
Encke, Hansen, Foucault, and Hind, is 91,839,000 miles. This extent of
space is traversed by the solar rays in 8 minutes 16 seconds; so'und would
take ﬁfteen years in passing through the same distance.
As Kepler has laid down in his celebrated laws, our planet moves with
an increased rapidity as it approaches nearer to the .sun, and travels more
slowly in proportion to its distance from that luminary; but its mean
speed may be estimated at nearly 19 miles a second, or sixty times the
rapidity of a ball from the cannon’s mouth. This speed, which makes one
dizzy to think of, is to be added, as regards each point in the surface of
the earth, to the rotatory motion which impels it round the polar axis.
Modiﬁed by this latter motion, the line described by any one point on the
terrestrial superﬁcies becomes a spiral.
After having turned round 366 times on its axis, our planet has termi-
nated its orbicular course, and is in the same position relatively to the sun
as at its starting-point; it has then accomplished its year. During this
period of time, composed of 366 terrestrial rotations, the sun has only il-
lumined each hemisphere in turn 365 times. How does this apparent
anomaly arise ? How does it happen that a complete movement of rota-
tion performed by the globe round its own axis does not exactly coincide
with the solar day ‘P The cause is this—that the earth in its rotation, car-
ried on as it is in its immense orbit, is constantly changing its position in
respect to the sun. As regards the ﬁxed stars, situate at an almost inﬁ-
nite distance from our planet, the earth remains, so to speak, always in
the same position; consequently, the sidereal day, that is, the interval
which separates two transits of the same star over the same terrestrial
meridian, has the precise duration of one rotation of our globe. After
each of its diurnal rotations, our earth presents to these far-remote stars
the same part of its surface, and if the light of the sun became suddenly
extinct, and if a star, such as Sirius or Aldebaran,became our great focus
of illumination, our days would have the exact duration of a terrestrial
rotation, that is, about 23 hours 56 minutes. But the sun, although a
ﬁxed star, is comparatively near to the earth. While the latter is perform-
* Vide the chapters as to'“ Rivers,” “Currents,” “The Atmosphere, and Winds.”
B

13 THE EARTH.

Fig. 1. Inequality of the Solar and Sidereal Day.
ing a movement of rotation, it alters its position 1,604,300 miles along the
course of its orbit; consequently, the sun, in its apparent progress, seems
to retrograde this distance, and in order that the earth should present to
it exactly the same portion ofits surface as at the commencement of its
rotation, it would be necessary for it to turn round four minutes more.
The next day, a fresh change in the position of the earth again adds four
minutes to the duration of the day, and so on till the end of the year.
These daily additions offour minutes to the length ofthe day form, during
a whole year, a period equal to the duration of‘ one of the diurnal rotations;
the result is that the sidereal days in the year exceed the solar by one.*
Thus the daily rotation‘ot' the earth round its axis produces the succes-
sion of days and nights, and, in the same way, its annual revolution round
the sun causes the alternations of the seasons. If the axis of the earth,
that is, the ideal line which passes through its two poles, were perpendic-
ular to the plane ofits annual orbit, it is evident that the portion of the
globe lighted by the sun wo'uld invariably extend from one pole to the
other, and that in both hemispheres the days and nights would always
consist of’ twelve hours each. But this is not the case. The earth per-
forms its revolutionary movements in an inclined position; its ideal polar
axis is sloped about 23° 28' from a perpendicular to its plane, and this po-
sition is so far maintained that as regards the comparatively rapid suc-
cession of days and seasons it may be looked upon as invariable. This _
* For n more complete explanation of all the astronomical phenomena relating to the earth,
.we must refer to the excellent work of M. Amétlee Guillemen, Le Ciel. Frcm this work we
have borrowed the above plate.
ORBIT OF THE EARTH.
obliquity of axis causes continued changes in the phase presented to the
sun. .The portion of the earth illumined by the rays of the sun varies
every day; for, although the planetary axis may appear to maintain its
extremity in a ﬁxed position as regards some point in inﬁnite space, in re-
spect to the sun it presents a constantly varying degree of inclination, in
consequence of the continual motion of the earth. Twice during the course
of the year it so happens that the solar rays fall perpendicularly upon the
equator of the earth; at every other period in the annual revolution, some-
times the northern and sometimes the southern hemisphere receives the
greatest amount of light.
The astronomical year commences on the 20th of March, at the exact
moment when the sun illumines the equator in a vertical direction, and
the line of separation between light and shade passes through the two
poles. The period of darkness is then equal to that of light, and admits
of exactly twelve hours at all points of the earth. Hence the name of
“equinox” (equality of nights). But after this day, which in the northern
hemisphere serves as the starting-point of spring, the earth continues its
translatory movement. In consequence of the inclination of its axis, the
northern hemisphere, being turned toward the sun, receives a greater quan-
tity of light, while the southern half of the globe is less vividly lighted.
The vertical rays of the sun now fall more and more to the north of the
equator, and the circle of light, far from arresting its progress at the poles,’
where the day of six months’ duration is commencing to dawn, extends
far beyond it over the regions of the north. On the 21st of J une, the day
of the ﬁrst solstice,* the axis of the earth being deeply inclined toward
the sun, this luminary shines on the zenith of the tropic of Cancer at 234°
north of the equator, and its light illumines the whole of the arctic zone,
that is, the portion of the earth’s surface extending to 234° round the north
pole. Then spring ceases and summer begins as regards the northern
hemisphere. In the southern hemisphere, on the contrary, autumn is giv-
ing place to winter. Above the equator long days are prevailing, inter-
rupted by short nights; while in the south it is the nights which last the
longest. In the arctic zone the sun performs its apparent course of diurnal
rotation entirely above the horizon. The six-months’ day, which spring
inaugurated at the north pole, attains its high noon on the ﬁrst day of
summer. At the same moment midnight arrives in the darkness which
is oppressing its antipodes.
Immediately after the 21st of June all the phenomena which took place
during the preceding season are directly reversed. . The sun appears to
retrograde toward the southern horizon; its vertical rays cease to fall on
the line of the northern tropic, and constantly approach the equator. The
zone of light in the northern pole and of shade in the southern equally di-
* The usual term “summer solstice” is altogether improper, as it is suitable only to coun-
tries in the northern hemisphere. The summer solstice of London is the winter solstice at
the Cape of Good Hope. The designations of vernal and autumnal equinox ought equally to
be abandoned.
29' THE EARTH.
in.-.‘ _ .4 .- .__. .....a__-__|4.‘..,_~n..>77,_. . ,7, .‘
.i/‘i-w/wn/nv- \ _ l " ' r . ‘A
‘ “lt'l/u um. r
O c t S e
"*"l e R;
I
‘gig/min”: .V/(rfl/i" I
‘#1 , ' .411”;
i
13 -.
t‘ .rt-z'»
‘a

Hymn/1.2"
Fig.2. Orbit 01’ the Earth around the Sun.
minish, and the days shorten in the northern hemisphere in the same pro-
portion as they lengthen in the southern; an equilibrium is gradually be-
ing reestablished between the two halves of the earth. On the 22d of
September‘ the position of the sun is again exactly above the equator, and
its light just reaches both poles. The equinox, or the absolute equality
of day and night in every part of the globe, occurs for the second time in
the year; but this moment of equilibrium is, so to speak, but a mathe-
matical point between the two seasons. The axis of the earth which, dur-
ing the six months past, turned the north pole toward the sun, new pre-
sents to him the south pole; the vertical rays ofthe central luminary fhll
to the south of the earth’s equator, and the southern hemisphere, in its
turn, is the best endowed ofthe two halves of the globe in the amount of
light it receives and in the length of its days. In the southern hemi~
sphere, spring is commencing; in the northern, autumn. Three months
afterward, on the 21st ofDecember, the sun comes directly over the south-
ern tropic, or the tropic of Capricorn, 234° south of‘ the equator, and the
whole of the antarctic zone is presented to the solar rays. Summer has
begun in the southern hemisphere, and at the same time winter commences
in that of the north. Then, as the globe moves on, these two seasons fol-
low each other in their course, until at length the earth attains a position
similar to that from which it started; the March equinox, the ﬁrst day of
spring in Europe, and the ﬁrst day of autumn in Australia, commences
anew the astronomical year.
CHANGES OF THE SEASONS’. ' 21
The elliptical form of the earth’s orbit and the unequal pace of the globe
in the various points of its course cause some considerable variations in
the duration of the seasons. In fact, from the 20th of March to the 22d
of September, that is, during the spring and summer of the northern hemi-
sphere, the earth takes 186 days to travel over the ﬁrst and largest half
of its orbit, while during the winter period, from the 22d of September
to the 20th of March, only 179 days are required to accomplish the second
half of its journey. The summer period of the northern hemisphere actu-
ally exceeds by seven or eight days, or about 187 hours, the correspond-
ing period in the southern half of the globe; added to this, in consequence
of the longer space of time during which the arctic pole remains inclined
,toward the sun in the regions north of the equator, the hours of daylight
exceed the hours of night, while in the south'fhe hours of darkness pre-
dominate. This is, however, to some extent compensated for; as, al-
though in the southern regions of the earth the summer lasts a shorter
time, our planet is then closer to the sun; it is at its perihelion, and con-
sequently receives a larger proportion of heat. There is, however, no
doubt about the fact, as it is proved by a direct observation, both of the
winds and currents, and also of their various temperatures—that, taking
an equal distance from the equator, the southern regions are colder than
those of the north. The problem is, to know if this phenomenon proceeds
from the varied distribution of the continents, or from the contrast ofsea-
sons presented by the two moieties of the earth. On the whole, does the
proximity of the central luminary confer on the southern hemisphere as
much additional caloric as the opposite hemisphere gains by its more pro-
longed exposure to the solar rays? Does it receive complete compensa-
tion ‘3 Not long ago, most astronomers admitted that it did; they main-
tained this, grounding it on the calculation that in each hemisphere the in-
tensity of the heat is in the inverse ratio to its duration. Other servants,
on the contrary, the best known of whom was Adhémar, the mathemati-
cian, author of an ingenious theory on the periodicity of deluges, assert
that, in consequence of the nocturnal radiation, the hemisphere which en-
joys the shorter summer must necessarily get much colder than the op-
posite portion of the earth’s surface. ‘Ve may add that,,in consequence
of the eccentricity in the orbit of the earth, the diﬁ‘erence of duration be-
tween the winter and summer of the two hemispheres may exceed 36
days*
If an equality of seasons between the two halves of the world does not
at present exist, it will not fail to be established after a long series of cen-
turics by means of a slow terrestrial movement, which has been known
by the name of the precession of the equinowcs. Just as a top (if we may
be allowed to avail ourselves of so old an illustration) turns round on .tbc
ground and bends over successively in every direction, thus describing
with its axis an ideal cone, so the earth revolves in space, and slowly
sways the line of its poles. This line, which is always sloped at an angle
* Stone, James Croll, Carrick Moore, Lyell, and Le Hon.
22 - ‘ THE EARTH.
of 66° 32’ to the plane of the terrestrial orbit, turns round with a slight
lateral motion, so as always to point to a new region of the sky; if it were
prolonged indeﬁnitely it would describe a circle amid the distant stars.
As the axis of the earth is constantly changing its direction in this way,
the plane of the equator must vary exactly to the same extent in its po—
sition as regards the sun. In fact, every year the exact moment of the
March equinox anticipates by about twenty minutes the time at which the
corresponding equinox fell in the year preceding. Each revolution of the
earth round the sun brings a fresh advance of twenty minutes in the de-
termination of the equinox; and as, during the long course of ages, the
axis of the earth does not intermit in this swaying motion, the time must
come, after a period of 12,900 years, that the conditions of the seasons.
will be altogether changed.‘ The hemisphere which hitherto received the
larger proportion of heat will receive the lesser share, and that half of the
globe which had endured the larger number of wintry days will now, in its
turn, enjoy the more lengthened period of summer. Then, after a second
period of 12,900 years, during which the relation between the seasons of
the two hemispheres is being gradually modiﬁed, the axis of the earth
completes its round of swaying, which has lasted for 258 centuries, and
the position of the globe in respect to the sun being nearly the same as
at its starting-point, a second cycle of seasons will then commence.
We might call this period the earth’s great year, if, at the end of it, the
earth were in an identical position to that which is occupied at the com-
‘ mencement; but this is not the case. The attraction of the moon, and
the disturbances caused by the vicinity of certain planets, are incessantly
modifying the curve described in the starry ﬁelds of space by the earth’s
axis, and complicate it with a multitude of spirals, the various periods of
which do not coincide with the great period of’ the swaying of the axis.
The successive undulations form a continuous system of interwoven spi-
rals. “ It is a manifestation of the inﬁnite.”*
But even this is not all. In addition to all the motions of the globe
which we have already pointed out—its diurnal rotation, its annual rev-
olution round the sun, the rhythmical swaying of its axis, proved by the
precession of the equinoxes, the nutation or more rapid swaying which is
caused by the attraction of the moon—we must now notice the enormous
translatory movement which is dragging it through endless tracks of '
space in the train of the sun. Not many years ago, this motion was en—
tirely unknown to astronomers, and yet it is going on with inconceivable
rapidity—a rapidity more than double that of the course of the planet
round its central luminary. In one second of time the earth moves about
forty-four miles toward the point of the heavens where we ﬁnd the con-
stellation of Hercules. ' During one year only, she travels 1382 millions
of‘ miles in this (lll‘QCtlOlL‘i' Does this enormous distance—which light it—
* Jean Reynaud, T erre ct Ciel, Stone, James Croll, Carrick Moore, Lyell, and Le Hon.
‘i According to Bessel. Vida Humboldt’s Cosmos, Faye's transL, part i., p. 162. Struve
estimates the annual movement at 149 millions of miles only.
I JIMENSIT Y OF SR1 CE. 1 2 3
self would take two hours and ﬁve minutes in traversing—form part of
an ellipse described by the whole planetary system round some centre of
attraction—a centre which Maedler, the astronomer, has fancied that he
has discovered in Alcyone, in the midst of the Pleiades? Or is it, as Ca-
rus* supposes, a portion of an orbit which has for its focus (like the curves
of multiple stars) a centre of gravity common to many stars—nothing but
a mathematical point everlastingly changing in inﬁnite space‘? WVe can
not tell; but certainly this movement of the globe we live on, and its prog_
ress through the unfathomable depths oilspace, must give us an idea of
the immense variety of the motions which make the heavenly bodies gy-
rate like particles of dust in a whirlwind. Our own little earth itself is
carried on from space to space, and never closes the cycle of its revolutions.
Ever since the time when its particles were ﬁrst grouped together, it has
been describing in space the inﬁnite spiral of its ellipses, and thus will it go
on turning and oscillating in ether until the moment when it will exist no
longer as an independent planet. For the earth, too,'must have an end;
like every other body in the universe, it comes into existence, and lives
only to 'die when its turn comes. Already its annual motion of rotation
is diminishing in speed ,1‘ certainly this slackening of pace is not very ob-
servable, since no astronomer from Hipparchus to Laplace has yet exactly
deﬁned it. But, unless some cosmical force acting in a contrary direction
compensates for the loss of speed caused by the friction of the tides against
the bed and the shores of the ocean, the impetus of our planet will every
century diminish. After various catastrophes which it is impossible to
foresee, the earth will eventually completely change its course of action,
and lose its independent existence, either uniting itself with other plan—
etary bodies, or breaking up into fragments; or it will perhaps terminate
its course by falling like a mere aerolite upon the surface of the sun.
* ZVatur and Idee. ' Jr Meyer, Joule, 'I‘yndall, Adams, Delauna-y.
24: THE EARTH.
CHAPTER III.
)ARIOUS OPINIONS AS TO THE FORMATION OF_TIIE EARTH.—LAPLACE,S HY—
POTIIESIS; GRAVE OBJECTIONS RAISED TO IT.—"TIIEORY OF A CENTRAL
FIRE; OBJECTIONS TO IT. -
THE origin of the earth is lost in the dark night of our ignorance.
From the observations and deductions they have made, none of our sei-
entiﬁc men have been enabled to afford us any exact information as to
the way in which our planet was formed, although new stars are constant-
ly showing themselves in the inﬁnity of space. The telescope serves only
to demonstrate the‘ appearance of these celestial bodies, and fails to dis-
close to us the mode of their formation. On one occasion only, in Decem-
her, 1845, astronomers had the good fortune to witness the division of a
comet—that of Biela; they saw it, in fact, break asunder and form two
nuclei of unequal sizes, which traveled on into space, one following the
other. But this isolated fact will not justify us in assuming a similar
mode of formation as regards all the heavenly globes, and in asserting that
the stars and planets are produced by a kind of bipartition or duplication.
CThe human intellect is still compelled to be content with mere hypothe-
ses as to the origin of our own and other planetary globes. All cosmog-
onies, from the legend of the savage, who imagined that t 10 earth sprang
from a sneezing ﬁt of his god, down to the theory of the great Buffon, ac-
cording to which the planets of the solar system are the fragments launch-
ed into space by a collision between a comet and the sun, the vague con-
jectures of the ancients, and the ideas struck out by modern science—all
alike are mere suppositions more or less plausible and ingenious.
The hypothesis which at the present day still receives the most ere-
dence is that which was ﬁrst proposed by Kant, the philosopher (1755),
and, having been developed by Herschel, was taken up and largely des-
canted on by Laplace in his Exposition (Zn Systéme (Zu lllonde. So great
is the authority of this illustrious geometrician, that a great number of
persons erroneously look upon his hypothesis as a clearly demonstrated
scientiﬁc fact. It is, therefore, hardly permissible to omit giving some
description of it, even in the briefest sketch of the primitive history of the
earth.
Laplace supposes, in the ﬁrst place, that the space in which the solar
system now moves was ﬁlled by a gaseous cosmical matter of a high tem-
perature, the dilation of which was excessive, compared even with the
most rareﬁed gases. This enormous nebula incessantly radiated heat
around it, and thus supplied a portion of its caloric to the surrounding
space; it therefore necessarily condensed gradually round a central point,
g
THE 012 Y OF LAPLA CE. 25
destined one day to become our sun. The particles of gaseous matter,
being mutually attracted to one another, were not only subject to the mo-
tion of condensation, but were also hurried on in an immense circle round
the axis of the system. The loss of calorie and the consequent concentra-
tion of the spheroidal mass had the effect of increasing the speed of rota-
tion. At the same time, the centrifugal force was proportionately in-
creased, and, under the inﬂuence of this force, the atmospherical mass, be-
coming ﬂattened at the two poles, assumed gradually the form of a disk.
The attraction which had hitherto retained in their place the molecules
of the circumference, and had prevented them from rushing off into space,
was at last counterbalanced by the centrifugal force; and although the
larger portion of the gaseous mass continued to condense around the cen-
tral nucleus, the outer zone, acted upon at the same time by two opposite
forces, ceased to modify its distance in respect to the axis of the spheroid,
and assumed the form of a circular revolving ring.
Other rings were in succession separated from the diminished mass in
the same way, and continued to describe their rotatory movement round
the nucleus or sun. According to the hypothesis, these rings were the
future planets of the solar system. The lightest were necessarily those
which were the most remote from the sun, on account of the greater tenu-
ity of the incandescent atmosphere of which they were formed. The heav-
iest were those which were subsequently constituted out of the denser’
gaseous layers which were situated nearer to the centre of the sun. It is,
we may remark, a matter of fact that the planets farthest removed from
the central focus, such as Uranus and Neptune, have the speciﬁc gravity
of cork, and that the density of the globes increases (although not follow
.ing any absolutely regular law) as they are in closer propinquity to the
sun, until we come to the small and heavy planets in the interior of the
system. Besides, the planes of the planetary orbits which are slightly in-
clined toward one another would point out the position of the sun’s equa-
tor at each of the epochs when one of the great disruptions took place,
which gave rise to a fresh planet.
Although constantly getting more compressed, owing to the gradual
loss of their caloric, these annular bodies retained their shape through a
more or less prolonged series of ages; but, as soon as one of these seg-
ments became denser than the rest (in consequence of some astronomical
perturbation), it exercised an ever-increasing force of attraction, and at
last, breaking up the zone of gaseous matter, gathered the matter round
itself in a concentric atmosphere. Under the inﬂuence of the laws of ro-
tation, the new planet soon assumed a spheroidal shape, analogous to that
of the body from which it had sprung. In consequence of the ﬁrst im-
pulsive force communicated to its molecules, its motion became twofold;
it continued its revolution round the sun, and began to turn round on its
own axis.
The formation of satellites is similarly explained by the gradual shrink
ing of the gaseous mass of the elementary planets. _ The rings separated
25 THE EARTH.
from the equatorial zone of these bodies would be likewise condensed, and,
contracting in consequence of the abstraction of their caloric, would be-
come so many moons. The pale rings of Saturn are the only objects in
the heavens which would recall the ancient shape of the spheres which
the condensation of the sun, and, afterward, that of the planets themselves,
have thrown off successively into space. Once upon a time, according to
the hypothesis, they were nothing but an equatorial enlargement of the
mother planet; some day they will become spherical satellites, like the
eight moons which now illumine the short nights of Saturn. '
Thus, according to Laplace’s ideas, the whole planetary system formed,
in long past ages, a portion of the sun. This luminary, composed solely
of gaseous particles much lighter than hydrogen, pervaded with its enor-
mous rotundity the whole of the space in which the planets, including
Neptune, are now describing their immense orbits. The diameter of the
solar spheroid must then have been 6500 times greater than it now is, and
its bulk must have surpassed its present volume by more than 860,000 mil-
lions of times. In the same way, the earth, before it began to get cool
and solidify, would have embraced the moon within its limits, and its di-
ameter would have been nearly six times greater than that of the planet
Jupiter. But, unsubstantial and aerial as it was, our earth had then noth-
ing but a cosmical life which could hardly be called material; it was not
‘until it became more solid and its outer crust was hardened that it actu-
ally commenced its real existence.
This is, no doubt, a brilliant hypothesis, and certainly the most beauti-
ful and simple that any astronomer has yet put forth. It accounts better
than any other for the uniform translatory motion of the planets in the
direction of west to cast; it also apparently agrees in a remarkable way
with certain facts in the subsequent history of the earth, as disclosed to
us by geology; ﬁnally, the marvelous rings which surround the planet
Saturn seem to proclaim the truth of the theory devised by Laplace.
There have been some experiments on a small scale which appeared to re-
produce in miniature the magniﬁcent spectacle presented in the primitive
ages by the origin ofthe planets. M. Plateau, a Belgian servant, managed
to make a globe\of oil revolve in a mixture of water and spirits of wine,
which was of exactly the same speciﬁc gravity as the oil. ‘Vhen the rev-
olution of the little globe was sufficiently rapid, it was noticed to ﬂatten
at the poles and to swell at the equator; after a time it throw off rings
which suddenly assumed the shape of globules actuated by a rotatory mo-
tion of their own, and turning round the central globe. Although these
planets in miniature owed their existence solely to the expansion of the
drop of oil and not to its shrinking, any one looking at it might well fancy
it was an exact representation of the solar system. i '
But Laplace himself, in putting forth this hypothesis, says that he does
so “ with difﬁdence,”* and no one has a right to be more conﬁdent than
the great geometrician. In fact, his conjectures do not account for the
* Exposition du Systeme a’u Mondc, p. 450.
F ORJI'A TI 0.\' OF PLAXETS. 2 7
presence of comets which gravitate round the sun in determinate orbits,
although, according to his hypothesis, they are “strangers in the solar
system ;”* they also fail to explain the elliptical form ofthe planetary or-
bits and the inclination of their axes; ﬁnally, they appear to be contra-
dicted by the retrograde motion of the satellites of Uranus. Some of the
distant nebulce, which were taken by astronomers to be masses of uncon-
densed cosmical matter, possess the most fantastic forms, which wouldbe
very diﬂicult to explain by means of the new hypothesis; some of the
nebulae, too, are variable, and the telescope discloses them to us under very
different aspects in succession. Finally, the discovery of the spectral
analysis—an eternal glory to MM. Kirchhoff and Bunsen—warrants us in
believing that the chemical composition of the sun differs very decidedly
from that of the planets forming its system; for the solar body, at least
in its external layers, does not contain either silex, tin, lead, mercury, sil-
ver, or gold. We must therefore confess that Laplacc’s celebrated and
seductive hypothesis is inadequate to account for all the phenomena which
have been observed. The human intellect ever thirsts for certainty, and
readily allows itself to be led away to look upon' mere conjectures as ab-
solute truths ; the ability of fearlessly doubting is not the meanest‘attri-
bute of genuine philosophy. lVhen the investigator is unable to discover
the truth, let him dare to avow his ignorance, and rest courageously on
the threshold of the unknown world.
Another hypothesis connected with Laplace’s brilliant astronomical the-
ory must be added, in order to describe the formation of the planetary
crust. When the gaseous ring became condensed into a globe, it would
not cease to contract, owing to the continued radiation‘ of its caloric.
The whole mass, having become liquid through the gradual cooling of its
molecules, would be changed into a sea of lava whirling round in space;
but this state was only one of transition. After an indeﬁnite term of cen-
turies, the loss of heat was suﬂicient to cause the formation of a light sco-
rz'a like a thin sheet of ice over the surface of the ﬁery sea, perhaps just
at one of the poles where nowadays the extreme cold produces icebergs
and a frost-bound sea. This ﬁrst scorz'a was succeeded by a second, and
then by others; next they would unite into continents ﬂoating on the sur-
face of the lava, and, ﬁnally, would cover the whole circumference of the
planet with a continuous layer. A thin but solid crust would then'havc
imprisoned within it an immense burning sea.
This crust was frequently broken through by the lava boiling beneath
it, and then, by means of the solidiﬁcation of the scorz'ce, was again united;
the cooling process would tend also to slowly thicken it. After a lapse
of time, which must have been immensely protracted, since the interval
during which the temperature of the territorial crust would be lowered
from 2000° to 200° has been estimated, at the very least, at three and a
half millions ofccenturies/y the pellicle at last became ﬁrm, and the erup-
tions of the liquid mass within ceased to be a general phenomenon, local-
*3‘ Exposition du Systeme (la Mmde, p. 475. 1' IIelmholz,
28 THE EARTH.
,
izing themselves at those points where the ﬁrm crust was the thinnest.
The surrounding atmosphere, replete with vapors and various substances
maintained by the extreme heat in a gaseous state, would gradually get
rid of its burden; all kinds of matter, one after the other, would become
disengaged from the luminous and burning aerial mass, and precipitate
themselves on the solid crust of the planet. When the temperature was
lowered sufficiently to enable them to pass from a gaseous to a liquid
state, metals and other substances would fall down in a ﬁery rain on the
terrestrial lava. Next, the steam, conﬁned entirely to higher regions of
the gaseous mass, would be condensed into an immense layer of clouds,
incessantly furrowed by lightning. Drops of water, the commencement
of the atmospheric ocean, would begin to fall down toward the ground,
but only to volatilize on their way and again ascend. Finally these little
drops reached the surface of the terrestrial scorz'a, the temperature of the
water much exceeding 100°, owing to the enormous pressure exercised by
the heavy air of these ages; and the ﬁrst pool, the rudiment of a great
sea, was collected in some ﬁssure of the lava. This pool was constantly
increased by fresh falls ‘of water, and ultimately’ surrounded nearly the
whole of the terrestrial crust with a liquid covering; but, at the same
time, it brought with it fresh elements for the constitution of future con-
tinents. The numerous substances which the water held in solution
formed various combinations with the metals and soils of its bed; the cur- ‘
rents and tempests which agitated it destroyed its shores only to form
new ones; the sediment deposited at the bottom of the water commenced
the series of rocks and strata which follow one another above the primi-
tive crust. ‘
Henceforward the igneous planet was externally clothed with a triple
covering, solid, liquid, and gaseous; it might therefore become the theatre
of life.* Vegetables and lowly forms of animals were called into exist-
ence in the water, and 011 the land which had emerged from it; and, ﬁnal-
1y, when the temperature ofthe surface of the globe had become less than
50°, allowing albumen to liquefy and blood to ﬂow in the veins, the Fauna
and the Flora would be developed, the remains of which are found in the
earliest fossil strata. The era of chaos was succeeded by that of vital
harmony; but in the immense series of ages we are dealing with, the life
which appeared on the refrigerated planet was little else than the “ mould-
iness formed in a day.”]L
According to the theory generally propounded, the solid crust was not
very completely formed; it is, indeed, much thinner than the layer of air
surrounding the globe; for, following the common estimate, which, how-
ever, is purely hypothetical, at 22 to 25, or, at most, 50 miles below the
surface of the earth, the terrestrial heat would be sufﬁcient to melt gran-
ite]; Compared to the diameter of the earth, which is about 250 times
greater, this crust is nothing more than a thin skin, a just idea of which
* De J ouvencel, Les Commenccments du Monde, p. 37 seq. 1' Dﬂllbl'c'c.
i Humboldt’s Cosmos ,- Studer’s P/zysz'kalisc/zc Geographic, vol. ii., p. 37, etc.
ill U TABILI T Y OF I TS SURFA CE. 2 9
0
may be given by a sheet of thin cardboard surrounding a liquid sphere a
yard in diameter. In the case of the earth, this liquid is a sea of lava and
molten rocks, having, like the ocean above it, its currents, its tides, and
perhaps its storms. The geological revolutions of the globe are only the
reaction of the subterranean undulations of this hidden hell, and the moun-
tains of porphyry, greenstone, and ophite are but the congealed ripples
of a ﬁery ocean. Those giants on the sea-shore, Etna, the Peak of Tene-
riﬂe, and the Manna Rea, bear witness by their eruptions and their lava-
streams to the tempests which are raging below the earth’s solid crust.
It is, in fact, very probable that a great part of the rocks which form‘.
the outer portion of our planet, especially the most ancient formations,
existed in former times in a state of fusion like that of volcanic lava. As
most geologists are of opinion, granite and other similar rocks, forming
the principal building-blocks in the architecture of continents, existed once
in a soft or semi-soft state; but even if this were placed beyond a ques
tion, it could not conﬁrm the hypothesis relative to the origin of our plan-
et, the tenuity of its crust, and the existence of a vast central ﬁre.
The ﬂattening of the earth at the two poles and the enlargement at the
equator have been alleged as unexceptional evidence that the globe once
existed in a state of liquid incandescence; in fact, any liquid sphere turn-
ing round on its axis would necessarily assume this shape on account of
the unequal speed of certain points of its bulk. But it may also be asked,
with Playfair, whether even a solid globe would not equally tend to en-
largement at its equator if it unceasingly rotated for an indeﬁnite series of
centuries? For no existing matter is altogether inﬂexible, and under the
powerful pressures exercised in our laboratories, certainly very inferior to
the inﬂuence of planetary forces, all kinds of solid bodies, as iron and steel,
become almost as yielding as liquids.* Besides, the observations and cal-
culations of astronomers and geometricians have led them to the belief
that the ﬂattening of the earth at the two poles is not a constant quanti-
ty, and that, therefore, there are other laws different from those of the mo-
tions of rotation and revolution, which assist in modifying the form of our
planet. Less probably at the northern than at the southern pole, the ir-
regularity of the sphere appears to be subject to periodical changes dur-
ing the course of ages, and is also complicated with several other inequal-
ities, elevations, or depressions which the oscillations of the pendulum and
the measurement of terrestrial arcs disclose to science. One of the grav-
est subjects of study presented by physical geography is precisely this
mutability of the surface of the earth, which, at various points of the globe,
rises or sinks with extreme slowness. Although we are still ignorant of
the certain cause of these risings and depressions, there is at least no rea-
son to believe that they are due to the centrifugal force developed by the
rotation of the earth.’r
Neither must it be forgotten that, under the hypothesis admitted by
* Experiences a’u Conservatoire des Arts et Métz'ers, 1864.
‘l’ Vida the chapter as to “ Upheavals and Depress-ions.”
30 THE EARTH:
those who assume the existence of a central ﬁre, our planet is to be con-
sidered as actually a liquid mass, as the external crust is in comparison
but a thin skin. Under these conditions, it would be difficult to believe
that this great ocean of lava is not, like the watery ocean, agitated by the
alternating motion of tides, and that it does not move twice every day
the raft, as it were, which is ﬂoating on its surface. It is diﬁicult to un-
derstand how it is ‘that the earth is not much more depressed at the poles
than it now is, and has not been transformed into a real disk. This ﬁat-
tening of the poles is not more considerable than the mere superﬁcial in-
equalities in the equatorial zone between the summits of the Himalayas
and the abysses of the Indian Ocean. M. Liais attributes the slight ﬂat-
tening of the two poles to the erosion which the water and ice in those
parts, irresistibly drawn as they are toward the equator, incessantly cause,
year after year and century after century, by the enormous quantity of
debris torn away from the surface of the soil, which they bear with them.
Lastly, M. Bischoff, having ascertained from the principal soundings that
have been taken that the sea increases in depth from the poles in the di-
rection of the equator, goes so far as to deny the ellipsoidal form as re-
gards the bed of the sea, that is, over the greater portion of the planetary
surface.
I The principal argument of those who look upon the existence of a cen-
tral ﬁre as a demonstrated fact is that, in the external strata of the earth,
so far as they have been explored by miners, the heat keeps on increasing
in proportion to the depth of the excavation. In descending the shaft of
a mine we invariably pass through zones of increasing temperature; only
the rate of increase varies in different parts of the earth, and according to
the strata through which the shaft is sunk. The heat increases more rap-
idly in schist than in granite, and in metallic veins more even than in
schist; in lodes of copper more than in those of tin, and in beds of coal
more than in metallic veins?" In the Artesian well at N euﬁ'en, in IViir-
temberg, the temperature increases one degree Fahrenheit for every 19
feet. In the mines of Monte Masi, in Tuscany, near the boracic springs,
the increase of heat is one degree for every 24 feet. Near J akutzk, in Si-
beria, the heat of the earth increases one degree for every 29 feet of depthqL
Almost every where, however, the progression is less rapid; and the mean
depth which in this greatsu'atiform thermometer corresponds to a degree
of heat is from 45 to 54 feetil In the mines of Saxe, the increase of heat,
according to Reich, is one degree for every 7 6 feet.
Still, the earth has not yet been explored to any very great depth. The
most remarkable excavations which have yet been made are those of Kut-
tenberg, in Bohemia, and one of the mines of Guanajuato, in Mexico; even
these have scarcely attained a depth of 1100 yards, not more than a six or
* Foxe, Gilbert, Reich von Dechen, quoted by Bischoff in his lVd'rmcZehrc, p! 169-171.
'E' Collegno, Geologz'a, p. 26. _
i Bischoff, lVdrmeleln-e, p. 254. The learned German professor endeavors even to trace
out in various countries clzt/zonisot/zcrmcs, or curves of equal subterranean heat.
ITS INTERNAL CONDITION. 31
seven thousandth part of the earth’s radius. It would, therefore, be some-
thing more than imprudence were we to attempt to form a judgment as
to the whole interior of the globe by the temperature of the external strata,
and to aﬁirm that the heat, increasing according to some constant propor-
tion from the surface of the soil to the centre of the earth, would attain
to a temperature of200,000°—a heat far beyond the power of man’s im-
a gination to conceive. In the same way we should have to conclude, from
the gradual cooling of the high aerial layers, that the decrease of heat
would continue up to the midst of celestial space, and that at miles above
the earth the cold is equal to 5000° below zero. The superﬁcial portion
of the globe is traversed incessantly by magnetic currents, taking their
course from pole to pole, and in this portion all those phenomena of plan-
etary vitality take place which are constantly modifying the elevation
and form of continents; this surface, therefore, must doubtless exist under
altogether special conditions as regards the development of heat. The
thinness of the earth’s crust is therefore any thing but proved by the grad—
ual increase of temperature in the shafts of mines and other excavations.
M. Cordier, being struck by all the objections which presented them-
selves to his mind as to the thinness of the terrestrial crust, has admitted
that this covering could not be stable without having at least from 7 5 to
175 miles of thickness. '
Quite lately, Mr. Hopkins having subjected to the calculations of the
higher mathematics all the elements furnished by the phenomena of the
terrestrial precession and nutation, has arrived at the following result.
He has proved that, either with or without a central ﬁre, our planet would
be actuated by periodical movements of a totally different character, if
the solid portion of its crust had not a thickness of 800 to 1000 miles—-
that is to say, about a quarter or a ﬁfth of the earth’s radius.* MM.
Thomson, Emmanuel Liais, and other servants, taking up and‘discussing
all these investigations, have endeavored to prove that, looking at the va-
rious astronomical phenomena, the interior solidity of our planet is an in‘
controvertible fact-.1 Nevertheless, the recent experiments of lVLDelaunay
on glass globes ﬁlled with water render it very probable that even if the
earth contained a mass of molten matter, this mass would rotate, together
with the crust, as if it were a solid body, and would adopt a similar course
as regards the attractions of the sun and moon. We are not, therefore,
warranted as yet in pronouncing any decisive opinion. The hypothesis
which seems, both to Mr. Hopkins and also to Sartorius von Waltershau-
sen, the historian of Etna, to harmonize best with the volcanic phenome-
na,I is, that there is no actual central ﬁre, but only internal seas of red-
hot molten matter scattered about in various parts of the inside of our
planet, situated not far from the surface of the earth, and separated from
one another by masses of solid strata.
* Philosophical Transactions, 1839, 1840, 1842.
‘l’ L’Espace Celeste et la Nature Tropicale.
I Vz'de the chapter on “Volcanoes.”
32 _ THE’ EARTH.
CHAPTER IV.
GEOLOGICAL STRATA. -— CONGLOMERATES. —- SANDSTONES. — CLAYS. -- LIME-
STONES.-—-FOSSILIFEROUS BEDS—SEQUENCE OF ORGANIC BEINClsr—GEN-
ERAL CLASSIFICATION OF STRATA.——-DURATION OF GEOLOGICAL PERIODS.
THE most ancient positive evidence relative to the geological history
of the earth is afforded by'- the ﬁrst sedimentary layers which can be cer-
tainly recognized as having been deposited by water on some primitive
ocean-bed. Below the superﬁcial strata of more modern origin we ﬁnd
others belonging to a remoter epoch, and then others of a still antecedent
formation; thus we proceed from stratum to stratum down to the naked
skeleton of the earth, or, at all events, to those rocks which the pressure
of the masses above and the planetary heat have gradually transformed
during the long duration of ages, so as to render their stratiﬁcation uncer-
tain. These superimposed beds, which have often been compared to the
pages of a book, furnish the date of their seniority by the order of their
succession; certainly'we can not say how many hundreds or thousands
of centuries havedelapsed during the formation of each sedimentary bed,
but we may at least learn the relative ages of the series of rocks.
Wherever these strata have not been disturbed since their ﬁrst origin,
they still lie in parallel and almost horizontal layers as at the bottom of
the sea which deposited them; in this case nothing is more easy th'air to
class them in their order of seniority. The geologist who descen‘ds the
shaft of a mine sunk vertically into the earth may, as it were, traverse the
whole series of periods down to the primitive ages; in a few minutes he
may see a kind of abstract of the geological history of the earth. In the
same way, in places where the agency of various meteoric phenomena and
the forces at work in the interior of the earth have cut through any por-
tion of the upper strata, causing steep escarpments, which show, as on an
immense wall, the superimposed beds, the order of succession of the differ-
ent rocks can not be the subject of doubt.* On the other hand,.in coun-
tries where the strata have been upheaved at various angles, being either
distorted, displaced, or sometimes even completely turned upside down—
where rocks springing from the earth in a liquid state, such as porphyry
and lava, have forced their way between the beds, the investigations of
the geologist become very difﬁcult, and much patience and sagacity are
required to attain any result. Finally, the greatest and most difficult
problem is to establish the harmony in age and formation between various
* The opposite proﬁle of the “Pyramid Mountain,” taken from vol. iii. of the Paciﬁc Rail-
road Report, has been revised by M. Mareou, the geologist, who was the ﬁrst to bring under
notice the existence of this remarkable mountain (Fig. 3).
THE CRUST OF THE EARTH. I
rocks separated by valleys, large plains, or even by the ocean.‘ Thus
doubt still exists as to a great number of details, and variance on these
points often arises among geologists. Nevertheless, whether deciphered
or not, these strata, with the various indications which are presented by
their minerals and fossils, are the only authentic annals of our planet.
They are the hieroglyphics, still in part mysterious, which relate to us in
their magniﬁcent characters the history of the world itself


These innumerable strata, so diverse in their position, inclination, and
thickness, are analogous to the beds of the same nature that we notice in-
cessantly in the course of formation. Mountains furrowed out by torrents
and cliffs, sapped by the waves, supply either to rivers or direct to the sea
masses of debris, which, spread out into shingle-strands or beds of pebbles,
are gradually changed into solid conglomerates. The crystalline rocks,
pulverized by atmospheric agencies and the friction of river and sea-water,
become ‘submarine sand-banks, which sooner or later are converted, under
the pressure of the superincumbent masses, into rocks of sandstone. The
tranquil waters of slow—ﬂowing streams and rivers, which neither carry
pebbles along with them in their course, nor are charged with sandy‘ mat-
-ter, are still loaded with small‘particles of ooze and earth, which they de-
posit on their banks and in the bed of the sea, forming these beds of clay
which also ultimately constitute important geological formations. On the
banks of the Mississippi there are enormous argillaceous beds which the
water of the river has left behind it; these are apparently no less ﬁrm
than the rocks which have for centuries met, the assaults of the waves and
C
‘34, . THE EARTH.
storms. In certain lakes .in Mexico, and especially round the reefs of
Florida, oolites like those of the J ura are daily being formed before our
eyes. Finally, ,in the shallows ‘of the sea, fresh beds are being formed, as
of limestone at Guadaloupe, or of drift brought by the sea, as upon the
great bank ofNewfoundland. In the same way, coral insects, madrepores,
and other marine animals are incessantly at work in building up new beds
similar to those of the ancient geological periods. The formations caused
in days of yore by the movement of the water, and the perpetual activity
of teeming marine life, all are still in progress, and disclose to us in what
way the earth’s surface was modiﬁed during a long series of ages.
Although all strata may be classed in a general way in one of the ﬁve
great series—conglomerates, sandstone, clays, gravels, and limestone—
nevertheless, in their various shades of distinction, their relative positions,
and the minerals which they contain, they present indications which allow
of their being classed according to their respective ages. But the organic
remains, animal or vegetable, which are contained in the greater part of
these various formations, are the means which afford us the principal data
for ascertaining, often with certainty, the order of succession of the vari-
ous layers. Natural history alone enables us to decipher clearly these
pages in the earth’s history.
That organic remains are preserved in the ground in an altogether ex-
ceptional way is a fact which naturalists have innumerable opportunities
of satisfying themselves of, in the study of the plants and animals of our
own time. Dead animals are soon devoured by beasts of prey and in-
sects; water, wind, and sun ere long dissolve all that remains ‘of ﬂesh— or
ligaments; the skeleton itself is ﬁnally reduced to dust. The inﬁnite le-
gions of inferior creatures which have no solid bones disappear in myriads
without leaving the slightest trace behind them, and the piled-up masses
of their remains are soon changed into humus and gas. Forest trees and
herbaceous plants disappear like animals, and furnish 'nutriment to other
existences. Scarcely have they perished ere the former organisms aid in
forming new ones—death is the constant food of life. The remains of ex-
tinct vitality can only be preserved for future ages by being suddenly re-
moved from the tooth of the animal and the action of the elements. Thus
organic remains which are clothed by petrifying springs with a covering
of lime, and the trunks of trees which are surrounded by sheets of lava,
become as indestructible as stone itself. . Animals caught in the ice, over-
whelmed by falling earth, or which have died in some deep and inaccessi-
ble cave, may be kept for centuries in a condition of perfect preservation,
and may pass into a fossil state. But although it is comparatively very
rare that a terrestrial being is preserved for future ages either whole or
only in fragments-the case is not the same as regards marine creatures,
which- are ingulfed immediately after death or even during their life in
the sand or mud which is brought by the waves; Thus, in the sediments
of former marine beds and deltas, we ﬁnd multitudes of fossil animals of
which even the most delicate parts are wonderfully preserved; we see
RARI T Y OF OR GANIC' REMAINS. 3 5
this in the beautiful specimens in our museums brought from the beds of
Solenhofen, Monte Bolca, Grignon, and Montmartre.
Besides all this, on those shores where the tides are considerable—in
the Severn, St. Michael, and the Bay of Fundy—the ooze brought by the
waves has frequently covered the footmarks of vertebrate animals, the
tracks traced out by crustaceae, worms, and molluscs, and also the marks
made by the rain-drops and by strong squalls of wind. This mud, grad-
ually hardening, may at last become beds of schist, sandstone, and clay;
and thus, after millions of years, similar imprints of an instant are found
graven on the rocks, deeper and more legible to the eye of the geologist
than the ambitious inscriptions of the kings of the world. But these
magniﬁcent evidences of the past are only common as regards marine
beings; there is very little chance of fossilization for any thing which
lives on the emerged strata, in the air, or in fresh water.
As the preservation of organic forms, or of impressions made by them,
depends on exceptional conditions, a great number of strata are partly
destitute of fossils, whilst immediately above and below them geologists
are able to discover multitudes of the remains of the ancient inhabitants
of the globe. Thus the deﬁciency of evidence in a stratum absolutely de-
cides nothing against the existence of life in any particular period of the
planetary history. The negative conclusions as to life which many scwcmts
have desired to deduce from the absence of fossils in certain beds are not
based on any sure ground. Besides, the exploration of the globe is scarce-
ly commenced, and a number of beds in which no relics had previously
been discovered have since presented to science plenty of geological treas-
ures; in addition to which, we must not forget that there are great unex-
plored tracts at the bottom of the sea, as well as on terraﬁrma.
The appearance and disappearance of fossil species are not in perfect
harmony with the succession of rocks, and consequently the 'idea is not
warranted which connects some kind of cataclysm with the end of each
geographical period. A continuity of life has linked together all the for-
mations, from the ﬁrst organized beings which made their appearance on
the earth down to the countless multitudes which now inhabit it. One
species would perhaps live but for a very short period of the planetary
history; another species would make its appearance in a certain bed; at
ﬁrst it would be rare, and as if trying to force its way into life; then it
would multiply from stratum to stratum, and afterward would either
gradually become extinct, getting less and less through a whole series of
ages, or suddenly disappear. Other generic forms appear to have passed
through every epoch, and representations of them exist after millions of
centuries. The duration of a species does not depend either on the various
revolutions which have modiﬁed the bed, or on any other external cause,
but on its own special vitality. In a general way, the duration of the
existence of any series of beings is in proportion to the more or less rudi-
mentary character of its organization. The inferior vertebrate creatures
have all pervaded a more extended geological cycle than that in which
36 THE EARTH.
superior vertebrate animals are found; Foraminifera have run through a
much longer series of ages than molluscs; the latter, as well as ﬁshes and
reptiles, have a much longer existence as species than Mammalia. Finally,
the great mammals of the Tertiary epoch enjoyed but a comparatively
short term of existence; they were unable to resist the variable inﬂuences
of climate so well as the inferior animals. The higher an organism is
raised in the scale. of being, the narrower are the limits between which it
is conﬁned; all that it gains in rank, it loses, if not in number, at least in
duration of existence as a species.* ~
In what order. did the various species of animated beings follow one
another on the earth‘? Not long ago, geologists put forward a very sim-
ple system on this point. According to their preconceived ideas, the infe-
rior animals, including the class of Crustacea, were the exclusive inhab-
itants of the surface of the planet during the formation of the most ancient
geological beds. Fishes made their ﬁrst appearance during the period of
the Old Red Sandstone; reptiles came into existence in those hollows and
marshy shallows where the vegetable remains were accumulating, which
subsequently became transformed into coal. Birds, properly so called,
ﬁrst took ﬂight at the Cretaceous epoch; next came quadrupeds in reg-
ular order, from the inferior species to the very highest. The ape did not
form one of their number until immediately before the appearance of man,
and the latter was created after all the other animals, as if to sum up in
his personall the long catalogue of anterior life.
The discoveries made during the last few years by indefatigable inves-
tigators,'such as Lyell, Forbes, Barrande, Owen, Leidy, Emmons, and Wag-
ner, have singularly disturbed the serial order 'of species which had been
previously established. Ferns, Lycopodiacea'a, and Oalamitece, which were
thought to be the only families represented in the Coal Measures, have
been added to by many other species, belonging to other families, and
even to the Dicotyledonous order. More than thirty species of reptiles
have been discovered in'those very strata in which, according to the views
of many geologists, not one ought to have been found. Mammals of the
marsupial order have been discovered in the Rhaetic beds of Somerset, and
even in the Trias, at the termination of rocks of Palaeozoic formation.
Apes, at least as highly organized as those of our day, lived during the
period of the Upper Miocene, and man was the contemporary of the cave-
bear, of the mammoth, the woolly rhinoceros, and other great animals now
extinct. No year passes in which geologists fail to discover in the terres-
trial strata new animal and vegetable forms, which transfer our geological
horizon to periods still more and more remote. The facts which prove
the existence of organisms of a superior class in the more ancient terres-
trial beds have become so numerous that dertain palaeontologists have
ventured to doubt the progressive development of the animal and vege-
table series during the various geological periods. In their view, it is in
* Collomb, Bibl. de Geneva, Arc/lives Scz'enfiﬁques, Aug, 1866. 'Wallich, North Atlantic
Sea~bed, p. 95. Lyell, Darwin, Gaudry, Carpenter, etc.


GEOLOGICAL MAP OF ENGLAND L.Ill.
6_ 5 ‘


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lhawu by-Awﬂlcmm after Ramsay. _ he“! by Erhard
HARPER, 5c BROTHERS. NEW YORK


E ARLIES T LIVING BEINGS. 37
each group of species, and not among animated beings as a body, that we
must seek for the order of development.* If, however, we embrace in one
glance the whole body of beings, instead of considering only the earliest
and the latest ones, we are bound to recognize that there has certainly
been a progress in the organic series. In its period of greatest exuberance
vegetable life preceded animal life; in the primitive ages plants destitute
of ﬂowers were much more numerous than the ﬂowering species; Crusta-
cete, molluscs, and other lower animals had their golden age before ﬁshes
and reptiles, and the latter appear to have been the lords of the earth be-
fore mammals appeared on the scene. Even among the latter it seems
very probable that progress was the rule, for most of the animals in the
Oolitic beds are marsupials, and it was not until the Tertiary age that the
larger mammals attained their more complete developmentf Agassiz
thinks that the types of the ancient epochs represent the embryos of now
existing beings, so that palaeontology teaches us of the infancy of all these
forms of existence which are now found in a fully developed state.
Be this as it may, the fossiliferous geological beds, from the most an-
cient to the most recent, are all linked one to another by species common
to two or more of their number. Thanks to the succession of their differ-
ent species, and in spite of the numerous variations in the names used by
them, geologists are now pretty well agreed as to the general classiﬁca-
tion of the rocks over the whole surface of the earth. The most ancient
formations, or the Palaeozoie, resting on the granite or other rocks of a
similar nature, and comprising the Taconic, the Cambrian, the Silurian,
and the Old Red Sandstone groups, are the earliest strata in which we ﬁnd
any remains of organic beings; in them, “in the dawn of vitality,” sprang
into life Eozoon Oanadense (if, indeed, it exists at all, except in the imag-
ination of certain geologists) and the Braintree trilobite (Paradowides


Fig. 4. Paradauides Harlani.
Harlam'), which disputes with the Eozoon the honor of having been the
“Adam” of the terrestrial Fauna. This period of the earth’s history, itself
the successor of periods all unknown, was followed by the age of Carbon-
* Lyell, Supplement to llfanual, p. 35. [Sir Charles Lyell has since (in the tenth edition
of his “ Principles of Geology,” 1868) fully accepted the Darwinian Theory.]
1' Bronn, Albert Gaudry, Owen, Hermann von Meyer, Lartet.
38 THE EARTH
iferous beds, including the Mountain limestone rocks and the various lay-
ers of the Coal formations. Above lie the beds of the New Red Sand-
stone. Next in the geological series come the numerous Jurassic and
Cretaceous stages, known as a whole under the name of Secondary rocks.
The last period preceding the present epoch witnessed the deposit of the
Eocene, Miocene, and Pliocene rocks, and is connected by the Quaternary
strata to the formations which are now being constituted before our eyes.
Finally, the incandescent lavas, trachytes, dolerites, and basalts which have
made their way from below and have traversed the stratigraphical series,
constitute a sixth class of rocks.
Although the general groups are the same in the two hemispheres, the
numerous geological strata in the various countries of the world differ
singularly in their fossils and other characteristics. Nowhere do they
present absolute harmony, and it is therefore very diiﬁcult to class them
certainly in their respective order of succession. In former times, as now,
animals and plants differed according to climates, and therefore the strata
which received all these débrz's, received each of them its own special geo-
logical character. In the varieties which the fossil Fauna and Flora pre-
sent to us, how much is owing to a difference of epoch, and how much to
a diversity of climate ? The solution of this problem is one of the great
tasks of science ‘3* "1
* Marcou, Roches du Jura, p. 240.
MODHTIUA TI 0N OF THE EARTH’ S S URFA 0E. 39
CHAPTER V.
INCESSANT MODIFICATION IN THE SHAPE OF CONTINENTS.--ATTEMPTS MADE
TO LEARN THE FORMER DISTRIBUTION OF SOILS AND CLIMATES.—OBJECT
OF GEOLOGY.—-PROVINCE OF PHYSICAL GEOGRAPHY.
WITH regard to the ages necessary for the accomplishment of the im-
mense geological processes, the history of which are disclosed to us in the
earth’s strata, they certainly must have been of prodigious duration; for
all the annals of humanity are but as a passing moment compared with
the cycles of the globe; the cosmogonical chronology of the Hindoos can
alone give an idea of the periods of the earth’s history. All the calcula-
tions which astronomers have made as to the duration of the great planet-
ary evolutions result in very formidable series of ,years, and it is in mill-
ions or thousands of millions of centuries that estimations are made as to
the duration of these aces. Professor Haughton, a mathematician, has en-
deavored to establish, according to the formula of Dulong and Petit, that
the mere fall in the temperature of 25°, occurring previously to the pres-
ent epoch of our planet, would require about 18 millions of years. In the
same way, the formation of each of the strata which constitute the sum-
total of the geological records of the earth’s surface must have taken up
a long series of centuries, before which the mind recoils in perplexity.
The unceasing transformations of all the rocks which compose the outer
layers of the globe could not have taken place without at the same time
modifying the elevation and outline of the land; thus the general con-
ﬁguration of the emerged portions of the surface has never ceased to
vary since the ﬁrst ages of the globe. The old mountain chains have
crumbled down, stone by stone, and particle by particle, and have been
distributed, in the form of sand and clay, over plains and seas; on the
other hand, ocean-beds have gradually been elevated, and have changed
into dry land, which has here and there been upraised into hills and ranges
of peaks. Strata, when scarcely formed, were soon invaded, and made to
assist in forming other strata. Every particle, as if caught in an eternal
eddy, never ceased to wander from rock to rock; and consequently, con-
tinental masses, which are, indeed, nothing but vast agglomerations of
particles, must have incessantly shifted their positions on the circumfer-
ence of the globe.
It would be of the highest scientiﬁc interest if we could follow, from
age to age, all these shiftings of the outward features of the earth’s sur—
face, and the oscillations of their elevation from century to century. The
harmony of the continental structure, even now so beautiful to contem—
plate, notwithstanding the apparent immobility of its outline, would as-
sume a different kind of grandeur if one could see with the mind’s eye the
40 THE EARTH.
inﬁnite succession of undulations which have rippled the surface of our
planet. Unfortunately, although the direct investigations of geologists
can point out to us those portions of our present continents which emerged
at any particular epoch, they can not disclose any thing to us as to those
regions which, although now buried by the sea, were once elevated above
its surface. Therefore the charts which are prepared of any geological
period can only be partial; but still, these charts, incomplete though they
may be, are none the less an admirable result of ingenious and patient in-
vestigation. It is beautiful, after an unknown lapse of centuries, to be 'ena- _
bled to recognize, among all the various continental regions, those which
were raised above the sea at the same epoch, and thus dimly to trace out
some of the features of the ancient architecture of the globe.
The fault of many geologists, in their too great hurry to ﬁx the com-
mencement of the present period, has been that they have looked upon
these ﬁrst beds of our continents as being the only land which existed at
this epoch of our planet. It is quite possible that there was a time when
the whole surface of the globe was covered with water, and that the ﬁrst
land was nothing but a mere shoal; then, perhaps, that islets, and then
islands made their appearance, and, grouping themselves into archipela-
gos, ultimately united into continents. But nothing warrants the idea
that during the formation of the strata examined by geologists, the pro-
portion between land and water has sensibly changed. Fresh land may
have risen up at points where an examination of the strata proves that
the ocean once ﬂowed; but to make up for this, there are numbers of facts
which bear witness to the disappearance under the water of vast tracts
of country. Age after age, the general plan of continents has been con-
tinually modiﬁed; our plains, and even our very mountains, have been
covered with the waters of the sea; while chains of hills and plateaux rose
high up in latitudes of the globe where the waves of the ocean'are now
rolling. In order to ascertain approximately the former extension of con-
tinents across our present seas, geologists have one means at their com-
mand—that of establishing the perfect harmony of the various strata of a
formation broken through and disconnected by the waves. For instance,
between France and England, the correspondent character of the strata
on the two shores of the Straits of Dover is plainly evident.
The fossil remains which are found accumulated at certain spots in the
earth whither the currents have borne them, likewise prove the ancient
extent of some countries which are now reduced to very small dimen—
sions. Thus Attica, which in the present epoch is a mere rocky promon-
tory of the Greek peninsula, must certainly, in the Miocene period, have
formed a part of a continent presenting vast plains, wide-spreading, grassy
prairies, and thick forests, which must have extended across the space
now occupied by the Archipelago and a portion of the Mediterranean'Sea,
stretching away far enough to unite itself to Africa. This is the tale told,
in a way evident enough to geologists, by the remains of gigantic animals
found in the Pikermi deposits. The droves of hipparions, like those of
EVIDENCE OF FOSSILS. 41


“kw-‘.5’: ~;-,-:-'.;.;.-: \‘ l \‘ I \"w x J
~ -' s7
"1 l :- 3:- , § - .
.::n"v,I:-="\‘,ﬂ \ O ‘ ..:.-. 0"‘-
\\\‘ ;-\“\\\
. _ .
\\ \l . \\ ' l
-


........ ' '


-
------ -
o----— -- ~-
-_---__ -——_
_———-_ -_
—-~-_ _-


s\\\\\\\\s =~2=~l=£= M1,.
' 0-dacwm13cda. , Jzwanioﬁdr.
Fig. 5. The Weald of Kent and the opposite French Coast.


the wild horses of South America, the ﬂocks of antelopes of various spe-
cies, the tall giraﬁ'es, the mastodons, the rhinoceros, the powerful Dinothe-
rium, the formidable Machairodus, stronger than the lion of the Atlas, and
so many animals of large size, thefossil bones of which are kneaded into
the soil, could not have existed on mountains either entirely bare or thin-
ly sprinkled with scanty shrubs, and in the narrow valleys which form
the Attica of our day. No, they required a vast continent like thatof
Africa, where we still see, in the portions not yet invaded by the white
man, such prodigious multitudes of hippopotami, elephants, antelopes, ze-
bras, and buﬁ'aloesi‘ ,
The fossils of the two series, animal and vegetable, serve to prove still
more directly the former existence of lands which have now disappeared.
In fact, if we ﬁnd the same fossil species in the corresponding geological
strata of islands and continents which are at present separated by arms
of the sea, and subject to diﬁ‘erentconditions of climate, we may natural-
ly conclude that the regions in which these species existed were once
united. A harmony of this sort between the Fauna and Flora have ena-
bled geologists to establish the fact of the former existenceof land joining
England and Irelandnt Ireland and Spain,1 and even Europe and America.
In exploring the lignite beds of the Tertiary formation in Europe, geol-
ogists have, in fact, found fossil tulip-trees, the remains of theLouisiana
cypress(Taococlium distz'chum), seeds of the Robina nuts of a United States
species, leaves of the maple, oak, poplar, pine, magnolia,,sassafras, and tax-
us; also of the sequoia—those giantsvof the Californian forests, and other
* Albert Gaudry, Animauxfossiles 'de Pikermi. ‘ I
T Murchison, Anniversary Address, 1863. 1 Edward Forbes.
42 THE EARTH.
North American trees, which do not now exist in European forests. Half
way between the two continents, the lignites of Iceland present an analo-
gous fossil vegetation. Unless a continent, or at least a series of adjacent
islands, had served as a bridge across the wide Atlantic, how was it possi-
ble for these American trees to have invaded the land of Europe ‘? In the
same way, in the Miocene strata of Nebraska, remains have been found of
the rhinoceros, the machairodus, and the palaeotherium—that is, exactly
the same animal fossils as in the corresponding beds in Europe. The for-
mer existence of an identical system of organic life in two continents, now
so entirely distinct in their Fauna and Flora, gives us the right to assume
that, at the epoch of the Tertiary lignite, the scattered lands and the few
clumps of mountains which formed, as it were, the rudiments of our Eu-
rope, were connected with the American coast by an isthmus, separating
the waters of the Atlantic from those of the Frozen Ocean. . This isthmus
was the Atlantis, and the traditions which Plato speaks of about this van-
ished land were perhaps based upon authentic testimony. It is possible
that man may have witnessed the submergence of this ancient continent,
and that the Guanches of the Canary Islands were the direct descendants
of the earliest inhabitants of this primeval land.*
At a still more ancient epoch, when the fossils which are now found in
the beds of the J ura formation were still being deposited at the bottom
of the sea, the Atlantic was in existence, but of very different dimensions.
It would appear that during these ages of the earth’s history, a vast con-
tinent, including the two Americas, Africa, the Indies, and New Zealand,
extended in an oblique direction as regarded the equator between the two
great oceans of the north and south. This continent, which, like the land
at the present time, covered scarcely .a third of the surface of our plan-
et, separated by its enormous mass many of those gulfs in which the re-
mains of organized beings were being deposited; this is proved by the
fact that the J ura formations of Texas, in the same latitude as those of
Southern Europe, do not present, among the few fossils they contain, the
remains of those numerous species of the Old World which, like their con-
geners of the present epoch, travel to-very considerable distances. If
there had been no obstacles between the two basins, this absolute contrast
between the- two Faunas would have beenimpossible. In the same way,
the species of the J urassic‘ formations of South Africa are completely dif-
ferent from those of the Himalaya, Persia, and Europe; this must lead to
theadmission of the former existence of an intervening continent which
prevented the migration ofliving creatures. Finally, the Australia of our
own day presents, both in its Flora and Fauna, the very greatest similari-
ty to the animals and plants which lived in the Jurassic seas of Europe
and on their shores. In looking at the kangaroos of Australia, which re-
mind, usof the marsupials of the Jurassic formations of England, and the
strange ornithorhynchus, scarcely less fantasticin its shape than the an-'
cient pterodactyle, half bird, half batrachian, or than ‘the problematical
* Unger, Die versunkene Insel Atlantis. Oswald Heer, Klee, Gaudry, etc.
OLD 0 ON TINEN T8. 43
Archzeopterz'a: of Solenhofen, one can hardly refrain from the belief that
Australia once formed a part of the ancient Jurassic continent. Besides,
the coast of New Holland is the place where we now ﬁnd the only living
representatives of Trigom'a which once inhabited the J urassic seas.*
Round the inland sea which has now become our present Europe, the
great continental mass threw out a large, crescent-shaped peninsula, at the
origin of which was the mouth of a considerable river, the delta of which
may still be traced out from the coast of the English Channel as far as
Westphalia. On the sheet of water which this peninsula protected from
the freezing winds of the polar zone, warmed, too, as it was, by the heat
of the equatorial lands, the mean temperature must have been much high-
er than it now is in the corresponding portion of the earth; it was, with-
out doubt, more than 68° Fahn, if we may judge by the presence of the
ichthyosaurus and plesiosaurusfr It must, however, be understood that
the outlines and various conditions of these long-vanished regions are still
very far from being known with any degree of certainty, and it will per-
haps require centuries of investigation before a chart of the Jurassic con-
tinent could be satisfactorily drawn up.
Circumstances very similar to those which have enabled us to form
some approximate idea as to the temperature of Europe in the Jurassic
period have also permitted savants to venture on some general indica-
tions relative to the ﬂuctuations of climate which are presented by the
other great periods in the earth’s history. Thus the mean temperature
of Europe was ﬁrst mild; then, during the Silurian ages, it became gradu-
ally raised; in the period of the Carboniferous formations the climate was
very warm and very damp, because the greater part of the land, then
mostly situate in the torrid zone, consisted of an uninterrupted series of
archipelagos. The epoch of the Trias was comparatively cold,<on account
of the great extension of the continent toward the poles. After the ages
of the J ura formations, which were very warm and very dry, came in suc-
cession a temperate period, that of the Chalk; then an epoch of heat, the
Eocene; and then times of cold, gradually increasing up to the Glacial
period; after which the temperature again increased. This is a very
brief abstract of the succession of climates in the region which is now Eu-
rope, following the inferences which Lyell,IMa1'cou,§ Oswald Heer," and
other savants have drawn from the facts which they have observed and
carefully classiﬁed.
We thus see what grandeur there is associated with the labor of the
geologist. Starting from the increasingly profound study of the present
strata, the science of geology has adopted as its task to reconstitute the
varying forms of continents and seas in each of the successive periods of
the history of the globe; it follows out, in the various epochs, the courses
of the winds and the currents, which also have shifted with the continents
* Marcon, Roches a'u Jura, p. 331. 1' Roches du Jam, 1). 326 seq.
1 Manual of Geology. § Roclzes du Jura, p. 335 seq.
ll Tertz'iz'r-Flora der Sclzwciz.
44 THE EARTH
themselves; it endeavors to measure, as if with the thermometer, the tem-
peratures which have prevailed in different ages in the various countries
of the earth; ﬁnally, it seeks, by all the connecting links which the scat-
tered debris can afford, to trace out the marvelous ﬁliation of animal and
vegetable species from the earliest fossils—of which all that has been dis-
covered is but a faintly-marked impress—down to the innumerable beings
which new stock our earth. Still dissatisﬁed with the ideal she has aspired
to, science entertains the hope that she will one day be able to point out
the exact conditions under which every organism was developed in the
periods gone by, and that she will be able even to specify, as regards ﬁsh-
es, shells, and sea-weeds, the depth of the water in which these beings
once lived. The astronomer explores the boundless inﬁnities of space;
the geologist penetrates into the abyss of time.
The investigation of various rocks testiﬁes more and more to the pro-
digious activity of the forces which are ever remodeling the earth. Just
as our planet, like all its sister orbs and all the stars of heaven, is borne
on in eternal motion, so all the particles composing the mass of the globe
are incessantly changing their place, and are circulating without repose
in a cycle no less harmonious than that of the heavens. In the ﬁrst en-
velope of the earth, the atmospheric ocean which sustains the life both of
animals and plants, continual eddies of winds, blowing from the pole to
the equator toward all points of the horizon, are continually circulating.
In the great ocean, too, of waters, every drop also rolls on from sea to
sea, and from the wave is borne up to the cloud, and from the cloud de-
scends to the river. The so-called solid portion of the planet is not less
mobile than the atmosphere and the water, though the shifting action of
its particles is slower; sometimes, perhaps, when, in a short interval of
days, years, or centuries, man has failed to see any vast modiﬁcations ac-
complished, he is tempted to say that the earth is immutable. Was there
not a time when he also designated as ﬁxed stars those distant luminaries
which nevertheless move through ether with so prodigious a rapidity ‘P
Rocks, mountains, and continents are all in a perpetual state of change,
and their particles move round and round the globe like the water and
the air. By the action of torrents and atmospheric agencies, mountains
are crumbled down and carried away into the ocean; new regions are up-
heaved out of the water, while others slowly sink and are ﬁnally sub-
merged; the earth itself is rent open, and gas and the molten matter of
vast strata make their escape. Finally, in consequence of the incessant
chemical reactions going on within the bowels of the earth, the composi-
tion of the rocks themselves is changed, and growths of crystals follow
one another in the metamorphosed stone, just as the Fauna and Flora on
the soil above.* An exchange of matter is likewise going on between the
earth and the celestial spaces, as is proved by the trains of burning stones
which become detached from meteoric bodies rushing through the atmos-
phere, and the tails of comets, through the invisible waves of which the
' * Otto Volger, Erdbeben der Schweiz, vol. a, p. 20.
GENESIS OF THE EARTH. 4 5
earth occasionally passes. Planetary vitality, like every other vitality, is
a continual genesis, an incessant eddy of particles, at one time ﬁxed, at an-
other free, which pass from one organism to another. Nevertheless, in
whatever aspect of its inﬁnite modiﬁcations the earth is contemplated, it
is ever beautiful in its form, and its consecutive phenomena take place
with a marvelous harmony.
Physical geography, in conﬁning itself to the present epoch, merely de-
scribes the earth as it is existing before our eyes. Its aim is not so am-
bitious as that of geology, which tries to recount the history of our planet
during the long succession of ages; but still, it is geography which 001-
leets and classes the facts; she it is that discovers the laws both of the
formation and the destruction of strata. She opens out a path for geol-
ogy to travel over, and each of her advances in the knowledge of existing
phenomena helps to render easier some victory of the human intellect
over the past history of the globe. Without her aid it would have been
impossible even to have ventured the initiative stepuinto the labyrinth of
vanished ages. I
PART II.
THELAND.
CHAPTER VI.
REGULAR DISTRIBUTION OF CONTINENTS.——IDEAS on ANCIENT NATIoNs ON
THIS PoINT.—HINnoo ‘LEGENDS—ATLAS AND THE GIANT CHIBCHACUM.—
HOMER’S sIIIELn—sTaABo.
THE globe of our earth is in evident conformity to all the laws of har-
mony, both in the spherical uniformity of its shape, and also in its con-
stant and regular course through space. It would, therefore, be incom-
prehensible if, on a planet so rhythmical in all its methods, the distribu-
‘ tion of continents and seas had been accomplished, as it were, at random.
It is true enough that the outlines of coasts and mountain ridges do not
constitute a system of geometrical regularity; but this very variety is a
proof of a higher vitality, and bears witness to the multiplicity of motions
which have co-operated in the adornment of the earth’s surface.
The uneven and yet harmonious conﬁguration of the continents is, as it
were, the visible representation of the laws which, for a long series of cen-
turies, have ruled in the external modeling of our planet. “There is not
a fundamental line in the outline of the earth which is not a line of ge-
ometry.”*
So long as the greater part of the surface of the globe was unknown to
geographers, and they were ignorant of the true form of the earth, it may
be easily understood that man, embracing in his feeble glance but a lim-
ited horizon, should have recognized nothing but chaos in the intricate
net-work of geographical lines. It was impossible for them to take into
account the laws which had inﬂuenced the distribution of continents, be-
cause they were ignorant of their very outlines; as the analysis of the va-
rious terrestrial forms was not yet completed, they were, of course, una-
ble to accomplish the synthesis of them except by making unproved as-
sertions, or by speculations in miraculous cosmogonies.
At all events, nations, in their infancy, being well assured beforehand of
the vitality of the bountiful earth which supported them, have, without
exception, looked upon nature as an immense organism endowed with su-
preme beauty. For some, nature was an animal; for others, she was a
plant; for all, she was an incorporated god. The ideas which they formed
on this point are in general the most precious matter which is handed
i * Jean Reynaud, Terre et Ciel, p. 26.
HARMONY OF THE C’ ONTINEN T8. 47
down in their traditions, either oral or written; for in these legends, in
which they display the loftiest manifestations of their poetical genius,
they sum up their persuasions as to the origin both of the earth and also
of their own race. For the comparative study of the history, manners,
and ideal of every nation, no book could be more useful than one which
would contain all the cosmogonical conceptions which havebeen devised
down to our own times. But, as may easily be understood, these legends
are more simple and rudimentary in their nature, just in proportion as the
cosmical features among which they were conceived, and of which they
are in a great part the reﬂection, were more subdued in their manifesta-
tions and phenomena. The people of the extreme north, who are in the
habit of digging out subterranean habitations in order to avoid the cold,
their country being for a great part of the year covered with ice and snow,
can not have their ideas as to the harmony of the globe inspired by the
same conceptions as the men of the south, who dwell at the foot of the
highest mountains in the world, and constantly contemplate all the great
phenomena of planetary life—monsoons, hurricanes, the sudden overﬂows
of rivers, and the rapid increase of immense tropical forests. To the Hin-
doos, every thing in nature is motion, never-ceasing creation, and startling
activity. According to one of their books, Brahma, the eternal laborer,
created the earth while surveying his own reﬂection in the ocean of sweat
that had fallen from his brow. s
The Hindoo legends as to the formation of the earth and the distribu-
tion of continents are very numerous; besides, most of these hypothetical
cosmogonies are remarkable for their boldness and for the deep convic-
tion they manifest of the vitality which animates the earth, and all that
it contains. However strange some of these grandly poetical theories
may seem to us, they are not on this account any less true than the dry
systems of mere nomenclature in which certain unhappy scholars have
considered the whole scheme of geography. According to an ancient
Hindoo belief—very similar to that of several of the American nations—
the earth is nothing but a burden placed on a gigantic elephant, the syna—
bol of intelligence and wisdom; while an immense tortoise, representing
the still rude forces of nature, bears the enormous animal over a shoreless
sea of milk, boundless as inﬁnity.
Subsequently, the ideas which the Hindoos formed as to- the origin of
the globe were singularly diversiﬁed, according to the various epochs and
sects. The Brahmins fancied that the earth was a'full—hlown lotus, ﬂoat-
ing on the surface of the waters. The two peninsulas of the Ganges and
the other Asiatic countries are the expanded ﬂower, the-isles scattered
over the ocean are the half-opened buds, distant lands are the softly spread-
ing leaves. The Ghauts and the Neilgherries are the stamens of the im-
mense ﬂower, while in the midst culminates the lofty Himalaya, the sacred
pistil, in which are organized the seeds of the world. Man, like the tiny
insect which sees inﬁnity in a rose, builds'his imperceptible cities near the
honey-cups of the ﬂower, and sometimes spreads his wings to glide over
48 THE EARTH.
the sea from the corolla of‘the Indies to that of Ormuz or Socotora. The
stalk of the plant disappears in the depths of the ocean, and, descending
from abyss to abyss, at last buries itself in the very heart of Brahma.
This fantastic, but yet somewhat grand conception, which at least at-
tributed to the earth some degree of motion and life, is very superior to
all the dogmatic theories of the Syrian priests and the Hebrew Talmudists;
the latter, in their terror of change, looked upon the terrestrial mass as an
immovable block solidly based on immense columns of stone or metal,
which were themselves lost in primitive chaos. These ancient and coarse
hypotheses are met with again in the more noble myth of the Greeks, ac-
cording to which the globe was placed upon the shoulders of a kneeling
giant. This was an idea which was in full harmony with the plastic ge—
nius of Greece, which ever sought to recognize in every thing the propor-
tions of the human form, deiﬁed, as it was, by strength and beauty. The
idea, in the main, had remained much the same, but it had assumed a
shape which was more poetic, and consequently more in conformity to the
genius of an infant nation. Imbued with similar ideas, the aborigines of
the plateau of Bogota tell how, in punishment for some crime, the good
goddess Bochica condemned the giant Ghibchacum to bear upon his shoul-
ders the burden of the earth, which previously rested upon pillars of the Zig-
num-m'tce wood. Earthquakes, therefore, were derived from no other cause
than the wearied or impatient movements of this Atlas of the New Vvrorldfi‘
With regard to the ideas in respect to the distribution of continents aiid
seas over the surface of the globe, they could hardly fail to be erroneous,
inasmuch as they took their rise among nations who endeavored to form
a judgment as to the whole of the earth by means only of the few coun-
tries which were known to them.
According to the poems of Homer, which are imbued with the ideas of
the ancient Greeks as to‘ nature, and also mankind and their ways, the
earth is a great disk, elevated at the edges by a'lofty' girdle of mountains,
round which the river Ocean rolled its swelling waves. In the centre of
the disk Olympus towered up with its three rounded summits, on which
stood the mansions of the ever-happy gods, and Jupiter, throned on its
loftiest crest, looked down through the clouds and saw the restless crowd
busy at his feet. The land, divided into two halves by the blue sheet of
the Mediterranean, stretched far away to the very verge of the disk, like
the raised ﬁgures which ornament the front of a shield. Down from the
heights of Olympus the immortals contemplated in one glance all the pen-
insula of Greece, the white isles of the Archipelago, the coasts of Asia Mi-
nor, the plains of Egypt, the mountains of Sicily, inhabited by the Oy-
clops, and the Pillars of Hercules -—-the boundary-stones of the ancient
world. All round, above the tract inhabited by man, stretched the crys-
tal dome of the ﬁrmament, borne up by the two columns of Atlas and
Caucasus. . -
But the discoveries of travelers and the calculations of the Greek as-
* Bollaert, Antiquarian Researches, p. 12. 1
EARL Y IDEAS OF T HE EARTH. 4:9
tronomers must have gradually modiﬁed this primitive theory. Strabo,
who was, however, one of the greatest travelers of antiquity, having trav-
ersed the earth from the mountains of Armenia to the shores of the Tyr-
rhenian Sea and the Euxine, and to the frontiers of Ethiopia, had already
formed a very just idea of the real distribution of the continents of the
ancient world, and discussed with wonderful Sagacity their mutual rela-
tions. Overstepping the limits of the regions already known, he went so
far as. to hazard‘the assertion'that, between western Europe and eastern


REGION OF DARKNESS
Galactophagi- . ' '~; , \J _.
Haws» , _ ‘


. a: ' "' "11,’.
> v _ -. _ \l'r‘ '
M-ir‘ﬁl "1:55 ' - '
Fig. 6. The World after the poetic


accounts of Homer.
Asia, there existed an inhabitedland forming an equipoise to the Old World.
In all his scientiﬁc audacity, he conjectured that whiehmodern geography
has since discovered—that “not only more masses of rock and islands,
large or small,but also whole continents, may beupheaved from the bed
of the sea.” As the great Ritter has stated, with a feeling which. may al-
most be called ﬁlial, Strabo is the real founder of geographical science, and
modern scwants have only resumed his work, after so many centuries smit-
ten with sterility, ﬁrst by the Roman Caesarism, and subsequently by the
barbarism of the Middle Ages. '
D
50 THE EARTH.
CHAPTER VII.
INEQUALITY OF LAND AND VV'ATER.—-THE OCEANIC HEMISPHERE.——THE CON-
TINENTAL HEMISPHERE.—THE SEMICIRCLE OF LAND.—DISTRIBUTION OF
THE HIGHEST PLATEAUX AND LOFTIEST MOUNTAIN-CHAINS ROUND THE
INDIAN AND SOUTHERN OCEANS.'—POLAR CIRCLE.—CIRCLE OF LAKES AND
DESERTS.—-COASTS ARRANGED IN ARCS OF A CIRCLE.
THE most prominent fact which strikes an observer in an examination
of the superﬁcies of the earth is the unequal extent of the ocean and of the
land which has emerged from it. Although at the two polar regions
there are still vast unexplored tracts forming about a sixteenth of the ter-
restrial surface, still it may be approximately stated that three quarters
of the surface of the globe is covered by sea. The plate gives an idea of

Fig. 7. Relative proportions of land and water in diﬁ‘erent latitudes.
the distribution of land and sea in the explored regions of the globe from
75° north latitude to 70° south.* An equilibrium between the two ele-
ments exists only on two parallels of the terrestrial circle, one of which is
in 45° of north latitude, half way between the equator and the pole. In
this part of the earth’s circumference, the land occupies exactly one half
of the surface of the globe.
The principal accumulation of water is in the southern hemisphere, and
' * Dove, Zeitschrzlftjiir allgemeine Erdkunde. J an., 1862.
LA ND AND IVA TER. 1
the continental masses, on the other hand, are grouped in the northern
half of the earth’s surface. This contrast between the two divisions of the
globe becomes much more striking if, instead of takingthe two poles as the
centres of our hemispheres, two points are chosen which aresituated, one
in the midst of ther'nost extensive tracts of ocean, and the other about the
centre of the group of continents. If we describe a great circle round
London, which at the present time is, in fact, the great focus of attraction
for the commerce of the whole world, almost all the continental surface.-


Fig. 8. Oceanic Hemisphere.
surrounding the basin of the Atlantic, rendering it almost an inland sea,
will fall within this hemisphere. The other half of the terrestrial surface,
the centre of which would-be situated somewhere near New Zealand, the
antipodes of Great Britain, is almost entirely ﬁlled up with the immensity
of water. The antarctic countries—Australia, Patagonia, and’ the adja-
cent archipelagos—form the only land‘which breaks the uniformity of this‘
oceanic hemisphere. According to a very plausible hypothesis, this ex-
uberancewin the development of continents on one side of the globe, and
the aﬁlux of the waters of the ocean towards the opposite hemisphere, are
52 . THE EARTH .
caused by the unequal weight of the materials which constitute the mass-
of the globe and the consequent non-coincidence between the actual cen-
tre and the centre of gravity?" ‘ ‘
The coast outline of the continents which surround the. great ocean.
tends to a form which is perceptibly circular; it is a kind of ring, broken
in two at the south near the frigid zone .of the antarctic circle. From the
southern point of Africa to Kamtschatka, and from the Aleutian Isles to
‘ Cape Horn, the land is arranged in an immense amphitheatre, the circum-


No. 9. Continental Hemisphere.
ference of which is equal to the circumference of the globe, and can not-
be less than 25,000 miles. They are not merely low shores which spread
‘in this hemieycle round the oceanic hemisphere; the highest plateaux, the
loftiest‘mount‘ains ‘of the‘world, are drawn out in a vast semicircle in those
countries which are adjacent to the Paciﬁc, and tend to, incline, toward
that ocean the centre of gravity of the whole of the continental bulk. .-
Thus it is along the side of the Indian Ocean, an appendage as it is to
the great Southern Ocean, that Africa presents its loftiest ‘ridges; there,-
* Herschel, Physical Geography,p. 15.. .

7
PL.
NORTH AM ERICA


numb, AVmll‘emin.
as
j
Bag‘? by Erhard‘): May-Twain


CONTOUR OF THE LAND. 53


Fig. 10. Basin of the Paciﬁc.
too, are found the snowy mountains of Kenia and of Kilimandjaro and the
plateau of Ethiopia, like a great fortress surrounded by bastions. East-
ward of the narrow entrance to the Red Sea stands another plateau, that
of the Yemen,‘ whose steepest slopes are likewise turned toward the shores
of the ocean. _
Farther on, this rampart of lofty ridges, which might well be called the
“ vertebral column” of the body of continents, is interrupted by the de-
pression of the Euphrates and the Persian Gulf; but it again commences
at the north of Persia. The Caucasus, the Elburz, the Hindu-Kutch, the
Karakorum, and the proud Himalaya, the summits of which rise more than
5% miles above the plains of Hindostan, all are, on an average, three or
four times nearer to the Indian than to the Arctic Ocean. This difference
would be still more increased if we did not take into account, as portions
of the great Asiatic body, the southern peninsulas which stretch away so
far into the sea. Taken as a whole, the continental mass may be divided
‘into two gradients, one of which descends rapidly toward the plains next
the Indian Ocean, whilst the other side, ribbed with divergent mountain
chains, inclines more gradually toward the immense marshy tw-zclras which
border the Frozen Ocean. ‘
The great plateaux of Central Asia, bounded on the north and south by
the mountain chains which radiate in a fan-like shape from the knot of the
Hindu-Kutch, form, in the direction of the northeast, the highest portion
of the continental amphitheatre; then, in the north of the valley of the
Amoor, they are prolonged up to a short'distance of the coast-line by
ranges of peaks, which tower over the ‘Sea of Ochotzk and Behring’s
Straits. Beyond this the waters of the Paciﬁc have opened out a passage-
to join the tides of the Frozen Ocean; but yet the line of mountains is
still prolonged. Arranged as they are, in the form of a broken isthmus,
on the south of the Straits, the Aleutian Isles unite'the two continents of
Asia and North America; one might almost fancy them the shoreline of
some ancient and submerged land.
0
54 THE EARTH.
The lofty peninsula of Aliaska, which follows on to the Aleutian range,
is the starting-point of the series of highlands which border the coasts of
the Paciﬁc along the whole length of the two American continents. Par-
allel chains, abutting in some places on large groups of mountains, bend
round the shores of Sitka, British Columbia, and California, gradually
merging into the plateau of Anahuac. The latter is prolonged on the
southeast by a volcanic chain, here and there interrupted; but on the
coasts of the Gulf of Darien the great chain begins again, and, plunging
the rocks which form its base deep into the waves of the Paciﬁc, extends


its double or tripleisnowy ridges down to the Straits of Magellan. The
other elevations of the surface of the ground he to the east of this back-
bone, as it were, of the South American continent, and attain a very much
less considerable altitude; they are, indeed, intersected and even crossed
by some of the rivers which take their rise in the perpetual snows of the
Andes. Added to this, the steepest slope of the principal chain is uni-
formly turned toward the coast of the Paciﬁc, and the distance from the
mouths of the Amazon to the summits of the Andes is on the average, at
POLAR CIRC’LE. 55
least, ﬁfteen times longer than the short span from the ridges of the latter
to the shore of the ocean.
The immense semicircle of high land forming the inner coast-line of the
mass of continents which extended from the Cape of Good Hope round to
Cape Horn is not, however, the only evidence of the forces which are al-
ways in action, tending to elevate the salient portions of the terrestrial
sphere, and operating in great circular lines. Thus in the chain of the
Andes is commenced a series of volcanic mountains and islands which
forms a vast circle round the Southern Ocean. This is the great ring of


‘IF-R ‘ of
Fig. 12. Circle of-Inland Lakes and ‘Seas.
active volcanoes which was for the ﬁrst‘ time described by. Leopold von
Bach, and designated byOarl Ritter as the “ Circle of Fire.“
Thus,also,' the continental and insular shores which are turned toward
the Arctic Ocean assume a circular curve. - As far as it is possible to judge
from the present state of our knowledge as to this part of the .world,'__it
appears as if a polar circle inclined about ﬁve degrees toward Behringls,
Straits would have for its almost regular circumference the ‘northern
* Vide the chapter on “Volcanoes.” '
56 - THE EARTH '
I coasts of Siberia, of Parry’s varchipela_<__>,io, Greenland, S pitzbergen, and Nova
Zembla. _
Another circle, inclined about ten degrees to the pole in the direction
of the meridian of Paris, would pass through the greater 'part'of the inland
seas of the Old and New Worlds. -- This curve would enter ‘the Mediter-
ranean through the Straits of Gibraltar, and, crossing this sea, as well as
the Euxine,.would unite the Caspian and the Sea of Aral, both of which,
during a recent geological epoch, formed but one sheet of water; it would
then be prolonged toward the Paciﬁc through the chain of the chief Sibe-
rian lakes, including the Baikal. On the American continent the curve


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Fig. 13. semicircle of Deserts.
passes through the Winnipeg Lake, the Mediterranean of the great lakes
of the St. Lawrence, then the Champlain Lake, and the Bay of Fundy.
Thus terminates this great series of continental depressions, which cer-
tainly was not formed at random. On the north of the Mediterranean, ‘
the most important of all the inland seas, the loftie'st mountains in Europe
form a rampart similar to that which bounds the South American shore
of the Paciﬁc. In fact, the Pyrenees, the Alps, and the Balkans form a
sort of wall, broken through with numerous gaps, which is much nearer-to
the Mediterranean than to' the northern seas-and presents also its steepest
slopes toward the south.
DESER TS AND SEA- 0 OAS T S. 5 7
Jean Reyna'ud has also thought that he could point out* the existence
of another terrestrial ring, which must likewise have been formed in obe-
dience to some great geological law. This third circle, inclined 15° (or
rather 20°) to the pole, passes through the Isthmus of Panama, which is
the deepest depression of the land of America, and crosses almost all the
great deserts in the Old \Vorld, many of which were covered with water
during the later terrestrial periods. These sandy or rocky tracts are ar-
ranged obliquely across the continents of Africa and Asia, and consists of
the Sahara, the sandy districts of Egypt, the Nefoud of Arabia, the salt
platcaux of Persia, and the Cobi, or Chamo, the latter inferior in extent
only to the African solitudes. It is a remarkable thing that this series of
dried-up seas is commanded on the north by various mountain chains, the

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Alps, the Taurus, the Caucasus, and the Altai ; like the Paciﬁc and the
Mediterranean, these new vanished waters were bordered on the north by
a rampart of high lands. Oscar Peschel has, however, proved that the
phenomena of climate constitute the real cause of the supposed “Equator
of Contraction,” and that this semicircle of deserts is to be attributed to
the general direction of the winds and the scarcity of rain.
Not only those various regions which are distinguished by some strik-
ing analogy in elevation and aspect are circularly arranged on the surface
of the planet, but the mere outlines of the continents'themselves seem to
be obedient to some rhythmical law, in conformity to which they present
* T erre et Ciel, Eclaz'rcz'ssements scientiﬁqucs.
58 a THE EAR TH.
a series of arcs of a circle, assuming a regularity which is‘ sometimes al-
most perfect. The coasts of the three southern continents, South Amer-
ica, Africa, and Australia, afford remarkable instances of this rule. The
coast-lines of all the peninsulas of the northern continent may likewise be
cut up into arcs of a circle, and multitudes of islands, of which Sicily can
perhaps be taken as a type, may be ‘compared to actual curving~sided tri-
angles. This circular arrangement of the coasts is so frequently re-
marked that many geologists have gone so far as to endeavor to class va-
rious countries according to the degree of the curvature of their gulfs and
bays.

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DIVISION OF THE LAND. 59
CHAPTER VIII.
DIVISION OF THE LAND INTO THE OLD AND NEW WORLDS.—DOUBLE AMERI—
CAN CONTINENT.—-DOUBLE CONTINENT OF EUROPE AND AFRICA.-—DOUBLE
CONTINENT OF ASIA AND AUSTRALIA.
ALTHOUGH we may consider the continental masses as arranged in cer-
tain great circles traced round the sphere, we must also recognize the ef-
fect of another law in virtue of which the various groups of land are ar-
ranged in three double continents, forming respectively three parallel
series.
At ﬁrst sight, it would seem as if the portions of the earth which have
have emerged from the waters, form, in fact, but two groups—those of
the Old and New Worlds: and that the shapes of these groups appear to
bear little or no resemblance to one another. Yet a careful examination
can not fail to reveal a striking unity’ of plan, where at ﬁrst sight all
seems disorder and chaos. The fact is, in consequence of the crossing
of the different upheaved portions of the earth—some in a circular direc-
tion round the seas, others parallel to the meridian—there is produced
among the continental groups a series of contrasts‘which so interfere with
the resemblances, as to cause that, in the general distribution of the land,
opposite forms should successively predominate. Nevertheless, this med-
.ley, by its inﬁnite variety, is the very thing which gives so great a har-
mony to the ensemble of the terrestrial outline.
In the comparative study of the conﬁguration of continents, '..;._".iiust
choose America as our type, because in this portion of the world the line
of upheaval, tending from north to south, forms a tangent to the curve
which is described by the disposition of the land round the Paciﬁc, and
is even coincident with it along a certain portion of its extent. In con-
sequence of this coincidence of the axis, the New World exhibits a very ‘
great regularity of shape. It is composed of two triangles, each pointing
its apex toward the south, and linked together by a very narrow isthmus.
These two halves of America, one of which belongs entirely to the north-
ern hemisphere, the other being tropico-meridional, form two perfectly
distinct continents, and yet they show so great a similarity of structure
that they are evidently the counterparts of one another. Nevertheless,
as the natural effect of the increasing divergence in North America be-
tween the continental axis and the circle of mountains which spread
round the Paciﬁc, this continent is much larger than its companion, and
its coast-line is much more indented. The more typical form, therefore,
is that of the southern continent.
In the Old World, Africa evidently follows the same model as South
(50 THE EARTH.
America. As regards their general structure, the two continents are
alike in their great triangular mass, with coasts slightly inﬂected; and
the similarity extends even to the details of their gulfs and promonto-
ries. The contrasts, are, it is true, very numerous; but they exhibit so
much regularity and rhythm, so to speak, that even in these we can not
fail to see a new proof of unity of formation in the two continental
masses.
As far as Europe is concerned, we should, at ﬁrst sight, be tempted to
say that there was no degree of correspondence between this part of the
world and the North American continent. In fact, this collection of pe-
ninsulas, which even in our days is still the most important region of the
whole world, on account of the high civilization of the nations inhabiting
it, might be looked upon as nothing but a geographical appendix—a mere
prolongation of Asia; in fact, we almost hesitate to compare it with
North America, the bulk of which occupies a superﬁcies twice as large.
Yet a geological study of the conformation of Europe proves that in re-
ality it forms a distinct continent. At some previous epoch it was sepa-
rated from Asia by a sheet of water, which stretched from the Mediterra-
nean to the Gulf of Obi, through the present Euxine, Caspian, and Aral
seas. At. the foot of the mountain chains of Oural and Altai extend those
immense steppes which, like most deserts, still retain much of their former
oceanic appearance, and form the eastern boundary of Europe quite as
effectually as would a second Atlantic. The arm of the sea which once
divided these two divisions of the world is, indeed, dried up; but, al-
though now united, the two lands none the less retain their distinctly de-
ﬁned characters.
Thus, geology bears its testimony in establishing the continental form
of Europe and its similarity to North America. The resemblance be-
tween the two quarters of the globe is kept up on the southern as well as
on the eastern side. It is very true that on the southern side the land of
Europe is no longer connected with that of Africa by an isthmus similar
to that which joins the two Americas; but, as even Strabo well knew,
an upheaving of scarcely a hundred yards would sufﬁce to form a tongue
of land from Sicily to Tunis, dividing the Mediterranean into two halves.
A submarine bank separates this sea into two deep basins, and, owing to
its steep elevation, may be considered as an actual isthmus. Added to
this, the‘ northern part of Africa—that is, the region of the Atlas, com-
prised between the former sea of the Sahara and the present coasts of
Morocco, Algiers, and Tunis—is certainly an ancient dependency of Eu-
rope. Modern science has established the fact that, as regards both its
Fauna and its Flora, as well as its geological constitution, the whole of
the eastern sea-coast of the Mediterranean—the north as well as the south
—forms an inseparable whole. Thus, M. Bourguignat has clearly estab-
lished, by his examination of living molluscs, that Northern Africa does
not possess one single species which is peculiar to it, and that all the
types of the animals which are found on the slopes of the Atlas proceed
D O UBLE C ONT I NENTS. 6 1
from the Iberian peninsula. The western Sahara and Tripoli being equal-
ly devoid ‘of any species specially belonging to them, it becomes evident
that these latter regions, at the commencement of the present epoch, had
not yet emerged from the bed of the ocean, and that Mauritania formed
the southern continuation of the Spanish peninsula;>24 the headlands of
Ceuta and Gibraltar then formed portions of one and the same chain of
mountains. The ancients were not ignorant that the western entrance to
the Mediterranean had once been closed, since they attributed to Hercules
the honor of having opened the gate between the two seas. Many au-
thors even regarded it as a vexatious innovation that the geographers
had made Europe and Libya two distinct parts of the world; for although
separated by the sea, the two regions appeared to them to belong to the
same geographical whole]L
The external outlines of Europe remind one forcibly of those of North-
ern America. In both continents, the coasts which border on the Atlan-
tic are deeply indented, and not only allow the sea to penetrate a long
way into the interior of the land in various places, but also threw out pe-
ninsulas far into the ocean. In Europe, the Mediterranean and the Baltic.
Sea correspond with the Gulf of Mexico and all those seas which extend
between Greenland and British America. But it must be remarked that
in Europe, the arrangement of which is ﬁner and more delicate than that
of any other part of the world, the peninsulas are more slender in form,
and the inland seas more surrounded with land. In Europe, the penin-
sulas have become islands, and the seas have become lakes. Neverthe-
less, Europe corresponds in its structure with North America to a great
extent, and forms, with Africa, a second pair of twin continents, parallel
to those of the New \Vorld.

.
\.\\‘\\\§\3\‘%§?5-f/;Fik—F\ ,7: :1
was. is ‘11‘:5"/><—t77*5"2§i7{ﬁ8r93'


Fig. 15. Term quadriﬁda.
Asia and Australia constitute the third pair of continents, although ,I
their form only very imperfectly reproduces the primitive type. There
is an interruption of equilibrium to the great advantage of the northern
portion; but in the general conﬁguration of these great masses we can
still discern the principal features which distinguish the other double
continents. Like North America and Europe, Asia is geologically iso-
lated; like these two parts of the world, she throws out numerous penin-
* Bourguignat, La Malacologz'e dc Z’Algérie.
‘l’ Sallust, Bell. Jar-9., c. 17; Von Hoff, Verd'nderzmyen der Erdoberﬂd'clze.
62 THE EARTH.
sulas into the seas which surround her; and although she is not directly
united to Australia by a continuous isthmus, yet the Sunda Isles, “like
the piles of a demolished bridge,” stretch across the sea between the two
continents. As regards Australia, both by its regular and almost geo-
metrical form, and also by its entire absence of peninsulas, it evidently
reminds us of the two other parts of the world which push their way far
into the Southern Ocean.
. \‘_\\\_
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.\
.\.\
Fig. 16. Mundus tripa'rtitus.
Finally, if we consider separately the Old ‘World, or eastern group of
continents, we may recognize a quadripartite division, or the separation
of the land into four parts arranged two by two on the north and south
of the equator. This is the idea that was taught by most of the ancients,
which also induced them to give to the world then known the name of
Terra guaclr'g'ﬁtlmi‘ Others, no less following certain systematic concep-
tions, fancied that the land that had emerged from the deep was shaped
like an egg, and composed of three portions, surrounding the sacred tem-
ple of Delphi, “ the umbilicus of the world.”
Thus, in the external form of continents, we ﬁnd two quite distinct
laws in action; one, according to which they are arranged in circles ob-
liquely to the equator, the other which distributes them in three lines par-
lel to the meridian. To this complication is due the apparent irregular-
of the double continents in the Old World, for there the two axes of
mation cross, and consequently there,too, is produced a great diversity
the relief of the land. The mutual resemblances and contrast exhibited
the two halves of the world can, however, be perfectly well explained
if we connect them with one or the other of these two orders of facts.
If we look upon the land as forming three parallel double continents, we
must then be struck with the similarity which they mutually present
both as a whole and in details; if, on the contrary, we admit the usual
division of the continental masses into two worlds, we discern the reason
of the contrasts, which are only another kind of resemblance. In this
way we may explain the variety in the forms of the continent of Europe,
by looking upon it either as the half of two twin continents parallel to
the two Americas, or as a great Asiatic peninsula, forming a portion of
the immense ring of land which extends round the ocean. Just as in a
* Joachim Lelewel, Pytizeas de Marseille.


CHALVS OF THE HLVD U-K UTO'H.
Woven fabric, we can discern both the warp and the woof in the marvel-
ous texture of the earth’s surface.
The principal feature in the relief of the Old ‘World is the enormous
elevation of the land near the centre of Asia, at the intersection of the
lofty chains of the Hindu—Kutch, in that region of grandeur to which the
epithet “the roof of the world” has been justly given. This elevated
spot, round which radiate the Himalaya, the Karakorum, the Kuenlun, the
Thian-Chan, the Soliman-Dagh, and other chains of mountains, is, in fact,
the point of the earth at which the two continental axes cross one anoth-
er, one tending from the north to the south, the other from the southwest
to the northeast, parallel to the outline of the Paciﬁc. At their meet-
ing-point the two terrestrial waves overlap one another, just as two bil-
lows coming together in the open sea from two diﬁ'erent points of the
horizon. There, at. the intersection of the axes, stands the real apex of
the earth, the orographical centre of continents; there, too, we ﬁnd, was
the centre of dispersion of the Aryan nations. By a remarkable contrast,
at the exact antipodes of this region of elevated plains and lofty mount-
ains, we ﬁnd those broad tracts of the Paciﬁc which are most destitute of
‘islands; and there, too, are probably situated the deepest profundities of
the ocean. ‘
64, THE EARTH.
CHAPTER IX.
PRINCIPAL ANALOGIES BETWEEN CONTINENTS.——PYRAMID FORM ‘OF POR-
TIONS OF THE IVORLD.——SLOPES AND DECLIVITIES.—CLOSED BASINS OF
EACH CONTINENT.—-SOUTHERN PENINSULAS IN EACH GROUP OF CONTI-
NENTS.-—-HYPOTHESIS OF PERIODICAL DELUGES.—RHYTI-IMICAL ARRANGE-
MENT OF PENINSULAS.
EVERY continent, considered by itself, may be compared to a pyramidal
mass having an enormous base and a summit placed far from the centre
of its ﬁgure. Thus Mont Blanc, the loftiest summit of the Alps, is sit-
uated at a comparatively short distance from the west and south coasts
of Europe. The latter, therefore, taken as a whole, may be looked upon
as a pyramid,the height of whichis not more than a thousandth part of
its base; the faces turned toward Asia and the Frozen Ocean. being four’
times as long, on the average, as the sides which tend toward the Atlan-
tic and the ll'Iediterranean. The Asiatic continent has for its apex the
lofty mountains of the Himalaya, and from these elevated points the face
of the country inclines in very different gradients toward the two op-
posite oceans: on one side the fall is rapid down to the plains and
gulfs of Hindostan; on the other side the descent is very considerably
longer.
The general outline of the relief of the continent of Africa is less
known; it is, however, probable that the. mountains Kenia and Kilimand-
jaro are the culminating points of the continental polyhedron. These
mountains, which rise very far from the centre of Africa, also exhibit on
one side a comparatively steep incline, and on the other a very gradual
descent. In Australia we see the same phenomena, for the most elevated
points of this continent are probably to be found in New South “Tales at
a short distance from the edge of the Paciﬁc; from these mountains to
the Indian Ocean the distance is at least six times as great.
The two Americas, also, may likewise be considered as two solid bod-
ies having their culminating points far distant from the centre of the
ﬁgure—one at Orizaba, or Popocatepetl, the other in the group of the
Bolivian mountains. In spite of the varied outlines of relief which con-
tinents exhibit, in spite, too, of the basins and depressions in their surface,
there are but few localities where the ground shows any hollows lower
than the level of the sea; and these hollows, such as the neighborhood
of the Caspian and the valley of the Dead Sea, are situated precisely on
the respective conﬁnes of two continents, Europe and Asia, and Asia and
Africa. Even the depressions of the Algerian Sahara, the surface of
which is in many places lower than the Mediterranean, are the bed of the


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ancient sea which once separated the real Africa from the districts of the
Atlas.
Another great feature of resemblance between the various continental
masses is that each of them contains one or more closed basins, where a
receptacle is found for the water—courses which can not ﬂow to the outer
side of the continent; these coneavities having their own peculiar system
of lakes and rivers, are, as it were, so many worlds by themselves. The
Asiatic continent, the largest of all, and that in which the supposed cen-
tre is most distant from the sea, is the continent in which/the inland hy-
drographical basins are of the greatest extent. They comprehend nearly
the whole area of the high plateaux of Tartary and Mongolia, namely, the
basins" of Lob-Nor, Tengri~Nor, Koko-Nor, and Oubsa-Nor; and on the
west of the great mountain chains of Central Asia they also embrace the
plateau of Iran, the basin of Balkach, and also the basins of the sea of
Aral and the lakes of Van and Ourmiah. By the depression of the Cas-
pian, the Asiatic series of lakes without outlet is connected with the Eu-
ropean system, which extends to the very centre of Russia, to the sources
of the Kama and the Volga. The whole of this region, the w ters of
whiclnfrom the hills of the Russian Valdai to the plateaux of Mongolia,
ﬁnd no outlet in the direction of the sea, embraces an area at least as ex-
tensive as that of Europe. The two continents of America likewise have
their isolated systems of lakes and rivers occupying a corresponding posi-
tion—one in the “ Great Basin,” between the Rocky Mountains and the.
Sierra Nevada of California, the other on the plateau of Titicaca, between
the chain of the Andes and the Cordilleras properly so called. Africa,
too, has several basins without outlet, the principal one being that of the
Lake Tchad, situated in the centre of the continent. Finally, even Aus-
tralia, in spite of its comparatively small extent, has its lakes, Torrens,
Gairdner, and others, which do not communicate with the sea."<
As Bacon formerly remarked, the three groups of continents exhibit
also a singular resemblance to one another in the pyramidal form of their
terminal points in the direction of the Antarctic Ocean. These three
southern peninsulas do not advance to an equal distance into the sea, as
they reach respectively to 36, 44, and 56 degrees of south latitude, but
they may be connected by an ideal circle, inclined 10 degrees to the
South Pole]L The distances between the extremities of the three conti-
nents are not very far from equal on the terrestrial periphery, as the
tracts of ocean between the Cape of Good. Hope and Cape Horn,Cape
Horn and Tasmania, Tasmania and the South of Africa are nearly in the
ratio of the numbers '7, 8, and 9.
Each of these promontories, pushed forward, as they are, from the rest
of the land, appears to have been partly demolished by the waves. Thus
the extremity of South America presents the appearance of an immense
ruin; the tortuous Straits of Magellan separate it from the Tierra del
Fuego, which is itself divided into numerous islets by a labyrinth of
* Vide the Map of the IVorZd, Pl. I. 1' Jean Reynaud, T erre et Ciel.
E
66 THE EARTH.


_//
Fig. 1?. Circle of Junction of the Continental Points.
channels, and is guarded on the south, as by a coaching lion, by the for-
midable headland of Cape Horn. At the southern point of Africa stands
another “ Cape of Storms,” to which a feeling of conﬁdence in the ap-
proaching discovery of India gave the name of the Cape of Good Hope.
To the east of this promontory, which is connected with the main body
of the continent by a system of plateaux and mountains, a great bank or
shelf pushes out far into the sea; this bank is doubtless the remains of
some vanished land, and the force of the marine currents still breaks over
it.* The Australian continent, too, has for its southern projection the
steep shore of Van Diemen’s Land; for, by its geographical position, this
island evidently belongs to Australia; the error, therefore, of Cook, who
looked upon Tasmania as nothing but a promontory of New Holland, was
more apparent than real. There is another fact which completes the re-
semblance between the terminal points of the three continents of the antarc-
tic hemisphere, namely, that each of the seas which extend to the east
of these countries washes some island or considerable archipelago. On
the east of Australia there is New Zealand; at the east of the South
American continent we ﬁnd the Falkland archipelago; east of Africa,
the large island of Madagascar.
* IIouzeau, De la Symétrie ales F ormes des Continents.
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PENINS ULAS. ‘ 67
These remarks of Bacon, since developed by Buffon, Forster, the com-
panion of Cook, and in modern times by Steifens, Carl Ritter, Arnold
Guyot, and others geographers, have given rise to the hypothesis that a
terrible deluge, coming from the southwest, once rushed over the conti-
nents of the southern hemisphere, crumbling them up, dismembering them,
and carrying their debris over the northern continents, thus forming the
long slopes which incline toward the Arctic Ocean. The land in the
north would thus be disproportionately augmented at the expense of the
south, of which nothing would be left, so to speak, but the skeleton. To
this great inundation, which carved out afresh the great continental
masses, Pallas, the Russian traveler, attributes the transport of the innu-
merable remains of mammoths which are found buried in the soil of the
Siberian tundras. This hypothesis has been, as we know, adopted since
by Adhemar and his disciples. In the opinion of these geologists, who
recognize the great agents of terrestrial renovation in a series of periodi-
cal deluges proceeding alternately from the north and south every 10,500
years, the bones found in Siberia were brought there by the last deluge
but one, which resulted from the breaking up of the ice at the south pole.
According to one of these hypotheses, the last dissolution of the ice came
from the south; according to the other, from the north. It is, therefore
prudent to set aside these contradictory ideas which attribute to some
cataclysm the peninsular form of the southern continents. Besides, at the
present day, there is no longer any doubt that both the mammoth and
rhinoceros were once natives of Siberia—the very country where their
remains are now found.*
Almost all the great peninsulas of the earth—as Greenland, Kamt-
schatka, and Corea, including even those which would suggest a sudden
change in the sea-level—extend in a southerly direction. Added to this,
each of the three northern continents, in their southern articulations, seem
to adopt as a type the three southern continents taken as a whole; thus,
each puts out three peninsulas into the seas which bathe its southern
shores. In Europe, Asia, and North America respectively, three groups
of secondary peninsulas correspond to the three great promontories of the
southern world.
In the Old World especially, these peninsular articulations are formed
with a considerable degree of regularity, and, so to speak, of rhythm and
measure ; in the different continents, they exhibit the most striking anal-
ogies. Arabia, in the proud and simple beauty of its outline, recalls to
mind the elegant and yet majestic form of Spain; Hindostan, in the gen-
tle undulations of its banks and the roundness of its bays, corresponds to
Italy; India beyond the Ganges, by its numerous indentations and the
enormous development of its coasts, seems the counterpart of Greece-—
that beautiful country, the outline of which has been so justly compared
to that of a mulberry-leaf In both continents, the peninsulas become
more and more articulated, and more and more, as it were, endowed with
* Dze neuesten Arbeiten iiber das llfammutlz, Mittkeiluizgen von Petermann, ix., 1866.
68 THE EARTH.
vitality as we proceed from west to east. The Mediterranean peninsulas
particularly present the remarkable phenomenon that the variety of out-
line is greater in proportion to their nearness to the rising sun. The nu-
merous bays which hollow out the coast of Spain all along the Mediterra~
nean shore are developed in regular arcs of a circle equal on the average
to a quarter of its circumference. The Italian gulfs—those of Genoa, Na-
ples, and Salerno—are spread out in perfect semicircles round the coast
of the peninsula; while the gulfs of Greece form very deep indentations
into the land, and, like the Gulf of Lepanto, might be called Mediterra-
neans in miniature.
It must also be remarked that on the east of the somewhat severely?
designed coasts of the analogous peninsulas of Spain and Arabia, the isl~
ands are but few and of small importance. Italy and India, on the con_
trary, the forms of which are richer, have each their large island, and,
with their southern extremities, almost touch Sicily and Ceylon respect-
ively. With regard to Greece and the Transgangetic peninsula, the seas
which bathe their eastern coasts are dotted over with innumerable islands
and islets, like a brood of young birds nestling under the wing of their
mother. The two other eastern peninsulas, which are also thrown off by
the great Asiatic continent, are each of them likewise accompanied by an
archipelago.
The three southern peninsulas of North America do not exhibit the
same regularity in their aspect as those of Europe and Asia. In conform~
ity with the somewhat narrow and elongated form of the continent itself,
two of these peninsulas—Florida and Lower California—seem attenuated
in comparison with the analogous portions of the Old WVorld. The other
peninsular appendage, which, being placed in the very axis of the New
"World, is much more developed, is none other than the isthmus of Cen-
tral America, now modiﬁed and distorted. In fact, a simple depression
' of the ground of about one hundred feet is all that is needed in order that
the Paciﬁc and the Caribbean Sea should unite their waters between the
two American continents; besides, it appears that, at a recent geological
epoch, a channel, at least thirty-seven miles wide, connected the two seas
across the plain which is now ﬁlled with a lava deposit, and is command-
ed on one side by the Sierra de Maria Enrico, and on the other by the
Sierra Trinidad.* A single feature of the earth’s relief may at the same
time fulﬁll several functions: thus, exactly at the antipodes of Central
America, the Sunda Islands are also an isthmus between the two conti-
nents of Asia and New Holland.
There are numerous other analpgies between the different parts of the
world which we might also mention; but most of them may be referred
- to those we have named, or else they belong more to the province of ge-
ology properly so called.
* Moritz Wagner, Mttheilungen von Petermann, 1861.
CONTRASTS IN AREA AND- F ORM
f.
/\
CHAPTER x.
NUMEROUS INDENTATIONS OF THE NORTHERN CONTINENT.——HEAVINESS OF
FORM IN THE SOUTHERN CONTINENTS.—-INEQUALITY OF SIZE IN THE CON-
TINENTS OF THE OLD “'ORLD.—-EXTENT OF COAST-LIN E IN INVERSE RATIO
TO THE AREA OF LAND.-—CONTRASTS BETWEEN THE OLD \VORLD AND THE
NE\V.-—THE ‘TRANSVERSE POSITION OF THE AXES OF AMERICA AND THE
OLD WORLD.-—CONTRASTS OF CLIMATE IN TIIE VARIOUS CONTINENTSZ
NORTH AND SOUTH, EAST AND WEST. '
THE contrast between the shapes of the various continental shores is
one which is very easily veriﬁed. North America, Europe, and Asia
have a very considerable extent of coast-line in comparison with their
bulk. They are penetrated for long distances by deep gulfs and inland
seas, and their outline is rugged with promontories ; it might be said
that the organization of these continental masses bears some resemblance
to an articulated body and its limbs. South America, Africa, and Aus-
tralia seem, on the other hand, to enjoy but a rudimentary conformation;
their contour is almost geometrically regular and simple, and their bays
and gulfs are so slightly indented into the land, that the regular line of
the coast is scarcely altered ; there is, too, an almost complete deﬁciency
in promontories of a peninsular form. In the great scale of terrestrial or-
ganization, these continents present an inferior phase of life. Neverthe-
less, this heaviness of contour and deﬁciency of peninsulas are in great
part compensated for by the more oceanic position of the southern conti-
nents and the prevalence in them of a tropical climate. In fact, under
the tropics, the air, being much warmer, is saturated by a larger quantity
of moisture; and the atmospheric currents, being more rapid and regular,
carry the sea-breezes across much wider areas. Thanks to the tropical
rains, trade-winds, and hurricanes, the enormous masses of South America
and even Africa are as much exposed to oceanic inﬂuences as other parts of
the world which are more deeply indented by gulfs and bays. The three
northern continents, on the contrary, the shores of which are so cut into
and pierced in every direction, owe .to their inland seas the ability (as re-
gards a considerable portion of their surface) of imbibing those aqueous
vapors without which they would be nothing but immense deserts.
The area of the continents is a fact no less important than their form,
and the contrasts afforded in this respect are also not a little striking.
\Vhile the two halves of America are almost equal in extent, the ‘four
continents of the Old World differ much in the'size of their respective
areas. Asia, by herself, includes a larger surface of land than the two
Americas together. Europe, pushed out into the ocean as a mere Asiatic
70 - THE EARTH.
peninsula, is four or ﬁve times smaller than the enormous mass with which
she is connected.- In the south, the surface of Africa is three times as
great as that of Europe, while Australia, compared with its northern
neighbor, the area of which is six times bigger, scarcely deserves more
than the name of a great island. It must, however, be remarked that, by
a very curious phenomenon of compensation,the two halves of each con-
tinental pair are arranged so as to balance on the terrestrial sphere. In
the western pair, Africa, which is the preponderant portion, lies to the
south, and the smaller Europe extends to the north. In the eastern pair,
it is just the reverse: on the north is the great continent of Asia, and on
the south the region of New Holland, which would correspond with Eu-
rope. '
AREA OF CONTINENTS.
FIRST PAIR.
North America ......................................... .. 7,953,315 square miles.
South Amen'ca ......................................... .. 6,949,674 “ . “
snconn PAIR.
Europe ................................................... .. 3,822,320 “ “
Africa ................................................... .. 11,244,958 “ “
THIRD PAIR.
Asia ..................................................... 16,771,879 “ “
Australia ................................................ .. 2,972,916 “ “
The continents may also be compared by pointing out the respective
distances of their ideal centres from the nearest point on the shore of the
ocean.
CONTINENTAL RADII.
FIRST PAIR.
North America. . ....................................................... .. 1087 miles.
South America ......................................................... .. 931 “
SECOND PAIR.
Europe .................................................................. .. 478milcs.
Africa .................................................................... .. 1118 “
THIRD PAIR.
Asia. ................................................... ..‘. ................ .. 1491 “
Australia ................................................................. .. 615 “
This great inequality in the size of the continents might furnish cause for
surprise, were we not well aware that, according to the beautiful law pro-
pounded by Geoffrey Saint-Hilaire, no function can be unduly developed
except at the expense of some other function. Europe is small, it is true;
but what an opulence of coast-line does she enjoy! What profusion of
gulfs and peninsulas diversify her outline, how many islands and islets
there are in her seas ! In Europe, land and water are arranged in alter-
nate layers as if to form an immense electrical battery, where the acid,
sheets of metal, and conducting wires are replaced by seas, land, and aeri-
al currents. Europe is so variously articulated that she enjoys a more
considerable extent of coast-line than either South America or Africa it-


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EXTENT OF SEA- 0 OAS TI 71
self, both of which ﬁll so much greater an area. Australia at ﬁrst sight
appears, from its solid form, to constitute a modiﬁcation of the law ac-
cording to which the smallest continental masses are the most highly
organized. But Australia must not be looked upon as an isolated body;
we are bound to take into account the elongated isthmus of islands and
islets which connects it with Indo-China. Along this former isthmus are
scattered numerous archipelagos, presenting an almost incalculable devel-
opment of coast-line, and consequently possessing all the advantages of
climate, richness, and fertility which are afforded by a maritime position;
there, too, more than in any other par-t of the world, the magniﬁcence of
terrestrial vitality is displayed in the splendor and variety of its pro-
ductions.
The following tables, which give in miles the absolute and relative
length of the sea-coast of each continent, are therefore necessarily incom-
plete. How shall we separate from Europe England,Ireland, Sicily, and
the Isles of Greece—all of them countries which have played so important
a part in the history of civilization? How can we neglect, in the New
NVorld, the West India Islands, and the islands lying to the east of the
continent of Asia—the Moluccas, the Sunda Archipelago, and Japan?
EXTENT OF SEA-COAST.
‘ FIRST PAIR.
North America ........................................................ . 29,969 miles.
South America ...................................... ... .............. .. 16,012 “
SECOND PAIR.
Europe ................................................................. .. 19,825 “
Africa ................................................................ .. 12,561 “
. THIRD PAIR.
Asia. ................................................................... .. 35,886 “
Australia .............................................................. .. 8,947 “
PROPORTION or SEA-COAST TO SURFACE.
FIRST PAIR.
North America ..................................... .. 1 mile to 265 square miles.
South America ..................................... .. 1 “ “ 434 “ “
SECOND PAIR.
Europe ................................................ .. 1 “ “ 192 “ “
Africa ................................................. .. 1 “ “ 895 “ “
THIRD PAIR.
Asia . . 1 “ “ 469 “ “
Australia ............................................. .. 1 “ “ 332 “ “
By taking account of the principal islands—Great Britain, Ireland, Sar-
dinia, Sicily, and several others—the total extent of the European coast-
line may be estimated at 26,716 miles, which will give one mile for 143
square miles of surface.
In the two continents of the New World, the plateaux and the plains
show a surface nearly equal in extent, and, in this respect, present a har-
72 THE EARTH
mony which does not exist in the Old World. All the western countries
of North America, as well as a great part of its eastern regions, consist of
plateaux, some level and others commanded by mountain chains. The
plains which extend between these two systems of elevated ground, and
embrace the ﬂuviatile basins of British America and of the Mississippi
and Missouri, are equal in surface to the higher regions along the edges
of the two coasts. In South America the plains are comparatively more
extensive. Nevertheless, if to the chain of the Andes and their subsidi-
aries, we add all the Colombian plateaux, those of Peru and Bolivia, the
groups of Famatina, Aconquija, and Cordova, the sierrcls of the Guianas,
the chains of the Brazilian coast and of Minas Geraes, the gigantic steppes
of Patagonia between the ridges of the Andes and the Atlantic coast, we
shall ﬁnd that the balance is kept pretty equal between the high and the
low lands of this part of the world. According to Humboldt, whose ﬁg-
ures, however, should be carefully criticised with all the means afforded
us by our increasingly exact acquaintance with the outline of the terres-
trial relief, the mean elevation of North America is 747 feet, and that
of South America would attain to 1149 feet.
The continents of the Old IVorld do not afford an equal harmony in
the general conﬁguration of their elevation. Asia, taken as a whole, is'a
vast system of plateaux, extending from the headlands of Asia Minor to
those of the Corea, and from the shores of Beloochistan to those of the
province of Ochotsk. The central region of Asia, surrounded by the
highest mountains in the world, is the most elevated district existing in
any of the continents, and in some places attains the mean height of 9000,
12,000, and 15,000 feet. The total area of the Asiatic plateaux is esti-
mated by Humboldt at ﬁve-sevenths of this part of the world; Mesopo-
tamia, the plains of the Ganges and of the Indus, China proper, and the
Siberian tunclras make up the other two-sevenths of the continent. As
if to make up for this, Australia is comparatively very deﬁcient in pla-
teaux and mountain chains; of all the divisions of the earth this is the
one which exhibits the least amount of prominence above the ocean level.
The mean elevation can as yet be given but very hypothetically, as a
great part of the regions of the interior is still unknown; but this conti-
nent must present about a third of the elevation of Asia—the latter be-
ing approximately estimated by Humboldt at 1162 feet.
Europe being situated, in the Old-World group, in a diagonal line as
regards Australia, affords, like the latter continent, a great preponderance
of plains and plateaux. Almost the whole of Eastern Europe is a level
country; and this district—a great part of which is cultivated, although
here and there covered with turf and heath—extends through Poland and
Prussia as far as the frontiers of France and Belgium. Over this im-
mense area, the level of the ground is so uniform that from N ijni-N ovo-
gorod to Cologne, a distance of 2454 miles, there is not a single railway
tunnel. In Western Europe, which, in a historical point of view, is the
real Europe, the more elevated regions are, it is true, very numerous;
PL. IX.


AUSTRALlA AND THE ADJACENT ARCHIPELACO
_
.
.
_
S
“A U


I'iné F‘ by .Erhard.


PLA TEA UK. 73
but most of them amount to mere mountain chains, on each side of which
extend considerable tracts of level country. The only plateaux of any
notable importance in the general conﬁguration of the continent are those
of the Iberian peninsula, Suabia, and Turkey; all three, with a kind of
rhythm, abut on mountain chains, the other faces of which command hor-
izontal ﬂats of alluvium. On the north of the Pyrenees and the Spanish
plateau lie the plains of the Garonne and Languedoc; on the south of
the Bavarian plateau and-the rampart of the Alps stretch the plains of
Lombardy and Piedmont, forming a continuation of the level surface of
the Adriatic Sea; ﬁnally, the low-lying lands of the Danube are separated
from the plateaux of Turkey by the Balkan chain, which extends in a line
almost parallel to that of the Pyrenees.*
On account of the plateaux existing in Europe being so few, the mean )
elevation of this continent is not much more than half that of Asia; ac-
cording to Humboldt it is about 672 feet. With regard to Africa, we
need hardly say that it is impossible to ﬁx the mean elevation with any
certainty; but modern travelers who have penetrated into the interior
of this division of the world have seen enough of it to warrant them in
stating that Africa is very similar to Asia in respect to the elevation of
the land. With the exception of Egypt, the plains of the Niger, some por-
tions of the sea-coast, and districts of the Sahara, which were once covered
by the sea, the continent is entirely composed of plateaux, most of which
abut on lofty mountain chains. The law of diagonals, which is followed in
the respective dimensions of the four continents of the Old World, is found
also to hold good as regards their general conﬁguration. Asia and Africa,
the two continents in which the plateaux predominate, are placed diagon-
ally to Europe and Australia, in which the plains are the most extensivei
Another great contrast between the Old and New Worlds is one that
is exhibited in the central portions of these groups. Between the two
Americas stretches a sea of an almost circular shape, surrounded on all
sides by a belt of islands and continental shore. The centre of the Old
NVorld, on the contrary, is occupied by the plains of Mesopotamia, and
high ground toward which tend several seas in an oblique direction.
The Persian Gulf, the Red Sea, the Mediterranean, the Euxine, and the
Caspian surround this central spot of the Eastern continents, and approach
the pentagonal mass obliquely at almost symmetrical intervals. Looking
at the form and direction of these seas, it seems as if the region which
they circumscribe had experienced a kind of wrench, as if it had been
drawn into some vast eddy.
Another very remarkable phenomenon of equilibration is exhibited in
the fact that the highest mountains of each of the two halves of the world
are situated in opposite hemispheres, but at an equal distance from the
equator. Near one of the tropics rise the lofty Himalaya and the other
great mountain groups of Asia; close to the other tropic stand the Boli-
vian and Chilian Andes.
* Carl Ritter, Europa. ‘l’ Guyot, Earth and Alan.
74 THE EARTH.
There is another difference between the various divisions of the world
which we must call attention to. In pursuance of the annular distribu-
tion of the continents round the great ocean, the western coasts of Europe
and Africa correspond with the eastern coast of the New World, and not
I with the western, as analogy would seem to dictate. On the north, Scan-
dinavia forms a counterpoise to Greenland. More to the south, the two
shores which front each other across the North Atlantic bear a striking
resemblance to each other in their numerous —indentations, their deeply-
penetrating gulfs, their peninsulas, and their islands, while between the
coasts of Europe and those of California and British Columbia there is no
symmetry whatever. With regard to Africa,_several geographers, includ-
ing Humboldt himself, have thought that this continent and South Amer-
ica had their corresponding coasts set in the same direction. But this is
.not the case; these two divisions of the world present the same mutual
contrast as the two hands of a man. There is symmetry, but not equal-
ity. In fact, the highest plateaux and the loftiest mountains in Africa
rise at the east side of this continent, while the chain of the Andes com-
mands the western shores of South America. The most important Afri-
can rivers—the Orange River, the Congo, the Niger, and even the Nile—
empty their waters,‘ either directly or indirectly, into the basin of the At-
lantic, into which are also discharged the immense rivers of the Colombian
continent—the La Plata, the Amazon, the Orinoco, and the Magdalena.
In the same way, the Saharan deserts, which tend toward the Atlantic
Ocean, answer to the llanos of Venezuela and the pcmzpas of La Plata ; the
latter being likewise inclined toward the same oceanic basin. Finally,
the two isthmuses of Suez and Panama, each at the angle of their respect-
ive continents, occupy a corresponding though opposite position. Sim-
ilarly, Cape Verd must be considered as the corresponding point to the
Brazilian promontory of St. Roch, and the Gulf of Guinea is represented
on the other side of the ocean by the wide semicircle of coast which opens
out on the south of Brazil. Even in the bed of the sea the symmetry
still prevails, since an upheaval of 4500 yards would have the effect of
calling forth in the midst of the Atlantic a long strip of land separated
from Europe and the New W'orld by two parallel channels.
In each of the two groups of continents, the steep and gentle inclines
are distributed respectively in contrary directions. In Europe, Africa,
and Asia, the most elongated incline of the land tends in a northerly and
westerly direction towardthe Atlantic Ocean and the Frozen Sea. In
the New \Vorld the more gradual slopes of. the continent likewise de-
scend toward the Atlantic coast—that is, in an eastward direction. We
thus have a contrast which is also a harmony: it is as if the faces of the
two worlds were turned one to the other, thus rendering more easy of ac-
cess their coasts, their plains, their rivers, and all the regions suitable for
the abode of man. '
Another contrast, which is perhaps the most important of all in the his-
tory of mankind, is that exhibited by the transverse position of the two
CONTRASTS OE CLIMATE.
groups of continents in reference to each other. The countries of the Old
World, which show the richest luxuriance and the most exuberant vital-
ity, lie between the Straits of Gibraltar and the Archipelago of Japan, and
extend from west to east in a line parallel to the equator; the New
World, on the other hand, stretches from north to south, in the direction
of the meridian. Thus, the double continent is set right athwart the
course followed by the winds and the currents, and across the path taken
by the human race in making their way from the other group of coun-
tries; it, therefore, receives and develops the germs of life, the elabora-
tion of which had commenced on the other side of the sea. This trans—
verse position of America in respect to the Old World is one of the prin-
cipal features of the planetary relief, and one also which exercises a de-
cisive influence on the future of the whole human race.
Finally, it must not be forgotten that the principal contrasts of the con-
tinental masses proceed naturally from all the modiﬁcations produced by
the diiference of longitude and latitude. These contrasts are those of
climate, and their real cause is to be found in the form of the earth and
its movements round the sun.
Thus, the astronomical contrast between the north and the south
divides distinctly the different parts of the world into two separate
groups. Almost the whole extent of'the' three northern continents be-
long to the temperate zone, and it is only their most advanced peninsulas
which are pushed forward—on one side into the frigid, and on the other
into the torrid, zone. With regard to the three southern continents, they
present their chief development between the tropics or in the south tem-
perate zone. They receive the greatest amount of annual heat, and con-
sequently become the theatre of the most remarkable phenomena of plan-
etary vitality. There the cross action of the winds and rains between
the two hemispheres takes place, and hurricanes take their rise; there,
immense deserts extend over vast areas; there, too, vegetation manifests
all its productive energy, and the terrestrial Fauna attains its greatest
force and its highest beauty. "
The contrast between the east and the west is also of the highest im-
portance in each group of continents; for all the train of climatic phe-
nomena which accompanies the sun in its apparent course round the
earth does not uniformly follow the latitude in a parallel line to the equa-
tor. In consequence of the unequal division of land and sea, there is a
modiﬁcation in the direction of the currents and winds, and also a trans-
position of the climates‘ themselves—sometimes toward the north, and
sometimes toward the south ; the most distinct contrariety in this respect
is thus produced, in some cases, between the western side of one conti-
nent and the eastern side of the continent opposite to it. It is principal-
ly between the Old and New Worlds that this contrast is most striking;
at equal latitudes, the western shores of Europe, and those which face
them on the other side of the Atlantic, have very different climates—a
fact which is caused by the changes produced by marine currents, the
winds, and all the'other atmospheric phenomena.
76 THE EARTH.
CHAPTER XI.
HARMONY OF SHAPE IN OCEANS.-——TIIE TWO BASINS OF TIIE PACIFIC—THE
TWO BASINS OF THE ATLANTIC.—TIIE ARCTIC FROZEN OCEAN AND TIIE AN-
TARCTIC CONTINENT.-—'CONTRASTS, AN ESSENTIAL CONDITION OF PLANET-
ARY VITALITY.
TIIE harmony of the continental forms is fully paralleled by that of the
oceanic conﬁguration. The Southern Ocean alone—that mighty breadth
of waters, in comparison with which all the other oceans seem but mere
arms of the sea—extends over nearly an entire hemisphere of our planet.
Notwithstanding its enormous dimensions, it none the less exhibits a most
harmonious ensemble, caused partly by the amphitheatre of shore spread
all round the Paciﬁc, from Van Diemen’s Land to Tierra del Fuego;
partly also by the marvelous belt of the Polynesian archipelago. These
numerous and lovely islands, which Ritter calls the “ Milky \Vay of the
ocean,” are dotted obliquely over the whole breadth of the south seas,
from the Philippines to Easter Island, dividing the immense basin of the
Paciﬁc into two sheets of water, distinct from each other both by their
winds, the course of their currents, and the undulations of their waves.
Thus the great hemisphere of waters constitutes a kind of oceanic pair,
in accordance with the same law which distributed the land in three con-
tinental pairs. .
The tortuous valley of the Atlantic, which separates the Old W'orld
from the New, is also decisively divided into two basins, differing in the
shape of their outline, their climates, winds and currents. An ideal line,
traced from the Cape Verd Islands to the nearest of the Antilles, marks
the limit of separation between the two halves of the great oceanic valley.
On one side, the South Atlantic spreads out in a vast semicircle between
the scarcely undulated shores of the more massively formed continents;
on the other, the North Atlantic gradually contracts toward the polar
regions, throwing out, both to right and left, gulfs, channels, and inland
seas. On the east, the lllediterranean, the British and the Irish Channels,
the North Sea, and the Baltic; on the west, the Caribbean Sea, the Gulf
of Mexico, the isle-dotted estuary of the St. Lawrence, Baﬁin’s Bay, and
Iludson’s Channel and Bay—all these appear to correspond on either
side of the ocean, and, by the resemblance of their outlines, add to the
harmony of the continents themselves. Thus the general form of the
two Atlantic basins recalls to mind the two continental pairs, the shores
of which they bathe. The northern basin, bordered as ‘it is by variously
articulated lands, is, from this very cause, the richest of the two oceans in
THE POLAR REGIONS.
indentations of every kind, and is also that which was destined by nature
to become the high-road of the commerce of nations.
The Indian Ocean, shut up, as it is, in the immense hollow formed by
the coasts of Africa, Arabia, the Gangetic peninsula, the Sunda Isles, and
Australia, can not exhibit the same characteristic of duality as the two
other oceans—the Southern Ocean and the Atlantic. If, however, we
take into account the ancient geological conditions of Asia, we may, per-
haps, be warranted in looking upon the Caspian, the Sea of Aral, and the
other lakes of Western Asia, as the remains of the former ocean which, in
the northern hemisphere, formed the equipoise to the Indian seas. There
would then have been three double oceans, just as there are three conti-
nental pairs. Added to this, it is probable that the northern and southern
polar regions likewise afford an instance of an equilibrium existing between
land and water. NVe are at present but very imperfectly acquainted
with the regions either of the north or south poles; but the explorations
of navigators and the investigations of meteorologists more and more
tend to conﬁrm the old hypothesis, which supposed that open sea extend-
ed round the Arctic pole, and that the circle of the south pole was occu-
pied by a covering of dry land. If this be really the case, the harmony
of the continental masses, and the sheets of water which are interspersed
among them over the surface of the planet, is admirably completed by
the contrast between the two poles of land and water which occupy the
two extremities.
The general similarities and the great contrasts which we have now
pointed out constitute but a small- number of the features of this kind
which the surface of the glpbe presents, and it would be an easy thing
thus to follow out our parallels from sea to sea, from river to river, and
from mountain to mountain. But the purely external symmetry pre-
sented by the continental conﬁgurations is a triﬂing matter compared
with the profound harmony resulting from the alternation of winds, cur-
rents, climate, and all the geological phenomena; it is not in the various
portions of the globe but in their working action that we must seek for
the real beauty of the earth. Planetary vitality is composed of perpet-
ual contrasts in a perpetual harmony, and these very contrasts are inces—
santly being modiﬁed. Continents, seas, and atmosphere—and, in a more
special way, every mountain, every peninsula, every river, every marine
current, every wind that blows—may be considered as the organs of the
globe on which we live; it is therefore by watching these organs at
work, and by studying deeply and thoroughly their action and reaction,
that we can best arrive at an acquaintance with the physiology of the
planetary body.
Physical geography is nothing else but the study of all these terres-
trial harmonies. An inquiry into the superior harmonies which emanate
from the relations of mankind to the planet which is the scene of human
life must be left to history, the task of which is to describe them.
78 THE EAR TH.
CHAPTER XII.
GENERAL ASPECT OF PLAINS.—ALLUVIAL PLAINS.—CULTIVATED PLAINS.—
UN IFORMITY IN UN CULTIVATED PLAINS.—-VARIETIES IN APPEARANCE PRO-
DUCED BY CLIMATES AND DIFFERENT PHYSICAL CONDITIONS.
TIIE portions of the terrestrial surface on which the vitality of the
globe shows itself with the least intensity and variety are those countries
which present the slightest diversities of level. In these regions, the ﬂat-
ness or slight declivity of the surface of the earth prevents the waters
from ﬂowing rapidly; the country exhibits the same amount of vegeta-
tion, or the same sterility, over vast extents, and its general aspect is often
most monotonous. Nevertheless, in spite of the uniformity of a ﬂat dis-
trict, the phenomena of nature are all the more easily observed there, be—
cause they are developed in a more simple and regular manner.
Nearly half of the continental regions is composed of low and compara-
tively level lands, the even or gently inclined surface of which still testi-
ﬁes to the action of the waters of the ocean, or of the inland seas by
which it was formerly covered. These are former sea-beds, which have
emerged from the deep; and, from the uniformity of their appearance——
often much resembling a tract of ocean—contrast sharply with the high
lands or mountains surrounding them. Some of these plains, which are
watered by streams and rivers, have been greatly modiﬁed by the courses
which the latter have taken; and by means of the fertile alluvium that
has been brought to them, and the moisture which penetrates them, have
spontaneously given birth to immense forests. They then lose their re-
semblance to the surface of the sea, except when looked at from the top
of some lofty bluff, around which the thick trees seem to crowd like bil-
lows. At length, when man comes to take possession of the plains, to
erect his towns, and to cultivate the soil, he introduces a great variety
into these uniform tracts, and never ceases to modify their primitive as-
pect. These low-lying regions, which, by reason of the ﬂatness of the
ground, are destined to be the scene of but slight activity in the planet-
ary life, have become the principal seat of mankind, and it is there that
civilization makes its most remarkable progress.
The plains which best retain their appearance of times gone by are
those which, owing either to the want of rain, or the almost complete ab-
sence of slope either in one direction or another, are watered by only a
small number of streams, or sometimes, throughout vast tracts of country,
are utterly without them. For this reason, in many parts of the globe, a
plain and a desert are almost synonymous. Setting aside the low lands
which have been brought under cultivation, the plateaux and the inter-
ASPECT 0F PLAINS.
vening mountain chains, we ﬁnd that there is a coincidence between most
of the large level plains and the continental deserts. Thus the western
and eastern regions of the Sahara, the Nefoud of Arabia, the steppes of
the Caspian, the Aral, the Balkash, and the tzmclras of Siberia, are at the
same time the most extensive plains and the most widely-spreading des-
erts on the face of the globe. The general axis of the principal plains in
the Old lVorld, as well as that of the deserts, mountains, and continents
themselves, is set in a direction from southwest to northeast; while in
the New \Vorld the axis of the low-lying lands tends from north to
south in a parallel line to the chains of the Rocky Mountains and the
Andes.
All lands which are bare plains, destitute of large trees, resemble one
another, on account of their uniformity. On the surface of these plains,
as on the sea, it is only necessary to scan the horizon round in order to
perceive clear proofs of the rotundity of the globe. Although the sight
reaches without difficulty over the bare ground, or its green carpet of
plants, yet the bases of hills and the trunks of trees which appear at the
limits of the plain are hidden by the convexity of the earth. At ﬁrst we
only perceive the summits of the hills and the branches of the trees; then, in
proportion as we draw nearer, the lower declivities and the trunks of the
trees begin to make their appearance, in the same way as, in the open sea,
the hull of a ship is not seen until long after the sails and masts have
come into view. Lastly, as on the ocean, the variable aspect of the sky,
to which, in hilly countries, we are in the habit of paying only a second-
ary attention, here regains all its importance, and becomes the principal
feature in the landscape. The uniform and motionless surface of the plain
slopes down toward the horizon, like the back of a gigantic shield, and its
whole extent offers no object which can arrest the attention; but above,
on all sides, stretches the enormous dome of the atmosphere, with its ﬁt-
ful play of light and shade, the successive gradation of its colors, from
deep blue to ﬁery purple—its clouds, which, chasing one another across
the sky, ﬁrst disperse and then cluster together; drawing themselves out
into long transparent lines, or accumulating in masses of a sombre gray.
Occasionally, when the air which hangs over the plain is unequally heat-
ed by the rays of the sun, distant objects assume a distorted shape, seem-
ing nearer than they really are, or, perhaps, inverted, producing that fan-
tastic illusion called a mirage, which was formerly believed to be the
Work of mocking genii.
Although all the bare plains on the various continents resemble one an- '
other in the curvature of the ground, the circularity of the horizon, and
the play of the atmosphere, yet their aspect sometimes varies much in
diifercnt countries, according to the geological nature of the soil, the mean
temperature, the changes of the seasons, the direction of the winds, the
' quantity of rain-fall, and all the other physical conditions of the region
generally. Thus, a clayey plain is hard and compact, like the ground of
a threshing-ﬂoor which has constantly been beaten with the ﬂail; another,
80 THE EARTH.
the rocks of which are of a calcareous nature, is intersected here and there
by ravines with perpendicular sides; another is sandy, and, under the
inﬂuence of the wind, is rippled with waves like the surface of the sea.
Some, but these are rare, present vast extents completely destitute of
vegetation; others offer, here and there, a solitary green plant; but every
one of them is a plant of the same species; and one may travel whole
days in these deserts without seeing any other representatives of the
vegetable world. The greater number of plains have, it is true, a Flora,
composed of a tolerably large number of species; but two or three plants,
which are commoner than the others, appearing uniformly on hundreds
and thousands of acres, have appropriated to themselves the whole dis-
trict, and thus give it a special character. Lastly, some solitudes are
temporarily, during the rainy season, or even during the whole year, mag-
niﬁcent and verdant prairies enameled with ﬂowers. These are the tracts
which man can most easily turn to account by breaking them up with
the ploughshare.
THE FRENCH LANDES.
CHAPTER XIII.
THE FRENCH LAXDES.—TIIE BRANDES AND THE ALIOS.—TIIE CAMPINE.——
THE HEATIIS OF HOLLAND AND NORTHERN GERMANYr—THE PUSZTA OF
HUNGARY.—-TIIE GRASSY STEPPES OF RUSSIA.'-—-TIIE SALT STEPPES OF
THE CASPIAN AND THE ARAL—THE TUNDRAS.
TIIAXKS to the rains blown up by the sea-breezes, the comparatively
small deserts of \Vestern Europe do not assume the formidable character
of the Sahara, or the Nefoud of Arabia. Those best known are the Zandes
of Gascony.
The old tracts of French Zcmdes embrace not only the department
which takes its name from them, but also include half of La Gironde, as
well as the extreme corner of Lot-et-Garonne, extending over nearly
2,500,000 acres. This region, which was once covered by the waters of
the Atlantic, is a plateau averaging 160 to 190 feet in height, and sinking
in a gentle decline on the northeast toward the Gironde and the Garonne,
on the west toward the lakes on the sea-shore, and on the south toward
the River Adour. The uniformity of the great plateau of the Zcmdes is so
great that, for a distance of twenty-eight miles between Lamothe and
Labouheyre, the railroad from Bordeaux to Bayonne is perfectly rectilin-
ear; one might call it a “ visible meridian.”
For some years past, the labor of man has done much in turning to ac-
count this vast domain, once so neglected; private individuals and com-
munities have, with equal ardor, sought to enrich themselves by replacing
the heath with pines and other trees, and there can be no doubt that, at
an early future, the Whole extent of the lcmdes will be covered with for-
ests and cultivated grounds. There are now but few places where we
can still see what the whole plateau once was, stretching from the edge of
the vineyards of Bordeaux to the country at the foot of the ﬁrst Pyrenean
hills.
In these uninhabited tracts the landscape is certainly deﬁcient in vari-
ety, but it always possesses a certain grandeur and a singular charm for
those who love nature in all her freedom. All round, within the limited
circle which is surrounded by the level line of the horizon, nothing is to be
seen but a thick underwood of brandes and various other kinds of heath,
springing up to the height of a yard or two above the ground. During
their ﬂowering-time these plants mingle a light shade of pink with their
delicate green, but they are always roughened with a number of heath-
branches, stripped of leaves, and black as if charred in a ﬁre. In other
spots tall ferns have taken possession of the ground and ﬁll the air with
their penetrating odor. Farther on we come upon large patches of furze
I“
82 THE EARTH
and broom, which ﬂower together in the spring and cover the plain with
an immense veil of gold. Mosses, grasses, and briers grow together along
the edges of the paths; water-lilies, and other aquatic plants, repose qui-
etly on the surface of the muddy pools; bunches of rushes and sedge

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, . _ ‘ _.".'T.'j' ';.~_A:"_;_‘._._~&
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Fig. 18. The “ Landes” of Gascony.
spring up in the spongy earth around the water. And this is all. Per-
haps, on the extreme horizon, a bluish line, pointing out the edge of a
pine forest, may be faintly visible.
Over a vast extent of the la-ncles the superﬁcial soil is composed of a
white and almost unmixed sand ; but in general it is very much mingled
THE LANDES OF GASCONY.
with vegetable remains, which give it a gray or blackish color, like char-
coal ashes. Below this upper layer extends a stratum of agglutinated
sand, generally of a rusty color, and bearing a great similarity in appear-
ance to ferruginous sandstone; the hardened dust known in the Zcmdes
of Médoc under the denomination of “alios” owes its color and its ﬁrm-
ness to the continual inﬁltration of rain-water, which carries down into
the ground various organic substances in a state of solution, and blends
them intimately with the arenaceous particles. In a general way alios,
notwithstanding its ferruginous appearance, contains the oxide of iron
only in an almost imperceptible proportion. When it is thrown into the
ﬁre it is noticed to carbonize slowly, and is then reduced to ashes; yet, in
certain localities, especially inr marshy districts where the argillaceous
iron is naturally formed, the subjacent layer is gradually changed into an
actual mineral. Generally, the bed of altos, which is hardest where it is
least thick, is completely impervious to water, like a stratum of rock.
tain-water, being thus checked by the continuous layer of altos, must
necessarily remain in the upper soil, and, during the wet season, the sur-
face of the Zcmdes would be changed into one great marsh if care were
not taken to cut trenches or drains, which receive the overﬂow of the
scattered pools, and carry it either to the different rivulets, or to the lakes
on the sea-shore. In order to cross more easily the sheets of water which
sometimes extend farther than the eye can reach between the patches
of heath, the shepherds of the Zmzdes have adopted the custom of walk-
ing and watching over their ﬂocks on stilts more than a yard high. In
this respect the Lanusquets, or Landescots, are without parallel all over
the world, and, if I am not mistaken, in the history of mankind.
Nearly all the regions of \Vestern Europe, which were in early ages
covered by the sea, and have since retained the uniformity of surface of
the former sea-beds, have long since come under cultivation ; such as, for
instance, the low ground of the ancient Gulf of Poitou, the ﬁlled-up estua-
ry of Flanders, the largest part of Holland, and German and Danish Fries-
land. But, farther inland, there are here and there tracts of lctncles like
those of Bordeaux. In France one may mention those of Sologne and
Brenne, which were formerly a vast forest of about 1,234,000 acres in ex-
tent, and are now being transformed anew by patches of pines, drainage,
canals, and other improvements. In Belgium the sandyjcmdes of the
Campine, which, since the establishment of the Germans and Batavi in
the neighboring countries, have always been a ﬂat surface of heaths dot-
ted over with pools, extended in 1849 over a surface of 345,000 acres; but
the brave Belgian husbandmen who laid siege to these Zandes continue to
reduce their dimensions at the rate of 3950 acres a year.*
In Holland and the north of Germany the belt of heaths assumes its
greatest width, and extends over a much more considerable surface than
that of the landes of Gascony. In Holland alone an extent of about
4,196,875 acres, more than half the territory, consists of a sandy soil,
* Emile de Laveleye, Revue des Deux Mondes, June, 1861.
84 - THE EARTH.
which was once nothing but a vast solitude, the uncultivated parts of
which still contrast most strikingly with the rich polclers of the coast. A
great part of this sandy region, which is elevated, upon an average, 48 feet
above the sea, is covered with spongy peat-mosses, which will readily
burn after having previously been dried by means of drainage-canals, and
cut into pieces of a proper size. One ﬁne day in the summer time the
peasants set light to these masses of dry turf, and soon the conﬂagration
spreads over wide extents, and. thousands of acres are burning at the
same time. When the north wind passes over these immense ﬁres it car-
ries with it smoking particles of the smouldering turf hundreds of leagues
away from Holland, and sometimes even to the centre of France, Switzer-


Fig. 19. Extent of the Heath-smoke in 1857.
land, Bavaria, and Austria. This is the origin of those dry fogs, or north-
ern fogs, which give a yellowish tint to the atmosphere, and sometimes
half hide the face of the sun.* However, when the wind is favorable,a
comparatively slack ﬁre transmits its smoke to very great distances;
thus, in 1865, at the time of the ﬁre in a part of the city of Limoges, the
cloud of smoke, which stretched away 'in long eddies toward the west,
was perfectly visible as far as Marennes, a distance of about 125 miles in
a straight line.
* Emile de Laveleye, Revue des Dew: Mondes, Jan., 1864. M. de Laveleye thinks that
the name of “ brandes,” given in Gascony to the high-growing species of heath, is derived
from the habit they have of burning them. In German, brand signiﬁes burning.
.PLALVS OF 11 UNGAR Y AND RUSSLI. 85
The Zcmdes of the north of Europe enjoy a colder climate than those
of Gascony, therefore their vegetation is less developed and not so diver-
siﬁed ; but it seems that in both belts of heath the composition of the soil
is nearly the same. In Germany and in Jutland, as well as in France, the
yellow color of the sand is due to the ‘gradual inﬁltration of the juices of
the plants, which are loaded with tannin; and the ferruginous-looking
tufa, which is found at a certain depth in‘ the substratum, through Which
the roots of trees can not penetrate, is no doubt nothing else than a bed
of hardened sand of the same nature as the alias of the French Zcmdcs.
In Jutland, where this bed is on an average from two to four inches in
depth, they give it the name of jern-al, or Tron-sand. In England, Scot-
land, and' Ireland a thin bed of “iron-pan,” of the same appearance, is
found under the large barren heath-covered moors.
Very different, indeed, in their vegetation are the large grassy plains of
Hungary and Central Russia; they are, in fact, immense prairies, not
less uniform than the Za-ndes, but presenting a much more lovely and
pleasing aspect, especially in the season of ﬂowers. The llfagyar Puszta,
so celebrated by Petteﬁ, was formerly a lake of more than 310 miles in
circumference, bounded on one side by the large bend of the Danube,
from Pesth to Belgrade, and on the other by the semicircle of the Carpa-
thians and the western mountains of Transylvania. The soil, which_is
nourished by the fertile alluvium that the Tisza, the Mares; and other
rivers bring down from the surrounding mountains, is very fertile, and in
the cultivated districts yields abundant crops. Vast extents, whichare
left as natural meadows, look like perfect seas of waving grasses, over
which roam in unrestrained freedom herds of half-wild oxen and those
uncouth horses which are ridden by the rude Uzi/cos troopers. The
beauty of these green and ﬂowering plains, dotted over with low, mud-
built houses, often hidden almost to the roofs in the tall herbage, is
heightened by the contrast afforded by the wide semicircle of blue
mountains forming the distant horizon.
The grassy steppes of Central Russia do not possess, like the Hunga-
rian puszta, this beautiful framework of lofty mountains, but they offer a
charm no less peculiar in the beauty of their ﬂowers and the graeefulness
of the ears of corn gently waving in the breeze. The vast region of the
Tchornosjom (black earth), thus named on account of the color of its soil,
is still in great part a sea of grasses, varied only here and there by vil-
lages, cultivated ﬁelds, and rivers ﬂowing slowly between steep banks.
The Tchornosjom, which extends over the valleys of the Den, the Dnie-
per, and the Volga, comprehends an area of- more than 197,500,000 acres,
nearly-twice the size of France, and throughout this immense district the
vegetable soil is of a depth varying from three to ﬁfteen, and sometimes
even reaching to‘thirty and sixty feet. Thus the geological nature of
the soil proves that this plain is not of oceanic origin; marine debris is
not found in any part of it, nor any of vthose irregular boulders brought
down from the mountain glaciers of Scandinavia. The “black lands”
86 THE EARTH ‘
were formerly an irregularly shaped continent, surrounded on all sides
by Water. Though they are incessantly fertilized by the remains of de-
cayed turf, yet they seem unable to nourish the roots of trees; forests,
therefore, are entirely wanting in these regions; thanks, also, to the nat-
ural drainage, there are no stagnant swamps. These lands, prepared for
culture by a grassy vegetation for many thousands of centuries, are
among the best in the world for the production of cereals, and sooner or
later they will become one vast ﬁeld of corn.*
To the south of the Tchornosjom there are, here and there, some oases
of the same nature which are equally remarkable for the richness of their

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Fig. 20. The “Black Lands” of Russia.
vegetation; but the greater part of the steppes are former sea-beds,
which have emerged at a recent epoch, and exhibit no traces of verdure
except in the spring. The heat of summer soon scorches up the grass,
and the ﬂocks which graze on these ‘vast plains are obliged to take ref-
uge by the ‘banks of the rivers in order to obtain their food. The only
oases of the steppes of the Don and the Dnieper are these districts in
* Ruprecht, Bulletin a'e Z’Académie dc Pétersbourg, vol. vii., No. 5.
THE RUSSIAN STEPPES.
which the inhabitants have been able to renew and purify the soil by the
use of spring water. Some villages, which were founded in the last cen-
tury by German colonists, are perfect little nests of verdure, the beauty
of whichcontrasts most strikingly with the formidable aspect of the sur-
rounding solitudes.
Nearly all the countries of Russia and Tartary, which are situated be-
low the level of the sea in the great Caspian depression, are steppes of a
still more arid and desolate character than those even of southern Russia.
They are interminable tracts of loose sand, interspersed with banks of
hard clay, like a threshing-ﬂoor‘beaten solid by the ﬂail, and beds of rock
here and there intersected by clefts in which a little vegetable soil some-
times accumulates. These steppes of sand or clay comprehend the prin-
cipal part of the western basin of the Caspian; the rocky steppes extend
to the east toward Tartary; lastly, the salt plains, which, by their eﬂiores-
cence,bear witness to the fact of the former extension of the sea, occupy
a considerable tract between the course of the Volga and that of the
Yak. There, too, is situated the desert of Narin, the clayey and barren
surface of which is scattered over with sandy plateaux covered with ver-
dure, and crossed from north'to south by a chain of downs sheltering the
pastures which lie half ‘hidden in the hollows.* ‘Vith the exception of
these scanty green patches,_which are frequented by some few. wandering
tribes, nearly the whole of the Caspian depression is the very picture of
aridity. No natural meadows reach the eye, like those in the steppes of
the Dnieper, the Don, and the Irtysh; and the pastures occupy only a
very limited breadth at some considerable distance to the north of the
present sea-shore. IVhen the locusts settle down there, which is fre-
quently the case, not a blade of grass is left, and the very reeds in the
marshes are eaten down to the level of the water.
It is well known what an inauspicious aspect the surﬁtce of the steppes
present in the middle of winter, when all is hidden under the snow, and
the freezing wind stirs up this silvery sea into waves and eddies. But
even in the most joyous season of the year the immense extent of white
sand and reddish clay, varied here and there with scanty shrubs of worm-
wood and euphorbia, with their sombre-colored leaves, likewise presents
a most forbidding aspect. The vast tracts of ground, which are crossed
by travelers in cars drawn by horses at full gallop, appears like aﬁery- _
colored sheet striped with long gray lines. Here and there ravines, hol-
lowed in the soil by the torrents of rain-storms, have to be crossed with
great labor; then some marsh, with its thick whitish waters seen in
glimpses through a forest of reeds, has to be avoided. In the distance a
border of blood-red saltwort betrays the presence of a salt pool, and quite
in the extreme horizon, heavy hanging clouds, in long rows, one above
the other, point out the vicinity of the sea-shore. The soil reﬂects an in-
tolerable amount of heat. At the same time the breeze, drawn as by a
centre of attraction to the burning surface of the steppes, raises before it
* I’allas.
88 THE EARTH.
columns of dust; at the side of the car the debris of withered plants may
be seen strangely bounding along by thousands and by millions; these
racers of the Steppes, which are rolled into balls by the wind, seem to be
having a contest of speed, and, keeping close to the earth, pursue each
other furiously, sometimes making leaps of several yards; one might al-
most fancy that they were human beings hurried along in some demo-
niacal race. At the end of each stage the traveler stops an instant before
a miserable cabin, halfburied in the sand. He catches a glimpse of a hu-
man face with haggard eyes and disordered hair, and then off he goes
again like a dart, to plunge anew into the desert. It is seldom that he
can distinguish in the distance the ln'bitléas of the Calmueks or the Kir-
ghizes, or the tombs formerly raised over the bones of warriors. F re-
quently hundreds of miles are accomplished without seeing any other
trace of man having passed over the same route, except the rats left by
the wheels in the hardened clay.* In these solitudes trees are almost
completely unknown, and the few that are found there are looked upon
with a kind of adoration, as if they were the miraculous gifts of some divin-
ity. Between the Sea of Aral and the conﬂuence of the Tchoni and the
Yatchi, that is to say a distance of 310 miles in a straight line, only one
tree is to be found, and this is a species of poplar, with drooping boughs,
the roots of which creep far into the arid soil. The Kirghizes have such
a veneration for this solitary tree that they often go several miles out of
their way in order to pay it a visit, and each time they hang an article of
their clothing upon its branches. From this custom the name of sincle-
Tic/iagatc/z, or “ rag-tree,” has been given to the desert poplarj
The plains of southern Siberia, which extend eastward as far as the Al-
ta'I' Mountains and the lake of Dsai-Sang, present a very diversiﬁed aspect
compared with the steppes of the Caspian, and even with the lcmrles of
France and the heaths of Germany. ' These plains are intersected in vari-
ous directions by chains of rounded hills, and by woods of coniferous
trees, which here and there ‘bound the horizon and give a little life to the
whole landscape. Besides the meadow grasses, hundreds of plants and
shrubs also embellish the surface of the ground. In the spring rosaceous
plants, thorny plum-trees, cytisi, tulips, and other plants, with white, pink,
yellow, and variegated ﬂowers, glitter on the greensward of the undula-
ting valleys of the steppel‘
In the north of Russia and Siberia the long plains which descend in an
imperceptible slope toward the Arctic Ocean are not less solitary than
the Caspian steppes, and have an equally formidable aspect. During a
great part of the year the circular space bounded by the horizon presents
nothing but an immense winding-sheet of snow rippled by the wind.
\Vhen this bed of snow melts under the summer sun, the lowest districts
in the plain, or tundra, appear dotted over here and there with plots of
I *‘ Von Baer, Kaspisclze Studien.—-Pallas.
‘l Zaleski, La Vie des Steppes Kirghizes.
i Humboldt, Asz'e Centrale and T ableanx de la Nature.
PLAINS OF SIBERIA.
Sphagnum and various other green plants, which grow and swell almost
like sponges by means of the half-hidden pools of water. Nearly the
whole extent of the soil is covered with reindeer moss and other whitish
lichens; and one might readily fancy that the interminable carpet of
winter snow was still spread before one’s eyes. In these regions, how-
ever, the earth is always frozen to a great depth, in spite of the rudiment~
ary vegetables which grow on its surface and the lagoons of water which
sparkle during several months in the marshy depressions of the soil?“
* \Vrangell.
l
90 THE EARTH
CHAPTER XIV.
SEMICIRCLE OF DESERTS PARALLEL TO THE SEMICIRCLE OF LANDES AND
STEPPES.—THE SAHARA.-—SANDS, ROCKS, OASES.—-THE DESERTS OF ARA-
ELL—THE NEFOUD.—-DESERTS OF IRAN AND THE INDUS.-——THE DESERT
OF COBI.
AT a great distance to the south of this zone of lcmcles, prairies, steppes,
and l’tlOZtll'ClS, which extends in an irregular semicircle from France to
Siberia, there is another zone of plains, deserts, and plateaux which
curvesround in a parallel direction to the former, and exhibits a still
more formidable and monotonous aspect. This zone, which is crossed by
an imaginary line called by John Reynaud the “ equator of contrac-
tion,”* comprehends the great Sahara of Africa and the deserts of Ara-
bia, Persia, Cobi, and Chinese Mongolia. This zone is in a great measure
destitute of water and vegetation, and, on the whole, is much less accessi-
ble to man than the northern solitudes. Not only is it more intensely
heated by the solar rays, but it also enjoys a. much less amount of moist-
ure on account of the chains of mountains which, at several points, im-
pede the passage of the rain-clouds, and especially on account of the po-
sition it occupies as extending diagonally across the most massive por-
tion of the two largest continents, Africa and Asia.
The most important group of deserts in the world is that of the Sahara,
which extends across the African continent from the shores of the Atlan-
tic to the valley of the Nile. This immense area is more than 3100 miles
from east to west, and is, on an average, more than 600 miles in breadth ;
it is, in fact, equal in size to two thirds of Europe. This is the part of the
earth in which the heat is most intense; although it is to the north of the
equator, yet, as regards most of the world, it is the real south/,1; and the
principal focus of attraction for the atmospheric currents. In this region
there is only one season, viz., summer, burning and merciless. It is but
rarely that rain comes to refresh these regions, on which the solar rays
dart vertically down.
The mean altitude of the Sahara is estimated at 2000 feet; but the lev-
el of the soil varies singularly in the different districts. To the south of
Algeria, the surface of the Chott Mel-R’ir, the remains of an ancient sea,
which communicated with the lVIediterranean, is at the present time more
than 165 feet below the Gulf of Cabes; while to the south and east, the
ground rises into plateaux and mountains of sandstone or granite to a
height varying from 3300 to 6600 feet. In the centre of the Sahara
stands the Djebel-Hoggar, the sides of which are covered with snow dur-
* Vide above, p. 56, Fig. 13. ‘r Carl Bitter.
DESERT OF THE SAIIAR-l.
ing three months in the year; from December to March* its picturesque
defiles are traversed by streams which ﬂow some distance and lose them-
selves beneath thesurrounding plains. This group of lofty mountains
is the great landmark which forms the boundary between the eastern
deserts, or the Sahara proper, and the group of western deserts, desig-
nated under the general name of Sahel. Farther to the cast, the cases
of Asben, R’at, and Fezzan, which extend obliquely toward the shores of
the Gulf of Sidra, might likewise be considered as the frontier between
the two regions.
The Sahel is very sandy. Throughout the greater part of its extent,
the soil is composed of gravel and large-grained sand, which does not
give way even under the foot of the camel. Some of the ranges of sand-
hills which rise in this desert are chains of small hills, composed of heavy
sand which resists the inﬂuence of the windﬂr But in many districts of
, the Sahel, the arenaceous particles of the soil are ﬁne and small. The
trade-winds which pass over the desert distribute these sandy masses
into long waves similar to those of the ocean, and here and there raise
them into movable sand-hills, which overwhelm all the cases which lie
across their path. Traveling toward the southwest, in which direction
they are driven by the wind,1 the sands reach the northern shores of the
Niger and'Senegal at many points of their course, and by their incessant
deposits gradually drive the waters of these rivers toward the south. T o
the west, the sand of the desert encroaches also upon the ocean. Off the
coast which stretches between Cape Bojador and Cape Blanco—pointed
out from afar by the highest dunes in the world—a line of sand-banks ex-
tends far out into the sea. These banks are constantly renewed by the
desert-wind; and the Arabs, who go to collect the waifs and strays from
shipwrecked vessels, can safely venture out several miles from the shore.§
A current of sand is, therefore, constantly passing across the desert from
northeast to southwest. The debris of rocks in a state of decomposition,
and the particles brought to the coast of the Gulf of Cabes by the tide,
which is very powerful at this point, are driven before the wind into the
plains of the Sahel, and thence, after a journey lasting hundreds and per-
haps thousands of years, they at last reach the sea-shore of the Atlantic,
in order to recommence in the oceanic currents another eventful odyssey.
Some parts of the eastern Sahara are equally sandy; but the principal
parts of the surface of this desert are occupied by plateaux of rock or
clay, and by groups of grayish or yellowish mountains. The chains of
sand-hills are numerous, and, like those of the west, they travel incessant-
ly under the impulse of the wind in a south or southwest direction." The
rocky plateaux are crossed and recrossed here and there by wide and
deep clefts, which are gradually ﬁlled by the drifted sand, and into which
* Duveyrier, Exploration da Sahara, vol. i., p. 1.20.
‘t Vide in vol. ii. the chapter on “Dunes.”
I Duveyrier, Exploration du Sahara, vol. i., p. 9. § Carl Bitter, Erdlc'una’e.
ll Georges Pouchet, Dongolah et la Nubie.
92 _ THE EA 13TH.
the traveler runs the risk of sinking, like the mountaineer into the cre-
vasses ofa glacier. In the hollows, patches of salt take the place of the
lakes which in more rainy countries would be found there.
Those districts of the Sahara which are destitute of oases present a
truly formidable aspect, and are fearful places to travel over. The path
which the feet of the camels have marked out in the immense solitude
points in a straight line toward the spot which the caravan wishes to
reach. Sometimes these faint foot-marks are again covered with sand,
and the travelers are obliged to consult the compass, or examine the hori-
zon; a distant sand-hill,a bush, a heap of camels’ bones, or some other
indications which the practiced eye of the Touareg alone can understam‘l,
are the means by which the road is recognized. Vegetation is rare, de-
prived as it is of the moisture which it requires; the only plants to be
seen are the Artemisia, thistles, and thorny Mimosas; in some sandy dis-
tricts there is a complete absence of all kinds of vegetation. The only
animals to be found in the desert are scorpions, lizards, vipers, and ants.
During the ﬁrst few days of thejourney some indefatigal'ile individuals
of the ﬂy-tribe accompany the caravan, but they are soon killed by the
heat;* even the ﬂea itself will not venture into these dreadful regionst
The intense radiation of the enormous white or red surface of the desert
dazzles the eyes; in‘ this blinding light, every object appears to be
clothed with a sombre and preternatural tint. Occasionally the traveler,
when sitting upon his camel, is seized with the wig/Z6, akind of brain~fe-
ver, which causes him to see the most fantastical objects in his delirious
dreams. Even those who retain the entire possession of their faculties
and clearness of their vision,are beset by distant mirages; palm-trees,
groups of tents, shady mountains, and sparkling cascades, seem to dance
before their eyes in misty vapor. “Then the wind blows hard, the travel-
er’s body is beaten by grains of sand, which penetrate even through his
clothes and prick like needles. Stagnant pools, or wells, dug with great
labor in some hollow, from the sides of which oozes out a scanty and
brackish moisture, point out, each day, the end of the stage. But often,
this unwholesome swamp, where they hoped to be able to recruit their
energies, is not to be found, and the people of the caravan must content
themselves with the tainted water with which they ﬁlled their ﬂasks at
the preceding stage. It is said that in times of great need the travelers
have been compelled to kill their dromedaries in order to quench their
thirst in the nauseous liquid which is contained in the stomach of these
animals.
Terrible stories are also told by the side of the watch—fires, of caravans
being overtaken when amid the sand-hills by a sudden storm of wind, and
completely buried under the moving masses; they also tell of whole com-
panies losing their way in the deserts of sand or rocks, and dying of mad-
ness after having undergone all the direst tortures of heat and thirst.
Happily such adventures are rare, even if the accounts of them are at all
* Daniel, Handbuch der Geograplzie, vol. i., p. 446. t Duveyrier, Exploration du Sahara.
OASE'S IV THE DESERT. e .
authentic. Caravans, when led by an experienced guide and. protected
by treaties and tribute against the attacks of plundering Arabs and Ber-
bers, nearly always arrive at the end of their journey without having un-
dergone any other suﬁ‘erin'gs than those caused by the intolerable heat,
the want of good water, and the coldness of the nights; for the nights
which follow the burning days in the Sahara are in general very cold. In
fact, the air of these countries being entirely destitute of aqueous vapor,
the heat collected during the day on the surface of the desert is, owing to ‘
the nocturnal radiation, again lost in space. The sensation of cold pro-
duced by this waste of heat is most acute, and especially so to the chilly
Arab. Not a year passes without ice forming on the ground, and white
frosts are frequent.* During his travels in the country of the Touaregs,
M. Duveyrier observed a difference of more than 129° F. between the low-
est temperature (24° and the highest (153° F.); but it is probable
that the real difference between the extremes of heat and cold amounts
to at least 144 degrees‘r
In all those countries in the Sahara where the water gushes out in
springs or descends in streams from some group of mountains, there is an
oasisI formed—a little green island, the beauty of which contrasts most
strikingly with the barrenness of the surrounding sands. These oases,
compared by Strabo to the spots dotted over the skin of the panther, are
very numerous, and perhaps comprehend altogether an area equal in ex-
tent to one third of the whole Sahara. In the greater part of this region,
the oases, far from being scattered about irregularly, are, on the contrary,
arranged in long lines in the middle of the desert. The cause of this is
either the higher proportion of moisture contained in the aerial currents
which pass in this direction, or, and perhaps principally, the subterranean
water which follows this slope, and here and there rises to the surface.
Thanks to this distribution of the oases, like beads on a necklace, the car-
avans dare to venture into the solitudes of the Sahara, their stages being
all marked out beforehand by the patches of verdure whichin turn rise on
the horizon. -
The oases are,par excellence, the country of date-trees; in the neighbor-
hood of Mourzouk there are no less than thirty-seven varieties.§ These
trees form the riches of the tribe, for their fruit supplies food to man as
well as to beast—to dromedaries, horses, and dogs. Below the wide fan
of leaves, which quiver in the blue air, are thickly-growing clumps of
apricot, peach, pomegranate, and orange-trees, their branches loaded with
fruit, and vines intertwining 'round the trunks ; maize, wheat, and barley
ripen under the shade of this forest of fruit-trees, and, lower still, the
modest trefoil ﬁlls up the very smallest intervals of the soil which is, as;
pable of irrigation. In order not to encroach on this-precious grou d,
which is the very life of the whole tribe, the inhabitants construct th ir
houses on the most unproductive land in the oasis, and even on the v ry
* Caregte, ‘I’ Exploration du Sahara, vol. i., pf 110i,
1 Derived from the ancient Egyptian word ouahe, signifying “habitation.” §V‘ge)l,
'94 . THE EARTH:
verge of the desert. Unfortunately, these wonderful gardens which the
traveler, just emerged from. the ocean of sand, looks upon as a place full
of, enjoyment; are for the most part- unhealthy, on account of the constant
evaporation of tepid and bad water which the irrigation-drains bring to
the foot of the trees; For this' reason the Caesars of the Lower Empire A
used to send convicts to the oases, in order that they might get rid of


‘is,


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them the sooner.* .‘But the supply of water, which is so-precious to. these
1 gardens, is badly regulated; at the time of heavy rains, which are, how-
e er, rare in the desert, the brook, suddenly transformed into. a'river,
s metimes destroys. the channels and'washes away the-trees; whereas, if
r taiped in vast- reservoirs, this water might be the means of extending
the himits of the oasis. ~ New tracts of cultivated ground may even be
* Humboldt, Tableaux de la ature.
ARABIAN DESERTS. .95,
created by boring artesian wells; this has, indeed, been done in some
places, though. in a rough manner, by the native tribes. In eight years,
from 1856 to 1864, the French engineers dug, in the Hodna and the Sa-
hara of the province of Coustantineh, eighty-three wells, which yield al-
together 11,859 gallons a minute, and nourish more than 125,000 palm-
trees; a few strokes of the boring-rod have thus changed the terrible as-
pect of the desert and adorned it with magniﬁcent groves. No doubt, if
all the subterranean springs of the Sahara were brought to the surface,
they might succeed in bringing a great part of it under cultivation, and,
in course of time, in modifying the climate as they have done in Egypt,*
by augmenting the quantity of rain and aqueous vapors.‘ Added to this,
the examination of the soil and the remains which are contained in it,
proves that at a recent geological epoch the Sahara was muchless sterile
than it now is. The tribes of the Algerian Sahara say that at the time
of the Romans the Ouad-Souf was a great river, but some one threw a
spell upon it and it disappearedj ~
To the east of Egypt, which may be considered as a long oasis situated
on the banks of the Nile, the desert begins again, and borders the whole
extent of the Red Sea. A large part of Arabia presents nothing but
sands and rocks, and toward the southeast, in the Dahna, there are soli-
, tudes which no traveler, either Arab or Frank, seems yet to have crossed.
To the north and east stretch the .Nefoucls, or “daughters of 3'the great
desert,” which are much smaller than the Dahna, but are nevertheless for-
midable tracts to travel over. One of these regions, which was crossed
by Palgrave, is that in which the mass of sand, formerly deposited there
by the marine currents, affords the greatest depth; in certain places it is
330, 400, and even 500 feet deep. ‘It can be measured by the eye by de-
scending to the bottom of the funnel-shaped cavities, which the springs
of water, spouting out of the adjacent granite or calcareous rock, have
gradually hollowed out in the bed of sand. This enormous ‘bed of mate—
rial, which represents chains of pulverized mountains, does not exhibit an
even surface, as one would expect, but, throughout its whole expanse,
presents long symmetrical undulations, similar to those waves which roll
in the Caribbean Sea under the even inﬂuence of the trade-winds. These
waves stretch from north to south, parallel to the meridian; it is probable
that they are owing to the movement of the earth round its axis. The
solid rocks beneath unresistingly obey the impelling force which carries
them toward the east,~but the movable sands which are above them do
not allow themselves to be carried away with an equal rapidity; each
day an inﬁnitesimal quantity remains behind and seems to glide toward I '
the west, like the waves of the ocean, the atmospheric currents, and ev-
ery thing that is movable on the face of the globeI The parallel flll‘l'!)ws
of sand in the Nefoud certainly rise to a greater height than those of
the other deserts, and differ much in their aspect from the smaller Waves
* Vide the chapter on “ Labor of Man.” ' " Carettu,
I Vide the chapter on “ Rivers.”
96 THE EARTH.
of sand formed by the wind; but the reason is, that the bed of sand in this
region is of a very great bulk, and because at this point the swiftness of the
globe nearly attains its maximum, on account of its vicinity to the equator.*
To the east of the Arabian peninsula, the chain of deserts is prolonged
obliquely across Asia. The principal part of the plateau of Iran, occupy-
ing a quadrilateral space, surrounded by mountains which stop the rains
in their passage, consists of sterile solitudes, some covered with saline-
beds, the remains of dried-up lakes, others spread over with shifting sands,
which the wind blows up into eddies, or dotted over with reddish—colored
hills, which the mirage renders either nearer or more distant to the eye
than they really are, incessantly modifying them according to the undu-
lations of the atmosphere. This plateau is only separated from the
steppes of Turkestan by the Elburz Mountains, and is continued toward
the east by the deserts of Afghanistan and Beloochistan, which are not
so large, and much easier to travel over. Even the rich peninsula of In-
dia is protected by a belt of sterile tracts situated on the right and left
of the Indus. Between each of the ﬁve rivers (Punjaub), which, by the
union of their waters, form the great river, stretches a line of steppes in
which the torrent-waters of the mountains are soon lost.' The soil of
these steppes is nearly every where barren, except on the edge of the irri-
gation canals constructed by the inhabitants at a very heavy outlay.
Beyond the mighty central ‘group, whence radiate far and wide the’
mountain-chains of Asiaythe steppes and deserts, mutually alternating
according to the topographical conditions, and the abundance or scarcity
of water, extend over a space of more than 1850 miles between Siberia
and China Proper. The eastern. part of this belt is called, according to
the languages, Cobi or Chamo, that is to say, the desert par excellence,
and, from its enormous dimensions, corresponds with the Sahara of Africa,
situated exactly at the opposite extremity of the long chain of solitudes
which stretches right across the Old World. The mirage, the moving
sand-hills blown up into eddies, and many other phenomena described by
African travelers, are found in certain districts of the Cobi, just the same
as in all other deserts. But the cold here is exceptionally intense, on ac-
count of the great height of the plateaux, which is on an average 4950
feet, and the vicinity of the plains of Siberia, which are crossed by the
polar wind. It freezes nearly every night, and often during the day.
The dryness of the atmosphere is extreme; there is hardly any vegeta-
tion, and a few grassy hollows are the only oases of these regions. From
Kiahkta to Pekin, there are only ﬁve trees for a distance of 400 to 500
miles, which is the width of the desert in this part of Mongolia} The
Gobi, however, like the Sahara, was formerly covered by the waters of the
ocean; even on the elevated plateaux, old cliffs may be noticed, the bases of
whi ah are worn away by the waves, and long strands of round shingle stretch
arougnd the area which was formerly occupied by a now vanished gulf.
* Giﬁ‘brcl Palgrave, Journal of the Geographical Society, 1864.
‘I’ Russell-Killough, Seize milles h'eues, p. 111.
PLAINS OF THE NEW WORLD. ()7
CHAPTER XV.
PLAINS AND DESERTS OF THE NEW’ wonLn—eoiirxnxrivn HUMIDITY OF
THE AMERICAN CONTINENTS.—DISTRIBUTION OF SAVANNAS AND STERILE
TRACTSr—THE PRAIRIES OF NORTH AMERICA.—THE LLANOS AND PAMPAS.
Tun American continent, being narrower and more exposed throughout
its whole extent to the moist sea-breeze than the larger mass of the Old
\Vorld, presents, therefore, but a very small number of districts in which
the dryness and sterility are to be compared to certain parts of the Sahara
and Arabia. It is true that plains occupy a relatively much larger area
in the New ‘Vorld than in the continents of Asia and Africa; but they
are for the most part regions which, from the abundance of water and
the deposit of ﬂuviatile alluvium, have become very fertile. Thus, the
low grounds which extend along the two banks of the Mississippi, and
especially the districts lying along the edges of the Amazon and its large
tributaries, are covered with immense forests, which are perfect seas of
trees and creepers, into which no one would dare to venture without a
guide, even if they are not completely impenetrable, except for the native,
armed with his machete. The selects of the Amazon are the regions
where vegetation exhibits its richest exuberance, and over the most ex-
tensive area.*
Plains which are devoid of trees occupy very considerable tracts of
land in the two Americas, and, notwithstanding the absence of all forest
vegetation, several~of them being formed of ﬂuviatile, or lacustrine alluvi-
um, are extremely fertile. In consequence of the composition of the soil,
the distribution of the rain-fall and water-courses, and perhaps, also, in
obedience to some still unknown law governing the apportionment of
plants on the surface of the earth, savannas of the various grasses alter-
nate suddenly with virgin forests. This unexpected contrast between
the wall of trunks, through which the sight can not penetrate, and the
unbounded extent of the grassy plain waving in the breeze, is one of the
most striking spectacles imaginable. In the basins of the Mississippi, the
Amazon, and the tributaries of the La Plata, these sudden transitions from
forest to savanna are frequently found ; next to the great rivers and large
sheets of marshy water, they are the most prominent feature of the land-
scape in the plains of the New World.
Taken as a whole, the grassy expanses of America are all—like the
landes, the steppes, and the tzmtlras of the Old \Vorld—regularly ar-
ranged in a line parallel to the axis of the continents themselves. In
North America, they are contained in the vast central basin formed by
*6 Vide the chapter on “The Earth and its Flora.”
G
98 THE EARTH
the Alleghanies and the ﬁrst spurs of the Rocky Mountains. In South
America, they likewise occupy a part of the depression in the middle of
the continent between the plateaux of the Guianas and Brazil, and the ﬁrst
groups of the Andes. _ Thanks to the rainy sea-breezes which blow over,
these plains either from the north or south, vegetation is here kept up, at
least, during several months of the year; and nowhere, even in the less
fertile districts, are real deserts to be found. These plains, which, as in
Africa and Asia, are likewise arranged in a line parallel to the belt of sa-
vannas and to the continental axis of America, are all situated on the
western side, on the slopes, or in the inner basins of the Rocky Mount-
ains and the Andes. They are, however, comparatively inconsiderable,
and intersected by ﬂuviatile valleys, some of which terminate in lakes
without an outlet, while others run down to the sea.
The savannas or prairies of Illinois and the other \Vestern States of the
American Republic resembled, not long since, the Magyar jmsztct and the
grassy steppes of Russia, except as regarded the difference of vegetation
attributable to climate. Some of those plains, which, at a former geolog-
ical epoch, were covered by the waters of Lake Michigan, have not yet
been transformed into cultivated ﬁelds, and they have a uniform and placid
surface like that of a lake. The ﬂowering grasses growing on them wave
and quiver in the wind like the ripple of the waves, and the clumps of
trees are dotted about like islands. Here and there these islands are
grouped into archipelagos, and the arms of the prairies which surround
them fork out and unite again like the arms of a grassy sea; one single
prairie, situated in the centre of the State of Illinois, is so vast, that, as far
'as the eye can reach,not one of these thick clumps of trees appears in
sight. But in consequence of the very rapid colonization of the \Vestern
States, these countries are every day changing their aspect. The traveler,
therefore, must not delay if he wishes to survey these immense prairies,
where the horizon, as on the sea, is only limited by the rotundity of the
globe—where the grasses are so high that they reach up to, and bend
over, the head of the traveler, and the roebuck can dart through them
without even being perceived! Ere long, these prairies will have ceased
to exist, save in the narrations of Cooper, the novelist; the furrows of
the unrelenting ploughshare will have converted them all into cultivated
ﬁelds. The Americans are active in turning them to account and in tak-
in g possession of this fertile land. The country, which is strictly surveyed,
is divided into townships of about six miles on each side, and subdivided
into square miles, which are again separated into four parts. All these
quadrilateral spaces are so accurately set as to aspect that each of ~their
sides points to one of the four cardinal points. The purchasers of small
or large squares never allow themselves to deviate from the straight line;
as true geometricians, they construct their roads, build their cabins, dig
their ponds, and sew their turnips in the direction of the meridian or the
equator. Thus the prairies, once so beautiful with their gently undula-
ting contour and their misty distances, now bear a strong resemblance
THE FAME-18. \\ _ 99.
to an immense chess-board. Even the railway engineers will hardly make
up their minds to cross the degrees of longitude in an oblique direction.
In the southern continent, the regions which correspond with the prair-
ies of the United States are the Pampas of the La Plata and the llanos
of Columbia. These latter expanses, so well described by Humboldt,*
are probably, of all the plains in the world, these which exhibit in their
appearance the most striking contrast, according to the different seasons
of the year. After the rainy season,these plains, which extend over the
immense zone contained between the course of the Orinoco and the
Andes of Caracas, Merida, and Suma-paz, are covered with thick grass,
and graminaceous and cyperaceous plants, among which the sensitive
and other species of mimosa here and there exhibit their delicate foliage.
Horses and oxen wander by millions over these magniﬁcent pastures.
But the soil gradually dries up, the water-courses become exhausted, the
lakes change into pools and then into sloughs, in the mud of which croco-
diles and serpents delight to wallow; the clayey ground shrinks and
cracks, the plants wither, and are torn to shreds by the wind; the cattle,
driven by hunger and thirst, take refuge in the neighborhood of the great
rivers, and multitudes of their skeletons lie bleaching on the plain. This
is the special time when the llanos most resemble the deserts of Africa,
which are situated farther from the equator on the other side of the At-
lantic—all at once, the storms of the rainy season inundate the soil, mul_
titudes of plants shoot out from the dust, and the immense yellow ex-
panse is transformed into a ﬂowery meadow. The rivers overﬂow their
banks, and the inundations will sometimes extend over a breadth of hun-
dreds of miles; the ancient islands, called “tables” or mesas, form the ‘
only land which appears above the troubled sheet of waters.
The llcmos of Venezuela and New Granada have an area estimated at
154,000 square miles, nearly equal to that of France. The Argentine
Pampas, which are situated at the other extremity of the continent, have
a much more considerable extent, probably exceeding 500,000 square
miles. This great central plain, which forms one of the most remarkable
features of South America, stretches its immense and nearly horizontal
surface over a length of at least 1900 miles, from the burning regions of
tropical Brazil to the cold countries of Patagonia. In so vast a territory,
the climate and vegetation must necessarily differ very much, and yet a
great monotony prevails, on account of the horizontal character of the
ground and the want of water. The rivers of the pampas, the Pilcomayc,
the Vermejo, and the Salado, which rise in the Andes and the Sierra
Aconquija, ultimately reach the great ﬂuviatile artery of the Parana, but
not without having lost a large part of their waters on the road, owing
to the evaporation-in the lagoons and marshes. Farther south, the Rio
Dulce, which also rises in the ravines of Aconquija, is lost in a salt lake at
some distanceto the west of the Parana. In the same way all the water.
courses of the provinces of Catamarca, Rioja, San Juan, Mendoza, and
* Tablcaux de la Nature and Voyage dans les Régions Equinoxz'ales',
100 THE EARTH.

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Fig. 22. The Pampas.
Cordova, growing smaller in proportion to their distance from the mount-
ains, ultimately spread out into marshes, or break up into pools ; the sand
of the desert gradually absorbs them. The Rio-Quinto, which formerly
reached the sea, and emptied itself to the south of the estuary of La Plata
into the bay of San-Borombon, now stops at about the middle of its for-
mer course; but to the east some lagoons connect it with the sources
of a small stream, which may be considered as the Lower Quinto. The
diminution of rains, and the increase of evaporation during the present
geological period, have resulted in severing the river into two parts.
THE PAMPAS. 101
The western plains, which partly surround the Cordovan group, are
dotted over with prickly plants, brooms, mimosas, and other shrubs of
scanty foliage. There is only a short turf growing upon the clayey and
compact soil, and here and there vast salt plains, completely devoid of
vegetation, glitter in the sun. These are real deserts, which were former-
ly crossed by travelers in caravans, just as in the solitudes of Africa and
Persia. The carriages which now run. regularly between the towns on
each side of the plain go across in a straight line, and theirdrivers do
not even take the trouble to trace out a road. Farther‘to the east, the ‘
pampa proper extends from north to south, between the Salado and the
regions of Patagonia. Here are situated the immense and celebrated
pasture-grounds which form the wealth of the Argentine Republic, on ac-
count of the cattle which overrun it by hundreds of thousands, and, in-
deed, millions. The grassy surface seems to be completely ﬂat ; no ob-
- j ect interrupts the majestic uniformity of the landscape, except, perhaps,
a herd of oxen, the yellow wall of some estancia, or a solitary tree spared
by the hatchet of the gauche. Pools, some brackish or saline, others ﬁlled
with fresh water, are scattered over the prairie, and continue the wavy
covering of grasses with their tufts of rushes and reeds. To the north of
the Salado, the great sea of grass is succeeded by thickets of mimosas,
and other prickly shrubs, which surround the small savannas. “Lastly,
beyond thewindings of the Pilcomayo, bunches of palm-trees are seen
here and there among the clumps, and the pampa, called in this district
the Great Ohaco, ultimately joins on to the large selvas in the basin of
the Amazon by swampy grounds and isthmuses of forest.
102 THE EARTH
CHAPTER XVI.
a
AMERICAN DESERTS.-—THE GREAT BASIN OF UTAHr-THE DESERTS OF COLO-
RADO.—THE ATACAMA AND THE PAMPA OF TAMARUGAL.——DEPOSITS OF
SALT, SALTPETRE, AND GUANO. '
IN North, as in South America, the deserts proper lie to the west of
the continent, and occupy the basins commanded by the parallel or di-
vergent walls of the Rocky Mountains. In both hemispheres it is the
want of rain which is the cause of the sterility of these expanses, to which
the moist winds can not obtain access, on account of the high mountains
by which the plains are surrounded; but, by a remarkable contrast, the
rains in the northern continent, which are stopped en route before reach-
ing the deserts, are those brought by the clouds from the Paciﬁc, and in
the southern continent those which come from the Atlantic with the
trade-winds. In the north, the ridges of the western chains, the coast-
range, and the Sierra Nevada are the impediments which detain the moist-
ure of the atmospheric currents of the neighboring ocean: in the south
it is, on the contrary, the eastern groups of the Cordilleras which, by op-
posing the course of the Atlantic trade-Winds from the northeast and
southeast, are the cause of the barrenness which exists on their opposite
declivities.* Besides, in both continents, most of the deserts, whether
plains or plateaux, seem to. have been, at some former geological epoch,
leveled by the waters of some inland sea.
The most northerly of these American deserts occupies, to the west of
Lake Utah, a part of the space called the “ Great Basin,” and is comprised
between the principal chain of the Rocky Mountains and the Sierra N e-
vada of California. The desert of Utah is an immense surface of clay,
dotted over with thin tufts of artemisia; in certain places, however, it ex-
hibits no trace of vegetation, and resembles a causeway of concrete, in-
tersected by innumerable clefts, forming nearly regular polygons. In the
midst of these solitudes no rivulet ﬂows, and no water-spring gushes
forth; only after jouaneying for many a long hour the traveler sometimes
comes upon some ﬁeld of crystallized salt, a White expanse, on which the
clouds and blue sky are reﬂected as on the surface of a lake. On the ex-
treme horizon some volcanic rocks may be seen, like great scorise, half
veiled by warm atmospheric columns, quivering like the air over the
ﬂame of a hot brazier. Across these vast plains, inhabited only by a pro-
digious quantity of extraordinarily-shaped lizards, the road employed by
' the emigrants used to pass, which was so soon destined to be supplanted
by the Paciﬁc Railway from New York to San Francisco. Since the dis-
* Vide the chapters on “ \Vinds ” and “Rain.”
UTAH AND COL ORAD O. 1
covery of California, thousands of men have perished in this desert, and
innumerable horses and oxen have died of thirst; the right direction of
the road is indeed recognized by their bones lying scattered over the
ground. The traveler is obliged to step during the night, for fear of
losing his way, when he no longer hears the sound of the skeletons crush-
ing under the feet of his steed.*
Separated from this desert by chains of mountains, among which are to
be found several shady valleys enlivened by brooks, there are some soli-
tudes extending southward which are less sterile than those of which we
have just spoken. The only vegetation which some of these exhibit is a
few scanty brambles here and there creeping over the ground; others are
clothed with a thin foliage of thorny shrubs; but the greater part of the
bare rocks or clay in these desert tracts appears just the same as when it
ﬁrst emerged from the water. Only a few pitalzayas, like gigantic wax
candles, stand solitarily at considerable distances from each other. Their
trunks, which rise to the height of from 48 to 60 feet, are as straight as
columns, and from the base to the summit have a nearly uniform thick-
ness, equaling sometimes the size of the human body; the branches, to
the number of two or three only, jut out from the trunk at a right angle,
and then stand erect, like the branches of an enormous candelabrum.
Owing to the regularity of their shape, their parallel sides covered with .
thorns, and their grayish-green color, these curious plants seem to be a
kind of intermediate substance between the tree and the rock, and give
to the landscape an aspect which is both fantastic and repulsive. In some
regions hundreds of miles may be traversed across the mountainous val-
leys and plains, and during the whole journey no other species of terres-
trial vitality can be seen'but these immense pitahayas. Even this amount
of vegetation is wanting in the most sterile districts of New Mexico and
Arizona. Thus the desert of Colorado, situated near the mouth of the
river bearing the same name in the Gulf of California, is a totally barren
expanse of clay and sand. In the evening, when the sun is setting far
away behind the ruddy mountains and darting its rays across the dusty
atmosphere, the traveler, when encamped in the bed of some dried-up
river on the border of this immense plain, which was, indeed, formerly a
lake, might easily fancy that he sees stretching before him the surface of
a sea of ﬁre]L
The deserts of North America, crossed here and there by fertile valleys,
extend eastward toward the basins of the Red River and the Arkansas,
where they blend with the savannas, and to the south into the Mexican
states of Chihuahua, Sonora, and Sinaloa. But in the tropical zone, which
commences beyond these points, the heavy summer rains and the much
smaller extent of the Mexican territory between the two oceans, have pre-
vented the formation of deserts. Regions destitute of trees and verdure
are only again found on the coasts of Peru, to the south of the Gulf of '
* Paciﬁc Railway Report—Jules Re'my, Voyage au Pays des lflormons.
T Paciﬁc Railway Report.
104 ' THE EARTH.
Guayaquil. The trade-winds, after having discharged their moisture on
the eastern slopes of the Andes, pass away through the air far above the
sea-shore on the western side of the mountains, and then sweep far out to
sea over the surface of the Paciﬁc. It is rarely that an atmospheric eddy
blows back upon these coasts even the smallest rainy current; sometimes
ﬁve, ten, and even twenty years elapse without a single drop of rain hav-
ing fallen in Payta and the other sea-coast towns. The greater part of
the houses in the rich and commercial city of Iqui'que were simply com-
posed of four walls, without the useless luxury of a roof Nevertheless, the
coasts of Peru are not completely destitute of verdure. Some small riv-
ers, fed by the snows from the Andes, and tapped throughout their whole
length by irrigation-drains, maintain a little vegetation in the valleys,
and, during the‘ season which is called winter, particularly in May, une,
and July, heavy dews refresh the soil of the mountains on the coast, and
cause the cactus and various bulbous plants to shoot forth here and there;
hence is derived the name of tiempo cle ﬁores given to this part of I the
_ ear.* The commercial towns situated on the sea-shore the ardens in
Y a g
the valleys, the rare grasses on the hills, and, lastly, the cliff-like deelivi-
ties of the Andes, which rise, ridge after ridge, up to their snowy sum-
mits, give to the whole landscape an animated character which is entirely
_ wanting in the deserts of North America.
The solitudes of the Andes most resembling the desert regions of the
Old World and of the United States are the elongated plateaux which
rise one above another between the sea and the principal chain of the An-
des, in southern Peru and on the frontiers of Bolivia and Chili; such as
the pampas of Islay and’ Tamarugal and the desert of Atacama. The
pampa of Tamarugal, so called from the Tamarugos, or tamarisks, which
grow in the hollows where some moisture oozes out of the soil, has a mean
altitude of from 2900 to 3900 feet. It is a plain nearly covered with beds
of salt, or salares, which are worked like rock quarries. The strata of salt
are so thick, and rain is so rare upon the plateau, that the houses of the
village of Noria, which are inhabited by the workmen, are entirely con-
structed of blocks of salt. Some deserts, situated to the east of the Tam—
arugal, on more elevated plateaux, contain a still larger quantity of salt.
The pampcl of Sal, which is overlooked by the volcano of Isluga, has a
mean altitude of not less than 13,800 feet, and its whole extent, which is
125 miles long and from nine to twenty-four miles wide, is perfectly white.
The depth of salt deposited upon this plateau varies from ﬁve to sixteen
inches, according to the undulations of the ground.
Whence do these enormous masses of salt proceed? Doubtless from
the sea or ancient lakes which formerly covered these countries and have
been gradually emptied by the rising of the soil. Saline matter saturates
even the rocks and clays, for a ﬁlm of salt again forms by eﬂlorescence
on all the ground in the desert from which crops have previously been
taken. The district of Santa-Rosa, which was completely cleared of salt
* Bollaert, Antiquities.
DESERT 0F ATA 011.1111. v105
in 1827, was all white again and ﬁt for working after a lapse of twenty-1
three years. Sea-salt is not the only production of these immense natural
laboratories; but nitrates, sulphates, carbonate of soda, borates of soda
and lime, are also found there and increase every year in thickness, thanks
to the ephemeral torrents which sometimes descend loaded with debris
from the adjacent Cordilleras. Saltpetre is also procured from the pampa
of Tamarugal,_and is the article which, during all the wars of Europe and
America, gave such great commercial importance to the town of Iquique.
About the middle of the eighteenth century, an Indian, named Negre-
res, discovered the existence of saltpetre in the pamper; having lighted a
ﬁre of brush-wood upon the soil, he perceived that the ground was melt-
ing, and that a stream issued from the midst of the ﬁrebrands and cinders.
From this date they began to work these beds; but it is only since the
last ﬁfteen years especially that this branch of industry has been carried
on to any considerable extent. According to Smith, the engineer, the
beds of nitrate occupy in the pampa of Tamarugal an area of 483 square
miles; in some spots, where the mass is not less than ten feet in depth, a
ton of saltpetre may be taken from a square yard of ground ; but reckon-
ing only on a product of 110 lbs. a yard, it is found that the total quantity
of saltpetre at present contained in the superﬁcial beds of the pampa is
not less than sixty-three millions of tens, or enough to supply the require-
ments of trade for 1393 years, if the working does not exceed, on an av-
erage, that of the year 1860*
The desert of Atacama, the largest of all those in South America, occu—
pies a wide belt of plateaux between the shores of the Paciﬁc and the
high rampart of the Andes, which separates Bolivia from the Argentine
Republic. This expanse of reddish-colored rocks, and crescent-shaped
shifting sand-hills, is so repulsively desolate a place that the conquerors
of Chili, whether Incas or Spaniards, never made up their minds to ven-
ture into it, in going along the sea-coast; they have been obliged to pass
far into the interior, by the plateaux of Bolivia, and to twice cross the
Andes before entering the Chilian valleys. Not long since, men of sci-
ence were the only travelers who dared to enter the desert of Atacama.
Nevertheless this formidable-looking country also possesses, like the
pampa of Tamarugal, great natural riches, which will not fail to summon
the labor of man and all the progress of civilization to these desolate re-
gions. Besides salt and saltpetre, this desert produces guano’r—that is,
heaps of the almost exhaustless droppings of all the sea-birds which set-
tle down in clouds upon the sea-shore. During the course of centuries
the ordure has accumulated into perfect rocks which the sun dries up,
and the surface of which is but rarely softened by rain. These masses
of detritus, which are, to all appearance, useless upon these barren shores,
are life itself to the countries of England, France, and Belgium, which
have become exhausted by the extent of cultivation; and, consequently,
this substance constitutes a most important element of national com-
* Bollaert, Antiquities, pp. 155, 240. ‘l’ Derived from the word huanu.
106 THE EARTH.
merce. The principal treasure, or national bank, so to speak, of the Pe-
ruvian Republic is represented by the heaps of excrement which cover
the Ohincha Islands, of? the coast of Callao. According to the various
calculations, from twelve to ﬁfteen millions of tons of excellent guano are
to be found there, a quantity which is worth to Peru more than eighty
millions of pounds sterling, an amount which, if well laid out, would en-
able the happy possessors to construct a magniﬁcent system of railways,
and to build a school in each of their villages. But they must be quick
about it, for the treasure of guano will probably be exhausted in twenty
years; already, since the year 1866, the northern island has been cleared
down to the solid rock.
I’LA TEA UX AND PLAINS. 107
CHAPTER xvn.
DIFFERENCE BETWEEN PLATEAUX AND PLAINS—MATERIAL IMPORTANCE
OF PLATEAUX IN THE ECONOMY OF THE GLOBE.—DISTRIBUTION OF ELE-
VATED REGIONS ON THE SURFACE OF CONTINENTS.
NOTVVITHSTANDING the variety of aspects and vegetation which is in-
troduced by the difference of climate, low-lying lands, among which, it
must be remembered, are included so many sterile deserts, play a much
less important part in the history of the globe than the more elevated
portions of the emerged surface of the earth. Both the organization and
the vitality, so to speak, of continents are owing to the external relief of
the planet; these inequalities in the surface are also the cause of the va-
ried development and distribution of climates, water-courses, products,
and populations over the whole world.
All the elevated portions of continents and islands may be naturally
divided, according to the height and inclination of the land, into plateaux
and mountain systems. By the word plateau we now usually understand
some extent of land raised to a considerable elevation above the level of
the sea; but the surface is not always uniform and level, as the name _
would seem to indicate. When the surface is very irregular, either fur-
rowcd by deep ravines, or dotted over with hills and mountains, the ideal
plain which would pass through the bases of all the mountains at a height
to allow for ﬁlling up all the intervening depressions is considered as the
superﬁcies of the plateau. There are, however, some plateaux which are
almost perfectly level, such as the staked-plains of Texas and some por-
tions of the Utah basin.
Low-lying lands, also, very often present a surface undulated with hills
and valleys, and connected with higher plateaux either by gradual slopes,
or by a succession of terraces, which may be looked upon either as the
rise of the plain or the descent of the plateau. The difference existing
between high and low lands is purely relative; we can only deﬁne them
by saying that a plain is a surface comparatively level, and commanded on
one or all sides by more elevated tracts, and that plateaux exceed in
height the land surrounding them. The ground which would be a plain
for the inhabitants of the mountains above it, would be a plateau for
those who live on a lower level. Thus, in Louisiana, where the surface is
so frequently inundated, undulations of the ground which are almost im-
perceptible to the eye go by the name of hills, because they are not in-
vaded by the ﬂoods of water; also, on the level surface of the sea, the
blocks of ice detached from the glaciers of Greenland and Spitzbergen
are commonly called mountains of ice, or icebergs. Agassiz, when con-
108 THE EARTH.
templating the heights of Obydos, in the midst of the interminable plains
of the Amazon, fancied that he was again looking upon the sublime
mountains of his native country.*
The absolute height of the several stages of elevation of the land is not,
therefore, the chief thing taken into account in the geographical division
into plains and plateaux, but the relation’which they bear to the conti-
nental mass of which they form a part. The country of North Hindostan
is more elevated than the plateaux of Suabia and Bavaria, and yet it must
nevertheless be considered as a plain, because it belongs to a continent
the general features of which are gigantic, in comparison with those of
Europe. In both parts of the world the respective proportions are re-
tained between the various stages of the continental ediﬁce. The pla-
teaux of Asia correspond to those of Southern Germany; the Himalayas
remind us of the Alps; Hindostan, with its plains and mountains, is the
counterpart of the Italian peninsula.
Although plateaux, precisely on account of their size and the grandeur
of their proportions, make less impression on the human mind than a
steep and rugged mountain chain, towering up between two countries
like an enormous rampart, nevertheless in their importance in the vitality
of the globe they are certainly superior to any other features in the con-
tinental conﬁguration. If the emerged surface of the planet were perfect-
ly level, the most dispiriting uniformity would every where reign. The
same phenomena would be produced over the whole extent of the conti-
nental surface from one ocean to the other; the winds, meeting with no
obstacle in their course, would sweep round the globe with an ever-equal
motion, like the long bands of cloud which the telescope discovers on the
planet Jupiter. There would be none of those elevated masses which, by
their transverse position to the natural course of the winds, produce an in-
terruption of the equilibrium, and drive back the atmospheric currents in
every direction. There would be none of those great refrigerators, as
they may be called, which condense the moisture in the clouds, storing it
in their reservoirs of ice and snow. Rain would fall every where to
nearly an equal extent, and the water, ﬁnding no declivity along which
it might be carried oﬁ? to the ocean, would stagnate in putrid marshes. A
perfect equilibrium of the forces of nature would have as’its effect uni-
versal stagnation and death. Supposing that men could exist on such an
earth as this, the uniformity of one great plain would be far from aﬁ'ord-
ing them any greater facilities for mutual communication; they would,
on the contrary, remain scattered round their miserable lagoons in all
their primitive barbarism. The migrations of whole nations down the
inviting slope of some of the vast continental plateaux, in quest of a new
country, like a great river seeking the sea, could never have taken place.
All civilization would have been impossible. Perhaps, as some geologists
think, the surface of the globe was uniform and without any prominent
relief when the Icthyosaurus swam heavily through the marsh-pools and
* Conversaeo" es sobre o Amazonas.
PLA TEA UX AND PLALVS. 109
the Pterodactyl spread his sluggish wings over the reed-beds. It was
then an earth for reptiles, it could not be a world for men.
If the great plateaux of the globe had been arranged round the Arctic
Frozen Ocean, and their long slopes had gradually sunk toward the In-
dian and Paciﬁc oceans, the full development of humanity would have
been equally impossible. In the north the altitude of the plateaux would
have doubled the cold of the frozen zone; all organic life, even that of
the most rudimentary plants, would have probably ceased to exist, and,
doubtless, the freezing winds, sweeping down from this citadel of snows,
would have changed into a second region of ice those temperate countries
which are now the ﬁelds of so many varied products, and where so many
powerful nations have taken their rise. The only habitable lands would
be the islands of the South Seas and the tropical regions of the continents,
if, indeed, man could exist at all in a climate where overwhelming heat
would be succeeded by icy winds blowing down from the lofty plateaux
of the north. But, even supposing that isolated tribes could have found a
footing in these countries, mankind in a general sense could not have ex-
isted; for by the word mankind we must not understand merely a multi-
tude of scattered individuals, but the whole human race, having a full
self-consciousness and knowledge of its destiny.
Whatever may have been the geological causes of the present distribu-
tion of plateaux over the various ‘continents, the following remarkable
fact must be recognized, that their height increases in proportion to their
proximity to the torrid zone, as if the rotation of the globe had caused,
not only the equatorial enlargement of the planetary mass, but also the
elevation of the continents themselves. In the Tropic of Cancer, the
mean altitude of the plateaux is nearly equal to that of the mountains in
the temperate zone, while the plateaux of the latter are, on the average,
the same height as the mountains of the polar zone.* In consequence of
this distribution of the various high lands, it comes to pass that, in every
latitude, certain portions of each continent exhibit an epitome of all the
climates which succeed one another over the circumference of the planet
from this latitude to the poles. Owing to these plateaux and the mount-
ains which crown them, the Iberian peninsula, Turkey, and Asia Minor
enjoy, at various points of their surface, all the varieties of a temperate
climate, and thrust their loftiest peaks into cold regions almost similar to
those of the poles. In countries of this sort, the traveler can change both
the climate and the features of nature round him by a journey of a few
days, or even sometimes of a few hours; while at sea, he must have made
a voyage from the tropics to the icebergs of the poles if he wished to
traverse the corresponding stages of climate. The fact of the gradually
increasing elevation of plateaux as we go south teiids actually to double
the number of the zones in the middle latitudes. A polar climate is,'as it
were, placed above the temperate climate. In Hindostan, three zones of
temperature merge into each other on the slopes of the-Himalaya, the
* Metcalfe:
110 THE EARTH.
lofty southern boundary of the Asiatic plateaux. The plains beneath,
where vast rivers ﬂow down to the sea and impenetrable forests extend
over vast tracts, are inhabited by an almost innumerable population;
higher up, we ﬁnd mountain torrents, long avenues of ﬁrs, and ﬂocks
wandering over wide pastures; higher still, there is little but brushwood,
mosses, snow, and masses of ice.* The function of these high lands in
the economy of the globe is to bring down the north into the very bosom
of the south, and to unite within a limited space all the climates of our
planet and all the seasons of the year. All these plateaux are, so to
speak, small continents emerging from the midst of the plains, and, like
the great continents bounded by the ocean, their phenomena, as a whole,
present a kind of epitome of the phenomena of the entire globe; they
may, in faet,be called so many microcosms. Vital centres, as they are,
of the planetary organism, they arrest the winds and the clouds in their
courses, and, discharging the rain, modify all the movements which take
place on the surface of the globe. Owing to the circulation of elements
which is incessantly taking place between all the more prominent por-
tions of the continental relief and the two oceans of the atmosphere and
the water, the gradations of climate on the sides of the plateaux are di-
versely blended, and are constantly bringing into mutual connection both
the Flora and Fauna of every country, and also different nations and
races of men.
* Vide the chapter on “The Earth and its Flora."
THE GREAT-FLA TEA UX OF CENTRAL ASIA. 111
CHAPTER XVIII.
THE GREAT PLATEAUX OF CENTRAL ASIA AND TIIE GATE OF THE HINDOO-
KUTCH.——PLATEAUX OF EUROPE; THEIR SYMMETRICAL ARRANGEMENT.—
PLATEAUX OF THE T‘VO AMERICAS.—~SIMILARITY BETNVEEN THE CLOSED
BASIN OF BOLIVIA AND THE DISTRICT OF UTAIL—PLATEAUX OF AFRICA.
PLATEAUX, like the continents themselves, exhibit an organization more
or less rudimentary, and a shape more or less articulated, and therefore
their importance as agents in the vitality of the globe proportionately va-
ries. Thus the great plateaux of Central Asia, which may be looked upon
as the very skeleton of the continent, exercise, it is true, an inﬂuence of
the very highest order in the general economy of the earth, but they are
almost cut off from all the rest of the world; their water-courses run into ‘
inland basins, without any outlet to the sea, and the nations which inhabit
them live in a state of almost perfect isolation from the other peoples of
the earth. The principal group of plateaux, which is bounded on the
south by the mountains of Karakorum and Kuenlun, on the west by the
Bolor, on the north by the Thian-Chan, the Altai‘, and the Daurian Moun-
tains, and on the east by the solitudes of the great Mongolian desert and
' the variously ramiﬁed mountain chains of the interior of China, constitute
an immense quadrilateral nearly equal in extent to the whole of Europe.
Among these elevated ranges there are some, as the Dapsang and the
Boullon, resting upon the Kuenlun, which exceed 16,400 feet in mean
height.* Round the greatest part of its extent this enormous fortress of
plateaux is rendered almost inaccessible by its formidable girdle of moun-
tains, snows, and deserts; only toward the northwest, between the Thian-
Chan and the Altai‘, several depressions‘ in the surface open out a road
through which, some centuries back, the terrible Mogul horsemen poured
down to enter upon their course of devastation through Asia Minor and
Eastern Europe.
At one of its angles, the great quadrilateral plateau of Central Asia
borders upon another elevated tract, of smaller dimensions but of nearly
similar shape; this is the territory of Iran, which, although likewise in
great part made up of deserts, does not form so much of a prison to the
people who inhabit it as the high grounds situated more to the east. On
the north it has several outlets toward the plains of Tartary and the Cas-
pian Sea, on the west toward the valleys of the Tigris and Euphrates, and
also is connected with the mountain-systems of Asia Minor—the long-
reaching peninsula pushed out between the two European seas. It is a
remarkable thing that just in the very vicinity of the central knot of
* Schlagintweit.
112 - THE EARTH.
mountains where the two great plateaux-systems of Mongolia and Iran
are united, the principal portal of the Aryan nations is situated—the de-
ﬁle through which passed the ﬂux and reﬂux, of wars, migration, and com-
merce. By a singular geographical contrast, this vital knot of the conti-
nent of Asia is at the same time both the spot where the two great pla-
teaux join one another, and also where the plains of I—Iindostan communi-
cate with those of Tartary and the Caspian. The diagonals both of the
high and low—lying lands of Asia cross at right angles on this point of the
Hindu-Kutch.* Here too is found, as regards the history of mankind, the
most remarkable spot of the whole earth. '
In Europe, too, the arrangement of the most considerable plateaux also
exhibits a singular symmetry. In the same way as in the continent of
Asia, all of them, with the exception of the narrow plateau of Southern
Norway, are situated in the south of Europe, and bounded on one side by
a chain. of mountains. On the west there'is the plateau of Spain,.backed
up by the great rampart of the Pyrenees, the mean height of the. plateau
being about 1980 feet; in Central Europe there is the plateau of Suabia
and Bavaria, commanded on the south by the lofty Alps of Switzerland
and thd Tyrol ; on the east there are the high lands of Turkey, situated
all along the southern base of the Balkan range. Thus the central pla-
teau of the‘three' extends northward from a system of mountains, whilst,
by a kind of polarity, the two others, situated at the two extremities of
Europe, are’ at the south of the range which serves as their base of sup-
port.]‘ These elevated districts ale-moreover, much more ‘richly organ-
ized than those of Asia, and call to mind the form of the continent of
which theyform a part, indented as it is ‘with its numerous bays and pen-
insulas. These plateaux also possess their promontories, which ~pushv out
far into the plains; wide valleys, too, break a way into their elevated lev-
els, thus providing numerous outlets to the peoples which inhabit the body
of the plateau and the country surrounding it. By means of their diver-
siﬁed outlines, the elevated countries of Europe are in no way isolated
_ from the rest of the continent; in no place are the rivers compelled to ac-
cumulate i'n stagnant lakes; every drop of water, every product of the
soil, and every man that dwells there, can ﬁnd'an easy pathway to the
surrounding plains.
Asa type of those elevated tracts, the edges of which are very sharply
deﬁned by steep ramparts which, however, thanks to the valleys which cut'
into them, are in no way like inaccessible fortresses, we may mention the
Causses, or the limestone masses of southern France. In the region of
the Jura, similar plateaux, especially that of Nantua, have been cut out
by the water with so much regularity that one involuntarily thinks of
the legendary giants who used to cleave mountains with a blow of their
swords. '
The plateaux of the two Americas are of much greater altitude than
those of Europe, and thus correspond to the continents on which they
* Carl Hitter, Erdkunde. ‘ 'l' Carl Ritter, Europa.
PLA TEA UX OF THE TW'O AMERICAS. 1 1 3
stand' With the exception of the secondary plateaux of the Alleghanies,
the Guianas, and Brazil, all the elevated tracts of land in America are
comprised between the various ramiﬁcations of the mountain chains which
rise up in the far west in the vicinity of the Paciﬁc. The plateau of Utah,
or the “Great Basin,” is a vast territory, the outline of which is of a bold
character, and guarded by parallel ramparts of rocks; it is bounded on


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Farther to the south extend the plateaux of New Mexico, Arizona, Ohi-
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H
114 THE EARTH.
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Fig. 24. Indented Plateau of Nantua-Department Ain.
On the south of the Gulf of Darien we have a cries of high plateaux
commencing with the enormous chain of the Andes. ' In every place where
this lofty chain divides into two forks, or spreads out its ridges in a fan-
like shape, it includes between the mountain spurs a plateau of4500, 6000,
or sometimes evenas much as 12,000 feet in altitude.
In Columbia we have the plateaux of Paste, Antioquia, Cundinamarca,
and Caraccas. Farther south, the two chains of the Andes and the Cor-
PLA TEA UX OF AJIE'RICA’ AND AFRICA.
dilleras, which separate ‘and then'unite only to divide again, includebe-
tween their snowy ridges the plateaux of Quito, Cerro de Pasco, Cuzco,
and Titicaca, and lean laterally on the high desert tracts of Atacama, be-
tween Bolivia and Chili, also on the hilly terraces of Cuyo, Westward of
the Argentine Pampas. Of all the South American plateaux, there is but
one which is so completely shut in by the rising ground round'it that it
is unable to discharge its collection of rain-water into the plains below.
This is the plateau of Titicaca; its mean elevation is not less‘than 13,200
feet, and, from its height. and extent, forms :the most prominent feature in
the proﬁle of ‘the Columbian Continent. This Bolivian plateau is the
counterpart of the “Great Basin” of North America. These two corre-
sponding “regions both alike occupy the central portion of their respective
continents, each being about 1860 'miles from the isthmus of ‘Central
America; they are also both situated between the forked extensions of a
great system of mountains, and, in the depressions of their surface, con-
tain lakes without any outlet to the sea. '
Geographically speaking, these‘ countries are as if isolated from the rest
of the world. ' It is with great difﬁculty that the semi-barbarous inhab-
itants of Bolivia are able to enjoy any of the intercourse of commerce or
civilization with the other American republics or the countries of Europe.
The plateau of Utah is the spot where the Mormons have established their
settlement in order to escape the pressure of their fellow—countrymen
round them; a full measure of the North American energy must indeed
have been necessary for pursuing the youthful theocratic community into
the deserts which protected them. The plateaux which witnessed the’ de-
velopment of the autochthonous civilization of the Aztecs, the Toltecs, the
Guatimaltecs, the Muyscas, the Chibchas, and the Incas, have one immense
advantage over the closed-up basins of Utah and Bolivia—‘they communi-
cate freely with the sea-shore by means of their open valleyshan'd the
courses of their rivers.
The African plateaux are still more isolated from the rest of the world
than the corresponding tracts of land in America; but it is not on account
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of their great height, or the perpendicular cliffs of the mountains which
command them; the cause is rather to be attributed to the conditions of
their climate, and to the situation of the continent itself. The greater
part of the elevated regions in Africa are but of comparatively low eleva-
tion, and their slopes aﬁ'ord an easy means of access. The plateaux of the
116 ' s ' ,.THEEARTI£
Cape Colony, the mean height of which, on the south, is scarcely 660 feet,
gradually rise toward the'north up to the desert of Kalahari, at an eleva-
tion varying from 2000 to 3000 feetabove the level of the sea. All that
we'at present know of the, interior.ofAfricafullyv warrants us in thinking
that the‘average height of theplateaux increases but very slightly as we
approach theequator. In the very centre of the continent, the region of
lakes, whence the Nile derives its source, does not present an elevation of
more than 4000 to 4600 feet; also, in the north of Africa, the plateaux of
Morocco and Algeria, along almost their .whole extent, are below 3000
feet in height. The most'remarkable plateau on the continent is that of
Ethiopia, over the entire extent of which—about 750 miles—a mean alti-
tude is maintained of 7000 to 8000 feet. The steepest escarpments of
this mass of land are turned toward the sea, as if , to defend the Abyssin-
ians from any attacks on the part of foreign nations. . But the descent on
the opposite or northwest side, in the, direction of the Nile, is twenty times
more gradual; and at this point Abyssinia would be easily accessible, if
it were not that by the desert character of the country, the incessant con-
ﬂict of tribe with tribe, and the miseries of the slave-trade, any way of
access to its frontiers is sewn thickly with perils. Although the African
continent is the least known of all the great divisions of the world, and is
also inhabited by the most barbarous races of men, yet, taken as a whole,
as regards its means of access to the intercourses of trade and civilization,
the natural obstacleswhich it offers are not to be compared'with those
presented by the mountainous walls of the plateaux of Central Asia and
of the Andes. In‘ the distribution of its mountain ranges, its elevated
tracts, its plains and its deserts, and also" in the general outline of its
coasts, Africa reminds one of the peninsula of Hindostan; it is an India
magniﬁed eleven fold,but is much less beautiful and well shapedthan the
wonderful Asiatic peninsula.
IS OLA TED MO UNTAINS. 11 7
CHAPTER XIX.
ISOLATED MOUNTAINS—MOUNTAINS IN GROUPS.-—CHAINS AND SYSTEMS OF’
MOUNTAINS—THE BEAUTY OF MOUNTAIN PEAKS.—-SACRED MOUNTAINS.
-—PLEASURES OF MOUNTAIN CLIMBERS.
ALTHOUGH mountains do not play nearly so important a part as pla-
teaux in the economy of the globe, they are, nevertheless, much better
known, on account both of the majesty of their appearance and the sharp
contrast which they present to the country round them, and also of the
variety of 'the phenomena of which they are thescene of action. Moun-
tains which tower up in‘ solitary greatness either from the bosom of the
sea or. from some level plain, produce, more than all others, an effect of
the'highest grandeur, and make the most vivid and durable impression
on the mind. The mind’s eye can hardly picture scenes'superior in beau-
ty to those formed bythe gracefully undulating slopes and purple sum-
mits of solitary-mountains like the Ventou‘x, Etna, the volcano of Tene-
riﬂ’e, Orizaba, andso many other peaks, at the base of which a whole ho-
rizon seems spread out. Some of those heights which in' mountainous
countries would scarcely deserve to receive a name, and would be hardly
looked upon as hills, make pretensions to be formidable peakswhen they
spring from the midst of a level plain, or on the edge of the sea. This
applies to a little hill of about 780 feet in height which stands in the cen-
tre of the inonotonously level districts of Lower Pomerania; this bill has
seemedso'prodigious tothe inhabitants of the country, on account of
the savage wildness of its cliffs, that they have‘given it the name of the
“_ Mountain of Hell” (Hollenberg). In' the same way, a ridge in Denmark,
which rises to about 557 feet in height above the level of the sea, has been
called the “Mountain of Heaven” (Himmelberg): it is an Olympus, like
that of Greece.
¢With the exception of volcanic cones, there are but very few solitary
mountains which rise'byth'emselves in the midst of a level country. In
almost all the countries of the ‘world—in those at least which possess an
at all strongly-deﬁned relief—we meet with summits in considerable num-
ber, either arrangedin groups ‘or in long ranges. Generally these moun-
tains which are grouped in the form of a circle surround a more elevated
central summit, and are also themselves surrounded by heights of asec-
ondary class, which abut upon lateral buttresses, and gradually sink down
to the level of the plain surrounding them. As instances of this sort, we
may mention the group of the Hartz Mountains inGermany, Mount Fer:
rat in Piedmont, Sinai in the Arabian peninsula, the lofty cluster of the
Sierra-Nevada of Santa Marta, which towers up to a height of 19,680 feet
118 THE EARTH.
in an insular tract bounded by the sea, the marshes, and the deep valleys
of the Rio-Cesar and the Rancheria. The chains, properly so called, which
are always distinguished by a considerable development of the length of
the upheaved ground, sometimes also have a dominant peak as their cen-
tral culmination, 011 each side of which the summits of the ridge become
gradually lower; but there is no range where this regular arrangement
is carried out with any thing like geometrical regularity. The greater
part of the mountainous upheavals are found to present a collection of clus-
ters, chains, and subsidiary chains, variously grouped, in which a long pro-
cess of study is required for duly ascertaining the direction of the ridges.
They must not be looked upon as chains, but as systems of mountains.
Owing to the diversiﬁed character exhibited by these numerous groups
of heights, both in their geological origin, the composition of their rocks,
the general direction of their axis, the position of their peaks, the vegeta—
tion which clothes them, the light which illumines them, and the atmos-
pheric agents which waste them, every mountain is distinguished from its
neighbors by certain characteristics of special beauty. From this very
fact, among all this assemblage of summits, every peak, whether charming
or magniﬁcent, which rears its ravined sides above the base of upheaval,
assumes an appearance of independent vitality, as if it enjoyed a distinct
individuality. The sight of these giants towering up over a wide-spread
horizon exercises a perfect fascination over the minds of some men, and
they are urged by a kind of instinct, often quite unreﬁecting, to bend their
steps toward the mountain, and to scale its acclivities. Through either
the grace or majesty of their form, their bold-proﬁle standing out sharply
against the clear sky, the girdle of clouds rolling round their rocks and
their forests, and their incessant variations of light and shade gleaming
through their ravines and recesses, mountains seem to assume an appear-
ance of personality, and one is almost tempted to look upon their rocky
masses as beings endowed with all the powers of vitality. Every moun-
tain, the summit of which in its bold tracery stands out clear from the
rest of the mass, seems to be so thoroughly an individual by itself, that in
most cases a name hasibeen given to it, often the half-poetic title of some
hero or god; and, in every-day language, we constantly attribute to it
even human qualities. Mountains, in fact, are truly enough geographical
indivi‘dualities, and, by the mere fact of their position in the midst of
plains, they modify in a thousand ways the climates and all the other phé‘s-
nomena of the districts round them. Farther, do they not exhibit within
a limited space an epitome of all the beauties of the earth ‘P Various de-
grees of climate and zones of vegetation are arranged in gradation on
their slopes; there, too, we may embrace in one comprehensive glance the
most diverse features of the earth’s vitality—cultivation, meadows, for-
ests, ice, and snow; there, at eventide, we may see the {fading radiance of
the sunlight illuming the lofty peaks, and endowing them with a marvel-
ous effect of transparency, as if the enormous mass were but a rosy-col-
ored drapery ﬂoating-lightly in the clear sky.
SA O'RED M0 UNTAINS. —- CL UB5. 1 ]_ 9
In days gone by the people used to worship mountains, or at least ven-
crate them as the seats of their divinities. All round Merou, the proud
throne of the gods of India, every stage of humanity may measure its prog-
ress by the side of other sacred mountains where the lords of heaven were
wont to assemble, and where all the great mythological epopées of the life
of nations have been brought to pass. The peak of Lofeu in China, and
the volcano of Fusi-Yama in Japan, are both sacred mountains. The Sa-
manala, or Adam’s Peak, whence can be enjoyed a view full of grandeur
over the well-wooded valleys of Ceylon, is also reverenced as a holy spot;
and on its loftiest peak stands a wooden temple, fastened down to the
granite mass by chains imbedded in the ﬁssures of the rock. This, ac-
cording to the Mohammedan and Jewish legend, is the spot on which
Adam, driven out of the earthly paradise, came to do penance for many a
long century; here, too, the divine Buddha left the mark of his footprint
when he took ﬂight to soar up into heaven. To the Armenians, Mount
Ararat is no less sacred than the Samanala is to the Buddhists, or the
peak which towers over the sources of the Ganges is to the Hindoos. It
was on one of the rocks of the Caucasus that Prometheus was bound down
in punishment for having stolen the ﬁre of heaven. For many an age
Mount Etna was the citadel of the Titans; the three brows oﬁOlympus,
which proudly rear their dome-like forms, were the magniﬁcent dwelling-
places of the gods of Greece, and when a poet wished to invoke Apollo,
he turned his supplicating glance to the summit of Parnassus. If the pol-
ished Hellenes thus venerated the mountains of their native country, how
great must be the adoration which would be paid by ignorant barbarians
to the mountain which bore upon its terraced ledges their miserable huts,
much as a forest-tree carries a bird’s-nest on its spreading-branches! The
mountain which affords them shelter seems to them to reign far and wide
over the earth, and in it they proudly recognize their father and their god.
In our day we have certainly ceased to worship mountains; but, at all
events, those that know them best seem to love them with a perfect love.*
To scale the loftiest summits has at the present time become a complete
passion‘; every year important ascents are made by thousands, independ-
ently of the minor expeditions which travelers undertake to the summits
of a secondary class and of easy access. Alpine Clubs, or societies of
mountain-climbers, composed in great part of some of the most energetic
and most intelligent savcmz‘s of Western Europe, have devoted themselves
to the task of vanquishing, one after another, every mountain-top which
had been hitherto considered inaccessible; they carry away from them a
stone as an emblem of their triumph, and they leave on them a thermom-
eter, or other scientiﬁc instrument, in order to facilitate the investigations
of any bold climber who may follow them. The Alpine Clubs have drawn
up a list of all the peaks which are still rebellious, and have fully discussed
the means of subduing them; they have also investigated multitudes of
ascents, and, by their charts, their descriptions, and their numerous meet-
'*‘Vide Mountaineering, by Tyndall, and the various publications of the Alpine Clubs.
120 THE EARTH
ings, they have largely contributed in throwing light on the architecture
of the Alps. The collected traveling journals of the members of these va-
rious clubs are unquestionably the source from which the most valuable
information may be derived as to the rocks and glaciers of the loftiest
mountains in Europe, and they also give us the most interesting narratives
of ditﬁcult ascents. In the far-distant future, when not only the Alps, but
also all the other accessible summits in the world, have become perfectly
familiar, the records of the Alpine Clubs will form the Iliad of mountain-
climbers; and people will talk of the exploits of a Tyndall, a Tuckett, a
Coaz, a Theobald, and of other heroes of this grand epopée of Alpine con-
quest, just as the exploits of noted warriors were.once the subjects of song.
Whence proceeds the deep-seated joy which is felt in scaling a lofty
summit ? In the ﬁrst place, there is a great physical pleasure in breath-
ing the fresh keen air, which has never been vitiated by the impure ema-
nations of the plains. Man feels renovated by merely tasting this atmos-
phere of life; the higher he mounts up, the more rareﬁed becomes the
air; deeper inspirations are necessary to ﬁll the lungs, the chest is swelled,
the muscles are at full stretch, a cheerful ﬂow of spirits pervades the mind.
The pedestrian who scales a mountain feels himself his own master, and
responsible for his own llfe ; he is not delivered over to the capriciousness
of the elements, like the navigator who trusts his fortunes to the sea;
much less is he like the railway traveler—a mere human package—paid
for, ticketed, and put in- a carriage, and then dispatched at a ﬁxed time,
under the surveillance of employés in uniform. On alighting, he regains
the use of his limbs and his liberty. His eye enables him to avoid the
stones that lie in his path, to measure the depths of precipices, and to dis-
cover the rocky projections and clefts which will facilitate the escalade
of the cliﬁ's. The force and elasticity of his muscles will enable him to
leap over safely the deepest creuasses, to maintain his footing on the steep-
est inclines, and to raise himself, step by step, up the most difficult pas-
sages. On a thousand occasions during the ascent of a steep mountain,
he must fully recognize that he is running a fearful danger should he ei-
ther chance to lose his balance, or allow a sensation of giddiness to dim
his sight, even for an instant, or should his limbs refuse their wonted serv-
ice. This consciousness of peril, joined to the pleasurable knowledge of
his activity and health, is the very serﬁation which, in the. mind of the
pedestrian, doubles his feeling of safety. With what joy does he after-
ward relate the slightest incident of the ascent—the stones rolling down
the mountain slope, and plunging into the torrent beneath with a dead-
ened sound; the root to which he hung suspended when he scaled a wall
of rock ; the streamlet of snow-water at which he quenched his thirst; the
ﬁrst glacier crevasse over the brink of which he stooped, and yet dared to
leap; the long and weary slope up which he so painfully climbed, with
his legs buried knee-deep in the snow; ﬁnally, the culminating peak from
which he saw, spreading away into the mist of the horizon, the immense
panorama of mountain, valley, and plain. \Vhen the traveler looks lqack
THE AS CENT OF 1H0 UNTALYS. 12 ]_
from afar upon the summit which he conquered at the cost of so much
exertion, it is with perfect rapture that he sees it again, or traces out with
his glance the path that he followed, from the valleys at its base to its
snow-clad peak. The mountain seems actually to look down and smile
upon him from afar; for him alone its snow glitters, and the fading sun-
light illumines it with his last ray.
With regard to the intellectual pleasure which mountain climbing af-
fords, which, however, is intimately bound up with the material joys of
the ascent, it is proportionately greater as the mind is more expanded, and
the various phenomena of nature have been more successfully studied.
The destructive action of water and snow is fully grasped by the scientiﬁc
traveler; he inspects the movement of the glaciers, and the rolling rocks
or boulders making their way from the summits to the plain; he traces
out the enormous horizontal or inclined strata; he perceives the masses
of granite upheaving the beds; then, when he at last stands on some lofty
peak, he can contemplate in its entirety the mountain ediﬁce, with its ra-
vines and its spurs, its snows, its forests, and its meadows. The hollows
and the valleys which the ice, the water, and the tempest have carved in
the immense relief, are clearly deﬁned, and the whole labor accomplished
during thousands of centuries by all the geological agents is plainly seen.
By going to the origin of the mountains themselves, a surer udgment can
be passed on the various hypotheses of saocmts as to the rupture of the
earth’s crust, the displacement of strata, and the eruption of granite or
porphyry. And besides, without alluding to that meaner impulse of van-
ity which instigates a certain number of men to distinguish themselves as
mountain-climbers, there is a sentiment of natural pride excited when we
compare our own littleness with the grandeur of the natural phenomena
which surrounds us. The torrent, the rocks, the avalanches, and the gla-
ciers, all remind man of his own weakness; but, by a natural reaction, his
intellect and his will rise up in opposition to every obstacle. He takes a
pleasure in conquering the mountain which seems to brave him, and in
proclaiming himself the victor over the formidable peak, the ﬁrst glance
at which had ﬁlled his mind with a kind of religious awe.
Owing to the increasing facilities of communication, and to the love of
nature so much developed in modern society—owing, too, to the example
which has been set by bold mountain-climbers, the elevated regions of cen-
tral Europe, where once but few travelers cared to venture, on account of
the want of roads, the steepness of the inclines, the.danger from avalanch-
es, and the dread of the unknown, are nowadays become the great centre
of popular attraction. These very mountains, so diﬂicult of access, which
tower up as a rampart between the north and south of Europe, have caused
Switzerland to become the great rendezvous of nations ; and, during the
season for traveling, bathing, and mountain-climbing, it. enjoys a ﬂoating
population of some hundreds of thousands—a number which increases ev-
ery year. Vevay, Lucerne, and Interlacken are like sacred cities to which
every lover of nature must pay his pilgrimage.
122 THE EARTH.
' CHAPTER XX.
VARIOUS FORMS OF MOUNTAINS—‘POVERTY OF POLISHED LANGUAGES IN
DESCRIBING THEIR APPEARANCE.——RICHNESS IN THIS RESPECT OF THE
SPANISH LANGUAGE AND THE ALPINE AND PYRENEAN PATOIS.-—TIIE NU-
MEROUS PROVINCIAL TERMS EMPLOYED FOR VARIOUS SHAPES OF HILLS
AND MOUNTAINS.
MOUNTAINS vary singularly in their shapes, according to their height,
their geological constitution, and the force and direction of the meteoric
agencies that assail them; so vast is the multitude of causes, in great part
unknown, which have labored either in concert or in succession in carving
out these projections of the earth, that every peak has its own special as-
pect. It would thus seem almost necessary to employ a particular desig—
nation, if not for every mountain, at least for each of the types to which
we may be able to reduce the numerous shapes of the earth’s protuber-
ances. Unfortunately, our languages manifest a remarkable poverty in
words well ﬁtted to bring before ‘the mind’s eye the precise outlines of
any particular summit. Whatever may be the appearance of two or more
mountains and the geological composition of their rocks, the geographer
and the author are compelled to avail themselves of the same terms in
designating them, unless, indeed, they have recourse to a long description
in cases where a single word ought to suﬁice. They are, in fact, obliged
to make use of words altogether unsuitable, such as the term “chain,”
which is invariably applied to ranges of hills.
‘The cause for this penury in exact geographical terms may be very eas-
ily understood. Most of the cities in which the various languages were
gradually reﬁned are situated on very level ground, or among hills very
slightly undulated'. There can be no doubt but that the French nomen-
clature in respect to mountains would have been much ‘richer and more
exact if, from Blois, Paris, and Orleans, lofty peaks had been visible in the
horizon. The richness and the propriety of the terms employed by the
southern Germans, the Spaniards, and Italians, when they wish to describe
in one word various kinds of hills and mountains, are certainly derived
from the fact that these nations have lived and formed their language in
full view of lofty summits. M. de Humboldt, in his Tableau de la Nature,
quotes the following terms employed by Castilian authors: joz'co,pz'cacho,
mogote, cucurucho, espz'gon, Zoma, tench'da, mesa, panecillo,ﬁm'allon, tablon,
pefia, peﬁon, peﬁasco, peﬁolerz'a, Toca partz'da, Zaja, cerro, sierra, serraa'zz'a,
cordillem, monte, montaa'ia, montaﬁuela, altos, malpaz's, Teventdzmz, bufa,
etc—all of which serve to designate the diverse forms of mountains, or
THE FORMS OF MO UN TAD’S. 23
chains of mountains. It ‘would be easy to (still further enlarge this long
list of names.
The inhabitants of the Pyrenees and French Alps use in their dialects a
great variety of expressions, each of which is especially devoted to some
particular type of mountain, and consequently serves to‘ depict to the
mind’s eye a perfectly diﬁ'erent form. Many of these names, inherited from
the ancient Celtic and Iberian dialects, well deserve to be‘admitted into
the French written language, the more so that they are in customary use
by all the French mountaineers from the sources of the Rhone to the
Pyrenees. I
In the Alps of Queyras and Viso, lofty peaks with escarped sides which
tower over all the neighboring summits are known by the name of brie
or brec. Of this kind is the beautiful pyramid-shaped mountain of Cham-
beyron (11,112 feet in height), which rises to the south of the valley of
the Ubaye, in the midst of a circle of pointed summits of a less height.


\ .// ‘SJ/7
D F)?” \‘f:
\
.54??? l


Fig. 26. “ Brie,” or Crest, of Monte Viso, seen from the East; after Tuckett.
Of this kind, too, is the Viso itself, at least on its northern face, for the
other side of the mountain presentstoo regular a slope to entitle it to the
name of brie. Above the upper valley of the Guil, black cliffs rise up, fur-
rowed by avalanches, then an enormous tower-like mass with perpendicu-
lar sides, and at last the truncated peak crowned with its thick covering
of snow. The apparently inaccessible terrace which so proudly ovcrtops
the Col de Valante, the secondary summits of Visoletto, and the rocks that
have toppled down from the heights—this is the brie of the Viso. To any
mountaineer who has never set eyes upon this proud summit, this term
will convey far more meaning than the vague designation of “mountain.”
In the same way, the old term pelve, now disused,which, however, we may
still recognize in the names of the Grand-Pelvoux, the Palavas, the Pelvas,
'the Pelvo, and several other mountains in Dauphiné, at once depicted to
the mind’s eye an enormous cone commanding all the neighboring sum-
mits. . ' ' ‘
The tucs and trues of the Pyrenees are also summits of lofty elevation,
124 _ ~ THE EARTH.
but not the highest points in theridge; they get this name on account of -
the bold outline of their upper cliffs, and not from their pre-eminence over
the mountain-tops round them. As instances of these tucs we may cite
those of Maupas, Montarqué, and Mauberme, in the Central Pyrenees.
The, tug'ue, the truque, the tusse, and'the tausse, all specify mountains
with wider bases and more gentle slopes than those of the‘ tuc ,'- b'ut'now-
adays these picturesque designations have been- gradually displaced by
the more general termofpz'c, which is applied without distinction to all
pointed and almost inaccessible'summits; _- It is aicuriou‘s fact that‘the
downs on the Atlantic sea-coast, which by the inhabitants of the interminé
able level 'of the French Laudes are looked 'upon as real mountains, ‘still
retain-this provincial name of tucs, although it has fallen into disuse for
the giants of the Pyrenees. few miles fromlArcachon, a down of about
260 feet high has .made such an impression on the imagination of the ini
habitants of the Landes that, by an emphatic pleonasm, they have st'yl'ed
it the True cle la Trugue.
Those very steep and pointed summits, which are generally designated
by the exaggerated but rather striking name of az'guilles (needles), have,
in most cases, received from the natives of the district much less ambitious
appellations, the most common of which is pic. The Pyrenees also include,
among some of their highest mountains, several pigues ,' as the Pique
Longue du Vignemale (11,049 feet high) and the Pique d’Estats (10,104
feet high). The enormous cluster of the Alps of Pelvoux has for its cul-
minating summit a pointed peak 13,461 feet high, which was once called
the Barre cles Ecrz'ns. But in Savoy and French Switzerland summits of
this form are principally known by the name of dent (tooth), almost sy-
nonymous with the designation horn, which is used in Central Switzerland,
starting from Mont Cervin or the Matterhorn,* that boldly modeled mass
which Byron looked upon as his ideal type of a mountain. The dents are
generally less pointed than the aiguz'lles, and are rounded off toward the

._ 1,‘; _
Fig. 27. The Pie du Midi d’Ossau, seen from the northeast; after V. Petit.
* Coaz, Alpenclub, vol.
‘J
THE FORMS OF MO UNTAINS; - 125
summit; but the transitions presented by the mountain outlines are so
gradual that it is diﬁicult to establish any very strict classiﬁcation. In
consequence, great confusion prevails in the nomenclature, and the greater
part of the summits in the Swiss Alps bear indiscriminately the name of
horn. In the Tyrol, too, the term kogel (leegel, skittle) is applied to moun-
tains of the most diversiﬁed shapes.
The four-sided pyramids which spring up so numerously in some moun-
tain ridges are called the caires, quay-res, esquerras, or guaz'rats of the Alps
and Pyrenees. Certain peaks of this kind have given a name to an entire
cluster of the French Alps—that of Queyras. If the point of the pyramid


)25 -
. H I //.;;,(:_?I’
Fig. 28. Einshorn de Splugen; after Coaz.
isreplaced by an elongated ridge, the mountain-top then becomes a tail-
Zante (edge). If, on the contrary, the summit terminates in a cubical mass,
it will be designated by the name tour (tower). Calcareous mountain re-
gions are the localities where we chieﬂy ﬁnd those enormous quadra u-
lar layers which seem as if they had been built in by the Titans. Fgew
spectacles in Europe are equal in beauty to that afforded by a view from
the Pie de Bergons over the limestone region of the Central Pyrenees, with
its perpendicular walls, its snow-covered terraces, its tower-like heights,
appearing to the glance almost inaccessible, and its carved-out gaps, like
openings purposely made between battlements. A similar appearance is
presented by the calcareous e'minences of La Clape, near Narbonnq, and
by the sandstone mountains in several districts. The faces of these per-
pendicularly hewn peaks are often designated by the very appropriate
names parois (side—walls), or parcels, murs (walls), or muraz'lles (ram-
parts). ‘
Tower-like peaks of comparatively smaller dimensions, which appear as
if they were ediﬁces built on the mountain-tops, have received in the Pyr-
enees the name of pene, or bougn. The téte (head) is a summit with regu-
lar and gently inclined terminal slopes, springing up from a mass furnished
with steeper sides. If the roundness of the summit is developed in the
form of a 'cupola, the mountain is then a sown (summit), or a elo‘me, as
Mont Blanc, the giant of Europe. In German Switzerland mountains with
ﬂattened summits, as, for instance, the Rhigi, are known by the name of
kulm. In the Vosges the ballons, and in- the Black Forest the boelchen,
126 ' THE EARTH.
/]l I
. ‘(ﬁr
' /

Fig.2‘). The Gross-Gloekner; after Payer.
represent mountains terminating in large summits, which seem blown out
in the shape of a bladder. The bases of these mountains are generally
very wide, and the slopes gently inclined.


Fig. 30. L’Esquerra des Eaux-Bonnes, seen from the southwest: after V. Petit.
The names applied to summit-s of a secondary class are no less numerous
than those given to the principal mountain-tops. A spur connected with
a rounded summit frequently receives in the Pyrenees the appellation of
turop, or turonnet ; and an escarped projection, extending with saw-like
indentations (kamm, in German), takes the name of serre, or some deriva-
tive of it, such as sarrat or 'serrere ; it is the Spanish sierra in miniature.
‘.401
"lindre de iﬁar'baré


I
. Bréche 1e Roland '
Tour dzglgbore came hfwedze Tame!)
‘A’ ' Etta-it


.i“
. 1"
_Ci:que
‘ de bavaxme
Fig. 31. The Mountains of Gavarnie, seen from the north: after V. Peﬂt.
NAMES OF NO UNTAIN .PEAKS. 127
A matte (muotta in the Grisons) is a mountain almost isolated from the
rest of the group, or even rising in the midst of avalley in an alluvial dis-
trict. Finally, some mountain names point out the nature of their rocks
or their vegetation. The Lauzet .or Lauzieresmountains are composed of
slaty rocks, and in the Pyrenees the numerous peaks called estz'bére, or
pradére, are completely clothed with verdure. The words puy, puig, pay,
pee/z, or puck, are general terms which are applied indiscriminately to all
the prominences either of mountain ridges or of the plain, from the Puig
de Carlitte (9563 feet high) down to the smallest elevations. It is re-
markable that the words which, in our more .classical language, are most
used to denote elevations of the surface, namely, montagne (mountain) and
eolline (hill), are taken in quite’ a different acceptation in the idioms of the


Fig. 32. Pene: Piz a Lun de Guscha; after Coaz.
inhabitants of the Pyrenees and Alps. “Montague” means only a greater
or less extent of pasture-land, and the term “ colline” applies to the dales
lying between two mountains.
In addition to the names employed by the inhabitants of the Alps and

Fig. 33. Téte: Wallenstock de Wolfenschiessen; after Coaz.
Pyrenees to specify various types of mountains,we must mention some
which are made use of in the Frenchtropical‘colonies, oneor two of which,
such as meme and piton, have found their way into literary language. In
volcanic countries, the mountains of igneous ,origin,* with summits round-
* Vide the chapter on “Volcanoes.”
128 . THE EARTH
ed like a cupola, like the Puy de Dome, or pierced with a crater like the
Puy de Sancy, are almost all designated by local terms of very striking
aptitude; but the greater part of these words remain unknown to fame.
Nothing can prove more'decisively how much modern communities still
adopt as their ideal a life altogether artiﬁcial, and without sympathy with
nature. Happily, a kind of reaction is steadily setting in. Attracted by
the beauty of the summits which once startled them, crowds of travelers
now ﬁnd their way to the mountains; they learn to know them, to love
them, and to describe them. Thus languages are enriched, and science
gains a further store of information.
INEQ UALITIES AND DEPRESSIONS 0F MO ZUVTAINS. 129
CHAPTER XXI.
INEQUALITIES AND DEPREssIoNs IN THE VERTICAL OUTLINE OF MOUNTAINS.
-—-ORIGIN OF vALLEYs, GORGES, AND OTHER DEPRESSIONS.—LONGITUDI-
NAL VALLEYS.——TRANSVERSE VALLEYS.—WINDING VALLEYS WITH PAR-
ALLEL SIDES.-—VALLEYS WITH DEFILES AND GRADATIONS 0F LEVELS.—
CLUSES AND cANoNs—cENERAL ARRANGEMENT OF VALLEYS.——-AMPHI-
THEATRES.—THE OULES OF THE PYRENEEs.
MERE height constitutes but the most inconsiderable element in the
beauty of mountains: the majesty as well as grace of their appearance '
is chieﬂy due to the distortions and dip of their strata, the circular dells
and glens which are hollowed out upon their slopes, their yawning de-
ﬁles, their abrupt precipices, and, ﬁnally, the broad valleys stretched out
at the base of the colossus, which, by the contrast that they afford, enable
us the better to appreciate the magniﬁcence of its proportions. Owing to
the variety of outline and scenery caused by all these successive depres-
sions, the mountain has assumed an aspect of grandeur and life which it
must originally have wanted. Like a block of marble transﬁgured by the
sculptor’s hand, the mighty mass, once a monotonous plateau or mere dome
of rock, has been gradually modiﬁed by meteoric agents incessantly affect-
ing it, and has been converted into one of those mountains, in the proud
proﬁle of which our forefathers recognized the face of a god. We may
easily ﬁgure to ourselves all the changes which have been effected in the
form of mountains by the various depressions of the soil, if we visit cer-
tain groups of heights, one side of which retains its old plateau-like as-
pect, while the other, sinking abruptly toward the plain, has all the ap-
pearance of an actual escarpment. There are many instances of this kind
in the region of the central plateau of France, of Auvergne, the Jura Moun-
tains, the Rauhe Alp in Wurtemberg, and in Bavaria. On one side stretch
long stony slopes; the ﬁelds are all unfertile, and the prospect is uniform,
and devoid both of movement and life. Then, all of a sudden, as we attain
the edge of the ridge, we see opening out below us a succession of decliv-
ities: hollows ﬁlled with water appear between the escarpments and the
fallen rocks; farther down in the increasingly misty depths we catch sight
of terraces and ledges crowned with ﬁrs, and trickling rivulets glittering
in the dells at the base of the cliffs. Far beneath our feet, at the very
bottom of the gulf, lies the peaceful valley, like another world, with its
winding river, its ﬁelds, its vineyards, its woods, and its busy towns.
What, then, is the origin of the valleys, gorges, ravines, and all the oth-
er depressions which we meet with in the elevated regions of the earth?
This is a question which must be considered identical with an inquiry into
I
130 THE EARTH.
the origin of the mountains themselves, a point on which geologists are as
yet very far from having come to any agreement. WVe can only state, in
a general way, that some of these depressions are primitive features of the
ancient conformation of the mountains, and owe their origin either to dis-
turbances of the strata or faults in the rocks; others have been gradually
eaten away by time, or hollowed out by snow, ice, rain, and water-courses.
Those who try to reconstruct in imagination mountain systems as they
must have existed in preceding ages assert with certainty that some val-
leys were contemporaneous with the mountain groups which surround
them. They also feel warranted in boldly declaring that this glen or that
ravine was cut out by meteoric agencies; but, as regards a considerable
number of the most important features of the mountain, doubt still con-
tinues to weigh upon their minds.
At all events, when extensive longitudinal valleys are included between
two mountain chains which are parallel to each other, but different in age
and geological formation, these valleys are indisputably of primitive ori-
gin; they are the hollow of the terrestrial crust formed naturally by the
slopes of the two acelivities which rise on the right and left. The whole
length of the valley itself must have been upheaved by the forces which
were at work on both sides of it under the adjacent masses, and it has
also been variously modiﬁed during the lapse of ages by the water-courses
which have traversed it. In one place its hollows have been ﬁlled up, in
another its rocks have been carried away—the water having deepened it
on one side to build it up on the other. But, notwithstanding all its
modiﬁcations, the geologist none the less recognizes the valley to have
been furrowed out in the same age as that in which the neighboring high
mountain summits were formed. Thus the great depression of the lower
Valais, which divides the peaks of the Finsteraarhorn and the Jungfrau
from those of Monte Rosa and Mont Blanc, is certainly a primitive valley
in all its essential features. For still stronger reasons, the vast cavity of
the Lake of Geneva, which b'ends round between the Alps and the Jura
Mountains, the lowest depths of which are but little above the level of
the sea, must have had an existence at least coeval with all the mountains
of Switzerland.
Certain transverse valleys, which break abruptly through a mountain‘
chain, and, as it were, cut it in two, must also belong—at least most of
them—to the primitive mountain conformation. Of this kind is the charm-
ing valley of Engadine, the slope of which rises almost imperceptibly up to
the foot of the Maloggia (5941 feet), above which towers, 7352 feet higher,
the summit of the Bernina. In the New Zealand Alps, Julius Haast dis—
covered a still more astonishing transverse valley, as the foot of it, com-
manded on both sides by peaks measuring 7800 and 9800 feet in height,
was only at an altitude of 1600 feet, scarcely one ﬁfth of the height of the
chain. Finally, in all the mountain ranges composed of volcanic cones
upheaved at intervals along the same ﬁssurein the earth, large transverse
valleys, which are, in reality, the remains of the former plain, are found in
ORIGIN OF VALLEYS. 131
great numbers. This may be especially remarked in Java and in the Chil-
ian Andes.* .
With regard to the ordinary transverse valleys which owe their origin
to some depression in the face of the mountain, and merge into a larger
valley or into a plain, being connected also with other glens which open
out right and left into the thickness of the mountain, it is always diﬂicult,
and often impossible, to distinguish between the eifects which must be re-
ferred to the action of water and those which are to be ascribed to other
causes which have co-operated in the formation of these gigantic furrows.
Even in these spots where, on the two sides of the valley, the layers of
rock all perfectly correspond, we are unable to tell whether the original
ﬁssure was not produced by a natural contraction of the beds, or by some
sudden movement of the crust. It is, however, quite sufficient to note the
geological labor accomplished every year by the torrent roaring along in
its deep bed, in order to be convinced how mighty its action must have
been during an immense cycle of centuries.]‘
Buffon has established the fact that a great many winding mountain
valleys are, from their origin to their outlet, walled in on each side by
parallel escarpments. The projections on the cliff on one face correspond


1? 28°k0'
Fig. 34. Channel of the Bosphorus.
* Via’e the chapters devoted to “ Rivers” and “Volcanoes.” ' a
T Vide the chapter on “ Rivers.”
132 ' . THE EARTH.
with the hollows on the other; the projecting and the re-entering angles
alternate on either side, so that if the two opposite cliffs were suddenly
brought close together, their windings and irregularities would mutually
coincide. Other valleys, however, present an altogether different kind of
formation: their sides, instead of running regularly in parallel curves,
are in some places very wide apart, in others very close together. They
thus follow a kind of rhythm very different to that of the ﬁrst type of
valley, and produce a succession of rounded basins, separated from each
other by narrow passes. In the Pyrenees, the J ura, and the calcareous
regions of the Alps, valleys of this kind are very numerous; but we .more
often observe a combination of the two modes of formation. At certain
points of their course, valleys run tortuously between parallel sides; at
others, they form successive basins. Thus the upper portion of the long
channel of the Bosphorus, which may be looked upon as a valley, although
now invaded by the waters of the sea, presents several stretches of water
almost like lakes, while farther down the channel the indentations of the
opposite banks are so regularly arranged that they might almost be ﬁtted
one into the other.
The variations in the shape of valleys may be explained by the different
natures of the rocks which the waters havehad to hollow out. Wherever
the material operated upon—gravel, sandstone, granitesfschists, or lavas
—are of an analogous composition, and thus every where present an equal
amount of resistance to the action of the water, the latter is able to pur-
sue its normal movement, and adopts a meandering course, which ap-
proaches each bank in turn, thus communicating the windings of its bed
to the valley it is hollowing out. On the contrary, when the rocks consist
of strata of unequal hardness, or are traversed by obstructing walls, the
water is necessarily compelled to spread out into a lake-like accumulation,
in the mean time eating away the banks in a lateral direction, until—the
barrier being at last penetrated—the sheet of water is poured down in a
torrent to some lower level. In this way there has been formed, during a
course of ages, a series of basins one above the other, some of which are
still partially ﬁlled with water, others entirely empty, all being linked to-
gether by narrow deﬁles, through which pours the mountain torrent.* In-
stances of a series of this kind of small basins of verdure, arranged like a
succession of steps, are very numerous in all mountainous regions. We
may mention the valley of Co in the Pyrenees, and in the Alps the lofty
valley of Isere, in which old lake-basins and gloomy gorges alternate with
great regularity.
The various channels or cuts which unite the various basins, and through
which are precipitated the impetuous ﬂood of the mountain torrent, are
called in the Jura by the name of cluses, and in the Alps are designated
as clus ,' but in these countries they do not limit themselves to cutting
through mere barriers of rock—they pierce even through mountain chains.
The basins of the Var and its water-courses are very rich in deﬁles of this
kind—enormous incisions carried right through the thickness of the lime-
* Vide the chapters devoted to “ Rivers” and “ Lakes.”
CL UiS'E'S AND CAXONS. 1 3 3
stone ramparts. Among these clus there are some which are really formi-
dable—those of the Leap, between Grasse and Nice; those of Saint Auban
and the Echaudan, and others which afford a passage to the waters of the
Var and its tributaries. These are tremendous deﬁles; each side of the
torrent is walled in with perpendicular or overhanging rocks several hun-
dred yards high, and the summit of the escarpmentis generally crowned
with the picturesque walls of some ancient village. These narrow gorges,
through which it is often found diﬂicult to carry a road or even a path,
must be classed among the most curious sights in France. The view of
these gloomy passes is all the more striking as one comes upon them im-
mediately after traveling over the fertile plains of the Mediterranean
shores, studded with villas, gardens, and olive-groves. The clus of the
Aube and its tributaries, those of the Upper Dordogne, the Tarn, and the
Lot, are also formidable in their appearance; but the most remarkable in
the world are probably the canons of Mexico, Texas, and the Rocky Moun-
tains, in which we see a river, almost without water, ﬂowing at a depth of
several thousand feet between perpendicular walls. According to New-
berry, the geologist, the great canon of the Colorado is not less than 298
miles in length, and in several places its perpendicular sides rise to a
height of 3300, 5000, and 6000 feet. '
In accordance with the size of the mountains, the nature of their rocks,
the abundance of their snow and rainfall, the elevated valleys exhibit the
most astonishing diversity of shape and aspect. In clusters of mountains
where the torrents rush down to the plain over a very steep bed, and
through sharp windings hollowed out in the body of the rocks, most of _
the tributary valleys, opening right and left of the principal ravine, are
constituted altogether like the latter, except perhaps that they are still ,
more winding, and thewater in them runs more rapidly; these, too, re-
ceive the streams of smaller glens which are still steeper than themselves.
Generally speaking, every tributary vale unites with the central valley at
the precise spot where the latter presents the convex side of its windings.
The result is, that valleys and their tributaries, as a whole, exhibit an ar-
rangement which is very similar to that of a tree with a succession'of
branches. In calcareous mountains, where the torrents run through a se-
ries of basins one above the other, and communicate by means of cluses,
the system of valleys shows a more rudimentary arrangement. In this
case, each basin is also the point of junction for two lateral valleys oppo-
site to each other, and ascending in a straight line toward the heights of
the mountain. The ensemble of all these symmetrical depressions reminds
one of the trees in gardens which are trained as espaliers, the opposite
branches of which creep along their supporters in parallel lines.
With regard to the dales, glens, ravines, and all the smaller depressions
of a mountain, from those deep gashes which legends tell us were made
by some giant’s sword, down to those gentle and graceful undulations
which .resemble the folds of drapery, their variety is so .‘ endless that it
would be impossible to classify them in any systematic order. Each
mountain, having its own peculiar individuality, differs in the character
134 . THE EARTH.
of its dales and glens, which, too, have each their special aspect of majesty
or grace.
'Almost every valley commences with a kind of amphitheatre of greater
or less extent, hollowed out of the thickness of the central mass of the
chain, and.formed by the union of the ravines and gullies of the surround-
ing mountains. The amphitheatres of a circular or elliptical form, which
we come upon all on a sudden after having wandered along winding val-
leys or on the sides of perpendicular cliffs, form a beautiful spectacle in all
their calm and peaceful grandeur. We must visit the calcareous moun-

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tain chains, such as the Central Pyrenees, with their perpendicular walls
and deeply-hollowed basins, if we wish to see these wonderful amphithe-
atres in full perfection. The most remarkable, on account of their vast
dimensions and the snow-clad terraces which surround them, are the oules
(boilers) of Gavarnie, Estaubé, and Troumouse, which the slow action of
centuries has hollowed out in the calcareous sides of the mountains of
Marboré. Undulating tracts of pasture-land furrowed by torrents, pro-
digious walls rising to 1500, or even 2000 or 3000 feet in almost perpen-
dicular height, gigantic steps on which whole nations might'ﬁnd room to
sit, cascades which either spread out over the precipice and ﬂoat away in
a diaphanous veil of mist or rush down into the valley like an avalanche,
the high summits, glittering with unstained snow, which rear their heads
high above the wall of cliﬁ's, as if to look over into the inclosure—all these
features we ﬁnd combined far 'in the recesses of these solitary mountains,
so as to-render the Pyrenean amphitheatre one of the grandest tableaux
in Europe.
.DEPRESSIONS IN MO UNTAIN RID GES. 1 3 5
CHAPTER XXII.
DEPREssIoNs IN MOUNTAIN RIDGES.—DIVERSITY IN THE FORM OF PAssEs
(COLS).——-RELATION BETWEEN THE RESPECTIVE 'ALTITUDEs OF SUMMITS
AND PASSES.—LAW OF DEBOUCHMENTS.——REAL AND IDEAL SLOPES OF
MoUNTAINs—EsTIMATEI) SOLID coNTENTs OF MOUNTAIN GROUPS.
MOUNTAIN necks or passes (coZs)—-that is, the hollows or depressions of
the ridge or summit, are, like the valleys, to be. attributed, to diverse
causes. Some are primitive features produced by the disturbanceorrup-
ture of the upheaved beds; others are excavations of more recent origin,
and are due to meteoric action and the crumbling away of the mountain
mass. . .
The variety of causes which have combined inthe formation of these
depressions sunk into the ridges, the varying force of resistance offered by
different rocks, and all the events of the incessant. conﬂict carried on for
centuries between the mountain summits and the air which surrounds
them, have combined in giving-to these passes the greatest diversity of
aspect. Some are mere turfy or snow-clad bands, between two rounded
brows; others are themselves narrow ridges of sharp-edged rocks, com-
manded on each side by pyramidal masses; these are fourclzcs (forks) and
Izow'guetzfes of the Pyrenees. Others, again, are deep ﬁssures carved out
between perpendicular walls; some, even, like huge gateways opening be-
tween the valleys from opposite sides, are actual breaches, which. we should
be inclined to think had been effected in the living rock by the ‘processes
of sapping and mining.
It has often been asked if there is not a constant analogy between the
altitude of summits and that of the passes which indent their ridges. It
might easily be foreseen that, as the mountains had been diversely worn
away by the effects of storms, snows, and water, the depressions of the
passes, which are the result of these long-protracted erosions, must be
looked for at various elevations in the‘ different groups. This, too, has
been proved by M. \Villiam Huber, as the result of patient comparative in-
vestigation. Thus, in the group of Mont Blanc, the proportion between
the mean height of the summits and that of the passes is as 1'28 to l ; in
the Monte Rosa group it is as 1'43 to 1; in the Jungfrau it is as 1'62 to l.
The relation between the highest summit and the lowest pass also differs
very considerably in different systems of mountains. . Inthe-Todi group
this proportion is as 2'68 to 1; it is only as1'53 to 1 in the Tessinese
Alps.* In a general way, the altitude .of the widest and deepest passes
of the Alps maybe estimated at one half of the height of thesurrounding
* William Huber, Bulletin de la Socz'étc' de Géograplzie, February, March, 1866.
136 THE EARTH
summits, while in the Pyrenees it is about two thirds. The more consid-
erable depressions which divide the Alps into distinct masses, toward
which tend a quantity of secondary passes, give, by the contrast which
they afford, a peculiar character of grandeur and variety to the orographic
system of Central Europe. The Pyrenees are much more uniform than
the Alps in their architecture, and, in consequence of the relative heights
of their passes, form one of the most beautiful types of the Cordillera
which can be found upon the earth.
It is a remarkable fact, brought to light by M. Huber, that the passes
which are hollowed out the most deeply in the mountain mass debouch
precisely in front of the most elevated peaks of the opposite group. Thus
the pass of the Simplon (6594 feet) opens directly in front of the group
of the Jungfrau (13,671 feet); and the Gemmi (7161 feet), the least ele-
vated pass in the Bernese Alps, debouches in the valley of the Rhone, di-
rectly in front of Monte Rosa (15,216 feet). In the same way, the pass
of Lukmanier (6289 feet) faces the summit ‘of Todi, and the pass of the
J ulier lies in the axis of the great Bernina group. It may, in fact, be no-
ticed with regard to nearly all the principal passes that, on the other
side of the valley, they are fronted by one of the highest mountains of
the divergent chains which radiate round the central nucleus of the St.
Gothard. ‘ 1
To what cause, then, are we to attribute this general situation of the
principal passes to which M. Huber has given the name of the “law of de-
bouchments ?” It may be explained in great part by the fact that the
most elevated mountainous masses generally rest on the widest and most
solid foundations; the torrents, consequently, pass round their bases, while
on the opposite side the phenomenon of erosion becomes more active, and
gorges are more and more hollowed out in the thickness of the chain.
During the lapse of centuries, the diﬁ'erences in vertical outline between
the escarpments of the two chains become very distinctly prominent. In
the Pyrenees, this relation of summits and passes in two different moun-
tain ridges can only be pointed out in a few instances, on account of the
general simplicity of the chain and the comparative height of the passes.
Nevertheless, here and there we ﬁnd some unquestionable examples of
this law; thus the entrance of Venasque opens exactly in front of the
Maladetta, and the deep depression of the pass of Puy Moren is opposite
to the summits of the Fontargente group. ~ ,
Looked at in an entirely general point of view, this “law of debouch-
ments” is nothing more than a particular instance of the law formerly
pointed out by Buﬁ'on as to the serpentine form which is presented by all
normal valleys. The salient angle of a chain corresponds to a hollow in
the mentoring angle of the opposite chain, the summit rises opposite to a
depression, and groups of very elevated peaks tally with some pass more
depressed than any of the others. Now, if the curves of a valley render
it very probable that an indentation of the ridge answers to the convex
portion of the stream, we may assert almost to a certainty that the line of
S UMIIII TS AND PASSES. 137
junction uniting two sharp bends of streams which are separated by a
chain of mountains will pass through a deep depression of the ridge.
The comparative studies which have been made by various geographers,
since Humboldt, as to the vertical outline of mountain chains, have been
directed not only to the comparative height of passes and summits, but
also to the mean inclination of mountain sides. The real slope of a moun-
tain ridge is, as is well known, the tortuous and variously inclined line
which is followed by a streamlet of water in its descent from the ridge to
the plain below; but it is not this more or less regular curve which is
constituted the actual side of the chain. It is, in fact, an ideal line pass-
ing through the secondary summits, and over the passes and dales, and
connecting the summits of the principal ridge with the base of the incip-
ient acclivities in the adjacent plains. This ideal line is never so much
inclined to the horizon as the appearance of the slopes and the sudden
contrast between the heights and the valleys would lead one to expect;
painters, too, seem very naturally to exaggerate by one third, or even by
half, the real relief of a mountain outline, so as to give the effect which
they truly enough produce on the eye of the spectator. On the French
side, the J ura—the general incline of which is, however, very gentle——
from the crest of Mont Tendre to the town of Arbois, presents a total de-
clivity of only 4288 feet—that is, a gradient of about 2'6 in 100, which is
but a moderate slope even for a coach road. The general inclination of
the Pyrenees is much more rapid, since, from the summit of Mont Perdu
to the plain of Tarbes—a distance of thirty-six miles as the crow ﬂies—
the declivity is 9980 feet, or a gradient of 5'2 in 100. But even this is a
much less rise than that of some of the high hills on mountain reads; it
is, too, very inferior to that of the railroad which winds in zigzags up the
sides of Mont Cenis. The most abruptly inclined mountain side which
can be found in Europe is that face of the Alps which is turned toward
the plains of Piedmont and Lombardy; from the summit of Monte Rosa
to the district of Ivrée, the mean slope exceeds 10 yards in 100, which to
the eye produces the effect of an immense Babel of towers and pyramids
placed one above another. Certain mountain groups in the New World
have still steeper sides; thus the Silla of Caraccas turns toward the Ca-
ribbean Sea a real wall rising at an angle of 54° to the horizon; this would
be a cliff of an all but inaccessible character if it were not possible to
scale it by zigzag paths through the gorges and ravines. It must, how-
ever, be understood that the declivity of mountain sides is not exactly the
same in every part of the mountain groups; although very steep at one
point, it may be tolerably slight at another, in accordance with the varie-
ties of heights, rocks, and climates.
The mean declivity is difficult enough to ascertain, on account of the
great diversity of slope in different places; but the total volume of a
chain of mountains is a much more difficult thing still to ﬁnd out, even
approximately. Humboldt, taking as his basis the scientiﬁc data (which
are still too incomplete) as to the heights of plateaux and mountains in
138 ' THE EARTH.
various continents, has endeavored to estimate the cubical mass of sev-
eral great mountain chains. According to his calculations, the total mass
of the Pyrenees, spread uniformly over the whole surface ofFrance, would
‘only raise the soil about 10 feet.* In like manner, if all the materials of
the Alpine masses were equally distributed over the continent of Europe,
they would only augment its height about 21% feet.'[ It would be very
useful to renew these. investigations, so as to arrive at'results which would
be more and more exact, as the orographical outline becomes better known.
The most perfect calculation of this kind which has ever been made is
probably that of Sonklar as to a portion of the Tyrolese Alps known un-
der the name of the Oetzthal group. This mass would be represented by
a- solid body having a‘ uniform height of 8333 feet, of which 5314 feet
would be for the‘plateau or pedestal of the mountainous region, and 3019
feet would be for the wholeof the peaks: This mass, if spread over the
whole of Europe, would only represent an increase of two feet in the
height'of the continent. We thus perceive that as regards the question
of bulk, mountain chains are much less important than plateaux like Spain
or Bavaria. .
* In Otté’s translation of Humboldt’s Cosmos, vol. i., p. 305, it is given as 115 feet—ED. '
1' Cosmos, F aye’s translation, vol. i., p. 353.
I Sonklar, Qi’tzthaler Gebirgsgruppe.
LAW OF MOUNTABV CHAINS. 139
CHAPTER XXIII.
HYPOTHESES AS TO THE GENERAL LAWS OF MOUNTAIN CHAINS.-—M. ELIE DE
BEAUMONT’S THEORY OF PARALLEL UPHEAVALS.—CHAIN OF THE PYRE-
NEES TAKEN AS A TYPE OF THE CORDILLERAS OR LONGITUDINAL CHAIN.
——VARIOUS IRREGULARITIES IN THE CHAIN.-—-THE PYRENEES AS AN ETH-
NOLOGICAL BARRIER.
SEVERAL geographers have fancied that they had discovered the law
of the general arrangement of mountains, and, without so much as wait-
ing until the whole surface of the earth became thoroughly known, have
traced out, according to their own notions, ranges of mountains more or
less hypothetical. Thus Buache, whose ideas were very prevalent for a
long time, imagined that the chain of the Pyrenees was prolonged under-
neath the Atlantic, then across the New World and the Paciﬁc, and, again
making its appearance in Asia, forming in succession the Himalaya, the
Caucasus, the Balkhans, the Alps, and the Cévennes, ﬁnally returned to
the point it started from; It was, in fact, the ancient image of the myth-
ical serpent coiling itself round the globe and biting its own tail. We
only need to glance at the maps which, at the present day, science enables
us to trace out, in order to see how completely primitive this idea was as
regards the harmony of the terrestrial conﬁguration. It is, on the con-
trary, by a singular variety of phenomena that the laws of nature are al-
ways revealed.
Of course it may be said, in a very general way, that the principal
chains of mountains, interrupted here and there by gulfs, arms of the sea,
or plains, form a kind of great circular cornice round the double basin of
the Indian Ocean and the Paciﬁc.* In like manner, it is certain that the
mean altitude of the elevations of the ground, both mountains and pla-
teaux, gradually diminishes as we leave the tropical regions and approach
the poles. But how numerous are the exceptions which come under our
notice when we study the endless variety of the geographical lineaments
of the earth’s surface! Some countries seem a perfect labyrinth of plains,
plateaux, and mountains, of every shape, form, and height. In one place
we ﬁnd granite peaks and domes of porphyry; in another, ridges of schist,
cut up into needle-like points; limestone ramparts and basaltic cones of
almost mathematical regularity of outline. The fact is this, that the se-
ries of mountains which have been elevated during each period of the
earth’s existence have been added to by successive series of subsequent
upheavals. Whatever the ﬁrst rule may have been, it has gone through
an incessant process of modiﬁcation during the lapse of ages.
* Vida above, p. 52.
140 THE EARTH
It becomes, therefore, the function of geology to decide as to the real
order of arrangement of mountains by describing the history of their
formation. M. Elie de Beaumont has endeavored to fulﬁll this great task,
and, by a bold generalization of scientiﬁc facts, has succeeded in drawing
up a theory of great simplicity. Taking as his starting-point the fact that
the steeply-inclined sedimentary strata which stretch along the side of a
mountain must necessarily have been upheaved, while the strata which
have remained horizontal have not been disturbed since their formation,
the eminent geologist has thus been enabled to assign a relative age to
each system of mountain chains. In fact, every chain which presents on
its slopes the vertical beds of any geological formation, and at the base of
which we ﬁnd the strata of a later age, must evidently have been upheaved
from the surface during the longer or shorter interval which separated the
formations of the two series of strata. Now, if we compare the direc-
tions of mountain systems of the same age, we ﬁnd that they are nearly
parallel in the set of their ridges. M. Elie de Beaumont has therefore
classiﬁed various mountain chains according to their direction, and has in
this way pointed out some very remarkable coincidences between ridges
of upheaval separated from each other by thousands of miles. One most
important fact which results from this classiﬁcation of mountains is, that
the most ancient systems are generally the least elevated. The Vosges
date from a much more remote epoch than the Pyrenean chain; the lat-
ter was uplifted before the Alps, which also belong to an age much ante-
rior to that of the Andes.
Nevertheless, this geological classiﬁcation of mountains is not so simple
as it appears at ﬁrst sight; for it is often very diﬁicult to determine the
real axis of upheaval of mountain chains—a fact which M. Elie de Beau-
mont found an opportunity of convincing himself of in studying the sys-
tem of the Esterel. A profound study of the earth’s strata will correct all
the false and incomplete elements which these theoretical ideas must con-
tain. Geography, which conﬁnes itself to a description of the earth as it
is in the present epoch, can only class the various chains of mountains ac—
cording to the regularity of their shape, their vertical outline, and the im-
portance which they assume in continents as the divisions of the water-
shed, as the laboratories of meteoric agencies, and as a barrier between
nations.
Among the mountain chains which assume an almost perfect regulari-
ty, we may mention the western portion of the Pyrenees. Just like a
branch of a tree, or better still, a stalk of fern, is divided and subdivided
right and left into small branches, leaves, and leaﬂets, so every knot in the
ridge gives rise on both sides to transverse chains, similar in every respect
to the mother-chain, except that they are much shorter, and sink by succes-
sive falls down to the level of the adjacent plains. The transverse chains
are also parallel, and separated from each other by deep valleys, down
which glaciers rush, torrents roar, or footpaths wind. The valleys on
CHAIN OF THE PYRENEES. 141
each side of the principal chain correspond closely and communicate with
each other by a col, port, or passage, that is, a depression opening between
two summits. Like the principal ridge, each subsidiary transverse chain
is also composed of a succession of summits, separated from each other by
passes, the height of which proportionately diminishes. Each summit gives
rise to two lateral spurs, which are, in fact, nothing but the rudiment of a
tertiary chain running parallel to the principal one; the secondary passes,
too, serve to connect short ravines which empty their streams into the
torrent of the principal valley.

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The portion 01 the great Pyrenean chain which is comprised between
the pass of Roncevaux on the west, and the port of Venasque on the east,
may therefore be considered as the perfect type of a regular ridge of
mountains. The eastern portion of the chain is not arranged in so order-
ly a way: an examination of the lines of the ridge will prove that at sev-
eral points it departs from the typical form.
The principal irregularity is to be found at about the centre of the
chain, at an almost equal distance from both seas. ‘Ve may there notice
that the Pyrenean chain is not of a simple conﬁguration; but that, on the
contrary, it is formed of two distinct lines, one of which is a continuation
of the regular western chain ; while the other, divided into three parts by
the Col de la Perche and the Col de Puymoren, commences on the shores
of the Mediterranean, under the name of the chain of the Alberes; at the
Costabona group it crosses the more important transverse ridge of the
mountains of Cadiz and Canigou, and, tending toward the east, forms the
clumps of Andorre, Montcalm, and Mont Vallier; then running parallel to
the chain coming from the Atlantic, it terminates on the right bank of
the newly-born Garonne. The Pyrenees may be compared to a regular
chain which has been divided into two by some gigantic fault, the two
halves of which, remaining ﬁxed at each of their sea-coast extremities,
have turned slightly and in contrary directions round these extremities,
as if on pivots.
142 THE EARTH.
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A transverse ridge, abutting at right angles to the northern chain, joins
that of the south to the Col de Pallas; another, likewise thrown out at
right angles from the range of peaks in the southern chain, tends more to
the west, and is only separated from the Mediterranean ridge by the nar-
row deﬁle of the Garonne. Thus the extremities of the two chains, and
the two lesser chains which unite them, inclose on all sides a deep valley,
resembling a terrestrial whirlpool, round which the mountains rise like
enormous waves. This is the district of Aran, the centre of the Pyrenees.
Although its rainfall ﬂows, by means of the Garonne, into the plains of
France, orographically speaking it belongs to neither of the two basins.
\Vith a greater show of reason than the valley of And'orre, the district of
Aran might have remained as a neutral republic between France and
Spain, the two adjacent states.
A second anomaly may be found in the fact that the highest summits
are not situated on the principal ridge. Thus Mont Perdu, the Posets
Peak, and the Maladetta rise to the south of the Atlantic chain of the Pyr-
enees: the ﬁrst of these mountains is connected with the central axis by
several elevated passes, but the peaks of the Posets and the Maladetta,
giants which front each other on each side of the Essera, form two almost
completely isolated groups. On the north side only, some snow-clad ridges
link them on to the principal system.
Nevertheless, in spite of all these irregularities, resulting from the in-
cessant labor of the agents which are at work in modifying the surface of
the globe, the chain of the Pyrenees must ever be considered as an in-
stance of a regular system of mountains, and, among all the ranges on
the face of the earth, but very few can even be compared with it in the
regular simplicity of its formation. The aspect of the Pyrenees is there-
T HE PYRENE'ES. 143
fore less diversiﬁed than that of the Alps and of several other mountain
systems. The long range bounds the horizon with a uniform wall, in-
dented with points like the edge of a saw (sierra), and, looked at from
the plain, its subsidiary spurs are scarcely visible. Although the mean
height of the central ridge of the Pyrenees exceeds that of the Alps by
about 300 feet,* and the plains of France are'lower than those ofSwitzer-
land, yet this superior comparative elevation produces less eifect on the
spectator on account of the regular arrangement of the peaks and the sim-
ilarity of their outlines. Few, if any, summits in the Pyrenees exceed by
more than 2000 or 2500 feet the mean height of the ridge (8037 feet),
while in the Alps many of the mountains rise more than 6600 and 8250
feet above the mean height of the range, and Mont'Blanc rears its termi-
nal point to an elevation of more than 15,700 feet. The mountains of the
Pyrenees more generally assume the form of mere cones rising from the
upheaved base. Some mountains, too, of considerable geological impor-
tance—as Néouvielle, and the mountains of 00 and Clarabide—are scarce-
ly to be distinguished by their vertical outline from the heights which
surround them. Peaks which are plainly disconnected from the rest of
the chain—such as the Canigou, Mont Vallier, the Pie de Tabe, the Pie du
Midi at Pan, and the Maladetta—are not very numerous.
In consequence of the simplicity of conﬁguration which prevails in the ‘
Ar \ Portdc Hal-cachet;


Pyreneau chain, we ﬁnd in these mountains but few of those longitudinal
valleys rising up to the right and left toward two parallel ranges of peaks,
and pushing their arms of verdure into all the gorges and even to the mo-
raines of the glaciers. In these mountains we see nothing but valleys
which cross the axis. of the ridge, and are steeply inclined down toward
the plain. The passes where the incipient ravines of these valleys take
their rise are often mere plateaux on the summit of the ridge, or else dark
gorges hollowed out in the rock by the long-protracted labor of various
atmospheric agencies. These passes are also more elevated on the aver.-
age than those of the Central Alps. It is therefore easy to understand
why it is that, among all the natural ramparts in Europe, the Central Pyr-
enees have always been the most insurmountable barrier of nations. Be-
tween the Col de la Perche, near M ontlouis, and the port of Maya, not far
from Bayonne, a distance of more than 180 miles, the chain of the Pyre-
nees is not crossed by any carriage-road.
* Humboldt.
Q
144 I THE EARTH
CHAPTER XXIV.
MOUNTAINS OF CENTRAL EUROPE.—CONTRAST BETWEEN THE ALPS AND THE
JURA.-—-THE JURA AS A TYPE OF A SYSTEM OF MOUNTAINS WITH PARAL-
LEL CHAINS.—-APPARENT CHAOS OF THE ALPSr—CENTRAL GROUP OF ST.
GOTHARD.—-GROUPS OF MONTE ROSA AND MONT BLANC.—THE ALPS CON-
SIDERED AS A FRONTIER.
THE great system of mountains which forms, as it were, the back-bone
of Europe, and the ramiﬁcations of which, like the limbs of a body, deter-
mine the very shape of the continent itself, is very different from the Pyr-
enees in the. richness and variety of its conﬁguration, the intersection of
its ridges, the ‘number of its more isolated groups, and its frame-work of
secondary chains. To the vertical outline and distribution of the Alps—
the glaciers of which supply, while they moderate, the water-courses of
Western Europe—the nations which inhabit the latter country owe indi-
rectly much of their vitality and civilization. Standing up like the bas-
tions of a fortiﬁcation, the chief Alpine groups form a protection to the
brave Swiss people. On the south, the ensemble of all the mountain groups
sweeps in a vast semicircle roundNorthern Italy, and is linked on to the
chain of the Apennines, which constitute the back-bone of the peninsula;
on the west, the spurs of the Alps form the most prominent feature of the
French territory, and by their transverse chains modify the relief of the
J ura; on the north, the gradation of plateaux, which abut on the moun-
tains of Switzerland, descend as far as the lanrles of Prussia ; ﬁnally, to the
east, the Carnic Alps extend into Bosnia and Servia in calcareous ranges
and plateaux, which are divided only by the Danube from the Transylva-
nian citadel of the Carpathians, and, through the Balkhans and the Pindus
Mountains, radiate out tothe shores of the Black Sea and the ZEgean.
The singular beauty of the Alps is still further enhanced by the contrast
which they present to the mountains which surround them. The contrast
is especially remarkable between the groups of the Central Alps and the
ramparts of the J ura which form the western boundary of the natural
territory of Switzerland. The chains of the J ura, more unpretending in
height in comparison with those of the Alps, are nevertheless very curious
in a geological point of view, and must be looked upon as the best type
of one particular formation of mountains—that of long parallel ridges.
Carniola, Herzegovina, and Bosnia also possess chains arranged in a simi-
lar manner. a In America, too, we might point out the Ozark Mountains,
andespeciallythe Alleghanies, which extend over a still more considera-i
ble area than the J ura, but they have been much less studied. They are,
besides, connected on both sides with granitic mountains; and the princi--
THE JURA AND THE ALPS. 145
pal mass of the system, which is often compared to long waves of the sea,
is complicated with numerous irregularities.


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The European Jura occupies a very considerable area in the middle of
the continent, from the banks of the Dreme to the mountains of Bohemi‘
The central portion of this immense tract of land is all that is commonly
understood under the name of J ura; for the more extreme points are very
variously inﬂected and intersected by masses of distinct formations. Thus,
in Savoy, the Mole and other peaks stand at the angles where the walls
of the Jura intersect the Alpine chains. The J ura, properly so called, ex-
tends from the southwest to the northeast, from the valley of the Rhone
to that of the Rhine, presenting a slight convexity toward France. It
consists of parallel and almost uniform ranges, which rise in successive
gradations, tending from the west to the east. These ranges are like so
many walls, with sloping declivities on one side, and terminating on the
other in abrupt escarpments. Intermediatev valleys separate these pawl.
K
146 THE EARTH.
'lel walls, the most eastward of which is by far the most elevated‘, and com-
mands, in all its height, the plains of Switzerland. Hollows or combes,
in the form of an amphitheatre, open out in the thickness of the J ura ram-
parts, and here and there cluses, or transverse deﬁles, enlivened by tor-
rents, out right through the chains and divide them into isolated frag-
ments. These fragmentary plateaux, which, in their extensions, follow
uniformly the same direction, have been often compared to those species
of caterpillars which creep along the ground in long processions. If we
take no notice of the cluses which divide the walls of the J ura into so
many bits, we may more poetically compare these mountains to the rip-
ples produced by throwing a stone upon some liquid surface.
The elongated brows of Mont Tendre, of Mont Noir, and the Weissen-
stein form magniﬁcent observatories, from which one can study at ease
the marked contrast between the J ura and the groups of the Oberland,
bristling with its pointed-summits, to the east of the Bernese depression.
At ﬁrst sight, these mountains seem to form a veritable chaos; but this
chaos appears much greater still when seen from one of the lofty summits
of the Alps themselves. WVe then perceive, round the whole line of the
horizon, points, pinnacles, and ridges, thrown together as if bychance, and
almost innumerable; they might well be called the congealed waves of
an immense‘ ocean. Very different from the J ura, the general formation
of which is so striking in its regularity, the Alps appear to be nothing but
a dreadful accumulation of disorder, and only a long course of study or
personal survey will enable any one to become acquainted with the gen-
,eral arrangement of their ridges. It may thcﬁ'iJc “Ijen that the ensemble
of these mountains is formed by separate groups throwing out branches
in every direction, like the rays of a star. Whilst the Jura, and the sys-
tems of mountains belonging to the same type, are composed of parallel
chains, the Alps are constituted by the juxtaposition of many groups with
divergent chains radiating from them.
M. Desor, taking as the basis of his classiﬁcation‘ of the Alps the various
nuclei of granite and protogene which have pierced through the more re-
cent rocks, has come to the conclusion that the Alpine system is composed
of ﬁfty distinct groups. This entirely geological division harmonizes in
neral with the results of a mere study of the vertical outline and direc-
tlon of the ridges; but the number of groups must be considerably re-
duced if those which are linked to one another by continuous ridges of
great elevation are looked upon as forming parts of the same chain.
The central mass, which is also the most important in a geographical
point of view, is that of the St. Gothard, situated between Switzerland and
Italy, at the summit-level of the -waters of the Rhine, the Tessin, the
Rhone, the Aar, and the Reuss; it is the knot or focus where the conver-
gent ridges of the surrounding groups unite like radii. On the northeast
stands the group of Todi; on the cast, that of Rheinwald; on the west
and south, the much more considerable clusters of the Finsteraarhorn and
Monte Rosa. The latter group is linked on to Mont Blanc, rising more to
THE J [IRA AND THE ALPS. 147

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the west; but at this point the Alpine system changes its direction, and,
as 'a whole, bends round toward the south. The two ﬁrst of the more im-
portant groups which rise on this side are those of the Grand Paradis,
commanding the plains of Piedmont, and that of the Vanoise and Grande
Casse, dividing the Tarentese and Maurian valleys. A real chain bends
round to the south, which is crossed by the Mont Cenis road ; the wind-
ing ridges of these chains go on to join the groups of the Grandes Rous-
ses and Belledonne on the west, that of the Grand Pelvoux on the south.-
west, and that of Monte Viso toward the south. The pyramid of Monte
Viso is the magniﬁcent boundary-stone which marks out the line of de-
markation between the Alps of Dauphiny and the Maritime Alps; it is
also the last mountain in the chain the height of which exceeds 11,500
feet. Beyond this point, the terminal branches of France and Italy, spread
out like the leaves of a fan, gradually sink down toward the sea. To the
north of Nice and Mentone, a small granite group rises to a height of more
148 THE EARTH
than 9900 feet, and two of its highest summits, the Gelas and the Clapier
de Pagarin, have small glaciers on their northern slopes. At this point
the great curve of the Western Alps comes to a termination, and the in-
termediate chain commences which unites the former to the ridge of the
Apennines. '
The Eastern Alps, situated to the east of the St. Gothard, also assume a
similar arrangement in groups. On the northeast of the Todi stands the
Santis ; to the east of the Rheinwald are the groups of the Bernina, Sil-
vretta, and the Ortelspitze; then follow, tending from west to east, the
groups of the Oetzthal, the Stubaier, the Gross-Glockner, and the moun-
tains of Hallstadt, beyond which the Alps proper lose their primary im-
portance. The summits of all these groups are more than 9900 feet in
height, and are clad with snow; like the western chains, they well de-
serve the name of Alps (white) which the Celts gave to these mountains.
Most of these Alpine groups exhibit a singular diversity of aspect, in
all the various details of their relief. There is meature in this mighty
architecture which is devoid of its own special characteristics of beauty,
and also there is no beauty which is not, by some unlocked-for contrast,
individualized in each mountain.
In the ﬁrst place, the central group of the St. Gothard, the knot from
which radiate all the principal chains, is not very lofty, and is, in fact, of
an altogether secondary class in comparison with the other Alpine groups.
It is a quadrilateral mass, surrounded on all sides by deep valleys and the
wide depressions of several passes—on the west the Furka, on the north
the Oberalp, on the east the Lukmanier, on the south the Nufenen, and is
crowned by summits, the mean height of which attains 9678 feet; the most
important, the Piz Rotondo, not exceeding 10,488 feet in altitude. It is
probable that, during the long' course of ages, the upper waters of the
Rhine, the Rhone, the Reuss, the Tessin, and the Toccia have had the ef-
fect of lowering the mountains of St. Gothard somewhat below the sur-
rounding summits.
Another anomaly in the Alpine system is the fact that the mean eleva-
tion of the snowy groups which rise east and west of the St. Gothard is
not in direct proportion to the heights of their crowning summits. In fact,
the true citadel of the Alps—that which, by the form of its mountains, the
number of its peaks, and the importance of its glaciers, deserves more than
any other the title of the culminating group—is the mighty bastioned
rampart of Monte Rosa, the mean height of which is not less than 13,457
feet. The supreme diadem of this association of mountains is at a height
of 15,216 feet, while Mont Blanc rises to 15,780 feet; but the group of
summits which surround this highest point of Europe is only 12,657 feet
in mean altitude, 800 feet less than the heights of Monte Rosa. Next fol-
low in order of elevation the groups of the Jungfrau, 12,312 feet; the Ber-
nina, 11,345 feet; the Grison Alps, 10,583 feet, and the Todi, 10,311 feet.
Taken as a whole, the various groups of the central Alps decrease in height
from west to east, and from south to north; their southern slope is uni-

9
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'IAP I’LI; '/ BFu CHERS. NEW YORK


STRUCTURE OF THE ALPS. 14:9
formly more abrupt than the northern declivities, which descend in long
branches toward the valleys of the Rhone and the Rhine.*
Considered in their ensemble, the Alps, like most mountains, serve as
chains, ethnological frontiers, on one side to the French and Germans, and
on the other to the inhabitants of Italy. The district of the Grisons, one
of the most inaccessible of all the Alpine regions, which by the labyrinth
of its ﬁve hundred valleys has been converted into the central citadel of
Europe, served as a refuge to the Rhetian peoples, who still speak, though
in a corrupted form, the language of their ancestors—the contemporaries
of the citizens of ancient Rome. The Alps, however, owing to their di-
visions into numerous groups and to the comparative lowness of their
passes, do not constitute an insurmountable barrier like the chain of the
Pyrenees. On the mountains and in the valleys of Switzerland, men be-
longing to three races—German, French, and Italian—are confederated so
Nordende 15082‘
_ nudism Spitze 1522:
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as to form a nation of brethren. German colonies, surrounded on all sides
by a Latin population, have established themselves on the mountain sides
facing the north; for instance, in the Viége valley and in the Sette Oom-
mum' in the environs of Bassano. Added to this, men of the Latin race
have colonized the southern slopes of the groups inhabited principally by
Germans ; ﬁnally, the ancient Allobroges, all alike. nowadays speaking
more or less impure French, inhabit the two sides of the Alps of Savoy
and Dauphiny. While, in the Pyrenees, the ridge of the mountains dis—
tinctly separates the two nations of France and Spain, it is, on the con-
trary, the bases of the Piedmontese mountains which serve as frontiers, if
not political, at least ethnographical, between two races. The valleys of
the Italian side, traversed by the streams of the two Doires, the Cluson,
the Pellis, and the Stura, have a population of the same stock as the val-
leys of Maurienne, Queyras, and Durance. Besides, as Ami Boué, the ge-
ologist, long ago pointed out, longitudinal chains are those which form
the least separation between peoples, owing to the resemblance of the cli-
* William Huber, Bulletin de la Société de Ge'ograplzie, February, March, 1866.
150 A THE EARTH
mate on the twoislopes; transversal chains, like the Pyrenees, are always
the frontiers which are the most diﬂicult to cross.
. For all the interchanges of commerce, as well as for the mutual inter-
course of peoples, the Alpine groups are also much more happily arranged
than the regular chain of the Pyrenees; and the traﬂic between the two
opposite sides has always assumed a very considerable importance. Twelve
carriage roads, some of which may be reckoned among the chefs cl’oeuvre
of-human industry, cross the ridges of the ‘Alps, and form the means of
communication between France, Switzerland, and Germany; a railway
also, now some years ﬁnished, passes to the east of the Greater Alps
through the Soemmering chain. Finally, four other railway lines are
gradually pushing their way into the depths of the lofty central moun-
tains, and, ere long, free communication will be established under the
rocks and glaciers, and we shall be able to make the beast that we have
leveled the Alps.
MOUNTAINS OF CENTRAL ASIA. 151
0
CHAPTER xxv.
MOUNTAIN CHAINS OF CENTRAL ASIA.—THE KOUEN-LUN, THE KARAKORUM,
THE IIIMALAYA.——THE SOUTH AMERICAN ANDES, A TYPE OF THE BIFUR‘
CATED CHAIN.
THE chains of the Himalaya, the Karakorum, and the Kouen-Lun ﬁll
the same position in the continent of Asia as that occupied by the Alps in
Europe. These three ranges of mountains have a common origin in the
plateau of Pamir—the “Roof of the World”—-from which also radiate to-
ward the north and west the ranges of the Bolor and the Hindoo-Kuch.
The triple rampart of Upper Asia is not less than 1550 miles in linear de-
velopment, and its breadth, including that of the plateaux and intermedi-
ate valleys, is toward the cast, that is, toward Sikkim, about 620 miles.
In each of the three chains the mean altitude of the summits exceeds that
of any other ridge of mountains in the rest of the world; this spot is, in
fact, the culminating point of the earth. Between the two extreme sides
the contrast is most decided. On the north, cold and arid steppes stretch
away over an immense extent; on the south lie spread out the burning
and wonderfully fertile plains which are watered by the Gauges and its
tributaries. The rocky and snowy ridges which tower up between the
two regions form an ethnological barrier more mighty than the ocean it-
self; they divide races of men and great systems of religion. There are
but very few points at which the Buddhist Mogols—thanks to the great-
er facilities which were afforded ‘them, by their residence on the high
plateaux, for crossing the mountains—have made their way down into the
southern valleys of the Himalaya.*
The northern chain, that of the Kouen-Lun, is very little known, and it
cannot as yet'be stated positively whether it may not contain some sum-
mits more elevated even than those of the Himalaya. It is, however,
probable, from the information that has been acquired by travelers as to
various points, that the ridge of the Kouen-Lun is the least lofty of the
three. The Karakorum, which is the middle rampart, is also that ‘of
which the mean height. is the‘most considerable; and in‘ its gorges the _
Indus andthe Brahmapootra take their rise. At‘ its base lies the valley
of Cashmere, which the Oriental posts celebrate aslthe “ abode 'of happi-
ness ;” its lovely blue lakes, surrounded with'g'ardens, reﬂectthe snowy
peaks of ﬁfteen or eighteen thousand feet in height. " The torrents which
ﬂow from both sides of the mountains cross the parallel chains through
prodigious deﬁles, which in some places reach a depth of thousands of
feet. ‘ i ' ' '
* F reres Schlagintweit, llfz'ttheilungen ron Petermannf
152 _ THE EARTH.

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The Himalaya, the best known of the three chains, has, however, been
but slightly explored in comparison with the European Alps. It is pro-
tected against all the attempts of explorers by the want of roads and even
paths; by its impetuously-rushing streams, entirely unbridged; by the
inaccessible forests of its slopes; by its formidable cliffs, and the height
of its lofty summits, piercing through the clouds into the attenuated air,
where man canscarcely draw his breath. On the face of the mountains
a zone of variable width extends, like a barrier of death. This is the Te-
ra'i, the unwholesome dampness of which, fostered by the rains of the men-
soons and the water descending from the Himalaya, steams in the sun in
long-drawn out mists, creeping over the trees, and spreads, far and wide,
fevers and pestilence. Finally, several of the mountain districts still be-
long to native sovereigns, who oppose, either by force or stratagem, any
advance of Europeantravelers. It is not many years ago that observers
were ﬁrst able to measure the highest mountain in the chain, and proba-
bly in the whole world. . This is the Gaurisankar, or Tchingo-Pamari, the
summit of which rises to a height of 29,002 feet, nearly twice the eleva-
tion of Mont Blanc. In the same range, up to the present time, two hun-
THE HIMALA YAS.—THE ANDES. 153
dred and sixteen summits have been measifred, seventeen of which exceed
24,600 feet in. altitude; forty are about 23,000 feet, and a hundred and
twenty more than 20,000 feet high. Next to the Gaurisankar, the high-
est known mountain is the Dapsang (283297 feet), in the Karakorum.
The great peaks of the Himalaya, contemplated from one of the head-
lands which stand out far into the plains of Hindostan, form one of the
most magniﬁcent spectacles which the eye of man can see and wonder at.
From the village of Durjeling, which the English have built upon a ter-
race more than 6000 feet above the level of the sea, in order to enjoy a
cold and bracing air like that of their native country, may be seen rising,
in all its formidable majesty, the colossus of Kinchinjinga, nearly ﬁve miles
high. At its base, as if in thebed of a gulf of verdure, a white torrent
of foam glitters through the palm-trees; higher up, a chaos of wooded
mountains, like the waves of a monstrous sea, are crowded and piled one
over the other round the great ‘tranquil'summit; above the multitude of
‘secondary peaks rise the long slopes of the mountain, ﬁrst tinged with an
aerial blue softer than that of the sky, then with a bright white, sparkling
like silver. From one snowy ridge to another, the eye rises at last to the
culminating point, from which the bold climber, ‘if he ever reaches it, might
see stretched out at his feet a prospect as extensive as that of the whole
of France.* '
Spectacles as grand as that of the Kinchinjinga, seen from Durjeling,
are numerous enough in the Himalaya, especially in the eastern-portion
of the chain, where the summits attain their principal elevation, and-‘where
the deﬁles of the valleys are most deeply hollowed out. But, although
these mighty mountains of Upper Asia are more majestic than the Euro-
pean Alps, they do not generally present an equal variety of aspect, an
equal grace of outline, or charm of landscape. In all its grandeur, the
Himalaya is uniform; its peaks are loftier, its snows more extensive, its
forests deeper; but there are fewer cascades and lakes; there are no pleas-
ant lawns and scattered groves; and we fail to notice the picturesque
chdlets nestling down in the glens or hanging over the brink of the preci-
pices.
The South American Andes, which in 1824—that is, before the discov-
eries of Webb and Moercroft—were looked upon as superior in elevation
to the Himalaya, are, in fact, 6600 feet lower in mean height. In sublim-
ity they are exceeded by the Asiatic mountains, in ‘variety of site by the
European Alps; but they are distinguished, especially in the volcanic 're-
gions, by regularity of form. Added to this, they constitute a chain which,
in a geographical point of view, is really unique, on account of the har-
mony which they exhibit with the continent which they crown with their
snowy ridges. This long range of mountains, so remarkable by its enor-
mous length (about 4350 miles), and by the great height which its peaks
maintain, over a space of about 50 degrees of longitude, is, however, less
regular than it appears at ﬁrst sight. The principal characteristic which
* Hooker, Himalayan Journal.
154 THE EARTH
distinguishes the Andes from‘every other mountain system is'found‘i‘n
the numerous forks, or rather bipartitions, of the Cordillera. In that part
only of their extent whichstretches from the frontiers of Chili to those
of Venezuela, the Andes divide eight times, forming large inclosures, each
containing a plateau between the two lines of peaks. At some points, in-
deed, the Andes separate in three scarcely divergent branches. '
Fromthe southern point of America, as far as the other side of Acon-
cagua (22,420 fe'et)—the giant of the Chilian Andes—the principal chain
throws out to the cast but very unimportant groups. There are only
some low ridges running above the Pampas parallel to the principal ridge.
About the 30th degree of latitude these uplands augment in number and
height, and then form a vast plateau, from which, in a northeasterly direc-
tion, branchesoff the great sierra of Aconquija. Other storms rise on the
enormous mass of the plateau between the mountains of Aconquija and
the great fork of the Bolivian Cordillera, in the 22d degree of latitude.
The western range, composedof broad domes of a regular shape, ap-
proaches the shore of the Paciﬁc, while the eastern chain, throwing out
several important branches into the-eastern plains, curves round the great
plateau of Bolivia, with its-long, row of serrated and snowy peaks, among
which towers the Illampu or Sorata (24,812 feet), the. highest mountain
in America. North of the lake of Titicaca the two chains are united by
a transverse rampart, but they continue to extend in a northwest direc-
tion parallel to the coast. Although-the eastern Cordillera is pierced in
a great many points by rivers which are tributaries of the Amazon, it can
still easily be recognized by the general direction of the fragments which
compose , it. ~ - -
_ At the knot of Cerro de Pasco the two Cordilleras again unite, but only
to divide again immediately into three chains, one of which, tending to
the northeast, merges in the Pampa del Sacramento, while the two oth-
.ers, inclosing between them the deep valley of the Maraiion, unite at the
extreme angle near the southern frontiers of Ecuador. More to the
north, we have several small plateaux covered with virgin forests ;' then,
on the other side of Loja, the two Cordilleras again separate their two
parallel ridges'of snow-clad ‘summits; ‘ Here,'too, lies the magniﬁcent ter-
race of Ecuador, divided- into three distinct plainstby the cross groups ‘of
Assuay andChisincha. ,Two of these plains, those of Tapia and Quito,
form the magniﬁcent avenues of volcanoes rendered celebrated by La
.Condamine, Bouguer, Humboldt, and other learned ‘travelers. On one side
rise Chimborazo, Carahuirazo, Illinissa, Corazon, and Pichincha; on the
other, Sangay, the ,most formidable volcano in the world, Tunguragua,
Cotopaxi, Antisana, and Cayamba, which crosses the line of the equator.*
North of theequator, the two chains unite in forming the group of the
Pasto plateau, which stretches nearly up to the second degree of latitude.
At‘this spot vcommence three distinct Cordilleras, which are not destined
again» to unite into another knot of mountains. The western Cordillera
1‘ Ville thechapter on “ Volcanoes.”
TH E ANDES. ’ 1 5 5
disappears close to the Gulf of Darien, between the valleys of the Atrato
and Cauca. The central Cordillera, on which rise the mighty summits of
Puracé, Huila, Tolima, and Herveo, divides the Cauca basin from that of
the Magdalena; lastly, the eastern Cordillera, or "the Suma-Paz (supreme
peace), bending round to the west of the plateau of Bogota, forks out into
two chains near Pamplona, one ‘of which terminates in the vicinity of
Maracaibo, under the name of the Sierra Negra, while the other, variously
ramiﬁed, bounds on the north the llanos of Venezuela, and, forming the
proud Silla of Caraccas, runs along the sea-coast, and pushes ‘out as a
promontory to the Bouche du Dragon, which separates it from the moun-
tains of the island of Trinidad. This point forms the termination of the
chain of the Andes. The immense, and spirally inﬂected’ extent of the
Cordillera has for its culminating summits three peaks—Chimborazo, So-
rata, and ‘Aconcagua—placed about 1240 miles aparton the mighty ridge;
but the summits which are higher than Mont Blanc may be reckoned by
hundreds. This enormous mountain chain seems to form so intimate a
part of the very construction of the continent, that numbers of the inhab-
itants of its plateau and slopes‘ look upon it as the back-bone of the whole
world; they can not fancy any country which is not commanded by the
Cordillera of the Andes.*
* Jules Remy, Nouvelles Annales des Voyages, February, 1865. ‘c .
156 THE EARTH
CHAPTER XXVI.
GRADUAL COOLING OF THE AIR ON MOUNTAIN SIDES.-—DIFFICULTY OF AS-
CENTS. “LIMITS OF MAN’S HABITATION.—-ILLNESS FELT BY MOUNTAIN
TRAVELERS.
BY uplifting their summits into the higher regions of the atmosphere,
mountains penetrate through zones of ever-increasing cold, and, owing to
this gradation of successive temperatures, nature assumes a marvelous va-
riety of climates and ﬁoras.* The sides of every lofty mountain present
a kind of epitome of all the phenomena which are exhibited in the im-
mense space comprehended between the plains at'its foot and the icy re-
gions of the pole.
The solar rays have actually more heating power on the soil of moun-
tains than in the plains, as is shown by direct observation, and also by the
marvelous colors of the sweet-smelling Alpine ﬂowers;1' therefore the
gradual cooling of the temperature on mountain slopes must be attributed
to the rarefaction of the successive layers of air. The investigations and
experiments of natural philosophers have proved that the air affords a
much easier passage to luminous than to dark radiations. The result of
this fact is that the‘heat poured down by the sun during the daytime
readily traverses the whole depth of the atmosphere in its way to warm
the surface of the planet, while the heat radiated from the ground during
the night can only escape into space in very small quantities. The lower
layers of the atmosphere thus act as complete screens in arresting the ra-
diatiomfrom the surface of the earth, and preventing the cooling of the
planet. By this very fact, however, slopes and summits of mountains are,
‘in proportion to their elevation, the more easily deprived of the heat which
warms the plains at their base, and they mount into tracts of air which
are the more chilled in proportion as they are vertically distant from the
denser atmospheric layers lying below.I Thanks to this progressive dimi-
nution of temperature in the aerial waves which bathe them, mountains,
already so beautiful in their outline and the majesty of their forms, add
to the magniﬁcence of their appearance by the contrast between their
forests and their glaciers, their pasture-lands and their snows.
What, then, on the average, is the proportion according to which the
temperature falls in ascending from the base to the summit of a menu-
tain ‘.P It is a ditﬁcult matter to settle it exactly, for aerial currents of va-
rious temperatures lie one above the other in the heights of the atmos-"‘
* Vide the chapter on “ The Earth and its Flora.” .
1' Ch. Martins. Helmholz, La Glace et les Glaciers.
I Tyndall, The Glaciers of the Alps.
LIAIITS OF MAN’S HABI TA TI ON.
phere, and sometimes we may rise from a comparatively cold zone to one
that is much warmer, as some of the aeronautic expeditions of Mr. Glaisher
have strikingly proved. Nevertheless, when the sky is clear and the air
is calm, the decrease of .the temperature takes place with a regularity
which is suﬂiciently certain to enable us to, calculate the law respecting
it, at least approximately. Just above the surface of the ground, an ele-
vation of 143 feet corresponds, on the average, to a fall of one degree
Fahrenheit; at the height of about 3000 feet, it ‘takes an increase‘ of height
of 294 feet to effect a diminution of heat amounting to one degree Fahr-
enheit ; and in proportion as we mount higher and higher, the interval in-
creases, so that at about 30,000 feet of elevation the temperature sinks
only one degree Fahrenheit for every space of 1055 feet.* The real rate
of the decrease of heat can not be so easily ascertained on the slopes of
mountains, on account of the inﬂuence of the ground and the ice. But we
may state generally that on the Swiss mountains the temperature of sum-
mer decreases one degree Fahrenheit for every vertical space of 290 feet;
in winter the same fall of temperature takes place for every 439 feet of
increased height]t _ ‘
The extreme cold of very lofty mountains renders them completely un-
inhabitable for man. No traveler has ever set his foot on the mighty
summits of the Karakorum and the Himalaya. The principal summits of
the Andes—Sorata and Aconcagua—are equally inviolate; and even
among the more unpretending summits of the Alps there are still a con-
siderable number on which, up to the present time, the snows and the gla-
ciers have formed a sufﬁcient barrier against any attempted ascents. The
highest point that the mountain climber has yet attained is the summit
of Ibi-Gamin, a mountain of Thibet, which rises 22,079 feet above the level
of the sea. Even at this considerable height the brothers Schlagintweit,
who accomplished this exploit in 1856, still found themselves more than
6500 feet below the culminating point of Gaurisankar. Since this date,
Mr. Glaisher’s balloon has reached an elevation of more than 13,000 feet
higher in the cold atmosphere of Great Britain. ‘
In all mountainous regions the permanent habitations of man cease at a
limit far below the most elevated points reached by the bold mountain
climber. St. Veran and Gurgl, the most highly-placed villages of France
and Germany, are situated at the respective altitudes of 6591 and 6197
feet; but in Switzerland the Hospice of St. Bernard, built many centuries
ago to shelter travelers when benumbed with the cold, is much more ele-
vated—its height is 8110 feet. There is another-conventfthat of Hanle,
inhabited by twenty Thibetian priests, which is the most elevated cluster
of houses in the whole world; it is situated at a height of 14,976 feet.1
None of the villages of the’ Andes, except perhaps that of Santa-Anna, in
Bolivia, have been built at so great a height.§ "
* Zurcher,Annuaire Scientzlﬁque,1864. 1' Helmholz, La Glace et les Glaciers.
1 Robert de Schlagintweit,Mittlzeilungen von Peternzann, 1865.
§ Reck, Geographisclzes Jalzrbulc von Belzm.
158 THE EARTH.
Travelers who venture to ascend the slopes of a lofty mountain not
only have to suffer all the rigors of cold and run the risk of being frozen
on their route, but they may also experience most painful sensations, ow-
ing to the rarefaction of the air. It is, in fact, very natural that, at an
elevation at which the pressure of the atmosphere is reduced to one half
or -even to one fourth that of the plains below, a certain uneasiness should
be caused by the sudden change, and the more so that some of the other
surrounding conditions, such as the calorie and the humidity of the air,
also become modiﬁed. Undaunted climbers like Tyndall, who have never
felt in their own persons the effect of this mal de montagne, expressly
deny that this exhaustion proceeds from any thing else than mere fatigue.
M. Jules Remy, too, has noticed only one mountain of the Andes on which
the phenomena of the puma or soroche are always developed in the organ-
ism of living beings; this is the Cerro de Pasco, the height of which does
not exceed 13,966 feet. Horses, mules, asses, and oxen are also, like man,
subject to the peculiar inﬂuence of these localities, while at much more
considerable altitudes the usual state of health suddenly returns. There-
fore, in this region of the Andes, emanations from the ground, and not the
rarefaction of the air, are the cause to which we must attribute the incon-
venience felt by travelers.* However, the investigations made on the sub- .
ject by Robert de SchlagintweityL can leave no doubt in our minds that
this mountain ailment is really felt generally, in other regions of the An-
des as well as on the Cerro de Pasco. Usually, indeed, the effects of the
soroclze are felt at a much lower elevation on the slopes of the Cordilleras
than on those of the Himalaya. In the latter mountains the traveler does
not begin to suﬁ'er from the attacks of this ailment until he has reached a
height of 16,500 feet, while on the Andes a large number of persons are
affected by it at an altitude of 10,700 and 11,500 feet. Added to this, in
the South American mountains the symptoms are much more serious; to
the fatigue, headache, and want of breath, which are likewise experienced
on the Himalaya, are added giddiness, sometimes fainting-ﬁts, and bleed-
ing from lips, gums, and eyelidsi At the same elevation as the paramos
of the Andes, or even as the lofty summits of the Himalaya, the aaronaut
——who, however, is spared all the fatigue of climbing—rarely suffers any
inconvenience ; but at 30,000 to 40,000 feet the malady shows itself, and,
if the balloon continued to rise, the aerial voyager would infallibly perish.
Therefore, at but a very few miles above our heads lies the region of
death, and into this terrible zone the loftiest mountains of the earth ele-
vate their White summits.
* Ascension du Pichincha, Nouvelles Annales des Voyages, etc., February, 1865.
‘l Zeitschr. f iir Erdlcunde, 1866. I Humboldt, Poeppig, Moritz Wagner, Philippi.
S UBSIDENCE OF MO U NTAINS. 1 5 9
CHAPTER XXVII.
GRADUAL SUBSIDENCE OF MOUNTAINS DURING THE LAPSE OF AGES—SUD-
DEN DOWNFALLS AND CHAOS.-—THE FALL AT FELSBERG.—-SLOW ACTION
OF METEORIC AGENCIES.
TIIE formidable mountain citadels which ‘tower up so high over the
habitations of man, along the sides of which creep clouds and thunder,
do not, however, escape a slow but certain process of sinking so soon as
the upheaving force which pushed them out of the earth has ceased to
act. Assisted by the force of gravity which is constantly tending to level
the surface of the ground, meteoric agents are unceasingly persistent in
the destruction of mountains. They open valleys and gorges, they hol-
low out passes, they undermine their summits, either by sudden down-
falls, or, more generally, by a slow and continuous erosion. Sooner or
later, the Andes and the Himalaya, those mighty continental ridges, will
become mere ranges of hills, like many another ancient mountain chain,
which, too, once formed the back-bone of a world.
Great mountain downfalls, although of no very great impogtiance in a
geological point of view, are among the most tremendous phenomena of
planetary vitality: whenever such a catastrophe has occurred, tradition
has handed down the recollections of it for long centuries. No event is
calculated to produce a more forcible effect in the popular mind. Per-
pendicular or overhanging rocks, which seem to hang suspended over the
plains, suddenly become detached and rush headlong down the mountain
side; in their rapid fall they raise a cloud of dust like the ashes vomited
forth by a volcano; a horrible darkness is spread over the once pleasant
valley; and the eataclysm is known only by the trembling of the ground
and the crushing din of the rocks striking together and shattering one an-
other in pieces. When the cloud of dust is cleared away, nothing but
heaps of stones and rubbish are to be seen where pastures and cultivated
land once were; the stream ﬂowing down the valley is obstructed in its
course and changed into a muddy lake; the rampart of rocks has lost its
old form, and on its sides, from which some debris are still crumbling
down, the sharpened edges point out the denuded cliff from which a whole
quarter of the mountain has broken away. In the Pyrenees, Alps, and
other important chains, there are but few valleys where we may not no-
tice these chaos-like heaps of fallen rocks. ’
The principal catastrophes of this kind which have taken place in the
mountains of Europe during the present era are facts which are well
known. Southward of Plaisancé, in Italy, the'- ancient Roman town of
Velleja was buried about the fourth century by the downfall of the only
too-well-named mountain of Rovinazzo, and the large quantity of bones
and coins that have been found proves that the subsidence of the rocks
was so sudden that it did not even afford the inhabitants any chance of
160 THE EARTH
escape. Tauretunum, another Roman town, situated, it is said, on the
banks of the Lake of Geneva, at the base of one of the spurs of the Dent
d’Oche, was completely crushed in AD. 563 by a downfall of rocks; the
declivity that it formed may still be seen advancing like a headland into
the waters of the lake, which at this spot is not less than 520 feet deep.
A terrible ﬂood-wave, produced by the deluge of stones, invaded the op-
posite shores of the lake, and swept away all the habitations—from Merges
to Vevay every town and every village on the banks was demolished;
and they did not commence to rebuild them until the following century.
Geneva itself was in part covered by the water, and the bridge over the
Rhone was swept away. According to MM. Troyon and Merlot, howev-
or, these disasters were caused by a landslip which fell from the Gram-
mont or Derochiaz across the valley of the Rhone, just above the spot
where it ﬂows into the Lake of Geneva. The eﬁ'ect of this was the for-
mation of a temporary lake, and the shores were devastated by an inun~
dation at the time of the destruction of the natural barriers by the accu-
mulated water.*
The great downfalls of rocks which have taken place during historical
periods, in the Alps and neighboring mountains, may, in fact, be reckoned
by hundreds. In 1248, four villages situated at the base of Mont Granier,
not far from Chambéry, were buried under a mass -of calcareous rubbish,
which the water-courses have now ravined out and moulded into little
hillocks; small pools, known by the name of abimes, are dotted about
amongst these heaps of debris, which are nowadays covered with cultiva-
tion. In 1618 the downfall of Monte Conto buried the 2400 inhabitants
of the village of Plurs, near Chiavenna. Two out of the ﬁve peaks of the
Diablerets fell down, one in 1714, and the other in 1749, covering the pas-
tures with a layer of cle'bris more than 300 feet thick, and, obstructing the
course of the stream of Lizerne, formed the three lakes of Derborence
which are now existing. In like manner, the Bernina, the Dent du Midi,
the Dent de Mayen, and the Righi have overspread with their fragments
vast tracts of cultivated land; but no catastrophe of this kind has left
more fearful reminiscences of horror than the fall of a section of the Ross-
berg on the 2d of September, 1806. This mountain, situated to the north
of the Righi, in the centre of the peninsula-like space formed by the lakes
of Zug, Egeri, and Lowerz, consists of a compact conglomerate, lying on
beds of clay, which hinder the inﬁltration of the surface water. At some
unknown epoch the falling rubbish of a mountain spur destroyed the vil-
lage of Rotten; but in 1806 the catastrophe was still more terrible. The
season which had just terminated had been very rainy, and the clay strata
had gradually changed into a muddy mass; at last, the rocks above, los-
ing their supporting basis, began to slip down the mountain side, plowing
up the ground in front of them like the b’ow of a ship pushes up the water
before it. Suddenly a general break up took place. In a moment, an
enormous mass, carrying with it forests, meadows, hamlets, and inhabit-
ants, rushed down into the plain. Flames, produced by the friction of
* Bulletin de la Sociéte' Vaudoise.
FALL OF AIO UNTAIN MASSE'S. 1 6 1
the rocks striking and rubbing against one another, broke in ﬁery- jets
from the half-opened mountain. The water deposited in the deep beds,
suddenly converted into steam, burst out with explosive force, and show-
ers of mud and stones were vomited out as from the mouth of a volcano.
The charming plains of Goldau (the Vallée d’Or), and four villages, inhab-
ited by nearly a thousand persons, disappeared under the heaps of debris ,-
the Lake of Lowerz was partly ﬁlled up; and the furious wave which the
falling mass drove up on to the banks swept awayall the houses on it.
The catastrophe occurred in so sudden a way that the very birds were
killed as they were ﬂying in the air. The portion of the mountain which
slipped down was not less than two miles and a half long, by about 350
yards wide and 35 yards thick; it was a mass containing more than ﬁfty-
four millions of cubic yards.* ' ‘

w ‘- . i
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43. Great Landslip of Goldau.
Whatever may be the geological importance of ‘these fearful mountain
downfalls, still they are but phenomena of a secondaryclass in compari-
son with the results produced by the slow and gradual action of various
atmospheric agencies—frost, air, and rains. These are the incessant and
indefatigable workers which, by their cbntinual labor, have enlarged the
ﬁrst clefts open here and there in the thickness of rocks, and have hollow-
ed out all the net-work of passes, amphi'theatres, combes, deﬁles, cluses,
glens, and valleys, the endless ramiﬁcations of ‘which add so much variety
to the mountain structure. Owing to these operations, continued with-
out intermission during the long centuries of ' geological periods, the lofti-
est summits are being gradually lowered, and the materials derived from
their slopes are spread far and wide over the plains, or home down to the
waters of the ocean.‘ ' . ' ‘ '
* Henri Zschokke. Otto Volger, Erdbeben der Scbwez'b,
L
PART III.
THE CIRCULATION OF WATER.
CHAPTER XXVIII.
SNOW-FALL ON MOUNTAINS.—LOWER LIMIT OF SN OVV.'--ZONE OF PERPET-
UAL OR PERMANENT SNOW’.
THERE are few sights more charming than that of the clouds sweeping '
in long trains over the sides of a mountain, and leaving behind them on
the slopes a covering of fresh-fallen snow. We may often notice that the
lower portion of a cloud breaks up into showers, and inundates with rain
the less elevated slopes, while higher up the colder vapors are discharged
in ﬂakes of snow. A line, which is sometimes uncertain, but is usually
pretty deﬁnitely traced across the declivity of the mountain, marks out
the limit of temperature above which the clouds fall in snow, and runs
with remarkable regularity above the verdant tracts which have been
Watered by the rain.
This lower snow-limit is traced round the mountain side at different
elevations, according to the seasons. In winter it gradually descends to
the base of the Alps and Pyrenees; in spring and summer it rises little
by little toward the summits, and even mounts above them when they
do not reach any very great elevation. For the most part, however, the
higher mountain chains have their ridges always covered with snow, and
a line may be drawn across their declivities, changing more or less in va-
rious centuries and years, above which the snow never entirely melts.
This is the so-called snow-Zine, or limit of the perpetual snow; it would be
better described as the limit of permanent snow.
Above the lower snow-line the snow is constantly being partially melt-
ed and then again renewed; thus the bed of snow-ﬂakes becomes gradu-
ally thicker and more heaped up, owing to the fall of the temperature in
these high regions. More snow, in fact, falls than the rays of the sun and
the heat of the earth can dissolve in one warm season; enormous masses,
therefore, ﬁll up all the gorges and ravines, and drifts of several yards in
depth cover these rocks and cliffs which are not too steep to allow the
snow to accumulate on their slopes. All lofty mountains are, therefore,
clad with veils of snow; but it is certain that if they rose to a still more
considerable ‘elevation into the regions of air, they would ultimately, and
indeed before long, reach a limit-line above the very snow itself. In fact,
SN 0 WFALL ON 310 UNTAINS. 1 6 3
the cold regions of the higher atmosphere contain only a very small pro-
portion of misty vapor; and the scanty ﬂakes of snow which would fall
on summits 45,000 to 60,000 feet high (if any such existed) would be soon
swept away by the wind or melted by the solar rays. On the sides of a
mountain of this elevation there would be a belt of permanent snow,
bounded on the lower side by a region of pasture-ground, and on the
upper by tracts of desert perfectly devoid of vegetation.* ‘According to
Tschudi, the quantity of snow which falls on that portion of the Alps
which is above a height of about 10,800 feet is comparatively very small.
Most of the clouds charged with snow-ﬂakes discharge their burden on
the mountain slopes at elevations of 7600 to 8600 feet. At these heights
moisture falls sometimes also in the form of rain; but at 10,000 feet the
clouds but rarely assume the shape of showers, and at 12,000 feet they
bring nothing but snow. Observations made in the Alps prove,however,
that the quantity of snow falling on different mountains varies singularly,
according to the altitude and the aspect of the slopes; and in each par-
ticular locality, according to the climatic circumstances of the year. At
the Hospice of Grimsel, situated at a height of 6148 feet, M. Agassiz no-
ticed a fall of snow in six months of winter amounting to 57% feet—equiv-
alent to ﬁve feet of water. Some years afterward, in the same place, W.
Huber, the engineer, ascertained that the thickness of the bed of snow
was 59 feet during a period of double this duration. On the St. Bernard,
at 8110 feet of altitude, the thickness of snow has varied during twelve
years (from 1847 to 1858) from 11% feet to 44;L every year. This would
give a difference of one and four in a yearly snow-fall on the same point
of the mountainf It appears that on the St. Gothard, at an elevation of
6867 feet above the level of the sea, the annual deposit of snow is more
considerable than on the St. Bernard; for in one night’s time the thick-
ness of the fallen snow was sometimes increased as much as 6% feet.I The
snow which falls on the mountain summits is but seldom composed of
those elegant shapes, the marvelous conﬁguration of which we so much
admire in the valleys. It usually consists of small granules as ﬁne as
dust, slender needles of ice, and stars with almost imperceptible ‘rays; it
is, in fact, sleet, and not snow, properly so called. It often happens that
the slightest change in the direction of the atmospheric currents substi-
tutes a fall of granular snow for one composed of ﬂakes, or produces the
reverse phenomenon. We can not, however, as Agassiz has pointed out,
establish any well-deﬁned distinction between the two different kinds of
sleety or ﬂaky snow.
It is very diﬂicult, or, indeed, impossible, to ﬁx the altitude above which
beds of snow may always be perceived on various groups of mountains.
This limit varies according to the aspect and inclination of the slopes,
the nature and color of the rocks, the force and average direction of the
winds, the quantity of the snow which falls, and all the meteorological
* Humboldt, Tyndall. ‘i Bibliotheque de Geneva.
12 Eugene Flachat, La Traverse'e des Alpes.
164 . THE EARTH.
phenomena of the region into which the summits rise. It is, therefore,
only approximately, and‘entirely in a general way, that we can venture
to point out the height of this unsettled line, ﬂuctuating, as it does, from
year to year, and from century to century, under the combined inﬂuence
of solar heat and atmospheric agencies. According to the brothers
Schlagintweit, the so-called limit of perpetual snow in the central Alps
would ﬂuctuate between 9000 and 9240 feet of altitude; and for the
group of Mont Blane, between 9400 and 10,200 feet. Nevertheless, it is
very certain that in September, 1842, a neighboring mountain to the
Jungfrau—the Ewigschneehorn, the German name of which signiﬁes peak
of eternal snows—showed nothing but the bare ground on all its slopes.*
In like manner, in 1860 and in 1862 the summits of the Alps presented
only partial stains of white snow, and tourists could cross the Strahleeh
(10,993 feet) without walking for a single instant on any snow, either
fresh or hardenedj In 1855 Sonklar could not perceive a trace of snow
on the Hangerer, a mountain in the Austrian Alps, which rises to a height
of 9994 feet]; Similarly, in the autumn of 1859, the summit of the Cha-
berton (10,295 feet), near Mont Genevre, was completely bare of snow.
With regard to the Pyrenees, in which the limit of permanent snow would
be from 9000 to 9240 feet in height, it is certain that the Montcalm, which
rises to an elevation of 10,101 feet, is topped by a kind of plateau which
is often perfectly clear of snow during the hot season, and even dotted
over with bunches of grass. On the Spanish side of the Pyrenees, toward
the middle‘ of August, nothing but the bare rock is to be seen, except in
the deep hollows which the south wind can not penetrate. The ideal
snowy zone with which geographers clothe the lofty Pyrenean peaks has,
in fact, no absolutely permanent existence. '
The same thing may be likewise aﬁirmed of a large number of mount-
ain chains that we are accustomed to class with those which are crowned
by perpetual snow. The'ideal line, therefore, which is traced 'in most
atlases as ﬁxing the limits of the snowy zone on the outline of mountains
can only be considered as having an approximate value. According to
Durocher, the line of perpetual snow, which passes at a height of 13,731
feet over the sides of the equatorial Ande's,'would be only 705 feet lower
than on the great mountains of Mexicoé—Popocatepetl and Orizaba.
There is another phenomenon which is much more surprising still: in the
southern hemisphere',"south of the Peruvian Andes, this snow-line ceases
to sink, and even rises to more than 16,500 feet of altitude. On the pla-
teaux of the Chilian and Argentine Andes, between 22 and 33 degrees of
south latitude, where the temperature naturally falls much lower than in
the corresponding regions‘ of‘Ecuador, the mean limit of snow is actually
higher; which, no doubt, isiowing to the great dryness of the winds.
Thus travelers have seen the slopes of . the Cordillera of Mendoza on the
* Desor, Nouvelles Excursions.
‘I’ Dollfuss-Aussett, Mate'riaux pour Z’Et'ude cles Glaciers, vol. v.
I @tzthaler Gebirgsgruppe.
LIJH T OF PERMANENT SNOW. 165
22d degree of latitude ‘swept perfectly clear of snow up to the height of
13,200 feet; at four degrees-farther north no white surface is .seen to
glitter on the Sierra Famatina (14,764 feet). In the Tropic of Capricorn,
the Sierra de Zenta, the summits of which rise 16,404 feet above thev
level of the sea, is but very rarely covered with snow'even during the
winter, and the layers of ﬂakes which are brought by the clouds im-
mediately melt. Lastly, according to Pentland,~the western'slopes of
the Bolivian Andes, which are very seldom blown upon by damp winds,
exhibit no instances of perpetual snow at a less height than 18,370 feet.
In a general way, any humidity that falls evaporates without giving rise
to the smallest rivulet of water, or even without moistening the ground.
Toward the middle of the day, the clouds may be seen from afar ﬂoating
up from the heights of the mountains like smoke, and disappearing at an
immense altitude in the deep azure; these are the snows of yesterday re-
ascending into the atmosphere in the form of vapor.* .
The astonishing contrast, as regards the lower snow-limit, between the
northern slopes and the southern side of the mountain chains of ‘Central
Asia, must be attributed to the unequal distribution of the rain-fall. The
climate is naturally much more rigorous on the north side of the Hima-
laya than in the valleys turned toward the south, and yet in the former
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Fig. 44. Limit of Permanent Snow in South America.
the snow-covered tracts do not descend nearly so low. This contrast is
so striking that every traveler has remarked it, and has even exaggerated
its importance, until the recent explorations of ‘ the brothers Schlagintweit.
According to Hooker, the botanist,on the southern sides of the Himalaya
the mean limit of perpetual snow exceeds,1'3,943 feet,‘ andon the opposite
slope rises to 18,589 feet of altitude ;,so vthat precisely the coldest side is
denuded of snow at a point 4646 feet higherthan thedeclivities exposed
* Martin de Moussy, Confederation Argentine, vol. i.
.166 i f ' THE’ EARTH.
to the ‘burning sun'of Hindostan. The comparative ‘observations of the
'brothers‘Schlagintweit have considerably reduced this enormous differ-
ence between the two‘ slopes. For the southern and northern slopes,
these travelers have ascertained the mean limits'to be respectively 16,049
feet and 17,237 feet, which‘ reduces the total difference to 1188 feet. But
farther on in these regions the contrast may be made more considerable,
for in Thibet many mountains, at an altitude of even more than 20,000
feet, may be seen denuded of every snowy particle. Lately, in accordance
with Humboldt, this great height of the snow-limit on the northern slopes
of the Himalaya was attributed to the reaction of the solar rays after
_ falling on the plateaux of Central Asia; but the brothers Schlagintweit,
by showing that Thibet is actually a large valley of mountains, and not a
.plateau, have put it beyond doubt that the cause of this contrast between ,
the'snowy slopes must be sought for in the system of winds. On the
north, the aerial masses which sweep over the Himalaya after having
traversed the whole of Central Asia are perfectly dried up; but on the
south, the monsoons which rush stormily through the gorges of Nepaul
and Sikkim are'charged with-an enormous burden of moisture, which falls
in snow on the high summits and in rain on the valleys beneath.
On the mountain chains which extend to the- north of the Himalaya
the mean limit of perpetual snow descends regularly as the chains lie far-
ther north. In the Karakorum, where this ideal line is higher than in the
Himalaya, on account of the great dryness of the air, the respective alti~
tudes are, in the southern chain 19,225 feet, and in the northern slope
18,438 feet; in the Kouen-Lun they are, on the south, 15,640 feet, and
14,960 feet on the north. As regards the other chains of Central Asia
no exact observations have been made, except for the Altai‘, in which the
mean limit of perpetual snow is at 7034 feet.
In ageneral way it is allowed that about the 7 5th degree of north lat-
itude the snow-limit coincides with the level of the sea; but, as Richard-
son has shown, no arctic regions have yet been discovered which in the .
height of the summer are covered with a permanent layer of snow, and
very probably none such exist.* Therefore, as regards these polar coun-
tries, as well as for most of the mountains in the temperate zones, the ex-
pression of “ perpetual snow” ought to be erased from scientiﬁc phraseol-
ogy. We must also refrain, notwithstanding the example set us by
many meteorologists, from laying down any general law in reference to
the mean limit of snow; for the atmospheric phenomena in the various
parts of the world are not yet suﬁiciently well known, and the distribu-
tion of heat, the direction‘ and humidity of the winds, vary quite as much
as the forms of the continents themselves. _
The more important point, therefore, is, not the mere recognition of the
uncertain and variable line of the lower snow-limit on mountain slopes,
but the establishment, as regards the most varied points, of the mean
quantity of snow which falls annually on the sides and summits of mount-
* Vide the chapter on “Climates.”
VARIATION IN THE SN 0 WLINE. 1
ains, these facts being derived from observations carried on season after
season and year after year. In like manner, as regards a river, neither
the low-water mark nor the point reached by the highest ﬂoods is the
fact which is the most essential to ascertain, for these levels relate but to
an instant of ﬂuviatile vitality, and their sole value is only as a means
of comparison with other such levels; the more useful questions are the
mean discharge of the ﬂow of water, and the resultant presented by the
incessant ﬂuctuations of the stream.
168 THE EARTH.
CHAPTER XXIX.
INFLUENCE OF THE SUN AND METEORIC AGENTS ON THE SN OH’. -— AVA-
LANCHES.-—PROTECTING FORESTS—DEFENSIVE \VORKS AGAINST DOVVN-
FALLS OF AVALANCHES.
THE accumulated layers of snow do not remain forever on the sides
and summits of mountains. Since every year, on the average, 33 feet of
snow fall on the mountains of the Alps, these peaks would, in fact, in the
course of a century, increase 33,000 feet in height, if the humidity falling
from the clouds in the form of snow-ﬂakes was not evaporated into the
atmosphere, or did not ﬁnd its way down into the valleys below.
The heat of the sun and meteoric inﬂuences commence the work of
clearing away the snow. It has been calculated that the solar rays will
melt as much as 20 to 28 inches of snow in a day, especially when the
upper layers are not very dense, and allow the heat to penetrate to some
depth under the surface. The rain and tepid mists which the winds con-
vey on to the mountain slopes also lend their aid in thawing the snowy
layers, and sometimes indeed with more eﬂ’ect than the rays of the sun.
The cold winds likewise assist by blowing up the snow into whirlwinds,
and thus transferring it to lower slopes where the temperature is higher.
There is not one violent wintry squall which does not remove thousands
of cubic yards of snow from the summits of lofty mountains, as may
easily be seen from below, when the peaks beaten by the wind appear to
smoke like craters, and the powdered ﬂakes are dispersed in whirlwinds.
The warm and dry winds, however, eﬁ'ect still more than storms in di-
minishing the masses of snow which lie heavy on the summits. Thus the
south wind, which is called folm by the Swiss mountaineers, will in
G
twelve hours melt or cause to evaporate a bed of snow three quarters of
a yard thick. It “eats up the snow,” as the proverb says, and brings
spring back again on the mountains. Next to the sun, the fohn is the
principal climatic agent in the Alpine districts.
It would be very important if we could establish the average propor-
tions of the masses of snow which fall upon the mountains which are lost
by melting and evaporation respectively. In valleys where the sides are
composed of hard rocks which retain the water on the surface, it would
sufﬁce to measure the annual discharge of the torrent, and to compare it
with the quantity of rain-water and snow which has fallen in the basin
during the same period, and we should approximately ascertain all that
has been lost en route, being drawn from it either by the innumerable
roots of the plants growing in it, or directly‘by evaporation. At all
events, it is certain that this latter cause of diminution is very important,
MEL TING OF MO UNTAIN SNO WS. 1 6 9
for even during calm weather, and at three or four degrees below freez-
ing-point, the superﬁcial surface of the snow constantly supplies to the
atmosphere a certain portion of aqueous vapor. Under the inﬂuence of
the sun and wind evaporation increases very rapidly.
But these slow and gradual means are not the only causes of. the dimi-
nution of the mountain snows; they also sink down in masses into the
valleys, and thus expose themselves directly to the inﬂuence of heat.
The masses which thus rush down the slopes are avalanches, likewise
called in the Alps lavcm‘r/es and c/zallanches. The greater part of these
downfalls of snow occur with great regularity, so much so that an old
mountaineer, who is clever at discerning the signs of the weather, can
often announce by a mere glance at the surface of the snow the exact
time at which the subsidence will take place. The path of the avalanche
is completely marked out on the mountain side. At the outlets of the
wide mountain amphitheatres in which the snows of winter are accumu-
lated, narrow passages open,'hollowed out in the thickness of the rock.
Like torrents, only that they appear but for a moment and are suddenly
gone, the masses of snow which are detached from the upper declivities
rush down the inclined beds afforded them by the narrow passages, and
descend in long trains, until, arrived at the ledge of their ravine, they
pour out over the slope of debris. Most mountains are furrowed over their
whole extent with vertical channels, down which the avalanches rush in
the spring. These falling masses become actual tributaries of the streams
which run below; only, instead of ﬂowing continuously as the rivulets
of the cascades, they plunge down all at once, or in a succession of falls.
On slopes where the inclination exceeds 50°, the snows not only de-
scend through the passages hollowed out here and there on the mountain
sides, but they also slide en masse over the escarpments. Their gradual
progress being more or less rapid, at ﬁrst they accumulate in heaps when
they meet with any obstacle in the less sloping portions of their track,
until, becoming animated with a suﬂicient momentum, they at last bre'ak
forth with a crash, and dash down into the depths below. The particular
way in which each avalanche descends is, of course, varied according to
the shape of the mountain. On perpendicular escarpments the snow on
the upper terraces is slowly impelled by the pressure of the masses above
it, and plunges over, straight down into the abyss below. In spring and
summer, when the white layers, softened by the heat, are falling away
every hour from the lofty summits of the Alps, the mountain climber,
standing on some adjacent headland, may contemplate with admiration
these sudden cataracts dashing down into the gorges from the heights of
the shining peaks. How many thousands of travelers, seated at their
case on the grassy banks of the Wengernalp, have witnessed with excla-
mations of pleasure the avalanches rolling down to the base of the sil-
very pyramid of the Jungfrau! First the enormous bed of snow is seen
to plunge forth like a cataract, and lose itself in the lower stages of the
mountain; whirlwinds of powdered snow, like a cloud of bright smoke,
170 THE EARTH.
rise far and wide into the atmosphere; and then, when the snow-cloud
has passed away and the whole region has again assumed its solemn
calm, the thunder of the avalanche is suddenly heard reverberating in
deep echoes in the mountain gorges, one might fancy it was the voice of
the mountain itself.
All these downfalls of snow are phenomena in the economy of mount-
ains, no less regular and normal than the ﬂowing of the rainfall into riv-
ers, and they form a part of the general system of the circulation of wa-
ter in every basin. But in consequence of the superabundance of snow,
its too rapid melting, or some other meteorological cause, certain excep~
tional avalanches, like the inundations caused by river-ﬂoods, produce
most disastrous effects by laying waste the cultivated grounds on the
lower slopes, or even by swallowing up whole villages. Catastrophes of
this kind and the falls of rocks are the most formidable occurrences in
the vitality of mountains.
The avalanches known under the name of poudreuses are those most
dreaded by the inhabitants of the Alps, on account not only of the rav-
ages immediately arising from them, but also of the whirlwinds which
frequently accompany them. Before the newly-fallen layers of ﬂakes
suﬂiciently adhere to the former snow, the mere tread of the chamois,
the fall of a branch from some bush, or even a resounding echo, is suﬂi-
cient to disturb the unstable balance of the upper sheet of snow. At'
ﬁrst it slides slowly over the hardened mass beneath, until, reaching a
point where the slope of the ground assists its progress, it rushes down
with an increasingly rapid movement. Every moment it becomes aug-
mented by fresh beds of snow, and by the debris, stones, and brush-wood,
which it hurries along with it. It makes its way’ over the ledges and
passages, tears down the trees, sweeps away the chalets which lie in its
path, and, like the downfall of the side of a mountain, plunges into the
valley, sometimes even reaching the opposite slope. All round the ava-
lanche powdery snow rises in broad eddies; the air, being compressed
laterally by the sinking mass, roars right and left in actual whirlwinds,
which shake the rocks and uproot the trees. Thousands of trunks may
sometimes be seen thrown down by nothing but the wind of the ava-
lanche, when the latter traces out for itself a wide path across whole for-
ests, and, as it passes, sweeps away the hamlets in the valley.*
The avalanches dc fond are generally less dangerous than those we
have just spoken of, because they are formed at a more advanced season
of the year, when the greater part of the superﬁcial snow is melted, and
the remainder of the mass is able to run through its regular passages.
As their name indicates, these avalanches are composed of the whole
thickness of the snow-ﬁeld. Lubricated, as it were, by the rivulets of
water which cross them and ﬂow over them, the beds of snow lose their
adherence to the ground, and slide in one lump, like marine icebergs de-
taching themselves from a ﬁeld of ice. Under the pressure of these mov-
* Tsehudi, Le Monde des Alpes, vol. ii.
DEFENSES A GAINS T A VALANCHES. 17 1
‘ing masses, the snow below at last yields, and the avalanche, loaded with
water'and mud, earth and stones, rushes through the passages and over
the rocks ; at last, ﬁnding its way into the valley, it dams up the stream
with a kind of dike, which sometimes-resists the weight of the water till
the middle of summer, and the gray or even blackish mass becomes so com-
pact that it assumes the hardness of rock. It is, in fact, a glacier in miniature.
Thickly-planted trunks of trees are the best protection against ava-
lanches of every kind. In the ﬁrst place, the snow which has fallen in the
wood itself cannot very well shift its place; and then, when the masses
_ descending from the slopes above "dash against the trees, they are unable
to break through so strong a barrier. After having overturned some few
of the ﬁrst trees, their progress is arrested, and the intermingled heaps
constitute a fresh obstacle for future avalanches. Small shrubs, such as
rhododendrons, or even heaths and meadow grass, are very often suﬂicient
to prevent the slipping of the snow, and where people are imprudent
enough to ‘cut them on the mountain slopes, they run the risk of clearing
the way for this formidable scourge. The danger is still more imminent
if a screen of trees is cut down in one of the protecting forests. The task
is then begun for the avalanche, which soon undertakes to complete the
rest of the labor by tearing up all that still remains of the former woody
rampart. A mountain which stands to the south of the Pyreiiean village
of Aragnouet, in the lofty valley of the Neste, having partially
cleared of trees, a tremendous avalanche fell down, in 1846, from the top
of a plateau, and in its fall swept away more than 15,000 ﬁr-trees.
The protecting woods of Switzerland and the Tyrol used t6‘ be defend-
ed by the national bann, and, as it were, “tabooed.” They were, and
still are, called the Bannwcelcler. In the valley of Andermatt, at the
northern foot of the St. Gothard, the penalty of death was once adjudged -
on any man found guilty of having made an attempt on the life of one of
the trees whichshielded the habitations. Added to this, a sort of mystic
curse was thought to hang over this impious action, and it was told with
horror how drops of blood ﬂowed when the smallest branch was broken
off. It was true enough that the destruction of each tree might perhaps
be expiated by the death of a man.
The inhabitants of some villages which are threatened with avalanches
endeavor to ﬁnd a substitute for trees in long stakes or piles driven into
the ground to resemble ﬁr-trees. This is what they call clouer l’avalanche
(nailing up the avalanche). At the same time, they hew steps at inter-
vals, almost like a staircase, so that the snow falling from the cliffs may
be arrested in its course or partially broken up. In some localities, too,
they construct lateral walls on purpose to contain the ﬂow of the ava-
lanche, as if it were a banked-up river; and if, after all these precautions,
the houses are still threatened, they furnish them, like the piles of a bridge,
with spurs or buttresses, made of stone or hardened snow, which, by
sprinkling, is gradually changed into ice.*
* William Huber, Les Glaciers.
172 THE EARTH
The village and the great establishment of the baths at Baréges, in the
Pyrenees, used to be menaced every year by avalanches rushing down
from an elevation of 4000 feet, at an angle of 35 degrees. The inhabit—
ants, therefore, were in the habit of leaving vacant spaces between the
two quarters of Baréges, so as to allow a free passage to the descending
’ masses. Lately, however, they have endeavored to do away with the
avalanches by means somewhat similar to those employed by the Swiss
mountaineers. They have thrown up banks about 10 or 12 feet bread
on the sides of the ravines, and have furnished these banks with an edg-
ing of cast—iron piles. Basket-work, and, here and there, walls of masonq
ry, protect the young growing trees, which are gradually improving un-
der the protection of these defensive works. In the mean time, until the
real trees are strong enough to arrest the course of the snow, the artiﬁcial
trees have well fulﬁlled the end they were destined for. In 1860, the
year when the defensive works were ﬁnished, the only avalanche which
slid into the ravine did not exceed 400 cubic yards in bulk; while the
masses which used to fall down upon Baréges sometimes attained to more
than 90,000 yards in volume.
CHANGE OF SNOW INTO I OE. . a 173
CHAPTER XXX.
GRADUAL TRANSFORMATION OF sNow INTo ICE—NEVES, on GLACIER-RES-
ERVOIRS.——-PHENOMENON OF EEeELATIoN.—-cRYsTALs OF ICE.-—GLACIERS
on THE FIRST AND sEcoND ORDER.
BY a succession of partial changes affecting the millions of frozen par-
ticles, the snow of the high mountain summits is changed into ice, and
the white ﬂakes falling on the peaks become those rivers of bluish crys-
tal which slowly make their way down between the sides of the gorges.
Imperceptibly the ﬁeld of snowvis changed into névé, and then into gla-
cier ; afterward becoming in succession stream, river, and wave, it ﬁnally,
under the form of aqueous vapor, recommences its ‘eternal circuit.
The alteration of opaque snow into‘ transparent ice is one of the most
interesting phenomena of planetary vitality. The newly-fallen ﬂakes be-
gin by ﬁrst settling down and hardening. Then, when the rays of the
sun have raised the temperature of the snow-ﬁeld to melting-point, a
number of small drops penetrate into the subjacent layers, and, being
again assailed’ by the cold, freeze into small envelopes, irregularly-crys-
tallized round solid molecules, and become cemented all together into a
compact mass. The snow may thus become
very hard, and on the edge of many of the
precipices it forms a kind of overhanging pent-
the eﬂ'ects'of the-weather without giving way.
We borrow from Forbes the design of one of
these elegant cornices, with its brilliant pend-
ants of ice.
In the end, the entire thickness of the snow-
ﬁeld changes its structure and becomes a mass
of granules, from which the air is‘partially ex-
pelled by the successive freezing and melting
1 produced by the solar heat. In this way are
formed the hard and granular beds of former snow, which lie upon the
upper slopes of all lofty‘mountains; ‘these whitish or dull gray masses
are known in the Alps and Pyrenees by the name of névés. In winter,
when the temperature often‘ remains below the freezing-point, even during
the day-time, the snow on high summits maintains its powdery state; but
as soon as it is subjected to the ﬁrst breath ‘of spring, it begins to assume
a granular form.* - -
The ﬁrst change in the particles of snow is but the prelude to still
* Desor, Ncuvelles Excursions et Séjours dans les Glaciers. -

Fig. 45. Cornice of Snow.
house, which resists for a considerable time
174c , THE EARTH’.
more important modiﬁcations. The heatv of the sun continues to melt
the surface-layers, and thus causes drops of water and laminae of ice of
an increasing size to penetrate into the néoé. Simultaneously the snow,
compressed ‘by its own weight, ultimately expels_by mechanical force the
greater part of the air which it contains, and gives to the opaque granules
of the néoé the structure and transparency of ice. The pressure of the
superinc'umbent layers is the principal agent in the transformation of beds
of snow. The brothers Schla'gintweit and Tyndall state that b'y‘the com-
pression of fresh snow they succeeded in obtaining slabs of transparent
ice; but there is scarcely a child who has not amused himself in trying
the same experiment by kneading a snow-ball with his ﬁngers. Under
the tread of the pedestrian, the coating of snow which sticks to his‘ shoes
ultimately becomes a piece of ice.*
In consequence of this gradual transformation, the mass of néoé becomes
more and more indurated and ‘compact. A cubic yard of snow weighs
on the average 187 lbs.; but the same volume of névé weighs more than
half a ton, and the various modiﬁcations to which the snow is subject
in, becoming transparent ice ultimately give it a weight of about 1980
lbs. per cubic yard. The material which constitutes the glaciers is twelve
times lighter than water when it commences its course, but at the end of
its career it is only one tenthv or onetwentieth part inferior in weight to
an equal liquid volume-f >
Notwithstanding these successive changes, the whole thickness of the
mass of néoé is composed of [strata of varying regularity, which are the
beds of snow deposited in successive winters.~ Each of the superimposed
beds exhibits on its surface a kind of‘ gray or yellowish crust, which is
formed by the mixture with the snow of bits of stone, dust, and even the
remains of insects; under this crust extends a thin layer of glazed ice,
caused by the freezing of the water which had melted on the surface.
The strata of the névé, being thus arranged one above the other like the
beds in a calcareous rock, are, in proportion to their age and the weight
that is laid upon them, all the more compact and ice-like in theirtexture.
In many places these strata may be perceived at the edge of the névé;
for wherever the rocks rise above the upper snow-limit a kind of cleft
may be noticed in the néoé, owing partly to the rending force exercised
by the whole mass on the upper beds, and still more, perhaps, to the
ﬂowing of the Water which trickles round ‘the base of the" rocks which
are warmed by the sun. Y
Below the névé, which is, in fact, the reservoir in which the ice begins
to form which afterward is to feed the glacier properly so called, the
frozen masses continue to become gradually modiﬁed as regards their
internal structure. It is very true that a great part of the ice, which is
melted by the rays of the sun, the rain, or the mild breath of warm winds,
‘remains in a liquid state, and in the form of rivulets ﬁnds its way through
* William Huber, Les Glaciers.
1' Dollfuss-Ausset, Mate'rz'aux pour servir it Z’Etude des Glaciers.
F ORJI A TI ON OF GLA CIERS. . 1 7 5
the crevices of the glacier, and joins the stream which ﬂows over the
rocks below. But there is another agent at work aswell as the sun in
the process of melting the ice in the very heart of the layers. This
agent is the pressure exercised by the upper masses on the ice lying
beneath them.
Natural philosophers have, in fact, proved that the melting temperature
of ice lowers forty-two ten thousandths of a degree (Fahr.) for every at-
mosphere=X< of pressure. At the foot of rapid slopes, where the enormous
weight of the layers above compresses the ice with the force of a large
number of atmospheres, the liquefying point of the mass is considerably
lowered, a greater ‘or less amount of latent heat is set free, and a portion
of the ice must melt and pass into water. Thus, in consequence of this
pressure, cells and liquid veins are here and there opened in the interior
;of the glacier, the mean heat of which is, however, only a mere fraction
of a degree lower than the freezing-point. The protracted and numerous
experiments of Agassiz have proved that in a deep hole sunk to a depth
of 200 feet in solid ice the thermometer marked on the average 31° 24'
(Fahr.), and that only in winter, and quite exceptionally, the temperature
was lowered to 28° 24' (Fahr.) ; in the open air the cold was most intense.
.Owing, therefore, to the comparatively high temperature of the ice, small


Fig. 46. Internal banded Structure of Ice.
veins of water are formed which penetrate its entire mass. evertheless,
the particles of ice which divide the thin ﬁlms of water remain separate
only for an instant; for even under a slight pressure, very much less than
that which is brought to bear upon glaciers, two morsels of ice surrounded
by water immediately approach one another, and unite to form a single
lump. Even in warm water two pieces of ice which are melting continually
strive to combine, and the, isthmus which joins them forms and reforms
until the last solid particles have disappeared. This is. the great .fact
.which was discovered by Faraday, and brilliantly demonstrated by Tyn-
dall, who has given it the name of regelatz'on.' This phenomenon takes
place at every point in the thickness of the glacier. Particles of ice
approach one another, and unite across the little veins of water which
permeate it in every direction; fresh liquid ﬁlms are formed under the
pressure above; fresh unions take place between the divided morsels of
ice; and, by this continual process of change,'the air contained in the
mass of that which once was snow is gradually expelled. Thus it happens
that the whole mass ultimately assumes an almost perfect transparency
and a beautiful azure color. It is, however, the case every winter that
* A weight equivalent to that of a column of water of about 32 feet.
176 THE EARTH
the clefts on the surface of the glaciers are ﬁlled up with fresh masses of
snow. These new layers, to which an intermixture of air-bubbles gives
a whitish tint, are dragged and thrown forward by the general move-
ment. In several glaciers, where mighty crevasses disclose the internal
structure of the whole mass, it is wonderful to see the alternate Stratiﬁca-
tions of gray snowand the blue belts of ice, just like the beds of a forma-
tion of rocks. On high elevations new’; and glacier are intermingled
together. In climbing Monte Rosa, Zumstein saw, down in a crevasse of
nine, real glacier ice, at a height of 13,989 feet, less than 1300 feet below
the summit. >
*Nevertheless, whatever may be the modiﬁcations which the snow un-
dergoes, it is a matter of fact that, even in the lower parts of glaciers,
granules are found similar to those of the névé, only these grains have be-
come transparent'and free of air-bubbles, and in their long course toward
the valleys have considerably increased in size. Some of them are as
large as a chestnut, or even a hen’s egg. These granules of ice are some-
times very irregular in shape, owing to the enormous pressure to which
they have been subjected, sometimes in one direction and sometimes in
another; but the phenomena of polarization which they present to the
light prove that they are really crystals,* and the whole glacier is an ac-
cumulation of granules confusedly packed together. From the moment
when the snow-ﬂakes fall in the shape of needles and stars, to the time
when they are reared up in blue walls, it never ceases, under all its va-
rious aspects, to retain a crystalline character.
The snows which are thus transformed into ice by the effects of press-
ure form the enormous masses which cover'the mountain sides and ﬁll
up whole valleys. Some of these glaciers—those of the Pyrenees, for in-
stance—only extend over the upper slopes of the mountain, and do not
descend through the gorges as far as the cultivated grounds at its base.
These are the glaciers which Saussure calls Secondary or summit glaciers.
Thereare other ﬁelds of ice which also take their rise on lofty peaks, and,
ﬂowing out into the mountain amphitheatres, make their way into the
lower valleys, uniting, on each side of their beds, with the ice of other
tributary gorges; these are glaciers of the ﬁrst order. There are some
which extend to a length of 12, 18, or 30 miles, and attain a thickness of
several hundred yards. These are easy to class; but in nature the transi-
tions are so gradual that, as regards the‘ greater number of glaciers, it is
impossible to point out precisely in which category they ought to be
classed. The distinction established by geologists is purely artiﬁcial.
* Sonklar, Qi'tzthaler Gebirgsgruppe.
EXPERDIENTS. 177
CHAPTER XXXI.
MOVEMENT OF GLACIERS.—-EXPERIMENTS AND TIIEoRIEs.——coNvExITY or
THE CENTRAL PART OF A eLAcIER—ITs SUCCESSIVE wINDINes—ERIc-
TIoN OF THE ICE AGAINST THE BOTTOM AND sIDEs OF THE BER—THE
GLACIER GAUGE.—INCLINATION on THE GLACIER BED.
THE Alpine mountaineers, from time immemorial, have been aware of
the fact that glaciers move onward, and convey masses vof rock from the
mountain summits down into the valleys; but it was unknown to most
‘ geographers, shut up as they were in their gloomy studies. At the end
of the sixteenth century, Simmler announced this marvelous fact, and
other savants repeated it after him; but it was not generally known until
the end of the last century, after the publication of Horace de Saussure’s
travels. This traveler, one of the ﬁrst of that generation of energetic
men who knew well how to combine scientiﬁc inquiry with skill, strength,
and endurance, and could also both hit upon and unravel the mysteries
of nature, veriﬁed the movement of glaciers, and attempted to propound
a theory for it. He was, however, content with stating his ideas in a
general way, without making any direct experiments to verify them.
This, however, fell to the share of Hugi. In 1827 he had a little hut
built on the glacier Unteraar, at the foot of the promontory of Ab-
schwung. In 1830 the hut was 110 yards lower down; by 1836 it had
traveled 780 yards; by 1841 it had reached a distance of 1561 yards
from its ﬁrst position; its movement, therefore, had been at the rate of
112 yards a year. Since that date, a great number of experiments of the
same kind have been made by other explorers. The measurements made
so carefully by Agassiz on the upper tributaries of the same glacier, the
Aar, the Finsteraar, and the Lauteraar, have proved that the two’ masses
have shifted their places, one from 52 to 89 yards, the other from 34 to
81 yards each year, according to the various positions of the measure-
ment—marks on the surface of the glacier. The motion was ascertained to
be the more rapid in proportion as the marks were nearer the central por-
tion of the ﬁeld of ice. Thus this important ‘fact was brought to light,
that the mass of the glacier occupying the centre of the bed‘ descends
more quickly than the portion situated in the vicinity of the two sides.
Henceforth the matter was set at rest that, without‘any exaggeration of
language, a glacier might be literally assimilated to a river.* This, how-
ever, is an idea that had already been suggested by M. Rendu, an excel-
lent observer of the mountains of Savoy. In a work on glaciers, pub.-
lished in 1841, he stated that there was a perfect resemblance between
the Mer-de-Glace, in Savoy, and a river, and that it would be impossible
* C'omptes Rendus cle I’Académie des Sciences, 29th of August, 1842.
M
178 THE’ EARTH.
to point out any phenomenon in any of the streams which might not be
found in the other.
To what cause, therefore, are we to attribute this gradual descent of
the river of ice in its rocky bed? At all events, it is certain that it is
not a mere .sliding of the. mass over its lubricated bed, for it has been
several times proved that above the zone in whichv the mean temperature
of the ground is below the freezing-point, that is, at about the height of
6600 feet in the Central Alps, the layers of the glacier are frozen to the
ground, and can not detach themselves from it by the mere force of grav-
ity. On their lower surface they melt but slowly, except at the spot
where the rivulet ﬂows, which. gathers all the surface-water sinking
through the c'reoasses. There are also instances of a stream running by
the side of a glacier from the névé to the terminal moraines without be-
ing able to penetrate the solid wall of ice adhering to its bed of rocks.*
Since the investigations and experiments of Tyndall, it has become
more than probable that the real cause of the onward motion of rivers of
ice must be sought for in the formation of innumerable ﬁssures, and in
the reconstitution of all the broken fragments into a fresh mass. Regela-
tion is taking place in every part of the glacier at once, and, as may be
easily understood, the particles of ice compressed by the masses above
them must always move in the direction of the slope when. they shift
their position in order to coalesce anew. This descending movement and
the junction of the particles are taking place at the same time as regards ‘
millions and millions of broken granules, and from this very cause the
Whole body of the glacier descends in the gorge which serves as its bed.
' Under the pressure of the enormous weight which pushes it forward, the
ice ultimately becomes so moulded as to ﬁt perfectly into its channel of
rocks, just as if it were a pasty mass. If the gorge becomes narrow, the
glacier assumes a more elongated shape in order to make its way into
the deﬁle; if the mountain sides widen out in a basin, the glacier spreads
out like a lake in the broad hollow. This remarkable plasticity of the ice
under pressure has caused several distinguished natural philosophers (as
James Forbes) to believe that the frozen mass, although so brittle, is of a
viscous nature, and ﬂows in the same way as treacle and honey.
Spring-time is the season in which the river of ice descends toward the
valley with the greatest rapidity. Then the phenomena of liquefaction
and regela'tion take place with the greatest frequency on the elevated
névé. Innumerable rivulets of water, set free from their icy prison, widen
the 'creoasses and lubricate the ‘slopes on which the solid river has to glide
slowly down. The blocks of ice, glued to the sides of their bed by the
frosts of winter, regain their liberty. It is probable that in summer the
progress of a glacier'is at least double as fast as it is during the cold sea-
son. ‘Thus, according to Tyndall, the progress of the Mer-de-Glace, near
Montanvers, is on the average about 13 inches a day in winter, and more
than 24%- inches a day in the summer; but, between the extreme rates of
speed, the difference is much more considerable. Every variation of tem-
* Sonklar. (Etztlzaler Gebirgsgruppe.

‘I, "273.’
I“. ".11" 3 "
l
1, ' “P
1;‘ I77,“ “ I ‘ .
hair as
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' >-‘ I v I. "\I ‘
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s: to’
——
after the Map of M‘ Mmulet.
I
, HAP *1. .aAO'i‘HF‘. 8:; Niall? YFIRV.
O


GLA C'IERS ’ 0 ONVEXI T Y. 179
perature, however, makes itself felt in the progress of the glacier, and al-
though experiments do not all agree on this point, it is probable that at
sunset the glacier slackens its course, and accelerates it again when the
luminary reappears above the ridges of the mountains; in the depths, as
on the surface, the sun imparts life and animation. As soon as the early
rays of daybreak have lighted up the glacier, its very nature seems altered.
Just as in the adjoining forest, the ﬁeld of ice is harmonious with a thou-
sand small yet joyous sounds; the little drops, falling on the projections
in the crevasses, tinkle as they are broken up; the gradually-forming riv-
ulet murmurs on its way; the slopes of gravel crumble down into the
crevasses ,' and here and there some block, uncemented from its icy ped-
estal, roars as it rolls down the incline. All these voices of the glacier
gain strength as the sun gets higher in the horizon: but if a thick cloud
suddenly interrupts the solar rays, silence is gradually re-established, and
the glacier waits for the return of the sun ere it resumes its song. The
enormous ice-river seems endowed with vitality; so much so that some
enthusiastic savants, as Hugi, have seriously asked the question—whether
the monster did not possess a soul? Numbers of mountaineers, in all
their simplicity of mind, fully believe it.*
Just as in liquid rivers, a raising up of the central portion of the glacier
corresponds in general ‘to the highest rate of speed in the moving mass.
The convexity of the surface of the icy stream must not be attributed to
an aﬂiux of the whole body toward the middle; the cause is, perhaps, the
fact that the central parts, being animated by a more rapid motion, have
not had sufficient time to evaporate and melt in as large quantities as
those at the sides, which are slower in their progress, and more intersect-
ed with crevasses. Sometimes, however, it is the case that the glacier ex-
hibits an exactly contrary outline, and is hollowed out like a gutter in
the central part. This happens when immense moraines cover a broad
surface of the ice on each side, and hinder their melting. An instance of
this fact is to be found in the glacier of Vernagt, in the (Etzthal’r
Not only does the river of ice act exactly like a liquid water-course by
its waves rolling on with much more rapidity in the central portion than
at the edges, but, similarly to all other rivers, it assumes the greater
amount of force in its current at the convex side of its successive wind-
in gs. Theory would have beforehand presumed this fact, which, however,
the experiments of Tyndall in 1857 have indubitably established. His
measurements, very carefully made across the various curves of the Mer-
de-Glace, have proved that the thread of the current shifts its position al-
ternately to the right and left of the medial line, and approaches each of
the sides in turn, sometimes one, sometimes the other. Thus the axis of
movement follows an undulating line, the windings of which are more de-
cided even than those of the gorge of the glacier. The ideal progress of
the frozen river is represented by the illustration on ‘the following page,
which would apply equally to the current of a liquid river.
* De Charpentier, Essai sur les Glaciers. ‘I’ Vicle inserted Plate, XIV.
180 _ a THE EARTH.


" Fig. 47. Windings of a Glacier.
The same cause which impedes the motion of a glacier at the edges-—
that is, the friction of the sliding mass against the rocks—equally dimin-
ishes the rapidity of its current along its bed. In this point, also, the ac-
tion of a glacier is perfectly analogous to that of a river moving at a'slow
pace. Forbes and M. Martins have proved this on the Mer-de-Glace and
the Faulhorn, by experiments which Tyndall has since renewed at the
risk of his life. Descending the sides of a precipice 137 feet in depth,
opening between the rocks and the glaciers of the Tacul (Mont Blanc),
he succeeded in ﬁxing three pegs at the summit, at the middle, and at the
base of the vertical wall of ice, so that he should be able to measure their
respective rates of. progress two days afterward.
The upper peg had. advanced 57} inches in the twen-
ty-four'hours ; Q the middle one, ﬁxed 36 feet above‘
the'.bottom,had onlyrmove'd.onward'4 inches'iu the '
same space of time; lastly, the'lower. mark, ﬁxed‘
more than alyardabove the rocky bed of ‘the'gla- '
cier, had only progressed at the 'rate of 2% inches a
day.* :Added to this, in certain places the cascades
of surface-water cutout ledges resembling stepsin
the sides of the creoasses, which, as it were, bring
before the eye the superior rapidity of the upper
layers of the ice. The water falls, in the ﬁrst place,
on some‘projection, which it‘ hollows out in the
shape of a basin; but, in consequence ‘of the on- '
ward motion of the glacier, the liquid column soon‘ f'j-I’l'f , ""11. 1' "
gets beyond‘ the ﬁrst projection, and drops down 4‘
upon a second, and then upon a third; it thus
forms. the succession of steps resulting from the
rapid 'advance'of the ridge of .ice from which the cascade descends.
A comparison of the experiments—alas! too‘ few—which have been
Fig. 48. Cascade ofyGlacier.
_ made up to the present time with regard to the speed of various glaciers
warrants us also in thinking that the advance of the current is acceler-
. atedjn proportion to the declivity of the slope; only, as M. Desor points
out, the volume of the matter in motion being by far the'prinei-pal ele-
. *‘ Tyndall, Glaciers of the Alps. ' . '
l
RA TE OF MOTION OF GLA CIERS.
ment in the increase of speed of the whole mass, the result is that small
glaciers at a very steep slope descend more slowly than larger ice-rivers
on a slight declivity.
Thus the advance of a glacier presents very considerable differences
in the rate of progress, according to the importance of the total mass in
width and depth, its proximity either to the edges or the bottom, the
winding of the sides, the degree of slope, the expansions and contractions
of
of
its bed of rocks, the state of the temperature, and the various seasons
the year. It is, therefore, impossible to estimate the mean rate ‘of
speed of a river of ice by taking as our basis a series of isolated observa-
tions; we must, on the contrary, study the movement of the ice in every
part of its bed, take account of every cause of acceleration and delay, and,
if
ning water.


the most varied character.
OI]
we may so speak, gauge .the glacier as we should gauge a river of run-
The movement of the ice, like that of rivers, takes place over slopes of


‘:3 “’ E 2 :s "j
:3: g I 49 <2)‘ 5 '
g g g5 g a.
g :5 as 3 ii i g 8
.' 8 o :3 2 ~42 ‘ _
o a: r4 . x‘
a as '
m . ,_-,____\ _.
\

0
I
Fig. 49. Slope of the Mer-dc-Glace.
The Mer-de-Glace, at Chamounix, is inclined
the average 5 or 6 degrees, but at many points in its course it presents
a'much more considerable declivity. Some glaciers, half suspended on
themountain sides, have an inclination of 25, 30, and'even 50 degrees, 'and
yet itis but. seldom that the masses lying on these formidable slopes take
to. sliding on theirbases so as to fall down like avalanches into the ‘val’-
ley berieath.* -They descend gradually and slowly, like other, glaciers
which are almost horizontal in‘ appearance, and: run down gorges the
slope of which does not attain'to ‘3 degrees. ‘
Aletsch is inclined only 4 degrees; those'of the (Etzthal,'on' the average,
5 or 6 degrees; those of Monte Rosa and the northern 'sides of the'Fin-
steraarhorn group are much more sloping, and incline 10,115; and-20 de-
grees, or, asthe upper glacier of Grindelwald, as much‘ as 27 degrees.
The ' immense glacier of
i 0 _ I \ q
* De Charpent1er,~Essaz s-ur les Glaczers.
182 THE EARTH
CHAPTER XXXII.
'MARGINAL, TRANSVERSAL, AND LONGITUDINAL eREvAssEs—sﬁuAes—Mou-
LINSrjBRIDGES on SNOW.—-VEINS OF FRESH ICE—SURFACE-STREAMS on
GLACIERS.-—GOUILLES.—-LAKES AND INUNDATIONS.—-DISCHARGING CHAN-
NELS.
. THE whole mass of the glacier does not advance in a perfectly continu-
ous way as a stream of water would do ; the layers of ice could not fol-
low all the windings of the gorge and adapt themselves to all the ine-
qualities. of the bottom without some extent of fracture. Thus ﬁssures, or
crevasses, are produced in the thickness of the apparently motionless riv-
er, and sometimes give to'the latter a most uneven surface.
Most of the crevasses in a glacier are found near the sides, and princi-
pally at the convexity of the bends, on account of the inequality of ten-
sion towhichrthe layers of moving ice are liable at these spots. The lay-
ers which are the closest to the bank are retarded by the friction of the


‘,4’ I, I) - aw, \ l
'24 " ‘I [It'll-i ' I.
Fig. 50'. Marginal Crevasses in a Glacier.
rocks, while farther into the stream the rapidity of the current of ice in.-
creases with its 'distance from the edge. This difference in the rate of
speed results in a greater tension of the mass in the direction of the move-
ment, and in consequence the ice on the edge has to resist a tractile force,
acting, as Sonklar and Hopkins have proved, in a line inclined 45‘ de-
grees'tothe bank. Finally, the ice gives way to the power which draws
it; it is rent open; and, as the laws of mechanics dictate, the marginal
Grfevasses are produced perpendicularly to the force of traction. The prin§
fapal force; of the movement being exerted in the directionzof a line tend_
mg up stream at an angle of 45 degrees to the bank, the ﬁssures in general
form at a similar angle to the bank, and also tend up stream; they are
ORE VASSES IN GLA OIERS. 183
consequently transverse to the course of the current; therefore, at ﬁrst
sight of these clefts, we should be inclined to say that the glacier advanced
with more rapidity near its edges; indeed almost all the ﬁrst observers
were deceived on this point.
The marginal crevasses, however, do not retain their early inclination of
45 degrees to the bank of the glacier, the motion of the current being more
rapid toward the centre than near the edges; the ﬁssure turns round
slowly, like the spoke of a wheel, and becomes less and less obliquely
sloped toward the bank; sooner or later it becomes perpendicular to it,
and then inclines gradually in the direction of the descent, describing a
more and more acute angle. But while this ﬁrst crevasse is thus bend-
ing round in a down-stream direction, ﬁrst one and then another marginal
cleft may be produced in the ice, subjected as it is to the tractile force of
the moving mass; and these planes of rupture are at ﬁrst likewise inclined
at an angle of 45 degrees in an upstream direction, and afterward bend


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round in the direction of the current. This sometimes results in an inter-
section of cracks, which transform the lateral portions of the glacier into
a perfect labyrinth of crevasses, in which it becomes diﬂicult to recognize
the regular order of the successive phenomena.*
The crevasses which are formed from bank to bank across the ﬁeld of
the glacier are caused principally by the inequalities of its bed. In
places where the declivity becomes more abrupt, the ice, being unable to
accommodate itself to this fresh slope, cracks right across, and by a series
of ﬁssures spreads out its surface to form an inclination similar to that
of the bed which it covers; the clefts, it must be understood, are all the
more numerous and wider as the fall is ‘more sudden. ' ‘
Below rapids and cataracts, rivers spread out into large and smooth
sheets of water; a similar phenomenon‘takes place in glaciers below any
very steep slopes. \Vhen they reach these more level beds, the masses
which have been separated by the ﬁssures again come close together, and
* W. Huber, Les Glaciers.
184 . THE EARTH -
pressing one against the other, resume the uniformity of surface. If a
second sudden fall of the bed gives a more rapid movement to the river
of ice, it will a second time descend in a cascade of crevasses, which will
become obliterated on the mass reaching some less important declivity.
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Fig. 52. Transverse Crevasses, seen in Proﬁle.


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The lower glacier of Grindelwald presents a striking instance (ﬁrst point-
ed out by Tyndall) of this succession of crevasses and level ﬁelds of ice.
From the tops'of a headland a clear idea may be formed of the general
aspect of the glacier, and of its alternately dislocatedand compressed
masses. The kind of semicircular curve which the transversal crevasse
produces by uniting with the marginal ﬁssures very often deceives the
sight, and would lead us to believe that the force of the current was more
especially exerted at the edges, if reason and experience did not teach us
precisely the contrary. It must also be added that these cross crevasses
are generally slightly curved in the direction of the motion.
In a similar way to the transversal clefts, those which extend in a lon—
vgitudinal direction are likewise owing to the direction of the bed. In


Fig. 53. Transverse Crevasses, seen in Plan.
every part of the bed of the stream where the longitudinal risings, similar
to the shallows of a river, force the ice to bend over laterally both right
and left, the latter must form parallel creoasses, and these ﬁssures can not
CREVASSES IN GLA CIERS.
185
close up until they have descended below the obstacle. Added to this,
there are often abrupt rises and falls in the bed which are so constituted
as to cause the simultaneous rupture 'of the ice in both a longitudinal
and transverse direction, and, consequently, the ﬁeld of ice is traversed
by crevasses which are semicircular or bent round in various directions.
Inthis way the appearance of the surface often reveals the irregularities
of the bed.
Lastly, glaciers also exhibit radiated crevasses, especially at their. ex-
tremities, when the base extends widely into the lower gorges. .-.The
pressure of the masses descending from the mountain heights compels'the

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ice down below to spread out laterally, and, in consequence, over the wnole
slope of the glacier there is a formation of radiating crevasses, sometimes
exhibiting the regular arrangement of the ribs of a fan. A‘bcording' to
various slopes and the inequalities in its bed, the ice presents the very
greatest diversity in its lines of fracture. These clefts form a: perfect lab-
yrinth on the surface of all glaciers which possess numerous’.tributaries,
and move along a winding and occasionally contracted bed. -
Any one who happens to be on a glacier at a time when a crevasse is

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Fig. 55. Longitudinal Crevasses, seen in Proﬁle.
developed can not possibly resist a certain feeling of . dread. The men-
strous river suddenly takes to cracking and groaning; dullreports, caused
by sudden ruptures, are every'moment heard in the interior. of the mass;
and a' prolonged whistling sound, like that made by glass when slit ‘by a
diamond, announces the gradual increase of the cleft. Nevertheless, when
all the voices of the glacier are hushed, it is sometimes quite in vain that
we seek for the. crack, on account of its extreme ﬁneness. The crevasse
widens very slowly, and it takes days, and sometimes even weeks, before
O
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186 THE EARTH
it vbecomes one of those formidable chasms which gash the surface of the
glacier. A : -
When the creoasses have arrived at their full development, they exhibit
a most striking spectacle. The two bluish walls sink down into dark-
ness which is unfathomable by the eye; stones, falling from the surface,
bound over the projections, and awaken dull echoes as they are lost in the
obscurity; a vague murmur of running water ascends from the depths;
and sometimes sharp gusts of cold a'ndbiting air issue out from the mouth
of .the abyss. While leaning over the brink of the gaping chasm one
feels a kind of dread, as if the noises and darkness of the gulf beneath
belonged to some new world, full of mystery and horror.


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When the-.crevasses are numerous, and intersect ‘one another in various
directions, it often happens that masses which are thus isolated, and are
also of a more compact nature, resist for a longer period the action of the
sun and wind. In consequence of all these inequalities, and, doubtless,
also on account of the difference in pressure operating at the base, the ice,
in some spots, assumes the most picturesque and fantastic shapes. Some-
times these blocks resemble knights clad in their armor, sometimes
strange animals, broken statues, pointed clock-turrets, or ruined colon-
nades. Tourists ask with astonishment how it is that nature, by nothing
but the slow operations of the forces of gravity and pressure, the winds,
and solar rays, is able to carve out the ice into groups so remarkable
both for their regularity and grotesqueness. The tower-shaped forms
which crown some of the abrupt falls of the glaciers have received from
the Swiss mountaineers the name of séracs; a term which reminds one of
the sérets—cheeses which split up into small cubical pieces.
- In the lower portion of the glacier surface the walls and pillars, which
are divided from one another by ﬁssures, seldom show perpendicular sides-
Their faces which are turned toward the south become wasted and worn
away, and thus assume the appearance of enormous congealed waves-
When the great river has this furrowed surface, it really becomes ‘a “ sea.
of ice.” Owing to the more rapid motion of the upper layers, it general-
l-y happens that the ice-waves present their steepest face in a downward
FEATURES IN GLA OIERS.
direction, and are less abrupt looking upward; when this latter sideiis
also that whichfronts the south, it ultimately becomes a more or less
inclined slope. '
In some places the ﬁelds of ice are also hollowed out into perpendicular
wells, known under the name of moulins (mills), on account of the roar-
in g noise of the water which is ingulfed in them. The formation of these
abysses may be very simply explained. The drops of water melting on
the surface combine into slender rivulets, which form tributaries of a
more considerable stream, which winds along its bed of ice. When this
surface-stream ﬁnds in its path some gaping crevasse, it sinks into it,-and>
immediately disappears in the depths below; but it often meets with
some crack crossing the ﬁeld of ice which is almost invisible. The water
makes its way into this crack like a blade of steel, and, gradually widen-
ing it, is swallowed up between the separated sides of the crevice. Soon
the incessant labor of the water succeeds in hollowing out a complete
well, which sinks down to the stream hidden under the glacier. This
moulin shifts its position with the whole mass surrounding it; but at
the spot where it was formed a new cleft is produced in the glacier by
the same causes as the ﬁrst, and the little stream gradually bores out in
it a second deep hole. Thus, on the same line, several circular wells are
hollowed out, the most elevated of which is the funnel of a cataract,
while each of the others has, in its turn, been deserted by thewater that

Fig. 57. Superﬁcial Torrents of a Glacier—after Tyndall.
formed it. Aloulins, like crevasses, are sometimes made use of by ob-
servers who wish to measure approximately the thickness of a glacier,
either by noticing the duration of the fall of a stone, or by employing a
sounding-line. In this way the thickness of some of the Alpine glaciers
has been estimated at 800, 1000, and even 1650 feet.
In winter‘ both moulins and crevasses are either altogether or in part
ﬁlled with snow, which makes its way into the interstices of the ice, and
vmoulds itself to ﬁt them just like lava ﬂowing into the clefts of a rock.
‘When themass of snow does not descend right diiwninto the depths of
188 ' THE EARTH .
the crevasse, andonly manages to unite the two edges of it, it forms over
‘the ‘chasm a kind of bridge, which. a mere shaking of the glacier will
sometimes suiﬁce to hurl down. These unsupported beds of snow consti-
tute the greatest danger for-travelers who venture'on to glaciers. There
-is.no visibleindication to point out the'vast gulf below, which descends
perhaps to a depth of hundreds of yards. The ﬁeld of snow is level, and
seems to invite one to walk over it ; ' but if an incautious travelersets his
foot upon the snow spread over the chasm before he has carefully sound-
edit, themass may suddenly give way, carrying with it the unfortunate
indivi'dual'whom it has failed to support. The greater part of the acci-
dents which happen every year upon the mountains are owing to the fall
of these snow-bridges acrossthe'chasms of the glaciers.
Generally the snow in the crevasses is the ﬁrst to melt and fall down in
the hot season, on account of its position being exactlyin the spot where
the surface-water chieﬂy ﬂows; but it often happens that, in consequence


Fig. 58. Chasms in a Glacier ﬁlled with Snow—after Tyndall.
of the motion-of ‘the glacier, some of these chasms ﬁlled with snow do not
fall in the way of any of the rivulets running over the surface. In this
case the snow gradually hardens, and ultimately becomes changed into
ice, under the pressure of the layers surrounding it. This recently-formed
ice is at ﬁrst distinguished by its whitish shade, its granular texture,
and a great“ abundance-of air-bubbles. Thanks to its color, it resists the
melting inﬂuences longer than the surface round it, and may sometimes
be distinguished from a‘ considerable distance by a kind of cone which
shows itself above the ﬁeld of ice. It also sometimeshappens that simi-
lar-white veins of transformed snow ﬁll up all the windings of the beds
of the temporary streams which are hollowed out in the thickness of the
glaciers.v In the tributaries of ‘the Mer-dc-Glace, Tyndall remarked sev-
eral of these moulds of former streams.
'Lakes, as well as miniature rivers, ﬁll up the depressions in some gla-
ciers. Sometimes they are mere ponds,‘ or gouz'lles, formed. in some unﬁn-
' ishederev‘asse,‘ in other cases they are like wells, and sink down to'the
rocks inthe bed of , the glacier. In“ some localities, the surfaces-water,
GLA CIERS AS BARRIERS. 189
ﬁnding no outlet to the valley beneath through the solid mass which
covers the ground, collects in a hollow between the ﬁeld of ice and the
sides of the rock. Cliffs of a deep blue tinge, with snow-capped summits,
border the lake-like sheet of water, which is still bluer than the ice itself.
Sometimes blocks, separated by ﬁssures from the masses above, break
away with a crash, and, as they plunge into the water, raise high waves,
which spread rapidly across the basin, and breaking on the opposite cliff-
like shore, describe 011 the surface of the lake a graceful net-work of in-
terwoven ripples. Little islets of still unmelted ice ﬂoat here and there
under the impulse of the Wind, which blows hard through the mountain
gorges. There are few sights more charming among the lofty mountains
than these little lakes surrounded by snow, like sapphires set in silver.
The greater part of these glacier lakes are formed by the waters of a
lateral gorge which is penned up by a natural barrier of ice. This water,
proceeding from the upper snows, or from secondary glaciers, which do
not descend to any great distance from the summit, ﬁnds its passage ob-
structed by the body of the principal glacier pushing on its way toward
the plain, and, thus arrested in its course, forms elongated lakes, the lower
extremity of which abuts on the barrier of ice. Some of these lakes are
' of a permanent character, and some merely temporary. The former, oc-
cupying deep depressions hollowed out in the rock itself, canwnot possibly
ﬂow down into the valley; the latter, being only kept back by ramparts
of ice, sometimes melt, and sometimes throw down the obstacle which
opposes their outlet. As soon as the icy wall yields to the" pressure of
the water, the latter pours out in a sudden and mighty rush, the lake is
changed into a torrent, or plunges in furious 'cataracts down into the
gorges beneath, and in a few hours discharges the liquid mass which had
been accumulating during a long period of years, or perhaps centuries.
The history of Alpine inundations is full of incidents of this kind.
Thus it was that the lake of Rofen, which had been forming for fourteen
days by the encroachment of the glacier of Vernagt, in the (Etzthal, sud-
denly opened for itself a passage. Within an hour’s time its basin was
completely emptied, the valley of Sulden was devastated by blocks of
rock and sand, and the Inn itself, swelled by the sudden ﬂood, laid waste
its banks as far as its conﬂuence with' the Danube. The temporary tor-
rent which the inundation threw into the Inn was not less than three -
millions of cubic yards of water, at the rate of 953 yards a second. This,
however, is a triﬂing matter compared with the mass of water that must
have rolled down if the lake of Rofen had found no means of escape for
several years.
The lower glacier of Giétroz, which ﬂows, at a height of 6036 feet, into
the valley of Bagnes, not far from the MonteRosa group, had in the
same way several times dammed up the passage of the stream of the
Dranse, a tributary of the Rhone; but in a general way the barrier of ice
melted at the beginning of spring, and no catastrophe had to be deplored.
In 1818 the case was different; the mass of ice descending from the up-
190 THE EARTH
per néeés was so considerable that the Dranse, being unable to ﬂow
through it, was driven back, and necessarily changed into a lake above
the obstacle. At the beginning of May, the dam of ice, which was about

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‘47.4 .


Fig. 59. The Glacier of Giétroz in 1818.
660 feet in length between the two mountains, was not less than 420 feet
high, and more than 30,000 feet in width at its base. The lake, more
than half a mile in width, was incessantly increasing, and its depth, which
in certain spots reached 260 feet, augmented, on the average, three feet a
day. Its contents might be estimated at more than six millions and a
half of cubic yards. The danger was a terrible one to the inhabitants
of the valley below. Under the direction of Venetz, the engineer, they
set to work to dig a draining channel across the rampart of ice, and suc~
ceeded, in fact, in gradually lowering the level of the water of the lake.
On the 16th of June, at four o’clock in the afternoon, the barrier gave
way; the pent-up water, driving before it both ice and rocks, suddenly
sprang into the valley with such rapidity that in twenty minutes the
whole basin was empty. This formidable cataract swept away woods
and chalets, and laying bare the rocks, and carrying away the very mead-
ows, emptied itself into the plain like a mingled avalanche of water, trees,
and debris, 300 feet in height, and preceded by a black and thick vapor,
like the smoke of a conﬂagration. The havoc was very considerable, not
DRAINING CHANNELS. '191
only in the valley of the Dranse, but also on the banks of the Rhone. In
order to avoid the return of a similar disaster, the draining channel of
the Dranse was cut out afresh every year beneath the glacier. This
operation gave an opportunity of ascertaining the adhesion of the ice to
the bed over which it ﬂows,* even at an altitude comparatively not very
considerable. The lake of‘Moril, which is penned up by the enormous
barrier of the glacier of Aletschn‘ also communicates with the valley of
the Rhone by a draining channel which carries off the overﬂow of its
waters.
* De Charpentier, Essai sur lcs Glaciers. 1' Vide p.207.
192 THE EARTH.
CHAPTER XXXIII.
DEBRIS LYING ON THE SURFACE OF THE GLACIEIL—HOLES IN THE SURFACE.
-—GLACIAL TABLES.—MORAINES; LATERAL, MEDIAL, AND FRONTAL—RIB-
BONS OF MUD.'—-MEASUREMENT OF THE SPEED OF GLACIERS.—-ABLATION.
'—~SUB-GLACIARY STREAMS.—-- TERMINAL ARCHES.“ CONTRAST BETWEEN
THE GLACIER ICE AND THE SURROUNDING VEGETATION.
LIKE all other rivers, the glacier bears along with it a certain quantity
of alluvium, which it ultimately deposits at the end of its course, after a
lapse of time which varies in length. The moving surface of the ice re-
ceives all the debris which has been detached from the bare cliﬂ's by the
action of thaw, rain, wind, or other meteoric agents, all the avalanches of
stones which come down with the snow from the ravines above, all the
fragments of those immense ruins which tower up in the form of needle-
shaped peaks or jagged ridges. Glaciers which are shut in between
schistose mountains, the sides of which easily crumble away, are often
quite black with debris ,' others, on the contrary, which are commanded
by more compact rocks, or long, snow-clad ‘slopes, retain partially the
whiteness of their surface; but all carry with them along one or both of
their banks a certain quantity of rocks and stones belonging to all the
geological formations of the basin. Borne along by the ice, this rocky
rubbish commences but slowly its journey toward the sea, where it ar-
‘rives, sooner or later, in the form of sand or mud.
Some parts of the debris which fall from the cliffs into the bed of the
glacier gradually make a hole for themselves and disappear in the depth
below ; others, on the contrary, seem to rise in consequence of the gradual
sinking of the surrounding surface. In fact, if a small pebble of a dark
color lies during the day on a bed of ice, it will rapidly absorb the solar
rays, and, melting the particles on which it rests, will descend slowly into
the little well which it bores by the action of its own heat; sometimes the
disappearance of all the debris gives the surface of the glacier an appear-
ance like an immense sieve. The result is, however, quite different when,
instead of isolated stones, great masses of rock roll down upon the glacier
in a body. These large heaps are, it is true, warmed on their surface by
the solar rays, but at the same time they protect the space of ice that they
cover against the heat._ Therefore, all round them, the surface-layers of
the glacier gradually melt and evaporate, while these lumps retain their
original height, and seem even to increase, like volcanic cones. Finally,
however, the base of the cone of ice which bears up these heaps of rock
gradually melts away, the debris slide down on the slope which has become
too steep to keep them up, and soon after the hillock sinks and disappears.
GLACIER TABLES. 193
A phenomenon of the same nature takes place when a large block of
stone—such as a slab of schist or granite—covers the ice and shelters it
from the rays of the sun. The surrounding surface slowly sinks, leaving
underneath the slab of stone a pillar like a marble column crowned with
a heavy capital. However, on the glaciers of the Alps and other mount-
ains of the temperate zone, these slabs of stone never lie horizontally on
their pedestals; being shone upon obliquely by the southern sun, they re-
ceive the most heat from this quarter, and they warm the corresponding
side of the pillar supporting them. Simultaneously the solar rays melt
away some of the lower portion of the pillar of ice, so that the slab grad-
ually bends over toward the south. As a matter of theory, as Tyndall

Fig. 60. Glacier-table; after Tyndall.
says,* these slabs ought to turn, like a kind of sun-dial, simultaneously with
the sun, and thus mark every hour of the day; but this daily rotation is
too slight to be perceptible, and the general result is all that can be ascer-
tained—that is, the inclination of the stones toward the south. Ultimate-
ly, the inclination becomes so rapid that the stone slab falls from the top
of its ‘column, and immediately after begins to form a second ; thus pillar
follows pillar under the rocky masses borne along by the ice. Some of
these natural clolm-ens have been noticed having an area of twenty-four to
thirty square yards. Among the variously-shaped rocks which are car-
ried along by the glacier, some attain a bulk of thousands of cubic yards.
' The rock called Blaustein, which we now see in the valley of Saas, is a
mass of serpentine ‘more than 10,000 cubic yards in bulk, which, in 1740,
was still upon the glacier ‘of Mattmarkf - .
It is perfectly natural that at ﬁrst all the rocks and debris which have
* Glaciers of the Alps. 1' De Charpentier, ‘Essai sur les Glaciers.
N
194 THE EARTH.
rolled down should lie at the footof the high walls of rock which over-
look the glacier. These heaps constitute the lateral moraines, or ranges
of stones, running in a line on each side of the bed of ice like roughly-
made ramparts, and participating in the movement of the frozen river.
Sometimes, however, these broken rocks are buried in the hollows which


Fig. 61. Lateral Mcraines.
open either at the base of the mountain, or at a little distance from it in
the heart of the glacier itself The moraine is then concealed in the
midst of the glacier, but, embraced as it is by the whole moving mass of
ice, it does not fail to descend toward the valley; and often, when the up-
per layers are melted, it again makes its appearance above the surface
and overtops the level of the glacier. Some of these lateral moraines rise
to a height of 70 or 80 feet above the current. On the Murzoll, in the
Austrian Alps, there are several which are more than 100 feet high.
Below the conﬂuence of two glaciers, the moraines which skirt both
sides of the base of the central promontory unite like the solid waves
which bear them along, and thus form in the middle of the river of ice a
third moraine, running parallel to those on the edges. If a' third tribu-
tary glacier runs into the principal current, a second medial moraine is
formed on the glacier, parallel to the ﬁrst; ﬁnally, however great may be
the number of the tributaries, each of them will unite one of its lateral
moraines to that of the principal glacier, so as to form another medial
ridge of debris. By examining the surface of a glacier of regular devel-
opment, such as the Mer-de-Glace, or the glaciers of Geisberg or Both-
moos, the number of ‘its tributaries may be reckoned by the number of
walls of debris which extend along the line of its current.
A number of these medial moraines disappear at their very source in
the depths of the erevasses. They remain buried in the heart of the
glacier until the layer above them is entirely melted, and then, after hav-
ing traversed a greater or less distance, they reappear on the surface as if
they had been upheaved by some great ‘eruptive force. It is curious to
notice how, at a distance of manyhundreds of yards, or. even 80111.6. miles,
.the enormous alluvium of rocks retains its‘ original direction. . The. rivers
of ice poured out by the tributary into the common bed‘ ﬂow on side by
side without mingling their masses; in the same way rivers, the waters
of which differ in color, like the Missouri and the Mississippi, roll on to-
gether in the same channel for a long time without intermixing their


LL .4
511891 Erhard, 12 r. Dusuay’bouin.
. ' ‘\ \_> \‘P ' “i
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Drawn by Arvuillemin afmr Son‘xlar
HARPER, a. BROTHE RS, NLW Y0 RK


TERMINAL MORAINES. 195
waves. The steep faces of the side glaciers sometimes exhibit most clear-
ly the vertical line which separates the contiguous masses of two tribu-
taries which have ﬂowed in above. -
After a long course of years, or even centuries, the masses of the lateral
and medial moraines reach the lower extremity of the glacier, and fall
one over the other down the slope of the valley. During a succession
of ages, the stones which are too heavy to be carried away by the action
of water are collected together in enormous heaps below the river of ice.
‘ \\ \<


\
d
z-j
'13,,
\‘ ‘
Figs. 62, 63, 64, 65. Frontal or Terminal Moraines.
These heaps constitute the great frontal moraines which obstruct the ap-
proach to so many glaciers, as these formidable slopes area-‘sometimes
hundreds of feet in height. These moraines, consisting of a vast rough
alluvium,pushed on by the ice, make their way for a greater or less dis-
tance into the valleys, according to the pressure of the masses above.
When the force of the latter increases, the accumulation of blocks moves
onward, and, in its irresistible progress, overwhelms plains, rocks, and tor-
rents. On the other hand, when the glacier recedes, the enormous barrier
in front of it remains isolated, like a rampart built up across the valley,
and, higher up, the glacier constructs another frontal moraine with the


4886


__.~~_-___._~ ___...___—.___._~_. ____..__-___- ..,_ .. .
N . .. ./ .
I
M / / / ,_ in w
Fig. 66. Proﬁle of the Valley of Avoca, New Zealand; after Julius Haast.
debris it carries down with it. In several gorges, especially in that which
extends below the glacier of the Rhone, and likewise in the New Zealand
valley of Avoca, six or seven moraines in a line have thus been abandoned
by the ice, the lower extremity of which has receded upward. But if the
196 . THE. EARTH.
frozen river reeommences its gradual advance, then these-heaps will be
added to the other debris, and all these old moraineswill unite in one gi-
gantic moving rampart. In a similar manner, glaciers which have dimin-
ished in size, and have stranded their lateral moraines on the adjacent
slopes, may, when they again increase, once more pick up these debris:
like a ﬂooded river carryingoff the drifted wood left upon itsbanks, the-
river of ice may impel the mass. of blocks a second stage toward the sea-
In addition to these various kinds of lateral and medial moraines, the
surface of some glaciers exhibits concentric bands of mud and rubbish, ar-
ranged, in some cases, with the greatest regularity. The Mer-de-Glace, in
the Mont Blanc group, is a remarkable instance of this singular distribu-
tion of these layers of mud 011 the glacier ﬁeld. The ﬁrst bands of mud
appear below the great cataract of séracs which are found between the
néoé of the Col-clu-Géant and the glacier proper. During the heat of
summer, when the renewed activity of the glacier communicates a more
rapid impetus to all the layers in motion, the fallen rubbish accumulates
in a circular rampart at the base of the escarpment,'and then, carried
away by the current of the river of ice, advances slowly in the rear of
other ramparts which had fallen previously. Mud, dust, and fragments
of every kind gradually ﬁll up the furrows made between the raised bar- .
riers of ice; the latter gradually melt, and ultimately assume the same


up 1'‘: ,| y I ‘ I I/
I’ ,1, I I Vu‘drﬁi I’ " ‘ii ‘/ I .
// \ as .11 m n... misfit" . l M ‘-" ..
7/ """";- s‘;_ / /’ [1,, V .,,, ,‘t \ . \ } -l'rlll//'/////fylt \ -------~ - n'lhl' 17 / 1 / Miran’ ' i .j- // I . . ;.
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- ____/
‘____


1 ” " *r’r‘’
1/ I i ""V Y
j‘l/Mi’im.hlllllknXt. \ ll, JW/
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Fig. 67. Ribbons of Mud,Mer-de-Glace; after Forbes.
level as the general surface of the current, but the belts of brown or red-
dish mud still retain their ribbon-like arrangement, and,like the concen-
tric undulations which form in smooth water, present at ﬁrst an almost
perfect semicircular curve. But at the contraction of the ravine atTré—
laporte, where the whole river of ice is compressed and is compelled to ‘
pass through a narrow _channel, the belts of mud are drawn out toward
the'centre on account of the increased rapidity of the'movement which
carries them along. These zones of mud, the curves of which are in a
contrary direction to those of creoasses, may, therefore, be looked upon as
regular ﬂoats indicating the direction'and exact progress of the current
of ice. Perhaps, also, in each interval between the ribbon-like belts we
ought to ‘see the precise measure of the annual growth of the glacier, and
thebelts would resemble the rings of wood which trees produce every
ANNUAL 1V0 TI ON OF GLA CIERS.
year, by which we are enabled to calculate the age of the trunks. If this
were the ease, the central part of the Mer-de-Glace would entirely pass
away in about forty years, and the average rate of speed would be about
23;}; inches a‘day, which agrees,‘ in fact, with the actual measurements
which have been made by various observers of the advance of the
glacier. ' '
When several generations of savants shallhave followed up, one after
the'other, this kind of investigation, we shall perhaps learn the exact speed
at which the stream ‘of ice 'moves onward.‘ This will be effected by drop-
ping into the deep fractures on the highest point of the glacier various
objects, which the mass will carry on with it down to the bottom of .the
gorge, and will ultimately leave bare at its terminal moraine. A ladder
which Saussure left, in 1788, at the foot of the Aiguille—Noire, when he as-
eended'Mo'nt Blane, was found, in 183.2,‘at a distance of 4757 yards below.
The ladder had,'therefore, descended during these forty-four years at an
average annual speed of 108 yards, or, nearly 11 inches a day. A knap-v
sack which, in 1836, fell into a crevasse of the glacier of Talefre, traveled
more rapidly than Saussure’s ladder; it moved on at the rate of 140 yards
a year, or nearly 14 inches‘in the twenty-four hours. But all these‘ ob-
servations fail in serving‘ as exact measurements of the real speed ‘ofthe
mass of the glacier, for it would be necessary to know'precisely if . the
foreign bodies which were carried along lay in the central part or onfthe
edges of the icy current, in its very heart or inthe vieinityofthe bottom.
However thi'smay be, approximate ealeulationslead to thebeliefthat the
snow that falls on the Col~du'-Géant takes about one hundred and, twenty
years ere it arrives, changed into ice, at'athe lower extremity of the Glacier
des Bois.* . - . ' ' - ' "
Human remains, too, have unhappily served as means for estimating
the rate of movement‘of'the ice. ‘In 1861, 1863, and 1865 the Glacier. des
Bossons has yielded up the relics of three guides who fell, in 182.0, into .the
ﬁrst crevasse opening at the foot of Mont Blane. These buried remains
had, therefore,'during a period of more than forty years, passed over a
space of about three miles and three quarters, des'eendin'g'at the rate of
160 to.' 170 yards eaehyear. In the year '1860 a more slowly-moving
glacier in the Austrian Alps, which ﬂows in the Ahrenthal, threw out a
well-preserved corpse, still clad in‘ a dress the ancient fashion of which
had been abandoned by the mountaineers for centuries} * :
Each glacier, taken as a whole,'may be looked upon as forming two riv-
ers, one of which takes years, or even a century, in descending from the
summits into the valley, having assumed the shape'of solid ice; the. other
ﬂows down in a few days, and in the day-time assumes the appearance
of a stream. ' In summer, the phenomenon, which. has been designated by
the name of ablation—that is,‘ the surface-melting of. the ice—takes place
rather rapidly; In the month of August, on the glaciers of the Central
' *Helmholz, La Glace'et les Glacicrsl' ' ' ‘ ‘ ' “ -' ' 1' Adamello- Grupp'e ; Mittlzeilu'ngen von Petermann.
198 THE EARTH.
Alps,* the thickness of ice melted averages from one to 1% inch a day, and
during a series of days which are favorable to the melting process the
layer of ice which changes into water is still more considerable. Accord-
ing to M. Desor, the mean ablation in a spot favorably situated in the
middle of the Glacier de l’Unteraar rose to 2% inches a day during sev-
eral months. On the Glacier du Gurgl ((Etzthal), not very far below the
lower limit of the névé, Sonklar found, in the month of August, ﬁve sur-
face-rivulets which together discharged 155} cubic yards of water a min-
ute, 45 gallons a second; and on the great glaciers of the Swiss Alps tem-
porary water-courses must doubtless be formed of much greater impor-
tance. In autumn and winter the amount of ablation is diminished,but
this phenomenon rarely ceases altogether, and in spots which receive the
solar rays, or are touched by the warm mists of the plain, small rills of
water hollow out a bed for themselves in the ice and among the debris of
the moraines. M. Desor has estimated the mean ablation on the Swiss
glaciers as amounting to 10 feet a year, or 03176 inch a day.’r
The thawed water which trickles over the surface of a glacier sinks into
the crevasses and the moulz'ns, and makes its way from ﬁssure to ﬁssure
to the deepest recesses of the gorge, now ﬁlled up by the frozen river.
Owing to its temperature being somewhat above freezing-point, the
water, when collected in this hidden bed, and here and there mingled
with the ﬂow from springs, thaws a certain quantity of ice above its
course, and thus opens out a free passage toward the valley. The stream
which gushes forth at the base of every glacier represents, in its annual
discharge, the whole of the snow which falls in the gorges and on the trib~
utary escarpments. All that has to be deducted is the moisture which
has evaporated, and the water which is lost in the clefts and holes of the
mountain. '
Thus several of the rivers which spring from glaciers afford a very con-
siderable ﬂow of water. The discharge of the Aar, as it springs from the
ice, ﬂuctuates between 5 and 30 cubic yards of water a secondI The
Rhone, the Rhine, and the Arveiron also form considerable streams as
they issue from their changeable grottoes. In summer, when torrents of
water rush forth from the glacier, they bear with them masses of clébrz's
and excessively ﬁne sand and mud, proceeding from the continual grind-
ing of the rocks by the under-surface of the glacier. The water holding
this matter in suspension is yellow, gray, or blackish, according to the
nature of the rocks over which it ﬂows in its sub-glacial course. During
the cold season, when it is all frozen along its rocky bed, the stream
usually becomes perfectly limpid ; nevertheless, a certain number of
mountain streams are mentioned, the color of which always resembles
that of the ice itself; the quantity of small clébrz's with which they are
charged gives them a shade both turbid and bluish, as if they were mixed
with milk.
* See Agassiz, Martins, and Sonklar. i‘ Excursions et Séjonrs dans les Glaciers.
I Dollfuss-Ausset, Mate'rz'anx pour servir a Z'Etude des Glaciers.
ICE-0A VERNS IN GLA CIERS. 199‘
An arcade of vast proportions generally rises over the source. Some
of these open out with gigantic and. almost regular portals with pointed
arches, hollowed out of the ruin-like cliﬁ' which terminates the glacier.
But each advance and each retreat of the mass of ice results in an altera-
tion of the shape and appearance of the grotto out of which the stream
ﬂows. Sometimes the vault above partially gives way under the weight
of the upper strata, and large sloping layers become detached from the
sides or from the arch; ﬁssures and crevasses, like the clefts in cavernous
rocks, out through the walls of ice in every direction, and every now and
then blocks break away and fall with a crash into the torrent. Visitors,
therefore, who wish to admire closely the vault of crystal, and to contem-
plate the lovely eﬁ'ects of light which are produced by the reﬂections of
sunshine passing through the transparent ridges at the edges, and falling
on the blue-tinted walls, are not able at all times to venture Without im-
prudence into the depths of the cavern. Blocks of ice and rocks often


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obstruct the ﬂow of the water, and it is but very rarely that these deep-v
ly-caverned water-courses preserve much regularity of form for any con-
siderable time.’ Nevertheless, several instances are mentioned of men
who, having fallen into the bed of the stream through a crevasse in the
upper part of the glacier, have been able ‘to ﬁnd their way again into the
open air, by following the course of the water across the scattered debris
and through the frightful darkness of these unknown gulfs. In the very
200 THE EARTH.
depth of winter, the entrance to'the terminal arches is sometimes entirely
obstructed by snow and ice; the cold checks the torrent, and freezes it at
the mouth of the glacier. This was the case in January, 1854, when the
bed of the‘Landquart, which is generally fedby the two important gla-
ciers of Sardasca and‘ Silvretta, did not receive a single drop of water.*
In 1839, the Arveiron itself was entirely dried up]L '
The mind is all the more vividly impressed with the majesty of these
great rivers of ice when the vegetation surrounding them is green and
luxuriant, and forms a more striking contrast with the white and blue-
tinted cliﬂ's. Some of the most beautiful glaciers in the Alps descend
' right down into'the midst of forests of ﬁrs, beeches, and larches ; and it
is through the green foliage of the trees that we catch a glimpse of the
white waves of the icy sea and the dark walls of the moraines. In other
places, ﬁelds of corn, or even vineyards and gardens, extend to the very
base of the solid river, and sometimes, it is said, they have to mount upon
fallen blocks of ice in order to gather the fruit off the branches of the
cherry-trees. Thus the cultivation of the temperate zone, and the ice-
ﬁelds of the pole, which on the continent itself are separated from each
other by thousands of miles, are here brought into close juxtaposition;
man’s labor and Nature in her inviolable grandeur come in contact here
without the least transition. This sudden passage into a virgin region,
devoid of all activity, conveys an effect of grandeur which deeply im-
presses the soul. It is difficult to restrain a species of dread at the sight
of these enormous rivers of ice slowly marching on, from century to cen-
tury, with their white or bluish layers, 300 feet high, descending gradu-
ally, en masse, a few inches a day, carrying with them the fragments of
mountains, and grooving out in their course deep ‘furrows in the bed of
rock through which they ﬂow. These glaciers seem as motionless as the
peaks which tower over them, and yet they roll on as surely as the
stream to which they give rise. The solid waves which‘ roughen their
surface rise and fall, in the long run, just as those of the sea. They, too,
have their eddies and their Whirlpools; and the mighty moraines which
they throw from them at the outlets of their gorges are as much an al-
luvium as the mud or sand of a river or the deposits forming along the
sea-shore.
* William Huber, Les Glaciers. ’[ De Charpentier, Essai sur les Glaciers.
GLACIERS OF LANGTHAL AND GURGL. PLXJII


0N0‘,
176.9-
lh‘awnbyAWillemin Sonkhn
HARPER. 8'. BROTHERS. NEW' YORK
Eng 9 by Erhard, \2 rDuguay‘Tkom‘n.
ADVANCE AND RETREAT OF GLA C'IERS. 201
CHAPTER XXXIV. '
PROGRESS AND RETIREMENT OF GLACIERS. '—-APPEARANCE OF THE BED
\VHEN ABANDONED BY THE ICE.-—ROCHES MOUTONNEES.-PARALLEL FUR‘
ROWS.
IN several parts of the Alps the mountaineers, inﬂuenced by the super-
stitious ideas of former days, continue to believe that the base of a gla-
cier advances and recedes alternately every seven years.* The fact is,
that if the progress and retreat of the ﬁelds of ice take place under the
inﬂuence of any regular law, thisv law, which, at any rate, must be dis-
turbed by a host of special local phenomena,vhas not yet been discov-
ered.‘ Since the date when regular observations ﬁrst began to be made
on the-forward motion'of the Alpine glaciers, they have been subject to
very considerable ﬂuctuations in their movements. Sometimes they have
advanced, sometimes they have receded, and'somet-imes, even, they have
remained stationary for several years together, but it appears that, on
the whole, they have moved onward. Several of the Swissa'glaciers—
those of Zmutt, Aletsch, the Rhone, the Aar, and Grindenwald—have in-
creased in length in'their rocky beds. m
It appears to be certain that, in spite of temporary retirements, some
ﬁelds of ice, even‘in the last century or two, have extended suﬂiciently
to close mountain passes which were once practicable even for horses.
Thus, several passes “in the groups of Mont Blanc, Monte Rosa‘, and the
Bernese Oberland,'which still remained open in the ﬁfteenth century,'and
were indeed used for troops, became more and more diﬂicult to cross, and
ultimately, during the course of the eighteenth century, have been ren-
dered inaccessible, either for horsemen or pedestrians]L The Lotschen-
pass,“ near vthe Gemini, which ‘was used less than a century back, is now
closed up. Several facts of this kind are instanced in the Tyrol. One of
the (Etzthal glaciers, thatof Gu'rgl, has certainly advanced a mile and a
quarter since the ‘year 1717, for that was the date when it commenced to
dam up the side valley of Langenth'al, in which the stream has accumu-
lated to form a lakejj In like manner, in Asia, the glaciers of the Kara-
korumv seem to have uniformly advanced during the course of a century
at'least. The pass of J usserpo was formerly'accessible to horsemen; it
can now onlybe crossed on ‘foot. The glacier of Baltoro and the ancient
pass of the Mustack have become impracticable.§ But this is not all,
* \Villiam Huber, Les Glaciers.
‘I’ Venetz, Denkschriften der Sckweizeriscken Gesellsclmft, Part I., 1830.
1 Sonklar, @tztkaler Gebirgsgruppe.
§ Godwin-Austen, Journal of the Geographical Society Qf London, 1846.
202 THE EARTH.
several Alpine glaciers are named as being of recent formation. Among
these are the Dreckgletscherli (“little glacier of mud ”) of the Fauldhorn,
which was not in existence at the commencement of the century; the
Rothelch, a ﬁeld of ice on the Simplon, dates from 1731; another, de-
scending from the Galenhorn, in the valley of Saas, was formed in 1811;
lastly, the ﬁne Glacier de Rosenlaui itself is of modern origin'.*
Are the glacial encroachments which have taken place on various
mountain chains to be attributed to some cause acting generally over the
whole planetary surface? This is the idea which M.'Adhémar asserted,
which, too, is still maintained by his disciplesfr According to their view,
the gradual cooling of the northern hemisphere during the present period
is completely proved by the increase. of the glaciers of Greenland, the
Alps, and the Himalaya; but the observations made up to the present
time are neither numerous nor decisive enough to,authorize any such con-
clusion. And even if there was a uniform advance into the valleys on
the part of glaciers every where, their progress might also be attributed
to an increase of the humidity contained in the air, or to some change in.
the general direction of winds. Numerous instances may be mentioned
of glaciers existing on the ﬂanks of the same mountain, advancing with
more or less rapidity according to the quantity of snow that falls directly,
or is displaced after its fall by the atmospheric currents. Sometimes,
even, a glacier has been noticed to increase in length, while near it, or on
the opposite side of the mountain, another ﬁeld of ice has diminished in
size. Phenomena of this kind are evidently owing to the unequal distri-
bution of snow on the various slopes. Very- considerable falls of debris
on the surface of a glacier will also result in the prolongation of the icy
current into the valley, because the layer of rubbish causes the annual
ablation to decrease to a very important extent. Perhaps, even, as Otto
Volgar points out, the gradual upheaval of certain mountain groups is
also one of the causes‘which contribute to the extension of rivers of ice]:
Nevertheless, if during modern times a certainnumber of glaciers have
unquestionably advanced, others have certainly receded, and consequently ,
their bulk has become lessened. Thus, in the Pelvoux group the two im-
portant glaciers of Bonnepierre'and Chardon have continued to decrease
in length and thickness since the year 1850, and this movement of con-
traction was still continuing in 1861. In like manner, in the Tyrolese
Alps, all the glaciers of the Adamello- group are diminishing regularly.
The Mandron, the most important of all, has been retiring at least since
1825, and in the year 1864 especially had lost about 66 feet of its length.
In the same year, the glacier of Fargorida lost nearly 100 feet, and the
inhabitants of the country say that since the beginning of the last centu-
ry it has continued to diminish in importance.§ It appears also that, in
certain places, the ﬁelds of ice reposing on the summits have also disap-
peared, ‘
* Tschudi, Le Monde desiAlpes, vol. iii. 1 ' 'l' Vide above, P- 67'
I Untersuchungen iiber das Phdinomen der Erdbehen, vol. ii. § Payer, Adamello- Gruppe.
MOTION OF THE ICE STREAM 203
During the forty years which have elapsed from 1826 to 1866, the glad
ciers of Mont Blanc have'also lost much both of their length and of their
force, evidently because the snow in winter has been less abundant, and
the summers on the average have been hotter. The Glacier du Tour,
which once invaded the valley of Chamounix, has retreated, on the whole,
567 yards since 1854, and does not reach. beyond one of the upper pas-
sages, invisible from the road. A stone which marks the precise spot
reached by the Glacier des Bois, or Mer-dej-Glace, in 1826, stood, in 1865,
at 424 yards from the arch of the Arveiron,* and at certain spots, accord;
ing to the evidence of M. Bardin, the ice had decreased more that 100'
yards. The Glaciers des Bossons and Argentiere, the two other great
glaciers of the valley, each of which used to threaten the village that was
nearest to their frontal moraine, have receded 362 yards and 197 yards
respectively during the period from 1854 to 1866. Although they have
diminished in length more slowly than the Glacier du Tour, it is evi-
dently because the basin which they occupy is much more considerable,
and the névés above have never ceased to feed them. We must also add
that, during these twelve years, the superﬁcial ablation has in every case
perfectly corresponded with the retirement of the ice. The Glacier des
Bossons has lost about 88 yards in thickness. Previously to 1854, the
lateral moraines lay much lower than the mass of the glacier; they now
tower over it at a mean height of 82 feet.1- ‘ ‘ ‘
The true system of action of glaciers seems to be pointed out by the
alternations of progress and retreat, established both by oﬁicial docu-
ments and scientiﬁc observations with regard to the lower part of the
Glacier de Vernagt, in the (Ezthal group. The ﬂuctuations of this river
of ice have been noticed for nearly three centuries, and the ehronicler
who mentions them for the ﬁrst time in 1599 adds that these motions to
and fro are the “natural habit” of the glacier. The Ver'nagt descends
rapidly toward the valley, and, striking against a wall of rock which
rises up directly opposite to it, obstructs the passage of the Rosenthal
waters, which there form a lake. Then the enormous obstacle gradually
sinks, the glacier slowly recedes toward the steep slopes, until some
fresh impulse of the névé again forces it on toward the bottom of the
valley.’ Without reckoning the less important ﬂuctuations, we ﬁnd that
the intervals between each great enlargement have been seventy-eight,
ninety-three, and seventy-three years, which gives an average of eighty=
four years. Like rivers of running water, the Glacier de Vernagt hasits
ﬂoods and low-water seasons. From 1843 to 1847, at the time of the last
irruption of the ice, it advanced 1455' yards, and spread out in the valley
over a width of 1382 yards. At the lower part the ice was not less than
518 feet above the stream, and, higher up, the glacier, at certain spots,
attained a thickness even twice as great. The swiftness of progression
of the front of the glacier was quite unexampled. During'the ﬁrst two
' * Payot, Bibliotlzéque de Geneve, September, 1866.
‘l’ Martins, Bibliotlzéque de Genéve, July, 1866.
204 ' THE EARTH.
years it exceeded 6% feet a day; at the end of the month of May, 1845,
it‘ attained a rate of progress of 42 feet in the twenty-four hours. On the
1st of June the speed measured was not less than 6 feet 3 inches an hour,
equal to about 150 feet in one day. The motion of the ice could be de-
tected'even with the naked eye. The thunder of the opening crevasses
and of the séracs falling down was incessant. Finally, however, this ter-
rible invasion, which threatened all the valleys below, was arrested, and
the stream of ice receded, giving a passage to the lacustral waters which
it had penned back. Since this epoch the lower portion of the Glacier de
Vernagt has continued to decrease, but still here and there, on its former
bed, it has left islands of ice protected against the heat of the sun by
masses of clébris. After resisting the elements for years, these isolated
heaps sink and ﬁnally disappear.*
By means of the temporary or permanent retirement of certain glaciers,
we are enabled to ascertain the effect produced by the gradual ﬂow of
these enormous masses on the bottom and sides of their rocky beds.
The numerous observations of M. Dollfuss-Ausset seem to have estab-
lished the fact that above 8530 feet, that is, above the ideal line of per~
petual snow, the Alpine glaciers only rub away the stone in a quite im-
perceptible degree, on account of the freezing which causes them to ad-
here to the surface of their bed. But below this altitude the incessant
friction of the ice and the gravel it carries with it gradually removes the
most prominent roughness, and ultimately gives a rounded surface to all
the projections. To use a comparison which is frequently applied, a
glacier passes over the ground like a gigantic plane; it works over the
bottom of its bed, and overriding all the projecting points, grinds them
down, pulverizes them, and reduces them to the condition of sand. It
subsequently makes use of this very clébris for rubbing away and polish‘
ing the rocks in its bed; hence, therefore, arises that mammillated aspect
of the old projections over which the heavy mass has glided for so many
centuries. Clefts and fractures appear like dark lines of shade on these
round, white, polished lumps, which sometimes have the appearance of
.heaps of wool placed upon the ground, or of ﬂocks of sheep. They are
thus known under the name of roclzes moutonnées, a name employed for
the ﬁrst time by De Saussure.
In making its way toward the plain, the glacier does not conﬁne itself
to rubbing off the more prominent parts of the rock; it also scoops out
the stone in certain places by means of the variously-shaped blocks of
greater or less hardness with which it is armed on its lower face, which
act as so many chisels on the rocks beneath them. The stones which are
slowly impelled toward the bottom of the glacier are scratched as by
stylets of stone, and the rocky bottom of the gorge itself is furrowed up
and down as by a ploughshare. The walls of the bed of ice are likewise
grooved by the rough edges of the blocks carried along on each side of
the current. Nevertheless, wherever the bed of the glacier is narrowly
* Sonklar, @tztkaler Gebirgsgrnppe.


GLA'QIER or VERNAGT
in the Autumn of 1856 P
I


4‘—' - ——_
Dugnayll‘r onin Drawn by A Vuill emin after Karl Sonklar.
~ HARPER 8c. BROTHERS. NEW YORK
sage by Erhard, 121-.


ICE-PLAJVHVG AND GROOVING. 205
conﬁned between two promontories, it is only the upstream faces of the
latter which present streaks, furrows, or other traces of rubbing, and the
down-stream faces retain all their natural clefts and original projections.
Sometimes, in portions of the bed abandoned by the ice, we may meet
with circular cups or basins, like the holes which the sea or rivers hollow
out on their shores. These glacier-cups originate in a similar way to
those in river banks and cliffs: they are formed by stones incessantly
turning round and round under the inﬂuence of sub-glacial torrents, or
the cascades pouring down into the gulfs of the moulz'ns.
206 THE EARTH
CHAPTER XXXV.
DISTRIBUTION GLACIERS OVER THE SURFACE OF THE EARTH.
MOUNTAIN summits which rise above the limit of perpetual snow do not
all give rise to rivers of ice; the concurrence of several meteorological
and orographical conditions is necessary in order that the snow and nevé
should be changed into glaciers. In the ﬁrst place, it is requisite that the
snow zone of the mountain tops should be of some considerable breadth,
and that vast beds of névé—those reservoirs for the supply of glaciers-—
should be formed in the mountain amphitheatres and in the upper pla-
teaux. It also requires that the winds which blow against the mount-
ains should be charged with an amount of humidity sufficient to leave
immense beds of snow on the summits and the slopes. Added to all this,
the gorges which open into the thickness of the chain must be of a gen-
tle inclination, so that the snow may not slide down immediately into the
valleys below in the form of avalanches; and the mountains themselves
must be grouped in such a way that their gorges unite to form a common
basin, where the snow may be ﬁnally elaborated in order to constitute
genuine rivers of ice. Lastly, it is indispensable that the various seasons
of the year should afford extremes of temperature sufficiently great to
allow of the phenomena of thawing and regelation taking place in the
masses of névé. It is owing to the great uniformity of climate that so
little ice is seen on the sides of the lofty snow-clad peaks of the equato-
rial Andes.
The large number of different conditions which must all be combined
as necessary to the formation of glaciers will readily show why these
rivers of transformed snows are comparatively very rare in the regions
of torrid and temperate zones. They are produced with a high degree
of uniformity and grandeur only on the sides of lofty summits; while on
mountains of less elevation, as those of the Vosges* and the Riesenge-
birge, they are formed in very snowy years in the recesses of ravines shel-'
tered from the sun. It is,‘however, only in the vicinity of the poles that
the ice-system manifests all its magniﬁcence, and indeed constitutes the
predominant feature of nature.
In Europe, the Central Alps form the orographical system in which all
the conditions necessary for the formation of glaciers are fulﬁlled at the
greatest number of points. These mountains, too, will ever remain for
savants the classical region of glaciers, for among them a De Saussure, a
Charpentier, an Agassiz, a Rendu, a Forbes, and a Tyndall have gone on
from discovery to discovery, and have ultimately brought to light the
* Collomb, Comptes Rendus de Z’Académie des Sciences, 1846, vol. xxi.
GLA CLE'RS OF THE ALPS. 207
true theory of the motion of ‘ice. There are in the Alps nearly 1100 gla-
ciers, a hundred of which may be looked upon as primary glaciers.* The
total surface of the ﬁelds of snow, neve, and ice on the Alps is estimated
by the brothers Schlagintweit at 1177 square miles, or about one seventh
of the whole area of the great mountains from the Pelvoux to the Gross-
Glockner. The glaciers of Mont Blanc alone, though inferior in extent to
those of Monte Rosa, cover a surface of 109 square miles. According to
M. Huber, their total mass amounts to nearly 1834 millions of cubic yards,
and represents a body of water equal to the whole of the discharge of the
Seine during nine years. a
The glaciers of the Alps descend on the average to a point about 7414
feet above the level of the sea, that is, about 1650 to 2000 feet below the
level of perpetual snow; but there are a great number of glaciers, and
they are generally the most important, the base of which is below the


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Fig. 69. Glaciers of the Alps—after A. and H. Schlagintweit.
a, a, Lower limit of persistent snows. b, b, Lower limit of secondary Glaciers.
mean altitude of about 7000 feet. The Mer-de-Glace, the receptacle of
the greatest part of the snow of Mont Blanc, reached 'in 1862, at the
source of the Arveiron, a point which is only 3659 feet above the level of
the sea. The Glacier des Bossons, fed by the snow of the same mount-
ain group, descended to a level of 3605 feet; lastly, the lower glacier of
Grindenwald, which of all the glaciers in‘the Alps pushes its way the far-
thest into the valleys below, has its terminal grotto placed at only 3225
feet’r above the sea-level. This fact must be attributed to the northern
aspect of the glacier, to the narrow straits of rocks through which it has
to ﬂow, and its rapid declivity, exceeding 14 degrees. With regard to
the Glacier d’Aletsch, which in its dimensions is the most important of all,
and rolls down a wide current over a total length of 23,304 yards, it does
not descend into the lower gorges, and in 1860 it stopped at an altitude
of 5137 feet ‘above the level of the sea. The Glacier d’Aletsch owes
* The brothers Schlagintweit. The Bavarian savants have omitted in their list many gla-
ciers both of the Western and even the Central Alps. The ice area in these mountains is
probably somewhat larger than they have estimated. it. i
T Studer, Bibliotlzéque‘de Geneve, September, 1866.
208 THE EARTH.
its enormous development to the great body of névé collected in the
high mountain hollows. This glacier has atotal area of no less than


130,000,000 square yards.
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The glaciers of the Tyrol are numerous, since, in the (Etzthal and Stu-
baier groups alone, Sonklar reckons 309 glaciers, 16 of which are of the
GLA 0123s 01? THE’ ALPS. 209
ﬁrst class. It is true that, in his enumeration, the learned explorer of the
(Etzthal has not omitted a single one of the small glaciers lying on the
sides of the mountains. Some of the rivers of ice,,espeeially the Vernagt,
the Gepaatch, the Murzoll, and the Gurgl, are important streams, and well
known to savants through the investigations of the brothers Schlagint-
weit, Simony, Sonklar, and other geologists; they are, however, inferior
in extent to the principal Swiss glaciers. This minor importance of the
Tyrolese ice-rivers, compared with those of the Western Alps, is principal-
ly'to be attributed to the unequal distribution of_ snow in the two coun-
tries during the various seasons of the year. Not only does it rain and
snow in larger quantities on the Swiss mountains than on those of the
(Etzthal, but in the latter groups the, snow falls principally in summer,
and consequently melts before it has a chance of increasing the mass of
the' glacier. The winter snows, which alone contribute to feed the ice-
rive'rs, are ‘more than twice as abundant, on the lofty summits of Switzer.
land, as on those of the Tyrol._* The annual layer of névé which is formed
on the Bernese Alps attains, according to Agassiz, a thickness of 2 to 2%
yards,;while on ‘those of the ,(Etzthal it scarcely reaches a yard. Never-
thelessfthe latter group affords an area of 221 square milesof ice, equal
to‘ one seventh of its ‘whole surface. __
The two" other principal groups of the Eastern Alps are those of the
Ortels‘pit‘ze, south of the (Etzthal, and the Gross-Glockner,-very much
more tov the east. In the latter is situated the ﬁne‘ glacier of Pasterze,
the dimensions of which, including thejnévé, are, according ‘topthe broth-
ers Schlagintweit, 10,274 yards in length, 4494 yards in width,- and 236
yardsiin depth. The rest of the Austrian Alps possess only two. isolated
glaciers,7that of Dachstein, not far from Hallstadt, and that of .Marmolata,
above the ‘plains of Venetiafr In orderv again to meet with‘ these mighty
ice-rivers,we must turn to the other extremity of the Alpine system, to
the south and southwest of the great central groups of Monte Rosa and
Mont Blanc. There each of the great groups of Piedmont and Dauphiny,
the 'Grand-Paradis, the Vanoise and Grande-Casse groups,- the Grandes-
Rousses, and especially the Oisans, afford glaciers of the highest im-
portance. , i 7 u '
The mountains of Oisans, Pelvoux, the Ecrins, and Aignille-de-Meije are
almost as distinguished as MontBlanc itself _ in the quantity. of ice they
bear on‘ their slopes." There, is no 'regionfin. theAlps in which ‘the phe-
nomena of these vast ice-rivers, can be -better studied than in the upper
valley of the Bane, situated at the-pointof junction between the Glacier-
Noir' and the Glacier-Blane, at the foot of the pyramid of Pelvoux. - Just
at the spot where the ‘lower, extremities -of these jmi'ghty- masses,--now con-
ﬁnedbetwe'en-two vertical-w-alls'of ice, unite their lateral moraines, they
present a most perfect and striking contrast. As viewed from the plain
of debris lying between the two moraines, which is traversed by the
* Sonklar, Gitztlzaler Gebirgsgmppe.
‘l Adolf Schmidt, Oesterrez'chiscbe Vaterlandslcunde.
. O
210 THE EARTH
stream of the Bane, the Glacier-Neil- is so loaded with detritus of every
kind that it looks like an immense ﬂow of mud, such as those vomited
out by the volcanoes of Java. The real nature of this mass could not be
recognized, were it not for the gaping crevasses into 'which blocks of
stone and trains of pebbles ceaselessly fall with a dull noise. At the foot
of the glacier leans the frontal moraine, more than 300 feet high, with
muddy rivulets trickling through its rocks and creeping away slowly
among the scattered debris of the plain. On the other side the Glacier-
Blane, almost entirely free from rubbish, is terminated by gigantic steps,
themselves supported by vertical buttresses somewhat resembling a lion’s
paw. The beds are‘ of a pure white, here and there streaked with red and
gold color. From the middle arch, which is admirably curved and sup-
ported by blue pilasters, ﬂows the tributary of the Bane, with water of a
milky white. To the east, on the other side of the valley, stands the Pel-
voux, resembling a Gothic spire enriched with turrets; between each of
its peaks there are small ﬁelds of ice, which look in the distance like slabs
of white marble.
To the south of the important Oisans group, the glaciers only appear
singly in the upper gorges of the loftiest mountains. In no place do
these small isolated streams combine to form an ice-river which, like those
of the great Central Alps, pushes its way down into the valleys at the
base of the mountains. The Vise, and some peaks of the Maritime Alps,
present small ice-ﬁelds; the last in this part of the chain is that of Cla-
pier-de-Pagarin, between Nice and Valdieri.
If we comprehend in one glance the whole map of Central Europe, we
shall see that the principal glacier groups are those which surround the
mountain summits of Mont Blanc, Monte Rosa, the Finsteraarhorn, Berni-
na, and (Etzthal. The following table, from which we clearly see that
Monte Rosa is the true centre of the region of ice, shows the comparative
importance of each system of glaciers.* According to Studer, it is owing
to the heightening of the temperature produced by the lofty plateaux of
Engadine, that the ﬁne group of the Bernina is distinguished from all the
rest by the comparatively small quantity of ice which it possessesf

Mont Blane. Monte Rosa. Finsteraarhorn. Bernina. (Etzthal.


Yards. Yards. Yards. Yards. Yards.
Mer-de-Glace.. 15,966 Graener.... 16,732 Aletsch.. .. 26,246 Mortirat... 10,170 Gepaatch.. 12,357
Argentiere . . . . 10,607 Ferpecle. . 15,529 Viesch . . . . 16,185 Forno. . . . . 9,623 Gurgl . . . 10,936
Bionnassay.... 10,498 Zinal .... .. 11,701 Unteraar.. 15,638 Hmtel'elS“ 1".061
Findclen .. 11,154 TschingeL. 9,514 MFPZOH - - - 9,623
' Zmutt.. . .. 9,404 Liitschen. . 8,530 Mittelberg. 3,530
Turtmann. 8,311 Oberaar... 8,420 Vernagt--- 8.311
Ried .... . . 8,311


The Pyrenees, which lie more to the south, are neither so high, nor so
well arranged in groups as the Alps; they consequently afford a much
less extent of snow-ﬁelds and glaciers. The area occupied by the latter
* In this table, which is borrowed from Sonklar (@tzthaler Gebirgsgruppe), glaciers less
than eight thousand yards in length have been omitted.
‘l' Bibliotlzeque dc Genet-e, September, 1866.
FORMER CLACIERS or THE VALLEY or THE ADtCE PLXV.

l


; ‘If. f_' i 1;,


Section of the former Glaciers ofthe VaIley'of-"lhc Adigr-
Drawn by A.Vuillemin. 3ft‘- Momllet Engdgb; Erhard
6”?) My»: -- 1 "
or'
face-

GLA CIERS OF THE HZMALA YAS. 211
has not at present been brought into comparison with the superﬁcies of
the whole chain, but it certainly does not reach a hundredth, and perhaps
not even a thousandth,part of the ‘total surface. ' The Pyrenean glaciers,
which are about a hundred in number, are almost entirely ,semeilhes, or
summit~glaciers, and do not descend into the lower valleys. There is,
perhaps, only one—the eastern glacier of Vignemale—which assumes the
shape of an ice-river,* and the spot in the gorge where it steps is as much
as 7 208 feet above the level of the sea. Nevertheless, although the Pyre-
nees can not be compared to the Alps either in the magnitude or the
development of their glaciers, those that are found in the former chain are
in no way less remarkable for ‘their deep cre'vasses, their blue-tinted walls,
their little lakes covered with thin ice, and all those other varied phenom-
ena which confer such a charm‘on the study of the Swiss glaciers.
The Carpathians are entirely devoid of glaciers. The mountains of the
Caucasus, which, in the general conﬁguration of Europe, may be considered
as the chain corresponding to that of I the Pyrenees, are much richer in ice-
ﬁelds. One, the Desdaroki, descends as low as 6495 feet above the sea,
which gives a vertical height of something less than 12,000 feet to the
whole of the Caucasian snow and ice-ﬁelds, between the lowest moraine
and the summit of Elburz, rising to an elevation of 18,405 feet.’r Never-
theless, the glaciers of the Caucasus are not equal to those of the Central
Alps, either in magnitude or beauty, which is, no doubt, caused by the
comparatively small quantity of rain and snow which falls in this part of
the Old Continent, and also by the large amount of summer heat which
prevails there.
The most important glaciers of the northern temperate zone are prob-
ably the enormous iee-rivers of the Himalayas and the Karakorum. In
comparison with the immense ﬂows of snow which descend from the prin-
cipal summits of Asia, the largest glaciers of the Alps must be considered
as belonging only to'a secondary order. The largest glacier in the Indian
mountains—that of Biafo, in the valley of Chiggar (Karakorum)—-is not
less than 36 miles in length, more than‘21 miles longer than that of
Alets'ch, in'Switzerland. The area that it occupies is several hundred
square miles in extent, and in its vicinity there are other ice-ﬁelds, such
as the Baltoro' and Mustack, which are but little inferior in magnitude.,’[
The quantity of ice which almost entirely ﬁlls up each of these important
valleys of the Karakorum can not be estimated at less than ten times that
which lies in the Mer-de-Glace andthe Mer-d’Aletsch. It is a very re-
markable fact, in regard both to these glaciers and those of the Himalaya,
that the ice-rivers are much longer and more abundant on the southern
side of the mountain than on the colder slopes which are turned toward
the north. This phenomenon must evidently be attributed to the larger
* Russell-Killough, Les Grandes Ascensions des Pyrenees.
i‘ Behm, Geographisches Jahrbuch, 1866. a
I Mont-gomerie, Mittheilangen von Petermann, vol. ii., 1863. Godwin-Austen, Journal of
the Geographical Society, London, 1864. '
212 THE EARTH
quantity of snow brought by the south wind, and impeded in its course
by the lofty summits.*
The northern mountain chains of the Old World are of considerably
less elevation than either the Alps or the Himalayas, and do not present
any glaciers so remarkable for their extent as those of the great central
groups of Europe and Asia. Nevertheless, the proximity to the pole com-
pensates in part for the inferior altitude of the peaks. Thus, the high
plateaux which terminate the Scandinavian mountains, exposed as they
are to the winds from the west, so fully charged with aqueous vapor, pre-
sent vast ﬁelds of snow, and the greater part of the ravines which sink
down toward the ﬁorcls on the coast are ﬁlled up with glaciers descending
as low as 1640 feet, or, as in the case of the Boudhusbraen, even to 967
feet above the sea. Among the numerous ice-rivers, the most important is
that of Lodal, which ﬂows from the immense neve-ﬁelds of the Justedal;
it is nearly ﬁve miles long and 880 yards broad,and descends to a point
only 1320 feet above the level of the sea. The total area of this glacier
is very inferior to that of some of the primary Alpine glaciers; it is esti-
mated approximately as being about one seventh of that of the great ice-
stream of Aletsch.
Although the Ural Mountains, like the Scandinavian, are situated un-
der a very high northern latitude, they do not possess a single glacier,
and do not even reach the limit of perpetual snow. On their summits,
the height of which varies from 4000 to 5000 feet, there are no continuous
snow-ﬁelds to be noticed in the middle of summer—no snow, in fact, but
isolated drifts in the cavities of the rocks. The surprising contrast be-
tween these mountains and those of Scandinavia may be explained by the
inferior quantity of rain-fall which is discharged in the former region, and
doubtless also by the comparative narrowness of the chain and its isola-
tion in the midst of the toanclras, which, although traversed by cold
winds in winter, in summer reﬂect the rays of a burning sun.’r Neverthe-
less the other mountain chains—much loftier, it is true—which surround
the south of Siberia,have their ﬁelds of perpetual snow and their rivers
of ice. In the Altai, the glacier of Katounia descends to a point which is
4068 feet above the level of the sea.
Even the plains of those desolate regions which stretch away to the
north of the continent of Asia have glacier-like masses in which nothing
is wanting but motion to make them resemble those of the Alps. The
snow, driven by the eddies of the wind, is heaped up in the hollows of the
ground, so as to form complete hillocks, which the heat can not entirely
thaw during the short days of summer; and after the middle of autumn
these heaps again begin to increase. In consequence of the partial melt-
ing and the successive freezings, the snow composing these hillocks is
changed ﬁrst into névé and then into ice, pure and blue, like that of the
Alps. The mass presents some clefts, caused doubtless by the sudden
change of temperature, but it does not shift its position on the surface of
* Thomson, Hooker. ’r Hofmann, Der Ndrdliclze Ural..
TILE All CTIO' I CE-FlE'LD/S'. 2 ]_ 3
the ground as glaciers'do; only the thaw-water, produced by the sun on
the surface of the mound of snow,'ﬁows down its sides and then freezes
again, thus giving a wider base to the hillocks. Many of these patches
of ice, which on sloping ground would serve as the beginning of a gla-
cier, are some hundreds of yards in length.
The countries of the Arctic zone—Spitzbergen, J an-Mayen,and Green-
land—are the domain par excellence oﬁnécé and glaciers. In those re-
gions the mountains are uniformly covered with snow above an altitude
varying from 900 feet to 1500 feet, and the ﬁelds of ice which ﬂow down
into the valleys reach very nearly to the sea-shore. The few travelers
who have climbed a summit from the height of which a vast extent of
country can be surveyed have seen, in that part of the horizon which is
occupied by land, little else than an immense white sheet, pierced here
and there by black pointed rocks.
The glaciers of these polar regions differ in no way from those of the
Alps, except that, in consequence of the inferior altitude of the snow, the
nave has a very considerable extent as compared with the glacier proper.
Sometimes, even, it has been asserted that the lower portions of the ice-
rivers of Spitzbergen present both the appearance and the structure of
névé ,' this, however, is an error. In these polar countries the glaciers
have also their crevasses and their moalins, their stratiﬁcation and their
blue belts, their moraines and sub-glacial streams. Only, the thickness
of the mantle of snow which covers the whole country, and the surface
of the glacier itself, generally give it a considerable uniformity of aspect;
the stones of the moraines appear on the surface in but few spots, and as
to the mass of debris which ought to accumulate in front of each glacier,
they must be sought for in the bed of the sea, into which the blocks are
precipitated which break away from the principal mass.
One of the largest ice-ﬁelds in Greenland, next to Humboldt’s enormous
glacier, which was no less than 69 miles wide at its lower extremity, and
those still grander ones discovered by Hayes, the American, in his recent
travels, is that of Eisblink, south of Goodhaab. The lower portion of the
enormous mass pushes out into the midst of the sea, forming a cape, the
length of which is more than 13 miles, and if a glance is thrown back to-
ward the heights between the two walls which inclose the river of ice,
the Eisblink may still be seen on the extreme horizon—that is, 35 to 40
miles away. The incline of this sea of ice is very gradual, and it blends
insensibly with the horizontal surface of the icebergs on the shore. As
the glacier does not terminate on the ocean coast in steep cliffs, it is im-
possible to discover the point underneath the ice which forms the bound‘-
ary between land and water. There is, however, a considerable mass of
submarine debris—the Tallert Bank—which stretches around in a-semi-
circle in the sea, just off the end of the glacier. This is probably a kind
of frontal moraine carried. down by the stream which incessantly ﬂows
under the Eisblink.
The greater part of the streams which descend from the mountains
214 THE EARTH.
in the interior of Greenland likewise remain hidden, during their whole
course, under enormous moving ice-ﬁelds, and only betray their presence
by bubbling up in different places, and by the muddy color and dimin-
ished saltness they communicate to the sea-water with which they are
mingled. Some streams which pour down a considerable quantity of
water hollow out for themselves wide beds under arches of ice, which
press with an enormous weight. on the pillars that support them, and
which are always tending to break down under the pressure of the
masses above. At the same time, the waves of the sea, the temperature
of which is much higher than that of the glacier, are melting away the
base of the columns, and incessantly sapping them by their repeated
shocks. This frequently results in the downfall of immense masses of
ice, like whole sides of mountains, which give way suddenly with a crash.
The downfall of one of these terminal cliffs of ice in Greenland and
other Northern countries presents a magniﬁcent spectacle—as in the gla-
cier of Horn Sound, on the south of Spitzbcrgen, a prodigious mass, 150,
300, or even 400 feet high, rests entirely on the sea, which has gradually
melted away the under portion of the ice with which the waves have
come in contact. At low tide the enormous overhanging mass, under
which it is quite possible to penetrate in a boat, hangs without support,
and is only kept up by its cohesion with the rest of the ice and with the
sides of the adjacent rocks. Still the mass continues to advance, and the
numerous partial ruptures which take place in its bulk cause a noise sim-
ilar to the crackling of the electric spark.* All of a sudden the great
crash takes place; enormous sections of ice break away from the cliff
with a roar like thunder, and sink down into the depths of the water;
they soon, however, reappear on the surface of the waves, oscillating to
and fro to ﬁnd their equilibrium, and, impelled by the winds and cur-
rents, ﬂoat away on the undulating billows/r
In the continent of the New World, the glaciers on the mountains
farthest to the north resemble those of Greenland and Spitzbergen in
likewise reaching the sea-coast; but in the south the lower limit of gla-
ciers rises rather rapidly. In a gorge at Mount Forbes, situated near the
52d degree of latitude, there is one which descends to the point of 4281
feet above the sea. Mount Renier, between the 46th and 47th degree,
has on its sides small glaciers over which the burning lava sometimes
ﬂows. But farther to the south there are no other summits, either of the
Rocky Mountains or the Sierra Nevada (not even those that rise more
than 13,000 feet in height), which have on them ﬁelds of ice; all that is
to be seen are the moraines and the furrows, telling the story of former
glaciers now disappeared. Neither are the névés of the Rocky Mount-
ains very extensive—a fact which may be explained by the dryness of
the air, and by the rapid evaporation which results from it.
In the tropical zone, the only mountains of America which exhibit
small glaciers are the lofty summits which exceed 16,000 feet in height.
* Vide the chapter on “ Waters of the Sea.” 1' Charles Martins.
THE AMERICAN I UE-FIELDS.
Of this kind are Orizaba; some peaks of the Sierra Nevada, of Santa-
Marta, and of the Sierra of Cocui, in New Granada; the Altar of Ecuador
(the former crater of which ‘is ﬁlled up with ice), and Illimani, in Bolivia.*
Nevertheless, these small glaciers, as compared with the extent of the
névé and the dimensions of the mountain chains themselves, have no geo-
graphical importance. I may, therefore, be allowed to repeat, in common
with most other authors, that the Andes are devoidvof ice, over an extent
of more than 3000 miles, from the conﬁnes of Venezuela to the centre of
Chili. The Descabezado de Maule, on the 35th degree of south latitude,
is the ﬁrst Chilian mountain on which we ﬁnd an ice-ﬁeld. But, south
of the peak, glaciers become more and more numerous, and, according to
Philippi, present in their structure and movement the same varied phe-
nomena as the beautiful glaciers of the Alpsf ()n the Patagonian coast,
south of Chiloe, the terminal faces of the ‘glaciers appear in‘ all the val-
leys in‘ close proximity to the sea-shore. Even in the’ latitude of 46° 50’,
a position corresponding to that of thehills of Poitou, in the northern
hemisphere, the ice-rivers4_make their waylto the sea, and the fragments
which are detached from them go ﬂoating away to the north. The fact
is, that the fall of rain and snow is very considerable ‘on the western
slopes of these mountains; added to this, it is a matter of certainty that
the mean temperature is lower in the southern hemisphere than in the
northernI -
Omitting any mention of the glaciers in the Antarctic regions, which
have never been closely examined, the phenomena of which must exactly
resemble those of the glaciers of the northern zone, there are still some
very remarkable ice-rivers in the southern hemisphere which-call for our
notice. These glaciers ﬂow down the sides of the Alps of New Zealand
——the great southern island. The glaciers on the eastern~side of the
chain do not descend so low as those on the western slopes, because the
quantity of rain and snow poured down on the former is much less con-
siderable. The great glacier of Tasman, which ﬂows toward the east,
terminates at a'point 2739 feet above the sea; while the glacier of
Waiau, which ﬁlls a gorge tending toward the west, descends as low as
700 feet above the sea-level, and hurls its debris among the green, ferns,
pines, beeches, fuchsias, and other plants of the lowlands. The position
of this glacier (43° 35') corresponds with the latitude of Cannes and An-
tibes in the northern hemisphere. -Now, in the Swiss Alps, the glacier
which descends the lowest scarcely attains the point of 3300 feet above
the sea. ‘We must go twenty degrees farther north, to'the coasts of
Norway, to ﬁnd the most southern glacier which has‘ its terminal face so
little above the sea asthat of the glacier of Waiau.§,_
* Behm, Geograpln'sclzes Jain-buck. r Mittlzeilungen von Petermann, vol. vii., 1863.‘
I Vide the chapter on “Climates.” .. ' . i .
§ Julius Haast, Bulletin de la Socie'té a'e Géograpizie, February and March, 1866.
216 THE EARTH
CHAPTER XXXVI.
THE GLACIAL PERIOD.—ANCIENT GLACIERS OF EUROPE.-—DISPERSION OF
ROCKS AND BOULDERS FROM SCANDINAVIA AND IN NORTH AMERICA.—
ANCIENT GLACIERS IN TROPICAL REGIONS.
A STUDY of the existing phenomena which are presented to us in the
Alpine glaciers has brought to light the unexpected fact that, at a com-
paratively recent geological‘ epoch, their dimensions were much more con-
siderable than they now are. Under the inﬂuence of meteorological con-
ditions which certainly diﬂ'ered from those of the present period, which
conditions, however, are still the subject of somewhat animated discus-
sion, the ice-rivers descended to great distances from the ridge, and reach-
ed the extremity of some valleys which, during the present epoch, have
become richly-cultivated tracts. This fact is evident from the striee run-
ning along in parallel lines at great heights on the mountain sides, also
from the gigantic moraines which in times gone by were pushed forward
as far as the outlet of the valleys, and the rocks which were formerly
transported by the ice from one chain of mountains and thrown upon the
opposite slopes of another chain. Indications of a perfectly similar char-
acter to those which mark the extent of the comparatively triﬂing ﬂuc-
tuations of the glaciers of our day serve also to measure the former de-
velopment of the enormous ice-rivers of the past.
One of these indisputable signs is the upper limit of the polis, that is,
the traces of rubbing left by the ice in its course toward the valleys. It
appears that on the sides of Monte Rosa, and the Bernese Alps, this limit
does not exceed a height of 10,000 feet; but the slope of most of the ice-
ﬁelds was then much less abrupt than it is at present ; ‘it did not exceed
two degrees, and at some points on the banks of the former glacier of the
Aar it was even less. The considerably larger quantity of the ice in mo-
tion at that time allowed the whole mass to make its way over a very
slightly inclined bed. Fig. 71, borrowed from M. Desor’s work,* will give
some idea of the dimensions to which the glaciers of the Aar formerly
attained.
In like manner, the glacier of the Rhone, which now occupies a mere
gorge in the Valais Mountains, ﬁlled in those days the whole space in-
cluded between the groups of the Finsteraarhorn and Monte Rosa, and
from every lateral valley and every ravine which opens out right and left
in the thickness of the chain it received a fresh addition of ice and mo-
raines. The immense ice-river thus extended as far as the shore of the
Lake of Geneva; it even went beyond it, and spread over the plains of
* Nouvelles Excursions et Sejour dans les Glaciers des Alpes.
ANCIENT GLA CIE'RS OF EUR OPE. 217
Switzerland up to the J ura, joining, at its lower extremity, the glaciers of
the Isere and the Ain. A ﬁeld'of 1000 feet of ice stretched over the val-
ley at the very spot where the Rhone and the Saone unite their waters,
and where the city of Lyons has since been built. On the Italian slopes
of the Alps, each of the great valleys, where, in the present day, nothing
but a few ﬁelds of névé are to be found in some of the higher ravines, used
i Zanteraaz-horn Meselen Hingmdlbom ’ B11211], m."


Jﬁttelgrgt


‘\-V 7

%Z//


/


.\\
n .
I smmssmmmssmmssssmss
-
. /
Iévé of QNévé of New’:v , ~ Valley_ Valley _
Finsteraa Lameraar. of Gauh- of Gaul: of Bath
Fig. 71. Ancient Glaciers of the Aar.
to serve as a bed for vast streams of ice, descending even to the plains of
Piedmont and covering the great Alpine lakes. One of these streams,
taking its rise in the upper ravines of Mont Genevre, Ohaberton, Mont
Thabor, Mont Ambin, Mont Cenis, and Rochemelon, ﬁlled the whole of
the Susa valley, extending even to Rivoli, at the outlet of the mountains.
Another glacier ﬁlled the valleys of the Adige, and advanced beyond the
Lac de Garde; these enormous Alpine glaciers were, in fact, twice or three
times the size of the largest ice-rivers which are now to be found in the
Karakorum and the Himalaya.
The former existence of these glaciers is proved not only by the pres-
ence of the strice and marks of rubbing on the rocks, but also by the front-'
al and lateral moraines which have been pushed forward in former days
to the very outlet of the valleys, or which have crumbled down on the
slopes. Thus, above the village of Monthey, in the valley of the Rhone,
there may still be noticed a mass of stones of very considerable dimen-
sions, forming a kind of rampart more than 3000 yards in length, and 200
yards in average breadth. This bank is formed of granite blocks, brought
from the Val de Ferret by a former glacier, and must once have been a
medial moraine, which, after the melting of the ice which carried it along,
was stranded on this promontory. At one time a number of former mo-
raines of this kind were found at various spots in Switzerland; but the
harder rocks having been much used as stones for building, these remains
are disappearing more and more every day. ‘
The question which has given rise to the most animated discussions
among geologists is the problem'how the moraines of the Alpine glaciers,
and the great stones which in former times they drifted along in their
course, managed to cross the great lakes of Switzerland and Lombardy.
Thus the town of Lucerne is built upon the debris which was once borne
218 THE EARTH.
along on the immense glacier of the Reuss, which, descending from the St.
Gothard, crossed over the depths of the Lac des Quatre Cantons. In like


I
I


Fig. 72. Ancient Moraine falling down.
manner, to the south of the Lake of Garda, the hills of Solferino, Cavriana,
and San Martino, on which was fought the terrible battle of 1859, are noth-
ing more than heaps of stones, which once served as an advanced guard
to glaciers.* Added to this, erratic masses of stone, or boulders proceed-
ing from the Alps—as is shown by the crystalline nature of these rocks
—,are found on the eastern slopes of the J ura; they are seen at various
heights, and even at as much as 3300 feet above the level of the sea.
Among these blocks—a few of which are from 5000 to 6000' cubic yards
in bulk—-there are some which the saoanis, from a study of their miner-
alogical composition, can clearly specify as having come down from cer-
tain mountains in the groups of the Finsteraarhorn, Monte Rosa, and
Mont Blanc. By what means have these blocks of rock been able to ac-
complish their journey before they became stranded on the mountain sides
of the Jura? Was the Lake of Geneva much more elevated at a former
epoch than it is at present, and did the enormous masses of ice, whichfell
into itfrom the glacier of the Rhone and ultimately ﬂoated to the oppo-
site bank, inclose blocks of rocks and stones like the icebergs of the north-
ern seas? ()r was it the fact that the glaciers ﬁlled with their masses
the deep cavities of all the lakes of Switzerland and Lombardy, and,like
the Rhone, which continues its course after. having so widely expanded
in order to form the Lake of Geneva, crossed over these lakes, and ﬂowed
out far and wide into the plains of France’ and Italy? This last hypothe-
sis appears probable, for on the sides of the mountains which overhang
these lakes, and especially round the lakes Maggiore, Come, and Garda,
the ancient strice of the glaciers are still to be perceived, and some of- the
insular rocks retain that moutonnéecl appearance which bears witness to
the fact that the ice had passed over themj Added to this, ‘the protec-
tion afforded by the masses of ice, which ﬁlled them up have probably
been the cause why the deep cavities of the lakes were not chokedup by
the debris which fell from the broken ridges above on to the moving bed
of the glacier. ‘ Some geologists have put forward. the hypothesis that‘the
* Martins and Gastaldi. Murchison,Journal of the Geographicai Society, 1864.
‘l' Martins, Bibliotlzégue de Genet-e, July, 1866. I '
ERRATIO ‘BLOCKS AND BO ULDERS. 219
beds of the Alpine lakes. were hollowed out entirely by the Alpine gla-
ciers. This view, so' ably advocated by Professor Ramsay, the director
of the geological survey of England and Wales, has lately received great
support from Professor Newberry’s investigation of the lake-system of
North America. -- . - _ -
However this may be, the enormous extent of theold ice-rivers of Switz-
erland is a fact henceforth unquestionable. Nor can it be doubted that
the same thing was the case in all the rest of Europe. 1 From one extremi-
ty of the chain to the other the Pyrenees present unequivocal evidences of
the glacial epoch, and in some valleys—those, for. instance, of Co and Ar-
gelez—the frontal moraines are still almost as distinctly visible as it the
ancient glacier had melted only the day before. In like manner, to the
west of Vosges, the natural banks of sand, gravel, and heaped-up rocks
which pen in the water of the little lakes of Gérardmer, Longemer, and
Frondomé, are nothing else but old moraines. Similar phenomena are
found in the mountains of other countries—Wales, Scotland, and Ireland,
in the Carpathians and the Riesengebirge.
Another proof of the enormous development of the ice system during a
comparatively recent epoch may be derived from the dispersion of the cr-
ratie rocks or boulders, which are found in such great numbers in the
countries of the north of Europe. It is now beyond all question‘ that the
numerous lines of rocks which are found here and there all over Northern
Russia have proceeded from the granite mountains of Scandinavia. When
an immense sea extended over Finland,between the Baltic and the Polar
Ocean, the blocks of ice which fell into the water that washed the base of
the Scandinavian mountains drifted away in ﬁotillas toward the south-
east to the shores of the continent opposite. The prominent angles of the
granite blocks contained in the masses of ﬂoating ice have traced out long
furrows over all the points and projections of the rocks in Finland, which
was then only a marine shoal. M. N ordenskiold has ascertained that al-
most'all these lines of erosion tend from the northwest to the southeast,
and that all the rocks with which the icebergs have come into contact are
polished on the side which faces toward Scandinavia, while on .the other
side they have in every case retained their uneven surfaces, their projec-
tions, and their clefts. With regard to the boulders themselves, they are
all more rounded by friction the more distant they are from the Swedish
mountains of which they once formed a part. All the phenomena which
once were eﬂ'ected on so vast a scale round the ‘shores of the Baltic are,
however, still taking place. During the winter of 1862-3, immense mass-
es of ice, coming from Finland,were cast upon the southern coast of the
gulf, and thrown up on the land to a distance of more than 300 yards from
the shore, and to a height of 30 feet above the level of the sea. The ice,
which was 40 to 50 feet deep, overwhelmed many dwellings and whole
forests; in the latter large quantities of stones were subsequently found,
which the ice left behind when it thawed?“ , . -
* Keyserling and Von Baer, Bull. de l ’Acad. de St. Pe'tersbourg,vol. v., April, 1863.
220 . THE EARTH .
These boulders are scattered in considerable numbers over the tounclras
and plains of Northern Russia; they are also found in Prussia and Poland
as far as the slopes of the Carpathian Mountains. They are seen round
the North Sea, on the coasts ofFriesland, England, and Scotland. The
investigations also of M. Behtlingk have shown that ' erratic rocks, or
boulders, have made their way, borne on masses of ice, from t'heﬁorcls of
Lapland toward the Northern Ocean. Thus the great island of the Nor-
wegian mountains was once a centre of dispersion from which the rocks,
instead of merely rolling to the bottom of the slopes, were. distributed in
various directions over the immense space included between the British
Isles, Spitzbergen, the Ural Mountains, Valda'i', and the Carpathians.
Strange to tell, numbers of these Scandinavian rocks, thus stranded be-
yond the sea, are still overgrown with lichens and other plants belonging
to Norwegian families. They might be compared to colonies of poor ship-
wrecked creatures cast upon a foreign shore.* _
In the gentle undulating plains of North America, boulders and other
clébris brought by ﬂoating ice are likewise found scattered overwide tracts
of country. The vegetable soil of some of the most fertile districts, such
as Illinois, Indiana, and Michigan, is in great part composed, of earth
brought by stranded icebergs, and here and there may be found in the
mass of this transported soil enormous blocks of granite which one belong-
ed to the Laurentian Mountains, or to some other rocky chain. in Canada.
Thus the effects of the ancient glacial period are still perfectly-visible
in the plains of the N ew,.as well as of the‘ _. :3, I‘ ‘
Old World. These are, in fact, the spots
where we should expect to ﬁnd the traces
of former glaciers; but even warmer coun-
tries exhibit on their mountain sides and
in their gorges most distinct traces of an-
cient ice-currents. Thus Hooker, the bot-
anist, noticed at the base of the Himalayas
the remainsof old moraines forming actual
barriers across the valleys; in Syria, too,
he felt justiﬁed in stating that the cele-
brated cedars of Lebanon grow on masses
of debris‘ of the same nature. At the foot
of the Sierra Nevada, of Santa-Marta, on
the coast of Columbia, where the mean
temperature is 80° (Fahn), masses of debris
are also found that the ice, which then de—
scended 1300 feet lower than it now does,
pushedi'in front of it to the very’ sea. Last- Fig. 73. Ancient Glacier ofYangma, in the
ly, Agassiz has likewise.- recognized the Himalayas‘ afternooker'
track of ancient glaciers in Brazil,‘ not far from Rio de Janeiro, and even
under the equator, at the mouth of the Amazon. ~ In fact, the reef of Per-
* Christ, Alpen ﬂora, in vol. of the Selzweizer Alpen-Cllnb.
. ~ ‘-

ALTERNA TION OF GLA UIAL PERIODS. 221
nambuco and the whole of the adjacent coast are nothing but a long se-
ries of moraines beaten and consolidated bythe waves. Every region of
the globe has therefore had its glacial period. But was this period coin-
cident in all the various regions of the globe, or did it ﬂuctuate from one
hemisphere to the other, prevailing at one time on the north, and at anoth-
er time south of the equator? We can not tell; it is,.however, probable
that a rhythmical ﬂuctuation of temperature took place during the lapse
of centuries from one pole to the other, and that consequently the glacial
periods have alternated in Europe and Africa, and in North and South
America. According to Hochstetter, New Zealand and Patagonia, where '
the ice descends so low, are now passing through their glacial period.
There are, however, hypotheses in abundance in respect to the extension
of the ancient glaciers, and on this point generally geologists are‘ still
very far from agreeing on any common theory.
222 THE EARTH.
CHAPTER XXXVII.
SECONDARY PART TAKEN BY GLACIERS IN THE CIRCULATION OF WATER.—
MOUNTAIN FLOOD-‘WATERS—ABSORPTION OF RAIN AND MELTED SNOW BY
THE EARTH, PEAT-MOSSES, AND ROCKS.——SPRINGS AND THEIR NYMPHS.
EXCEPT in the polar regions, only a very small portion of the atmos-
pheric waters become ﬁxed in glaciers, to remain lying on the mountain
sides for years or even centuries. The proportion of water which falls
from the clouds in a liquid form is much more considerable, and conse-
quently plays comparatively a much more important part in the economy
of the globe. Rain and melted snow, being incomparably more active
than ice in its circulatory movement, either ﬂow away at once on the sur-
face as rivers, or disappear into the depths of the rocks, whence they will
gush out at some distant spot in the form of springs, or will perhaps con-
tinue their subterranean course as far as the abysses of the ocean.
In mountain gorges where the ground or bare rock will not allow the
rain and snow-water to sink in, the stream runs down rapidly toward the
plain, carrying with it along the bottom of its bed the debris which is
washed away from the slopes. After an exceptionally heavy rainfall, it is
often diﬁicult to form any clear distinction between one of these tempo-
rary torrents, a fall of rubbish and mud, or an avalanche. In this case,
the masses of half-melted snow, mixed with liquid mud, are hurried on by
their own weight, and slide down the slopes, driving before them heaps of
loose stones and rubbish. The whole semi-liquid body very soon sinks
down into the ravine which forms the channel of descent. The water and
dirty show are mingled in one dark and miry mass, in the midst of which
rocks and stones bound about as they roll along; in this moving chaos
the fragments of debris are constantly coming into collision with a crash
that shakes the rocky banks, while the ﬂow of the torrent tears away their
base. In many places these enormous masses totter in their turn, and
soon participate in the immense downfall. A noise like thunder is the
harbinger of the avalanche, and announces it from afar to any persons that
may happen to be in its line; but these phenomena, which are at the same
time both earthfalls and avalanches, last but for a very few instants. The
torrent carries away with it and tosses about like pebbles enormous rocks
thirty feet square, and when it has passed away it leaves nothing behind
but thick layers of mud.
These semi-liquid avalanches are, fortunately, not very frequent, at least
in Europe ; but all the heavy rains which fall on the mountain slopes, and
even on the more or less inclined soil of the low-lying lands, cause the for-
mation of torrents and temporary streams. These constitute ﬂood-waters.
Dashing down all the deﬁles, ravines, and depressions of the ground, they
ABSORPTION OF MOISTURE’. 223
wash away all the clébris which is accumulated in them, clearing off the
vegetable soil, plants, and brushwood, and plowing up their beds when the
rock is not of too compact a character; when they reach the river ﬂowing
through the plain, they pour into it masses of mud and heaps of pebbles
carried away from the hills. They are, in fact, real geological agents, and
their operations during a day, or perhaps only an hour, contribute no mean
share in the modiﬁcation of the earth’s surface.
If all soils were absolutely impervious, there would be no springs, and
the whole of the liquid mass furnished by rain and snow would ﬂow away
over the surface of the ground like the torrents and ﬂood-waters of the
mountains. The greater part, however, of the water which falls upon the
ground sinks in the ﬁrst place into the depths of the earth. There it be;
comes more or less perfectly puriﬁed from the foreign bodies with which
it was charged, gradually rising to the temperature of the strata through
which it passes, and becoming impregnated with the soluble salts which it
meets with. Ultimately, when the water, in sinking down, encounters im-
pervious beds, it can penetrate no farther, and, ﬂowing laterally to the out-
crop of the beds, makes its escape in the form of springs.
The absorption of the rain and melted snow takes place in various ways,
according to the nature of the soil. Ordinary vegetable earth only allows
the water to penetrate to a very slight depth, especially when the rain
falls in showers and the slope of the ground is favorable for drainage. As
mould is capable of absorbing a very large quantity—indeed, more than
half its own weight, it prevents the strata beneath from receiving its due
share of moisture, retaining almost the whole of it for the use of the vege-
tation which it nourishes. In fact, it requires an altogether exceptional
rainfall to saturate any ordinary arable soil to the extent of a yard below
the surface. Water passes with much more facility through sandy and
gravelly beds; but compact loams and clay will not allow it to penetrate
through them, retaining it in the form of pools or ponds on the surface of
the ground.
The action of vegetation is not conﬁned merely to imbibing the water
falling from the clouds; it often, also, assists the superabundant moisture
in penetrating the interior of the ground. Trees, after they have received
the water upon their foliage, let it trickle down drop by drop on the
gradually softened earth, and thus facilitate the gentle permeation of the
moisture into the substratum; another part of the rain-water, running
down the trunk and along the roots, at once ﬁnds its way to the lower
strata. On mountain slopes, the mosses and the freshly-growing carpet
of Alpine plants swell like sponges when they are watered with rain or
melted snow, and retain the moisture in the interstices of their leaves and
stalks until the vegetable mass is thoroughly saturated and the liquid
surplus ﬂows away. Peat-mosses especially absorb a very considerable
quantity of water, and form great feeding reservoirs for the springs which
gush out at a lower level. The immense ﬁelds of peat which cover hun-
dreds and thousands of acres on the mountain slopes of Ireland and Scot-
224 THE EARTH
land may, notwithstanding their elevation and inclined position, be con-
sidered as actual lacustrine basins containing millions of tons of water
dispersed among their innumerable leaﬂets.* The superabundant water
of these tracts of peat-mosses issues forth in springs in the plains below.
Rocks, like vegetable earth, also absorb water in greater or less quanti-
ties, according to their ﬁssures and the density of their particles. If the
soil is formed of volcanic scoriee, or porous beds of pebbles, gravel, or
sand, the water rapidly descends toward the underlying strata. Some of
the harder rocks, especially certain kinds of granite, absorb but a very
small quantity of water, on account of the small number of their clefts;
others, on the contrary, as most of the calcareous masses, imbibe every
drop of water which falls on their surface. There are some rocks which
have their layers broken and cracked to such an extent that they resem-
ble enormous walls of rubble-work; the rain instantly disappears on them
as if it had fallen into a sieve. But the greater part of the calcareous
rocks belonging to various geological periods are formed of thick and reg-
ular strata, cleft at intervals by long vertical crevices. Below the sur-
face-beds, perhaps, are layers of soft marl, which the water penetrates with
difficulty, although it can soften and carry away its particles. Here are
formed, rill by rill, the subterranean rivulets which ultimately spread all
over the substratum of marl, following the general slope of the bed.
After a more or less considerable lapse of time, the stratum of marl ulti-
mately becomes saturated, and the water then ﬂows out through caverns
which are variously modiﬁed by Subsidences—faults in the strata and the
perpetual action of the streams. The springs which'proceed from calca-
reous rocks of this nature are in general the most abundant, owing to the
length of their subterranean course. The water which falls on vast areas
on the surface of plateaux is ultimately united in one bed. A liquid mass
of this kind, which springs up suddenly into sight, just as if it merely is-
sued from the soil, drains perhaps an extent of country of many hundreds
or thousands of square miles. '
Thus, according to the nature of the rock on which the rain falls, the
latter ﬁnds its way again to the surface, either at a considerable distance
from the spot where it fell, or else springs out in little rivulets immedi-
ately below the' place where its drops were ﬁrst gathered. On a great
many mountains we are surprised to meet with springs gushing out at a
few yards from the summit. These jets have, indeed, often been consid-
ered as the evidence of some miraculous intervention. Among others,
we may mention the “ Sorcerers’ Spring,” which gushes out on one of the
highest points of the Brocken, the culminating peak in the Hartz Moun-
tains. The position of this spring is, in reality, 19 feet lower than the
highest part of the terminal plateau, and it has been calculated that if it
served as the drainage outlet for all the rain falling on the top of the
mountain, it might well supply rather more than a gallon and a half a
minute. Now, as a matter of fact, it scarcely furnishes a third of this
quantity. It is, however, but very rarely that it altogether fails, and in-
* Vide the chapter on “ Lakes.”
SPRDVGS AND THEIR N YMPHS. 225
stances of this have been seldom recorded.* In the principal islet of the
Ohausey group, which is only 770 yards long by 275 broad, there is also
a constant spring, and the question is whether the rain which falls on this
rock is sufficient to supply the fountain, or whether it is fed by the ﬁltra-
tion of water from the neighboring continent/r The valleys which lie at
the mountain foot, or even the plains that border on less important heights,
are, however, the principal spots where springs gush ‘forth in the greatest
number. Springs form a special charm in those unassuming landscapes
in which nature develops all its beauties within a restricted space. Stand-
ing on the bank of some little brook which bubbles as it glides along,
lending, as it were, to nature an almost articulate voice of kindness, the
eye embraces a graceful ensemble which can hardly fail both to charm and
soothe. Almost involuntarily a feeling seems awakened within us of liv-
ing sympathy with the objects around, all of which appear as if made to
harmonize with man’s condition. The spectator feels softened, and is not
oppressed and bewildered with admiration as when surveying a mighty
cataract, a glacier, or the waves of the sea. Besides, can we look upon
even a tiny spring without an instinctive feeling being stirred up within
us that in it we see the real fountain-head of all civilization ‘P In this lit-
tle corner of the earth every thing is arranged as heart could wish for the
needs of the ﬁrst husbandman. There are overhanging trees to shade
him, a hillock to shelter him from the rude wind, pure water for his gar-
den, and stones to build his hut. What more could he require ere he
commenced those great labors in the improvement of the earth which
have made us, his descendants, what we now are ‘E’
If a blasé inhabitant of our cities is unable to contemplate a spring with-
out some degree of poetic feeling, how much more vivid must this senti-
ment have been among our ancestors, who lived in the very bosom of na-
ture! Some ancient nations, indeed, worshiped fountains as if they were
divinities. The Greeks, who knew so well how to ascribe even to inani-
mate objects a fellow-feeling both in their passions and in their joys, have
given a personality to each of their fountains, transforming them into some
graceful nymph or some glorious demigod. Travelers can not refrain
from astonishment when they perceive the humble springs of Hippocrene
or Oastalia, and the mere rivulets of the Scamander, the Alpheus, the
Ilyssus, or the Eurotas, on which the poets of Greece have conferred such
imperishable glory. What! they cry, are these miserable streams the
fountains and rivers that the Hellenes honored with statues and temples?
Are these slender crystal rivulets, gliding among the rocks, the objects
which were invoked as patrons for powerful cities, and were sung of in
their poetry in almost divine rhapsodies ‘P These springs seem very triﬂing
things to us—to us barbarians of the North, who only know how to appre-
ciate the colossal, and reserve all our admiration'for great rivers, such as
the Mississippi or the Amazon. Yet who can ever adequately describe
* Von Kliiden, Handbuch der Erdkunde.
1' Audoin and Milne-Edwards, Le Littoral de la France.
P -
226 THE EARTH.
the ineﬁ'able beauty of the smallest spring, no matter whether it ﬂew be-
tween two ﬂowery banks under the mysterious shade of overhanging
trees, or slowly trickles from a dark grotto under white chalky rocks, or
jet up in glittering pearls from a pebbly bed, dancing the grains of sand
on its tremulous drops—each fountain has its own special character of
grace or stem beauty. One is the charming Acis, escaping from the lava
rocks under which the Cyclops wished to overwhelm him; another is the
nymph Arethusa, swimming under the sea so as not to mingle her blue
water with the troubled wave; another, again, is the virgin Cyane, bath-
ing the ﬂowers which she once gathered to weave a coronet for Proserpine.
It is easy to understand the veneration which is felt for springs by the
inhabitants of tropical countries, who live on an arid soil and under a
burning sky. Even on the borders of deserts and on the oases, water-
sources are rare, and their inestimable value is all the more appreciated.
That slender spring, which trickles from the cleft of some rock, is the
agent which nourishes the grass, the grain, and the fruit which are neces-
sary for the subsistence of a whole tribe. Should its water happen to
fail, the whole population is obliged to migrate immediately, or else die
of hunger or thirst. The inhabitant, therefore, of the oasis professes a
kind of worship for the bounteous element which is to him the source of
life. In climates more favored in their rainfall, man’s love for water-
springs naturally lessens in proportion to their abundance; but some
relics of this sentiment may be found in the hearts of every nation—those
even that inhabit the best-watered countries. This instinctive veneration
for rising springs is probably the cause of the Swiss mountaineers not con-
sidering the torrents of muddy water issuing from the terminal arch of a
glacier as the real source of rivers; this honor they award to the little
unassuming rills which trickle out at the foot of the rocks. In their idea
the true Rhone is not the furious water-course which dashes out of the
glacier; it is a slightly thermal spring which glides among the rocks
some hundreds of yards below the frontal moraine. This spring-water,
which—differing from the ice-torrent—never fails in winter, is ferruginous
in its nature, and stains the snows in its bed with a reddish hue; hence,
they say, the name of Rhone (Rothen).*
Neither the charm nor even the utility of springs are the sole causes
why they are so much beloved; the mystery of their origin also promotes
this feeling. We are fond of inquiring as to the origin of these jets of
pure water, and of tracing out the paths that they have followed through
the bowels of the earth before they emerged into the light of day. From
what mountain summit has this charming fountain nymph descended, and
in what grotto has she made her abode? Such are the inquiries which
the uninitiated might make at the sight of a spring—inquiries, too, which
savants are yet far from having answered. What a multiplicity of studies
and investigations have yet to be made ere we can trace out, without fear
of error, the circuit accomplished by a drop of water through the rocks,
rivers, and clouds!
* H. de Saussure, Voyages dans Zes Alpes, rel. iii.
VARIATION IN SPRINGS’. 227
CHAPTER XXXVIH.
VARIATION IN THE DISCHARGE OF SPRINGS. --—ESTAVELLES. —EQUALIZA-
TION OF THE SUPPLY IN SPRINGS WITH DEEP SOURCES.-—INTERMI'ITENT
SPRINGS.
IT may be stated generally that the discharge of a spring varies accord-
ing to the quantity of rain. After an extraordinary rainfall, all springs
have a tendency to increase and overﬂow, with the exception of those
which, owing to the form of their subterranean bed, are unable to yield
any more considerable body of water. It sometimes happens that, during
exceptionally rainy seasons, springs gush out from rock-crevices which are
almost always dry, and form temporary rivulets. These are called fon~
taines cle clisette (scarcity springs), fonts famineuses (famine springs), or
bramafans (hunger cries). The farmers very justly look upon their ap-
pearance as the formidable foreboding of a year much too wet for their
crops.
With regard to springs of a permanent character, there are a consider-
able number which, issuing from a rock which is split and rent in every
direction, form supplementary oriﬁces after any great amount of rain".
Among the mountains we may often notice that walls of rock, which in
ordinary seasons have little rivulets of water trickling along their base,
will, in a rainy season, be enlivened by cascades dashing down from vari-
ous heights of the jointed face. In gorges, and on gently inclined slopes,
phenomena of the same nature are developed; but in some cases it is dif-
ﬁcult to recognize the intimate connection which exists between the va-
rious springs which rise at different intervals of space along the same val-
ley. In fact, at ﬁrst sight, one can hardly understand how a temporary
ﬂow of water, gushing out a mile or two above a constant spring, can
nevertheless be connected with the same subterranean stream, and so form
a kind of waste-valve for the lower oriﬁce. In Languedoc these supple-
mentary ﬂows are called estavelles, a term which has been recently intro-
duced by M.Fournet into scientiﬁc language.
The calcareous slopes of the J ura present some remarkable instances of
estavelles, among which those in the environs of Porrentruy are specially
worthy of notice. Four copious springs, which rise in the town itself, are
the outlets of a subterranean water-course fed by the mountains rising to
the southwest. Owing to certain depressions in the ground, and to the
sound of underground currents which are here and there heard, the con-
cealed stream may be easily traced as far as the well, or cream (hollow), of
Gena, about two miles and a half from the town, situated at the foot of a
bill. In a general way, all that can be seen at the bottom of the hole is a
228; - THE EARTH
little stream of water making its way down toward the valley; but after
heavy rain or a rapid thaw of snow, the water bursts up with a roaring
noise from the subterranean cavities, and, pouring furiously into the
meadows, spreads over the surface of the ground, and ultimately runs
down to the town of Porrentruy. Beyond this estavelle, where several
subterranean water-courses unite, the slope of the valley becomes more
and more steep, and other wells or cream of the same kind are seen, from
which the overﬂowing water of the stream beneath temporarily issues.
Estavelle I.
Creux des Pres.
stavelle II
Estavelle III.
/ Creux de Gena
Town of Porren-
t1 uy
Outﬂow.


i m
. sum
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Higherup still, the escarped ravine of Rochedor commences, where, dur-
ing the whole year, the rivulet, running sometimes below and sometimes
above the surface of the ground, passes through a series of chasms. At
one place it springs‘ up suddenly to the top of the rocks, and then as sud-
denly disappears, only to gush forth again at some distance down the ra—
vine.* , . ' a
‘The estavelle' which is the most remarkable in France for its abundant
ﬂow of water during the rainy seasons is situated, like the springs of Por-
rentruy, on one of the slopes of the Jura. It is called the Frais-Puits,
and rises at the opening of a little valley about-two miles and a half
southeast of Vesoul. In ordinary seasons, a spring of some importance
--,that of Champdamoy—is the ,sole outlet for all the rain that falls in the
basin; but when the subterraneous caverns are notcapacious enough to
contain the whole of the accumulated liquid mass, it ﬂows out through
the oriﬁce at Frais-Puits, about a mile and a quarter above Champdamoy.
Sometimes, indeed, it is a perfect river which rushes forth from this abyss.
It inundates the meadows of Vesoul over an extent of several square
miles, and ﬂoods the little stream in the valley, inﬂuencing even the, Saone,
‘ which receives the surplus of the sudden overﬂow. The Frais-Puits, in
conjunction with'another estavelle, a tributary of the Vesoul stream, has
been known to discharge the enormous quantity of 133 cubic yards of
water per second, ‘equivalent to double the liquid mass of the Seine at its
passage under-the bridges of Paris. ' A - a ‘ ' ' - - ' ' -
We thus see that very heavy rain has the effect of causing springs to
gush forthin spotswhere, in a general way, theyydo not exist; (but we
must also notice that every precipitation of moisture, even the most in.-
considerable, has its proportional inﬂuence on the discharge of fountains
* F ournet, Hydrograplzie Souterraine.
INTERMITTENT SPRINGS. ‘229
and springs. The nightly freezing of melting snow, the increasing intens-
ity of the solar rays, the intermittent activity of the phenomena of evap-
oration taking place on the surface of the soil—in fact, every meteoric
agency, incessantly tends to modify the action of water springing forth
from the earth, and causes it to change every day and even every hour.
It must, however, be understood that springs are all the less subject to
the inﬂuence of the rain, sun, and wind the farther the subterranean
streams have traveled, and the deeper they have descended into the bow-
els of the earth. All the hinderances which the percolating water is sub-
ject to from the friction of its liquid particles against the rocky sides of
its underground course, and all the delays which it is forced» to submit to
in the cavernous lakes, have this result—that the sudden variations which
the changes of the seasons cause on the surface of the ground are modiﬁed
and weakened in these subterranean beds. Down in these depths the sea-
sons seem to blend one into the other, and their effects are mutually coun-
terbalanced. Owing, therefore, to the long and winding channels which
feed them, springs are able, as it were, to regulate themselves, and to fur-
nish, during the whole year, a supply of water which varies but very
slightly. In a certain number of thermal springs rising from ﬁssures
which descend to a very considerable depth in the earth’s crust, the equi~
librium of the liquid mass is so perfectly established that any variation
answering to the different seasons can scarcely be perceived. “There are,
however, certain hot wells, replenished from reservoirs with which they
ﬁnd rapid and easy means of communication, which show a great variety
in the amount of their discharge, according to the quantity of rain or
snow which has fallen in the country. Thus, in July, 1855, after a long
succession of stormy weather, the hot wells at Pfeﬁ'ersyin Switzerland,
sprung out in such abundance, both from their usual source and also from
several other clefts in the rock, that they were obliged to let a 'great quan-
tity of the water ﬂow away into the Tamina without making any use of
it. The following year, on the contrary, the hot wells received such an in-
considerable supply that it was feared that they would dry up altogether.*
The springs which cause the most astonishment are those which for a
time ﬂow plentifully, and then all at once cease running, but, after an un-
certain lapse of time, again make their appearance. One might almost
fancy that some invisible hand alternately opened and shut the secret
ﬂood-gate which gave an outlet to the subterranean stream. The cause
for this phenomenon of intermission is easily explained. When the water
brought by the underground stream is collected in a capacious cavity in
the rock, which communicates with the exterior surface through a siphon-
shaped channel, the liquid mass gradually rises in the stone reservoir be-
fore it rushes out into the air. It is necessary that the reservoir should
be ﬁlled up to the level of the siphon, in order that the latter should be
primed, and that the water should ﬂow out as a spring into the external
basin. If the water in the reservoir is not replenished with suﬂ'icient ra-
* Otto Volger, Erdbeben in der Schweiz, vol. iii.
230
THE EARTH.


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piclity, and is unable to keep at least on a level with the external outlet,
the jet of water will immediately cease, and can not recommence until the
upper part of the liquid mass has again risen up to the highest point of
the siphon.
After an indeﬁnite period of repose, the spring then enters
on a new phase of activity.
The comparative durations of the intermissions vary according to the
capacity of the retaining reservoir, the height‘ and the diameter of the
siphon, the position of the outlet-channel, the abundance of the subterra—
nean water, and the force of the evaporation- Nevertheless, the action ~
of each spring is incessantlymodiﬁed by the frequency or scarcity of rain,
and the jet of water increases or shortens the duration of its appearance.
Occasionally springs which are generally intermittent are recruited by
subterranean channels to an extent suﬁicient to enable them to ﬂow with-
out interruption for weeks or whole seasons. At other times, after long
periods of dryness, the spring entirely ceases to gush out; and the visitor
who, on the faith of some old book, stands waiting, watch in hand, for the
predicted appearance, runs a good chance of gazing vainly for many a
long hour upon the dried-up basin of the fountain. It also often happens
that the fall of rocks, or the opening of fresh clefts, alters the course of
the subterranean stream and destroys its periodicity. Thus the Buller-
born, a spring in Westphalia, which formerly burst out of the ground
about everyalternate four-hourswith'suﬂicient force to turn the wheels
of several mills, has now,-since the commencement of the eighteenth cen-
tury, become‘ a much less considerable stream, but runs constantly.*
*on Klocden, Handbucli der Erdkande.
ASO'EIVDLVG SPRIAIGS. 2
CHAPTER XXXIX.
ASCEN DIN G SPRINGS. —- ARTESIAN WELLS. -— TEMPERATURE OF JETTING
SPRINGS.
THERE are many of these subterranean streams which, before they break
forth in springs, do not ﬂow over beds continuously sloping in the direc-
tion of their current, as is the case with water-courses on the surface of
the ground. There are some indeed which ﬁrst descend into the bowels
of the earth, either by a uniform declivity or by a series of cascades or
rapids, and ultimately reascend from the depths toward the surface, or jet
out vertically from the ground. Let us follow in our imagination a rill
of melted snow trickling down from the mountain side through the crev-
ices of the earth to a depth of some hundreds or thousands of yards be-
low the surface of the ground. So long as this water does not meet with
any impervious stratum, it continues to sink toward the lower abysses.
But if its progress is arrested by a bed of retentive clay or any other layer
through which it can not pass, it will spread out over this layer, and will
follow all its inﬂections. Should this stratum curve gradually upward to-
ward the surface of the ground, or should it even rise suddenly, the sub-
terranean stream will reascend, as if in a tube, so as to place itself in a po-
sition of equilibrium with the other liquid masses which continue to de-
scend from the heights.
Added to this, in obedience to the law which compels liquids to seek
the same level in all connected reservoirs, a rivulet of water will never
fail to dart forth as a spring as soon as it ﬁnds an outlet below the cav-
erns in which the water is collected from which it proceeds. Likewise, if
the spot where the gushing out takes place is on a much lower level than
that of the feeding reservoirs situated above, the liquid jet must necessa-
rily shoot up in a column above the surface of the ground. This is the
case at Chatagna, in the department of the J ura, where a natural jet cl’eau
springs up to a height of 10 or 12 feet. In the grotto of Male-Mort, near
Saint-Etienne, in Dauphiné, the jet of water is not less than 23 to 26 feet
in height.* But the water of the fountains being always more or less
charged with sediment, the deposit accumulates in the form of a circular
hillock around the oriﬁce, thus almost always ultimately raising it to the
level of the top of the liquid column. As an instance of these rising foun-
tains, we may mention the famous springs of Moses Mesa), which
gush out in a charming oasis not far from the shores of the Gulf of Suez.
These springs, the temperature of which varies from 70° to 84° '(Fahr.),
now ﬂow from the top of several small cones of sandy and slimy debris
which they have gradually thrown up above the level of the plain. They
are also shaded by olive' and tamarind trees. At a certain distance from
* Fournet, Hydrologie Souterraine.
232 .7 . THE EARTH.
the spot where these small streams gush out, there is a line of dried-up
cones. These are the former fountain-heads, which are now abandoned by
the water on account of their too great elevation.*
This phenomena of the springing up of deep-lying water from the bow-
els of the earth is a fact established beyond all doubt by direct observa-
tions; for, 'many'centuries ago, the absolute necessity of ﬁnding springs of
water in arid countries disclosed'to thenations inhabiting’ them the exist‘-
ence of these sources ascending from the depths of the earth." In the “dos-
erts' of Egypt and Algeria, the‘ natives, from‘ the most remote antiquity,
had learned how tobore wells 30,40, and even 90 feet into these liquid
veins,'and'thus, in the very midst oflthe sands, they ‘caused the rising col-
umns' of water to 'spout out, casting life and riches all around them. The
inhabitants. of certain valleys in'Aﬁ'ghanistan and Arabia, fearing to lose a
drop. of thelprecious-xwater .which'com‘es .down to them from the moun-
tains, have had the foresight to take possession of the brooks at their issue
from the gorges, and to .inclose them in subterraneous tunnels, inclined ac-
cording to the general slope of the soil. The water, thus protected from
the heat of the sun, does not evaporate at all en' route ; it reaches the foot
of the declivity almost without waste, and, ascending by a vertical well
intofthe__outlet:reservoir,ﬂows immediately into the irrigation trenches.
The greater part of these channels are pierced here and there with aper-
tures, through which the cultivators .of the banks of the river draw the
water‘ne'cessary for their crops. ‘ Some of these subterranean streams are
not less than 3.6 miles in length. They are rudimentary imitations of the
very work which nature herself accomplishes inorder to elaborate her
springs and cause them to gush out from the surface of the soil.
Thanks to the eﬂicacious means of boring which modern ingenuity has
placed in the hands of geologists, men do not content themselves with
piercingfth'e beds of clay, sand, and stone to any triﬂing depth, but pene~
trate'h-un'dreds 'of yards, in order to give an upward egress to the veins of
water which have descended fromthe mountains or distant plateaux. . By
‘means of the second-sight which study gives him, the savant can point out
beforehand with almost perfect precision. the course of the subterranean
waters, and even. the. quality of the ﬂuid. Thus the engineers bored
through the soil in the environs of Calais in the hope (which was j ustiﬁed
.by the result) of touching 'upon the waters whi'chhad come from the hills
of England under the Straits of Dover, and making it spring up in theirv
wells. They have also dug with perfect conﬁdence in the precise spot
where saline or medicinal waters'ﬂowed under the ground. In the Alge-
rian Sahara, the engineers markbeforehand, in the middle of the barren
and arid desert,‘ the place where an abundant spring ought to gush out, and
every blow of the ,borin g-rod brings to the surface a jet of water, which is
soon surrounded by tents and the budding palm-trees of an oasis.
- Thus, although the sight of man can not penetrate through the beds of
.rocks piled one‘above another, yet the subterranean course of the streams
is none the less visible to his mind’s eye. Besides, these subterranean
* Mittbez'lungen van Peterma-nn, I861.
ARTESIAN WELLS—TEMPERA T URE. 233
waters act exactly in the same manner as those which ﬂow on the surface
of the soil; they also carry along their alluvium, and thus contribute their
part toward modifying the relief of the globe. In many places, especially
at Tours, the artesian wells have ejected the remains of plants, branches,
moss, snail-shells, and other debris which the rains had probably carried
away some weeks previously into the depths of the earth. At Elbteuf the
water of a well contained living eels.*
Many artesian wells reach a very considerable depth. The celebrated
well of Grenelle is not less than 1771 feet deep, and the water which rises ‘
from the bottom of this abyss also ascends 91 feet. The salt‘ water which
rises from the artesian spring of Neusalzwerk, near Minden, proceeds from
a depth of 2394 feet. A spring of sulphurous water at Louisville, in Ken-
tucky, rises in a bore 2086 feet deep, and the water leaps up 170 feet from
the oriﬁce. A well dug at St. Louis, on the Missouri, to supply a sugar
reﬁnery, exceeds 2624 feet in depth. The quantity of water which-it is
possible to obtain from the various borings is very considerable,‘ and, in
many cases, would be still larger if the ascending tubes had a widerdiam-
eter. The spring of Neusalzwerk yields 321 gallons a minute; an arte-
sian well of the Oued R’ir, that of Sidi-Amran, supplies in the same space
of time 884 gallons, or 5 cubic yards. That of Passy, at Paris, yields 7
cubic yards. In some spots, a large number of artesian wells unite into
one single rising column, the waters of two or more sheets of ﬂuid rising
one above another. Thus, at Dieppe, in borin'g a well 1092 feet‘in depth,
they came successively upon seven very abundant water-bearing strata.


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Fig. 76. Artesian System of Oued R’ir; after Duhocq.
In all artesian springs the temperature rises the farther the-well. de-
scends below the level of the sea. ' The jet from the well ofGrenelle
marks 82° (Fahr.), 64° (Fahr.) more than that of Passy; that is to say,
that at this point of the terrestrial crust the increase'of heat is 1° (Fahr.)
for each interval of 55 feet in depth. The thermometrical study of other
artesian springs has given results differing little from this, and it can be
strictly stated that for every space of from 40 to 55 feet. of vertical height
the temperature increases on an average 1° (Fahr.) from the surface of the
soil to the lowest beds which the excavations of man have yet penetrated]t
In the springs of Sahara the increase of temperature is," according to M.
Ville, 1° (Fahr.) to 36 feet of depth. ' ' _
* Buff, Pbysik der Erde. 1- Vide Ibove, p. 30, 31.
234, THE EARTH
CHAPTER XL.
COLD AND THERMAL SPRINGS.
As artesian wells only differ from natural springs in the change of direc-
tion given to their waters, the same laws must apply to all subterranean
currents, consequently the depth to which the water descends into the
bowels of the earth may be approximately ascertained by the temperature
of a spring. It may be conﬁdently aﬁirmed that, in a general way, cold
springs—that is to say, those the mean temperature of which is lower
than the heat of the soil—descend from mountains, and that thermal
springs proceed, on the contrary, from beds lying deep in the interior of
the earth.
In the innumerable multitude of springs, either cold or thermal, which
rise from the earth, we may observe the whole range of possible tempera-
tures from freezing-point up to the boiling-point. A spring which ﬂows
from the side of the Hangerer, in the Oetzthal, at a height of 6742 feet, is
only 1° warmer than ice.* On the Alps, the Pyrenees, and all the other
chains of snow-clad mountains, near the summits small rills of water are
very frequently met with, the temperature of which is scarcely higher
than that of melting snow. Even at the bases of mountains, and especially
those of a calcareous nature, a great number of springs are found which
are much colder than the surrounding soil. Geologists who have applied
themselves to the study of subterranean hydrography have had many op-
portunities of proving the truth of the fact that drainage-waters at ﬁrst
maintain a temperature considerably lower than that of the rocks. This
is so because, in addition to the water, the air also enters the subterranean
channels and circulates in all the net-work of clefts and crevices, and,by
incessantly gliding over the wet sides of the channels, produces a rapid
evaporation of moisture, and, in consequence, refrigerates the surface of the
rocks and even the stream itself The temperature, therefore, of springs
which proceed from the interior of cavernous mountains is always several
degrees lower than the normal temperature of the soil.
The greater number, however, of subterranean rivulets which ﬂow at a
small depth below the surface of the rocks or earth, and gush forth in
springs after having slowly traversed a slightly inclined extent of ground,
ultimately acquire a temperature scarcely differing at all from that of the
soil. The simplest means of approximately ascertaining the mean tem-
perature of any particular spot is to plunge the thermometer into the
spring-water; for, as the extremes of heat and cold are inoperative at a
depth of only a few yards below the surface of the soil, the greater num-
* Sonklar, (Etztkaler G'ebirgsgruppe.
THERMAL SPRINGS. 235
ber of liquid veins are not liable to the changing inﬂuences of the outer
air, and, in consequence, show at their emerging point the real average cli-
mate of the locality. In winter the Sorgue of Vaucluse seems to smoke,
on account of the rapid condensation of its vapor, which is cooled by the
atmosphere. During the severe winter of 1819 to 1820, when the Rhone
was completely frozen over, and might be safely crossed from Avignon to
Villeneuve, M. F. de Lanoye tells us, the whole extent of the Sorgue re-
mained perfectly free from ice.
Springs which have a higher temperature than the soil are called ther-
mal springs. These are the springs the depth of which may be roughly
estimated by calculating a descent of 55 feet for each degree (Fahr.) be-
yond the normal heat of the surrounding soil. Thus the springs of Plom-
bieres, which have a temperature of 149° (Fahr.), would take their rise
5413 feet below the surface; those of Chaudes-Aigues, the heat of which
is found to be not less than 17 8° (Fahr.), issue from beds situated 6889 feet
from the surface of the soil; lastly, the gushing rivulet of Trincheras, in
Venezuela, which marked 206° (Fahr.) at the time of Boussingault’s visit
in 1823, would proceed from rocks at a still more considerable depth.
It has been the subject of direct observation in the wells of the Geysers,
in Iceland,* that the deep water in the interior of the earth may attain a
temperature considerably above 212° (Fahr.) ; but on reachingvthe surface,
this boiling water, nearly all of which jets forth in the vicinity of volca-
noes, must necessarily be transformed into steam. It must, moreover, be
remarked, that the high temperature of several springs is owing to acci-
dental causes. When the volcano of J orullo made its appearance in 1759,
two small rivulets—the rios of Cuitimba and San Pedro—were covered
with intensely heated scoriae, and reappeared farther down their course as
thermal springs. In 1803 the lava was still warm, as the temperature of
the springs measured bylHumboldt exceeded 1490 (Fahr.);j but travelers
who have recently visited the district of J orullo aver that the water ﬂow-
ing from the base of the:volcano has gradually cooled since the commence-
ment of the century, and_that soon it will have-reached the normal tem-
perature of the surrounding soil. In the same way the water of Bertrieh-
bad, in Luxembourg, has gradually discontinued to be either warm or min-
eral in its character ever since the lava of a small eruption has ceased to
come in contact with the burning‘ furnace which produced it.,’[
It is to be remarked that nearly all thermal springs which do not‘owe
their high temperature to the vicinity of volcanoes issue forth from‘ faults
which open on the surface of masses of a crystalline nature, and principally
at the side of modern eruptive rocks which have been thrust up through
older strata. This must evidently be the case, for in piercing the terres-
trial crust the upheaved matter has broken through the parallel layers
which detained the sheets of water, ahd by this rupture of the strata has
opened channels by which the springs can ascend toward the surface of
* Vide the chapter on “ Volcanoes. ” 1' Humboldt, Cosmos, 181; Part.
I Poulett Scrope, Volcanoes.
236 THE EARTH.
the soil. One fact, also, that proves the existence of these deep ﬁssures
whence thermal waters spring is that their temperature sometimes changes
suddenly in consequence of earthquakes which obstruct the former faults,
or else open them out to far greater depths. At the time of the earth-
quake at Lisbon, the temperature of a spring of Bagneres de Luchon sud-
denly rose, it is said, from 46° to 122° Fahr. (?), and since that date, now
more than a century ago, the action of the spring is not modiﬁed. It is
also said that the thermal springs of Bagneres de Bigorre suddenly be-
came cool at the time of the great earthquake in 1660.*
The inﬂuence of rains and seasons has much less effect upon thermal
waters than upon cold springs which proceed from the upper layers of the
soil. A great number of warm springs, however, undergo certain changes
in their yield of water, which must be without doubt attributable, at least
partially, to the same causes as the variations in the discharges of super-
ﬁcial streams. In Auvergne, in the Pyrenees, and in Switzerland, several
springs, perfectly protected against any inﬁltration of rain-water, ﬂow in
much greater abundance at the very same period when the adjacent tor-
rents become swollen. It is true that the increase of thermal water must
be partly caused by the lateral pressure exercised by the cold waters sat-
urating the soil and forcing back all the small scattered rills toward the
central spring. But the liquid mass proceeding from deep beds is also
much stronger (for the temperature of deep springs increases simultane-
ously with the yield), doubtless because the subterranean rivulets, when
increased in volume, are less retarded in their course, and lose less heat in
‘mounting toward the surface of the ground. At Brig-Baden, in the Val-
ais, the water, the mean temperature of which is in autumn and winter
from 71° to 72° (Fahr.), rises to 113° and 122° (Fahlz) when the breath of
spring melts the ice on the J ungfrauﬂr Many of the phenomena, however,
exhibited by thermal springs are still rather diﬂicult to explain. The
greater number, therefore, of savants who devote themselves to the study
of subterranean hydrology admit that the tension of gases which are pro-
duced in the interior of the earth plays a principal part in the emission of
thermal waters.
Most thermal springs contain mineral substances in solution; there are,
however, a certain number which are almost as pure as rain-water—such
as, for instance, the celebrated waters of Plombieres, which do not even
contain ﬁlm of salts; also that of Gastein, Pfeﬂ'ers,Wildbad, and Baden-
weilerJ: The springs of Chaudes-Aigues—those in France which have
the highest temperature, 158° to 1 76° (Fahr.)—eontain only a small amount
of mineral substances. The inhabitants of Chaudes-Aigues use the water
to prepare their food, to wash their linen, and to warm their houses.
Wooden conduits, erected in all the streets of the town, supply, on the
ground ﬂoor of each house, a reservoir which serves to heat it during cold
weather, and thus dispenses with ﬁres and chimneys. In summer, small
* Lyell, British Association at Bath, 1864. 1' Filhel, Eaux des Pyre'ne'es.
I Buﬁ',Ph3/sik der Erde.
THERMAL SPRINGS—HEAT UTILIZED. 237
sluices, placed at the entrance of each conducting tube, stop the warm
water and throw it back into the rivulet which ﬂows at the bottom of the
town. M. Berthier, a chemist, has calculated that the heat furnished daily
by the springs is equal to that which the combustion of more than four
tons and a half of coal would produce. It is sufficient to give a comfort-
able temperature to the interior of the houses and to warm the streets
themselves. The snow, which falls in great abundance during winter,
melts immediately after its fall.* There are not perhaps in the world any
thermal springs the heat of which is better utilized.
* Allard and Boucomont, Eaux Thermo-mine'rales d ’Auvergne.
233 THE EARTH
CHAPTER XLI.
MINERAL SPRINGS.—INCRUSTING SPRINGS.——METALLIC VEINS._SALT
SPRINGS.
SPRING-WATER, cold as well as hot, is rarely, if indeed ever, pure from
all admixture; thousands of samples analyzed even in our time by chem-
ists do not furnish a single instance of spring-water which does not con-
tain a greater or less proportion of calcareous or magnesian salts. The
purest water that the French chemists have yet found is that of the Dome,
a small river of Ardeche, and this may almost be compared to distilled
water. In the other mountainous regions of Central France, water, con—
sidered quite excellent in its character, is charged with two, three, four, 01'
even ten times more calcareous matter. The water of the Seine contains,
on an average, thirty-six times more extraneous matter, and some wells
at Paris and Marseilles, the water of which is, notwithstanding, used for
drinking, are 250 to 350 times less pure.*
Among the various substances which spring-water brings to the surface,
those which are most common proceed from the strata which serve to con-
stitute the very frame-work of the globe. Chalk, especially, occurs in dif-
ferent proportions in most springs, either under the form of sulphate of
lime, or, more often, as carbonate of lime. Water which contains carbonic
acid in solution is charged with calcareous matter dissolved away from the
sides of the rocks through which it passes; then, by means of evaporation,
it redeposits the stony substances which it previously held in solution.
Hence arise all those calcareous concretions which form around so many
springs; also the stalactites in caverns, and even those dangerous incrus-
tations which accumulate in the boilers of locomotives.
Nearly all countries of the world possess some of these curious springs,
which cover with a calcareous crust any object placed in their waters.
Among these incrusting springs, those of Saint Allyre, near Clermont, Ri-
voli, and San Filippo, not far from Rome, have justly become celebrated.
These latter have, in a space of twenty years, ﬁlled up a pond with a bed
of travertin 30 feet thick, and, in the neighborhood, entire strata of this
same rock may be seen having a depth of more than 328 feetﬂr The
springs of Hammam-Mes-Khoutine, in the province of Constantine, are also
very remarkable on account of the considerable amount of their deposits.
This water, which rises at a temperature of 203° (Fahn), and from which
a high column of steam always rises, is frequently compelled to change its
point of issue on account of the dense beds of travertin which are gradu-
* Robinet, Discussion sur les Eaux Potables.
‘l’ Lyell, Principles of Geology.
IN OR USTIN G SPRINGS’. 239
ally deposited upon the soil. Most of these deposits are of a dazzling
white hue, striped here and there with bright colors, and are developed in
mammillated strata; other concretions, accumulating gradually round an
oriﬁce, have taken the form of cones, and are like the small craters near
a volcano, some of them rising to a height of as much as 33 feet; lastly,
there are masses of travertin which stretch out in a kind of wall below the
ﬂow which deposits them. One of these walls, which is interrupted at in~
tervals by heaps of earth upon which large trees grow, is not less than 4921
feet long, 66 feet high, and, on an average, from 33 to'49 feet wide.*
The thermal waters of Algeria are, however, surpassed in grandeur and
beauty by the springs of the ancient Ionian city of Hierapolis (holy city),
which at the present time ﬂow in the solitary plateau called Panbouk-
Kelessi (Castle of Cotton), on account of the cotton-like aspect of the
white masses of travertin of which it is composed. On reaching this spot
from Smyrna, something like an immense cataract may be seen in the dis-
tance, 328 feet high and 2% miles wide; this is famed by the walls which
the water has gradually constructed, column after column, and layer after
layer, by ﬂowing over the edges of the plateau and gushing out on the
slopes. Here and there, real cascades glitter in the sun, and their spark-
ling surfaces light up the dead whiteness of the crystal walls. As a spec-
tator ascends the declivities, the masses deposited and carved out by the
water appear in all their strange beauty; one might fancy that they were
colonnades, groups of ﬁgures, and rude bas-reliefs which the chisel had
not yet perfectly set free from their rough coverings of stone. And all
these calcareous deposits which have been fashioned by the cascades dur-
ing a succession of ages open a multitude of cup-like hollows with ﬂuted
edges fringed with stalactites; these graceful reservoirs—some of which
are shaded with yellow or veined with red, brown, and violet, like jasper
or agate—are ﬁlled with pure water. Higher still follow two steps of the
plateau on which stood the ancient thermal ediﬁce and the Necropolis of
Hierapolis. There, whitish masses cover the ancient tomb-stones and ﬁll
up the conduits. The ground is crossed in various directions by the ter-
nler beds of rivulets, which have gradually stopped up their own courses
by depositing concretions upon them. Above one of the widest of these
dried-up channels, the magniﬁcent span of a natural bridge displays its
graceful form, like an arch of alabaster, streaming with innumerable sta-
lactitesf At what date did this majestic structure take its rise, and how
many years and centuries did the process of its formation last? N 0 one
knows. According to Strabo, the channels of the baths of Hierapolis were
soon ﬁlled up by solid masses, and if Vitruvius can be believed, when the
proprietors of the environs wished to inclose their domain, they caused
a current of water to run along the boundary-line, and in the space of a
year the walls had risen.
Silica, which is still more important than chalk in the formation of ter-
* Grellois, Les Depots Oalcaires de Hammam-Mes-Klzoutine.
1' Tchihatchef, Le Bosplzore et Constantinople.
240 THE EARTH.

restrial rocks, is also sometimes deposited on the edge of springs, but in
very small quantities; only these waters which are of a very high tem-
perature can dissolve silica in suﬂicient quantities to form a deposit round
their outlet, and produce beds of any considerable thickness. Among the
springs which are charged with silica, the best known are the Geysers of
Iceland, the boiling waters of which deposit round their oriﬁce circular lay—
ers of siliceous eoncretions several yards high.* Other volcanic springs
are no less active, and even at a long distance from any volcano there are
few thermal springs which do not contain silica in quantities more or less
perceptible.
Concretions and crystallizations formed by thermal waters in the very
interior of ﬁssures or lines of fault have geologically more importance than
external deposits, and can be produced at a much lower temperature than
in the open air. M. Daubrée has seen these phenomena in action at the
springs of Plombieres. The ancient Roman masonry which was used for
storing and supplying water is ﬁlled with zeolites or siliceous crystals, ev-
idently owing to the prolonged inﬂuence of the water and its slow chem-
ical reaction on the calcareous cement and the bricks. The intimate struc-
ture of these materials has been modiﬁed by this water, the heat of which
does not, however, exceed 140° to 158° (F8.l11‘.). It is doubtless a similar
chemical action, due to these thermal waters; which has produced in all
* Vida chapter on “Volcanoes.”
MINERAL VEINS. 241
the ﬁssures of Plombieres the vein of quartz, opal, and ﬂuor spar which
are found there. The enormous deposits of a quartz-like nature in an ad-
jacent valley, that of Roches, are results of the same geological work.*
It is probable that at 33,000 or 39,000 feet deep in these abysses, where
the water, still retaining a liquid state, may attain to a temperature of
500° to 600° (Fahr.), the chemical operations of subterranean waters are ac-
complished with much more activity than in beds near the surface. Most
geologists think that thermal vapors can dissolve not only those metals
which melt at low temperatures, such as tin and lead, but also copper,
gold, and silver. Veins containing metals are probably only ﬁssures in
which these ‘thermal vapors have become cooled, and have then deposited
the metallic substances with which they were charged. Gold, silver, and
copper remain in the depths of the earth, and the waters bring up to the
basin of the spring nothing but a small quantity of salts, silicates, and
gases. Then follow the gradual movements of the crust'and the geolog-
ical revolutions which cause the metallic veins to rise to the level of the
ground, or, at least, which bring them nearer to the surface]l
The various dislocations of the terrestrial strata, the cooling of the wa-
ters, and, perhaps, in many instances, the obstruction of channels by de-
posits of ore, explain why, in the present period, so small a number of
thermal springs issue from metalliferous beds. N evertheless, many 10-
calities might be mentioned where this phenomena takes place at the
present time. A spring at Badenweiler, in the Black Forest, issues forth
at a few yards from a vein of sulphuret of lead. In the granitic plateau
of Central France other springs are likewise found to be associated with
this metal. Various thermal waters in the Black Forest, like those of
Carlsbad and Marienbad, are in close connection with veins of iron and
manganese. Oligiste iron is found in the ﬁssures of the springs of Plom-
bieres and Chaude-Fontaine. In Tuscany sulphureous fumaroles proceed
from the veins of antimony. In France and Algeria the waters of Syl-
vanes and Hammam R’ira issue forth from beds of copper. Lastly, near
Freyberg, a voluminous thermal spring has been discovered in a vein of
silvelzjj
Among the mineral substances which some springs bring to the surface
of the soil, the most important, in an economical point of view, is common
salt. This substance, being one of those which dissolves most readily in
water, all the liquid veins which pass over saline beds become saturated
with salt; therefore springs of this kind, which ﬂow in great abundance,
give rise to salt-works of more or less importance. The masses of com-
mon salt which make their way every year from the interior of the earth
may be estimated at thousands of tons. The springs of Halle, which rise
on the northern slope of the Alps of Salzburg (Salt Town), and are man-
aged with the greatest care, annually produce 15,000 tons of this mineral.
* Daubrée, Bulletin de la Société de Géolog'z'e, 1859.
‘l’ Lyell, British Association at Bath, 1864.
I Daubrée, Bulletin de la Société de G'éologie, 1859.
Q
242 THE EARTH
The salt springs of Halle, in Prussia, which have been worked from time
immemorial by a company, furnish 10,000 tons of salt every year. Other
parts of Germany also yield for consumption thousands of tons of white
salt, which is producedby the evaporation of saline springs. The mass
of salt furnished by the single artesian well of Neusalzwerk, near Minden,
in Prussia, represents every year a cube measuring 7 8 feet on each side.*
Though not so rich as Germany in saline springs thus turned to account,
most of the civilized countries of the world possess salt-works which are
also very important. France enjoys the springs of Dieuze, Salins, and
Salies ; Switzerland, those of Bex; Italy has the springs in the environs
of Modena, and many others besides. In England, near Chester, there are
some mines of rock-salt in which numerous liquid veins issue forth which
are impregnated with salt. Lastly, the United States have the celebrated
springs of Syracuse. But how many saline springs, still more abundant,
ﬂow uselessly along in the solitudes of the world!
Not far from the “ spot where Troy once stood” is the valley of Touzla-
sou, which owes its name (Salt Water) to its numerous salt springs. The
mountains which rise around its circumference are variously shaded with
blue, red, and yellow, and the rocks are incessantly decomposing under
the action of the liquid salt which oozes out from, and trickles down their
sides. The plain itself is covered with a variegated crust, while jets of
boiling-water,— saturated with salt, burst forth in every direction. Here
and there pools are found, the moisture of which, by evaporating in the
sun, leaves upon the soil beds of salt as white as snow. Near the mouth
of the valley springs become more and more numerous. Lastly, in the
place where the cliffs approach near together, so as to form a deﬁle, a
magniﬁcent spout of water jets out from one side of the rock. This jet is
not less than a foot in diameter at the oriﬁce, and falls again after having
described a parabola of more than a yard and a half Other springs shoot
out on both sides, the constant temperature of which is more than 212°
(Fahn); these, together with the principal jet, form a rivulet of boiling
and steaming water. It would be easy to extract from these springs an
enormous annual supply of salt; but the negligence of the Turkish gov-
ernment, who have appropriated the valley of Touzla-sou, has prevented
more than one thousand tons a year being obtained]L
Springs of salt water are used for the treatment of diseases as well as
for the extraction of salt. They constitute one of the most important
groups of medicinal waters, according to the various susbstances which
they contain in solution. The other springs made use of, 011 account of
their healing virtues, have been classed under ferruginous, sulphureous,
and acidulous springs. These waters also contain, in different proportions,
a variable quantity of gases and salts which they have dissolved in their
passage over subterranean beds of every kind. It is probable that the
proportion of gases dissolved in the water ﬂuctuates with all the varia-
tions of temperature and pressure of the surrounding air. It even ap-
* Buﬂ', Pkysilc der Erde. Tchihatchef, Le Bosphore et Constantinople.
HOT AND SALINE STRINGS’. _ 243
pears that a simple movement of the liquid is sufﬁcient to alter the con-
stituents of the water as regards its gaseous elements; but, on the whole,
the chemical composition is tolera-bly permanent, and there is no doubt as
to the particular virtue of every spring which renders it ﬁt for the treatment
of one or many special diseases. Thanks to this healing power, of all the
resources of which science, still imperfect, is yet ignorant, medicinal w‘ -

Fig. 78. Saline Springs of Touzla.
ters serve as a guide to a more familiar acquaintance with nature, for
every year thousands and hundreds of thousands of visitors are attract-
ed by them to the most picturesque and majestic spots on the face of the
earth. ‘
In fact, mineral springs, which, for the most part, are also thermal, hav-
ing flowed from deep beds, nearly all issue forth at the point of contact
between older rocks and more modern formations. Now these points of
contact are especially found in 1'nountainous countries, which also receive
from the atmosphere larger quantities of water than plains do. Mineral
springs are most numerous and abundant in mountain valleys, and there,
consequently, the great thermal institutions are established. In Europe
the chain of the Pyrenees is probably the richest in mineral, sulphureous,
saline, ferruginous, and acidulous springs. According to Francis, the en-
gineer, in 1860 more than 550 mineral springs, 187 of which are used, ﬂow-
ed upon the French slopes of the Pyrenees. These waters supplied 83
244 THE EARTH.
hot baths in 53 localities, the principal of which are Bagneres de Bigorre,
Luchon, Eaux-Bonnes, and Oauterets. The most abundant springs, those
of Graus d’Olette, form a sort of mineral stream, yielding more than four
gallons a second, or 2322 cubic yards a day. In Algeria the spring of
Hammam-Mes-Khoutine yields 6 gallons a second.
There are regions, some volcanic and some not, in which nearly all the
springs are thermal and mineral; springs of pure and fresh water being so
rare, they are there considered to be most precious treasures. One of
these regions comprehends a large part of the plateau of Utah. In this
place numerous thermal springs issue forth, to which have been given the
vulgar names of the Beer, Steam-boat, Whistle springs, etc., and into one
of which the Mormons plunge their neophytes. The springs which are
not thermal are loaded with saline and calcareous matter. It is only in
spring, at the time when the snow melts, that the springs, which then be-
come very abundant, yield comparatively pure water. During the dry
season, salt and carbonate of lime become concentrated in the nearly ex-
hausted springs, and give to the liquid ﬂow an unpalatable taste. Pal-
grave, the traveler, informs us that all the springs of the country of Hasa,
in Arabia, are also thermal.
It can readily be understood that when all these substances escape from
the interior of the rocks, together with the water which holds them in SOs
lntion, they must leave empty s-aces in the earth. During the course of
long centuries whole strata are dissolved, and, under a form more or less
chemically modiﬁed, are brought up from the depths and distributed on
the surface of the soil. The thermal waters of Bath, which are far from
being remarkable for the proportion of mineral substances they contain,
bring to the surface of the earth an annual amount of sulphates of lime
and soda, and chlorides of sodium and magnesium, the cubic mass of
which is not less than 554 cubic yards.* It has also been calculated that
one of the springs of Loueche, that of Saint Laurent, brings every year to
the surface 8,822,400 pounds of gypsum, or about 2122 cubic yards; this
quantity is enough to lower a bed of gypsum, a square mile in extent,
more than ﬁve feet in one century. But this is only one spring, and we
have reckoned one century only; if we think of the thousands of mineral
springs which gush from the soil, and of the immensity of time during
which their waters have ﬂowed, some idea may be formed of the import-
ance of the alterations caused by springs. In time they lower the whole
mass of mountains, and no doubt, after these sinkings, violent oscillations
of the earth may often have taken place);
* Ramsay. Lyell, British Association at Bath, 1864.
’r Otto Volger, Ueber das P/zz'inomen 'der Erdbeben, to]. ii.
SUBTERRANEAN WA TEE-00 URSES. 245
CHAPTER XLII.
SUBTERRANEAN RIVERS.—THE SPRING or VAUCLUSE, THE TOUVRE.-—-SUB-
MARINE AFFLUENTS.—THE RIOS OF YUCATAN.-—-THE “MUD-LUMPs” on
THE MISSISSIPPI.
IN regions where the strata are pierced with wide and deep caverns,
and especially in calcareous countries, the waters sometimes accumulate
in suﬂicient quantities to form perfect streams with long subterranean
courses. At their issue from the caverns, these waters form a contrast
with the rocks and hills around, all the more striking because the latter
are completely devoid of moisture, and fearfully sterile, while on the brink
of the limpid stream the fresh verdure of plants and trees is at once de-


Fig. 79. Vaucluse and the Sorgues.
veloped. Like a captive, joyous at seeing the light once more, the water
which shoots forth from the sombre grotto of rocks sparkles in the sun,
and careers along with a light murmur between its ﬂowery banks.
Among these subterranean streams, the most celebrated, and doubtless
one of the most beautiful, is the Sorgues of Vaucluse. The vaulted grotto
from which the mighty mass of water escapes opens at the mouth of an
amphitheatre of calcareous rocks with perpendicular sides. Above the
spring rises a high white cliff, bearing on its summit a ruined tower of the
Middle Ages; the rock is every where sterile and bare; there is nothing
but a miserable ﬁg-tree, clinging to the stone like a parasitical plant to the
bark of a tree, which has plunged its roots into the ﬁssure of the cave,
and greedily absorbs with its leaves the moisture which ﬂoats like a mist
above the cascades of the spring. After heavy rains, the liquid mass,
which is then estimated at 26 or even 32 cubic yards a second, ﬂows in a
246 . THE EARTH
a
wide sheet high above the entrance to the cavern, which is then altogeth-
er inaccessible. WVhen the waters are low, they ﬂew bubbling across the

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Fig. 80. Course of the Touvre.


barrier of rocky debris which obstructs the entrance; at that time it is
quite possible to penetrate under the arch, and to contemplate the vast
basin in which the blue waters of the subterranean stream spread out be-
fore they leap into the open air. Soon after its issue from the cave and
amphitheatre of Vaucluse, the Sorgues is divided into numerous irrigation-
channels, which spread fertility in‘ the country'ovcr an area of more than
7 7 square miles. The subterranean course of the aﬂluents which form the
stream is not ascertained; but it is known that most of them commence
.1-2 or 15 miles to the east, in the plateaux of Saint Christel and Lagarde,
which are pierced all over with avens or chasms, into which the rain-water
‘sinks and disappears. -
‘In another part of France there is a second important subterranean
stream, which is much less known but no less remarkable than that of
Vaucluse; this is the Touvre' of Angouléme, continuing the course of the
Bandiat, the waters of which, like those of the Tardoire, are swallowed up
in several abysses at distances varying from 3 to 7 miles to the east and
northeast. The three principal springs of the Touvre ﬂow slowly out of
a deep cave, hollowed out at the base of an escarped cliﬂ'; another spring
bubbles up in a basin of rocks; the third emerges from a sort of bogg
S UBMARLVE' 0 UTLETS OF RIVERS. 9 47
.J
meadow intersected by drains. At the outlet of their subterranean courses
these three enormous springs immediately form three streams, which re-
unite, leaving' between them two long peninsulas of reeds and other aquat-
ic plants. Below the junction, the Touvre, which is here more than 100
yards wide, passes round a rugged hill, and, dividing into several branch-
es, turns the numerous mill-wheels of the important gun-foundery of Ru-
elle; then, after a course of ﬁve miles, it ﬂows into the Oharente at a small
distance above Angouléme. Among the hundreds and thousands of trav-
elers whom steam annually conveys over the bridge of the Touvre, there
are few who are aware of the curious nature of the source of the river of
limpid water over which the train passes in its noisy career.
Omitting to mention the streams which accidentally pass under the
strata of rocks during a small part of their course, or of the subterranean
outlets of certain lakes,* a multitude of other instances might be brought
forward of masses of water, more or less abundant, which appear above
ground after having traversed a considerable distance under the earth.
Of this kind is the graceful spring of Nimes, the blue transparent water.
of which, reﬂecting the foliage of pines and chestnut trees, glides in its
gentle ripples over the semicircular steps of an old Roman staircase. Of
this kind, too, is the spring of Vénéran, near Saintes: this spring, which
was formerly sacred to the Goddess of Love, gushes from the ground in a
gorge of rocks, and, passing through a mill, the wheel of which it turns, it
suddenly disappears, being swallowed up in an abyss; thus it appears on
the earth to work but for an instant.
Numbers of water-courses do not reappear on the surface 'of the soil
after being swallowed up in the earth, but ﬂow straight to the sea by
means of subterranean channels. On nearly the whole extent of the con-
tinental shores, and principally in localities where the coasts are of a cal-
careous nature, the outlets of submarine tributaries may be noticed, some
of which are perfect rivers. Most of the springs of the department of
Bouches du Rhone jet up from the bottom of the sea, but at various dis-
tances from the shore. One of them, that of Porte Miou, near .Oassis,
forms on the surface of the sea a considerable current, which drifts any
ﬂoating bodies to a great distance]L At Saint Nazaire,Oiotat,Oannes,
San Remo, and Spezzia, other streams also issue from the midst of the salt
waves, and attempts have even been made to measure approximately their
discharge. lVLVilleneuve-Flayosc estimates at 24 cubic yards a second
the quantity of water discharged into the sea by all the hidden afHuents
of the Mediterranean between Nice and Genoa. Some of the submarine
springs of Provence and Liguria proceed from enormous depths. The ori-
ﬁce of the spring of Cannes is 531 feet below the level of the sea; that of
San Remo rises from a depth of 954 feet; lastly, at four miles to the south
of Cape Saint Martin, between Monaco and Mentone, another stream of
ﬂesh water empties itself under a bed of salt water, near 2296 feet deep.I
* Vide the chapter on “ Lakes.” 1' Marsigli, Histoire Physique de la Mer.
i Villeueuve-Flayosc, Description Ge’ologz'que du Var.
248 THE EARTH
The coasts of Algeria, Istria, Dalmatia, and the Herzegovina also pre-
sent numerous instances of submarine streams; on the eastern shores of
the Adriatic the traveler may even have the pleasure of contemplating
the delta of a considerable river, the Trebintehitza, visible through the
sea-water at the depth of a yard. The abundant springs of fresh water
which pour out into the open sea to the southwest of the Cuban port of
Batabano are well known, since Humboldt described them, and it is ob-
served that the lamantins,.or sea-cows, which dread salt water, delight in
frequenting these parts. Lastly, the Red Sea, which does not throughout
its immense circumference receive a single permanent stream ﬂowing on
the surface of the ground, nevertheless receives some which spring from
the bottom of its bed. The shores of the United States, the calcareous
soil of which is probably pierced with caverns from the very centre of the
continent, perhaps are the coasts which pour into the sea the most abun-
dant subterranean rivers. Near the mouth of the stream of St. John, a
submarine stream of perfectly pure water spouts in bubbles as far as one
to two yards above the level of the sea. Off the Oarolinas, and Florida,
salt water has been known to change into brackish water under the inﬂu-
ence of the sudden increase of its subterranean aiﬂuents. In the month
of January, 1857, all that part of the sea which is adjacent to the southern
point of Florida was the scene of an immense eruption of fresh water.
Muddy and yellowish water furrowed the straits, and myriads of dead ﬁsh
ﬂoated on the surface and accumulated on the shores. Even in the open
sea the saltness diminished by one half, and in some places the ﬁshermen
drew their drinking-water from the surface of the sea as if from a well.
It is affirmed by all those who witnessed this remarkable inundation of
the subterranean river that, during more than a month, it discharged at
least as much water as the Mississippi itself, and spread over all the strait,
31 miles wide, which separates Key West from Florida.*
On the coasts of Yucatan, the fresh waters which take a subterranean
course down to the sea do not appear to ﬂow like rivers which have a
narrow bed and attain considerable speed, but more in the form of a wide
sheet of liquid with a nearly imperceptible current. Cenotcs open here
and there over the surface of the country; they are a kind of natural
draining-well or hole, not very deep, into which the inhabitants descend
to draw spring water. At Merida and in the environs the subterranean
water is found at a depth of 26 to 30 feet; but the nearer we approach to
the sea, the thinner the layer of rock becomes which covers the liquid
veins; on the sea-shore fresh water is found nearly on a level with the
soil. The height of the veins varies several inches, according to the quan-
tity of rain; but in every season, the mass of water descending from the
plateau of Yucatan is poured into the sea through innumerable outlets.
Over a great extent of the shore of the peninsula, these hidden springs
furnish collectively a mass sufficiently large to counterpoise the waters of
the sea. Under the pressure of the marine current which runs along the
”‘ Raymond Thomassy, Essai sur Z’Hydrologie.
ORIGHV OF “MUD—L UMPS,” ET 0'. 249
coast, there is formed, between the open sea and the liquid mass which
has made its way from the land, a littoral bank like those barriers which
the waves construct before the mouths of rivers.* This embankment,
which protects the coasts of Yucatan like a breakwater, is not less than
171 miles long, and is cut through by the sea at two or three points. The
channel, which stretches like a wide river between the bank-of alluvium
and the Yucatan coast, is, not without reason, designated by the inhabit-
ants by the name of stream, or riaf ‘
Among the remarkable phenomena which perhaps owe their existence
to subterranean water-courses, we must mention the sudden or gradual
appearance of those hillocks of clay (“mud-lumps”) which rise, to the
great danger of navigators, either in the middle of the bar of the Missis-
sippi, or in the immediate vicinity. Like small volcanoes of mud, the
“ mud-lumps” generally appear under the form of isolated cones, allowing
a rill of dirty water to escape from their summits. Some of them are ir-
regular on their surface, on which lateral oriﬁces here and there show
themselves, some in full activity, others abandoned by the springs which
formerly gushed from them. The water of some “ mud-lumps” is loaded
with oxide of iron or carbonate of lime, which, with the agglutinated
sands, form hard masses, having the consistence of perfect rocks. These
hillocks vary both in their height and shape. The greater part remain
hidden at the bottom of the water, and even their summits do not reach
the level .of the river or sea; others hardly raise their heads above the


Fig. 81. Mud isla d in course of formation.
waves; the most considerable, however, rise to a height of 6, 9, or even
19 feet, and their base covers an area of several acres. M. Thomassy is of
opinion that the mouths of the Mississippi probably owe to one of these
hillocks the name of Cabo ole Loclo (Mud Cape) which was given to them
by the Spanish pilot, Enriq‘ues Barroto.
It is evident that the “ mud-lumps” were not formed by the alluvium of
the river, as several geologists at ﬁrst supposed. The~ great elevation of
some of the mud hillocks above the ﬂood-waters and tides suffices to ren-
der this hypothesis inadmissible. The sudden way in which most of these
water-volcanoes make their appearance, the anchors of vessels, and the re-
mains of cargoes which have been found on their surface, their conical
form, their terminal craters, and all the springs, “ which seem to spout out
as if from a subterranean sieve,” indicate, on the contrary, the existence
of a subterranean force always at work to upheave this band of hillocks.
Messrs. Humphreys and AbbotI think that this power consists in the dis-
* Vide chapter xliii. ’r Arthur Schott, llIittheilungen von Petermann, 1866.
It Report on the Mississippi River.
250 THE EARTH
charge of hydrogen gas proceeding from the alluvium of the Mississippi.
According to these engineers, great masses of vegetable products—trunks
of trees, branches, leaves, and seeds—brought down by the waters of the
river, drift upon the bar; these are afterward covered up, and, as it were,
imprisoned under a bed of mud, and, fermenting, produce gases which
ultimately distend their covering, and, puﬁ‘ing it up into a multitude of
cones, escape into the air, after having pierced the soil which held them
captive.
This hypothesis suﬂiciently explains the upheaval of the soil and the ex-
istence of the inﬂammable gases which are occasionally discharged from
the craters of the “mud-lumps,” but it leaves unexplained why the mud
poured from the sides of the craters is transformed into a hard and com-
pact clay, devoid of vegetable matter. M. Thomassy is of opinion that
the hillocks of these bars are the oriﬁces of regular artesian wells natural-
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ly formed by a sheet of subterranean water descending from the plateaux
of the interior and ﬂowing below the Mississippi and the clayey levels of
Louisiana.* However this may be, the mode in which these mud hillocks
are formed is well enough known to render it easy to clear them away
from the mouths of the Mississippi and to protect the interests of naviga-
tion. When a cone of clay makes its appearance on the bar, a charge of
powder is introduced into it and explodes it. Thus, in the year 1858, the
southwest passage was cleared of a “mud-lump” which formed a consid-
erable island; a single charge was suﬂicient to annihilate the whole. The
island suddenly sunk; in its place a wide depression was formed, the cir-
cumference of which resembled that of a volcanic crater; at the same time
an enormous quantity of hydrogen gas was discharged into the atmos-
phere.
* Ge'olbgie de la Louisiane. Essai sur Z’Hydrologie.
SYSTEM OF UNDERGROUND RIVERS. 251
CHAPTER XLIII.
SYSTEM OF SUBTERRANEAN STREAMS—JOINTS AND FISSURES OF BOOKS.—
STALACTITES.——THE INHABITANTS OF CAVES. -—-THE MAMMOTH CAVE. —"
CAVERNS OF CARNIOLA AND ISTRIA.
. ABOVE the springs, the course of subterranean rivulets is generally in-
dicated by a series of chasms or natural wells, which disclose the stream
beneath. The arches of caves not being always strong enough to support
the weight of the super-incumbent masses, they necessarily fall in some
places, leaving above them other spaces into which the upper beds suc-
cessively sink. The débrz's of the ruin is afterward cleared away by the
water, or dissolved, atom by atom, by the carbonic acid contained in the
stream, and gradually all the loose rubbish is carried away. In this man-
ner, above the subterranean rivulets, a kind of well is formed, which is
designated in various countries by very different names. They are called
sinks in the United States; dolinas in Carinthia; catavothras in Greece;
pots, entomzoz'rs, and cream in the J ura; embues, cmbucs, go'ulcs, gouz'lles,
gom'gs, gow'gues, bc'toz'rs, boz't tout, cmselmoz'rs, emposz'eu, avens, scialets, m-
gagés, garaga'é, in southern France ;* swallow-holes, sand-pipes, sand-galls,
etc., in England.
By means of these natural gulfs it is possible to reach the subterranean
streams, and to give some account of their system, which is exactly like
that of rivulets and rivers ﬂowing in the open air. These streams also
have their cascades, their windings, and their islands; they also erode or
cover with alluvium the rocks which compose their bed, and they are sub-
ject to all the ﬂuctuations of high and low water. The only important
difference which superﬁcial waters and subterranean currents present in
their phenomena is that these streams in some places ﬁll the whole section
of the cave, and are thus kept back by the upper sides, which compress
the liquid mass. In fact, the spaces hollowed out by the waters in the
interior of the earth are only in a few places formed into regular avenues,
which might be compared to our railway tunnels. Throughout its thick-
ness, the rock opposes an unequal resistance to the action of the water, on
account of the diversity of its ﬁssures, its strata, and its particles. When
the faults are numerous and the strata not very compact, the current grad-
ually hollows out vast cavities, the ceilings of which fall in, and are car-
ried away by the water almost in single grains. Where beds of hard
stone oppose the ﬂow of the rivulet, all it has done during the course of
centuries has been to hew out one narrow aperture. This succession of
widenings and contractions, similar to those of the valleys on the surface,
* Fournet, Hydrologz'e Souterraz'ne.
252 THE EARTH.
forms a series of chambers, separated one from the other by partitions of
rock.‘ The water spreads widely in large cavities, then, contracting its
stream, rushes through each deﬁle as if through a sluice.
On account of these partitions, it is very diﬁicult, or even impossible, to
navigate the course of subterranean rivers to any considerable distance,
even at the time the water is low. When it is high, the liquid mass, dc-
tained by the partitions, rises to a very high level in the large interior
cavities, and often reaches the roof above. Sometimes when, through the
clefts of the rocks, a communication exists between the cave and some
hollow above, the surplus water from the subterranean streams makes its
appearance there. Thus the Becca, which ﬂows beneath the adjacent
plateau of Trieste, does not always ﬁnd space enough to ﬂow freely in its
lower channels, and Schmidl has seen it ascend in the chasms of Trebich to
a height of 341 feet. It may be understood that the pressure of such a
column of water often shatters enormous pieces of rock, and thus modiﬁes
the course of underground streams.
When the water, impelled by force of gravitation, seeks a new bed in
the cavernous depths of the earth, and disappears from its former channels,
these are at ﬁrst much easier of access than they formerly were; but ere
long, in most caves, a new agent intervenes, which seeks to contract or
even completely obstruct them. This agent is the snow-water, or rain,
' which percolates, drop by drop, through the enormous ﬁlter of the upper
strata. In passing through the calcareous mass, each one of these drops
dissolves a certain quantity of carbonate of lime, which is afterward set
free on the arch or the sides of the cave. When the drop of water falls,
it leaves attached to the stone a small ring of a whitish substance; this is
the commencement of a stalactite. Another drop trickles down, and,
trembling on this ring, lengthens it slightly by adding to its edges a thin
circular deposit of lime, and then falls. Thus drop succeeds drop in an
inﬁnite series, each depositing the particles of lime which it contains, and
forming ultimately a number of frail tubes, round which the calcareous
deposit slowly accumulates. But the water which drops from the stalac-
tites has not yet lost all the lime which it held in solution; it still retains
suﬂicient to enable it to elevate the stalagmites and all the mammillated
eoncretions which roughen or cover the ﬂoor of the grotto. It is well
known what fairy-like decorations some caverns owe to this continuous
oozing through the vaults of their roofs. There are few sights in the
world more astonishing than that of these subterranean galleries, with
their dead-white columns, their innumerable pendants and multiform
groups, like veiled statues, all yet unstained by the smoke of the visitor’s
torch. These stalactite caverns can only retain this primitive beauty on
the condition of not being given over to idle curiosity. But yet how large
is the number of those vulgar admirers who, under the pretense of loving
nature, seek only to profane her!
When the action of the water is not disturbed, the needles and other
deposits of the calcareous sediment continue to increase with considerable
STALA CTITES.-FL ORA AND FA UNA OF CA VES. 2 5 3
regularity. In some cases, each new layer which is added to the concre-
tions may be studied as a kind of time-measurer, indicating the date when
the running water abandoned the cave. At length, however, the soft con-
centric layers disappear, and are replaced by forms of a more or less crys-
talline character; for in every case where solid particles exist, subject to
constant conditions of imbibition by water, crystals are readily produced.*
Sooner or later, the stalaetites, increasing gradually in a downward direc-
tion, meet and unite with the needles rising from the surface of the ground,
and, forming by their number a kind of barrier, obstruct the narrower
passages and'elose up the deﬁles, separating the cavern into distinct cham-
bers. Any objects which lie on the surface of the ground in these drip-
ping caves gradually become hidden by the calcareous concretion which
thickens round them. Generally speaking, when geologists ﬁnd in these
grottoes the remains of men or animals—~the former inhabitants of the
mountain caves—they are covered with a crust of stone, slowly deposited
by the dripping water. In 1816, in one of the caves of Adelsberg, a skel-
eton—probably that of some bewildered visitor—was discovered, which
the stone had already enveloped in a white shroud; but these bones have
now, for some years, been ﬁrmly ﬁxed in the thickness of the rock, added
to, as it constantly is, by fresh layers; indeed, the lateral cave itself will
soon be ﬁlled up by stalaetites, and will cease to exist. In like manner,
the skeletons of three hundred Cretans, who were smoked to death by the
Turks in 1822 in the cave of Melidhoni, are gradually disappearing under
the incrustation of stone which has enveloped them with its calcareous
layers/r
In the gloom of these dark recesses there is still some little manifesta—
tion of life. Since, however, plants of a higher order are unable to dis-
pense with light, fungi form the only vegetation which we meet with, and
even these growths of darkness do not always arrive at their full develop-
ment; they often present monstrous and anomalous forms, which puzzle
the botanist, and hinder his attempts at classifying them. Some fungi
never reach any further development than a mass of confusedly organized
cells; others grow so as to cover a considerable surface. The Fauna, be-
ing more independent of light than the Flora, reckons a much larger num-
ber of representatives in these caves. Not only do these subterranean
cavities serve as places of refuge for various birds, and as dens for several
kinds of beasts of prey, such as foxes, badgers, hyenas, which carry thither
the prey which they have caught (as our ancestors the troglodytes once
did), but they are also inhabited by several families of animals which only
exceptionally, or through accident, ever emerge from the depths of the
caverns. Among the latter there is at least one mammal, a species of bat,I
which is found in the caves of Istria, the Apennines, and the Algerian
mountains. The subterranean pools and streams of Central Europe also
contain several varieties of a strange reptile—the‘Hg/pochthon, or Proteus
* Kuhlmann, Presse Scientiﬁque,1865. ‘I’ Perrot, L’Ile de Crete.
I Miniopterus Srhreibersii.
254 THE EARTH.
-——the eyes of which, being useless in the darkness, are almost aborted.
Insects are the class which is best represented in these subterranean re-
gions, but none present these vividcolors which the light of the sun con-
veys to most of their congeners. All are clad in'a dull garb which blends
With thev dark shades of the rock. The most curious of these insects is a
species of ﬂy (Phora macnlata) which never uses its wings, and various
Coleopiera (Anop/it/ialmus), in which the eyes are entirely wantin 0‘. Then
follow spiders, centipedes, crustaceans, and molluscs. M. Schiner, who has
made a special study of the Fauna of caves, enumerates twenty-three spe-
cies of animals which inhabit the caverns in the vicinity of rl“rieste alone;
but these species form, doubtless, but a very small proportion of the sub-
terranean tribes which live in the caves scattered far and wide ‘over the
whole earth. It is said that the caves in Kentucky contain a species ‘of
blind crayﬁsh; also whitish rats, of a very large size; and lizards, wan-
dering gloomily in this world of darkness; and, lastly, a species of yellow
cricket, which crawls like a frog, guiding its course by means of enormous
antennae.
One of these Kentucky caves, called the “Mammoth Cave,” is the lar-
gest which is at present known. The whole of its extent has not been
as yet fully explored, for it may be almost called a subterranean world,
having a system of lakes and rivers, and a net-work of galleries and pas—
sages without number, which cross and recross one another, going down
to'an‘ immense depth. From the chief entrance to the farther recesses of

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the cave, the distance is reckoned to be not less than 9%; miles, and the
whole length of the two hundred alleys that ‘have been traced out in this
enormous labyrinth is 217 miles in extent. This “Mammoth Cave” once
O'A VERNS OF UARNIOLA. AND ISTRIA. 255
served as a retreat for savage tribes, for skeletons of men of an unknown
race have been found buried in it under layers of stalactite.
This district, which is the most remarkable among all the calcareous
countries of Europe for its caves, its subterranean streams, and its abysses,
is unquestionably the region of the Carniolan and Istrian Alps, which ex-
tends to the east of the Adriatic, between Laibach and Fiume. The whole
surface of the country, as in certain plateaux of the J ura in France, is ev-
ery where pierced with deep boat-shaped cavities, at the bottom of which
the water forms a kind of whirlpool, like the water ﬂowing out of the hold
of a stranded ship. Many mountains are penetrated in every direction
with caverns and passages, just as as if the whole rocky mass was noth-
ing more than an accumulation of cells. On one steep cliff-side may be
noticed all kinds of perforations at different heights—arched portals, and
oriﬁces of fantastic shape; on another there are numbers of springs of
blue. water gushing from the caves, or from the rocks heaped up at the
foot of the cliff, and forming rivulets which disappear a little farther on
in the ﬁssures of the ground, as if through the holes of a sieve. The whole
surface of the plateaux, whether bare or covered with forests, is scattered
over with wells, or funnel-shaped holes communicating with subterranean
reservoirs. The geography of the underground labyrinth of the Illyrian
caves is as yet only sketched out, and yet a considerable number of sa-
vcmts, at the head of whom stands M. Schmidl, have devotedsinany years
‘of their lives to this study. Thanks to their investigations, some of the
passages in these caverns, especially those of Lueg, are ahrrgst as well
known as the corridors and chambers of a palace.


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One of the Istrian rivers, the subterranean course of which, although
still unknown as regards a great number of points, has given rise to a
most continuous course of investigations, is the celebrated Timavus. (Ti-
mavo), which falls into the sea near Duino, about’ twelve miles. to the
north of Trieste. Virgil’s description* no longer applies to the ‘mouths
* “ Fontem superare Timavi
Unde per ora novem vasto cum murmure montis ‘
It mare praeruptum, et pelago premit arva s'onanti.”.
256 THE EARTH.
of the Timavo; at present they do not reach the number of nine, because
either the extermination of the woods of the Carso has diminished the
mass of the water, or the action of the stream and the alluvium of the
delta have modiﬁed the form of the shore. But still it is a magniﬁcent
spectacle to see the outlet of the three principal torrents of water, which
rush foaming out of the heart of the rocks, and are navigable from their
mouths to their very source. A river of this importance must certainly
receive the drainage of a vast basin, and yet all the neighboring valleys
seem perfectly devoid of rivulets, and their surface presents little else but’
the bare rock ; in fact, the whole of the rain and snow-water runs away
through underground caverns. We do not meet with any tributary until
we reach a spot 21 miles southeast of the mouth of the Timavo. This
tributary, known under the name of the Recca, is lost in the rock under a
high arch on which stands the village Sant Canzian; it appears again at
the foot of two precipices, and then ingulfs itself in the depth of the rocks
by a series of beautiful cascades, beyond which explorers have not traced
it. Farther on, the course of the subterranean torrent is only indicated
by abysses opening here and there in the midst of the plain. In 1841, M.
Lindner, who was seeking in every direction for springs of water to sup-
ply the city of Trieste, the inhabitants of which were threatened with
drought, formed the idea of sending some miners down into the chasm of
Trebich, situated about four miles to the northeast of the city. After
eleven months of labor the miners at last reached the ﬂoor of the lower
cave, 1062 feet below the surface of the plateau, and there, in fact, they
found the Recca of Sant Canzian ﬂowing at their feet. The descent into
this cave is by means of ladders, and it is thus rendered accessible by the
work of man.
The most remarkable net-work of caverns in this region of the Alps is
that which spreads out from the southwest to the northeast across the
Adelsberg group of mountains, between Fiume and Laibach. The princi-
pal cave is especially curious on account of its size, the variety of its cal-
careous eoncretions, and the torrent which runs roaring through it; cer-
tainly its vast compartments, its innumerable white and rose-colored pend-
ants, its abysses wrapped in shade, and the eternal echo of its rushing wa-
ter, would produce upon visitors a much more striking effect if its pro-
prietors had not conceived the untoward idea of decorating their property
with rustic or Chinese bridges, elegant staircases, and pyramids adorned
with sentimental inscriptions.
North of the town of Adelsberg the traveler passes along the base of
a hill with steep and bare sides, bringing into view the sharp edges of its
highly-pitched calcareous beds. On the right the stream of the Poik
winds peaceably in the valley; and then, its course being arrested by a
headland, turning suddenly, it ﬂows into the interior of the mountain
through a kind of high portal, opening between two parallel beds of rocks.
Unless the water in the stream is very low, it is impossible to follow it
over the accumulation of rocks upon its bed; but on the right, at a height
GROTTO OF ADELSBER G. 257
of a few yards, there is another entry, through which the traveler may de-
scend dry-shod into a vast cavityor chamber, where the Poik again ap-
pears issuing from its narrow passage of rocks. At this point the cave
div
ides; on the north the stream, the depth of which varies, according to


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the season, from a few niche 30 or 33 , buries itself in a winding
avenue, which has been trave ' 'n a boat a ' as a point 1027 yards from
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th trance; he northeast, a hi avenue, discovered o n 1818,
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258 - THE EARTH
The full length of the principal cave is not less than 2575 yards; but very
probably some other and still longer avenues may yet be discovered.
Although it is impossible to go in a boat along the subterranean por-
tion of the Poik for a greater distance than 1027 yards, by traversing the
surface of the calcareous plateaux we can at all events trace out the sub-
terranean stream by means of the funnel-shaped holes which open above
its course. One of these gulfs, the Piuka-Jama, is situated about a mile
and a half to the north of the entrance of the Adelsberg caves; the only
way to descend into this is by clinging to the branches of the shrubs and
sliding down by the assistance of a cord fastened to the top of the rocks.
By these means the entrance to a kind of air-hole may be reached, from
which the Poik is visible foaming over its bed of rocks, and only a slope
of debris is to be descended to reach the edge of the stream. It can only
be followed in the down-stream direction for about 275 yards; but it can
easily be ascended for a distance of 495 yards by passing under a high
portal with lofty pillars, and in this way a point can be reached which is
less than a mile from the place where the stream disappeared in the cave
of Adelsberg.
Farther down the stream the Poik is not visible again until it emerges
from the mountain, where it is known under the name of the Planina; it
rushes out through a circular arch at the base of a perpendicular bluff
crowned with ﬁr-trees. It really is the Poik, as is proved by the equal
temperature of water and the sudden increase of its liquid mass after a
storm has burst at Adelsberg; but the stream always issues from the cave
much more considerable in bulk than it is when it enters, owing to the
tributaries which pour into it on both sides during its subterranean course
of ﬁve to six miles. One of these rivulets, which comes down from the
plateaux of Kaltenfeld, joins the Poik at a little distance from its outlet.
Above the conﬂuence the principal stream can be ascended in a boat to a
distance of more than 3500 yards, which, with the other explored parts of
the subterranean river, makes about three miles. Below the point of out-
let the stream is partially lost in the ﬁssures of its bed, and then, joining
the Unz, goes on and empties itself into the Danubian Save.
About a dozen miles to the southeast of the Adelsberg and Planina
caves extends a large plain surrounded on all sides by high calcareous
cliffs, at the base of which nestle seven villages. In this hollow, the most
elevated portion of which is under cultivation, the remainder being cov-
ered with rushes and other marsh plants, there are to be found more than
400 funnel-shaped holes resembling those in other parts of Carniola.
These dolinas, the average depth of which is from 40 to 60 feet, have each
their special name, such as the “ Grand Oriole” (great sieve), the “Oriole-
dfroment” (corn sieve), the “Tambour” (drum), the “ Cave” (tub), the
“Tonneau” (cask), pointing out the form or some remarkable peculiarity
of each abyss. During extremely dry seasons there is only one of these
cavities which contains any water; but after continuous and heavy rain,
the water of a stream which is swallowed up in the rocks a little above
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260 THE EARTH.
a subterranean channel, and, further on, empties itself into the Unz, below
the Planina.
Lacustrine basins of this sort, ﬁrst emitted, and then again absorbed by
a subterranean water-course, are rather rare; there are, however, some
other remarkable instances of them in Europe. Thus, in the Oriental
Hartz, in the midst of a beautiful spot surrounded by ﬁr-trees, the charm-
ing lake called Bauerngraben (Peasants’ Ditch), or sometimes Hungersee
(Lake of Famine), sometimes makes its appearance; but when this mass
of blue water has ﬁlled but for a few days its basin of gypsum rock, it is
suddenly swallowed up, and ﬂows away by subterranean channels into
the stream of the Helme. The celebrated lake of Copais, in Boeotia, may
likewise be compared to the Zirknitz lake, at least as regards certain por-
tions of its basin. '
NAMES OF WA TER-OO URSES. 261
CHAPTER XLIV.
RIVERS—VARIOUS DENOMINATIONS OF WATER-COURSES.~—DETERMINATION
OF THE PRINCIPAL BRANCH AMONG THE AFFLUENTS OF A RIVER.-—-RIVER
BASINS AND WATERSHEDS.——FORKS OF CERTAIN RIVERS.
GEOGRAPHERS have long discussed, and are still discussing, the precise
import of the names which are used to designate running waters. How
are we to lay down any distinction between a river and a stream, or be-
tween a stream and a rivulet? Obviously no absolute difference can ex-
ist, as all water-courses are alike composed of liquid masses impelled by
their own weight over an inclined bed. The only relative difference
which at ﬁrst sight it seems easy to establish consists in the greater or
less quantity of water which each bed contains; but even this mode of
estimation must vary in every continent and in every country, according
to the importance of its h ydrographical system. Many a European river
would seem nothing but a slender rivulet, and would scarcely be thought
worthy of a name, if it were situated in the immense basin of the Ama-
zon. Added to this, the mass of water alters its bulk according to the
various seasons. Many rivers in tropical regions which ﬂow very abun-
dantly during the rains, are during the dry season often entirely dried up,
or changed into a series of pools.
All the phenomena of nature being full of diversity, she has omitted to
furnish any ﬁxed rule for the classiﬁcation of water-courses; but some
geographers, desiring, at any rate, to assume an appearance of authority
‘in matters relating to the earth, have given the name of river (ﬂeave) to
the liquid masses which empty directly into the ocean, and apply the
name of stream (riviere) to mere afﬂuents which are themselves fed by
tributaries of the second order, or rivulets. In virtue of this purely scho-
lastic distinction, the Argens, the Seudre, and the Leyrc would be rivers,
while the Tapajoz and the gigantic Madeira would only have the right to
the title of streams. Our ancestors, the Celts of Western Europe, who
understood much more about nature than many of our modern sacants,
employed the same name (although variously modiﬁed by use) for distin-
guishing water-courses of all sizes, viz., the Rhine, the Rhine, the Arno,
the Orne, and the Arnon. All running water was in their eyes a river.
The principal difficulty which systematical geographers meet with is
that of determining, as regards each basin, which is the chief branch; that
is, which is to be considered the river par excellence, all the other water-
courses being mere tributaries. In some cases, certainly, it may readily
be perceived to which artery of the river-basin the pre-eminenee unques-
tionably belongs; but more generally it is diﬂicult, or even impossible, to
262 THE EARTH
pronounce with any certainty on, this question. Is it the Seine or the
Yonne, the Adour or the Gave-de-Pau, the Rhine or the Aar, the Inn or
the Danube, the Mississippi or the Missouri, the Maraiion or the Apurimac
(U cayali),which has the best right to impose its name on the principa’
artery which bears onward to the sea the mingled water of the two riv-
ers? Does the point in question chieﬂy depend upon length of course?
If it does, the Saone and the Rhﬁne are only tributaries of the Doubs,
which has a total development, from Mont Rizoux to the Gulf of Lyons,
exceeding that of the Rhone by 93 miles. In like manner, the Mississippi
would thus become a tributary to the Missouri,which has a course more
than 1615 miles longer—an excess which is equal to three times the length
of the Seine. In deciding which of the upper tributaries is the principal
water-course, would it be more to the point to compare the quantities of
the liquid supply which each brings to the common fund? In this case,
the Yonne, the Aar, and the Inn are rivers which are fed by the Seine,
Rhine, and Danube respectively. Ought we not rather to consider the
more or less rectilinear direction, and the comparative geological unity of
the valley of each aﬁiuent, as the principal signs which should determine
the real river? Then the Rh0ne and the Seine are nothing but seconda-
ry water-courses in comparison with the Saone and the Yonne, and the
Yonne itself must yield its preeminence to the Cure.
The savant who devotes himself to the unthankful task of seeking out
the principal branch in a river system has therefore to take account of
the most diversiﬁed points of detail: the average mass of water, the length
of the course, the general direction of the valley, and the geological nature
of the soil; but, whatever may be the result of his investigations, he must
ultimately yield to the all-powerful authority of tradition. For it is tra-
dition, and not science, which has invested rivers with their titles and dig-
nity; it is the voice of our ancestors, founded on a thousand circumstances
in connection with mythology, the history of conquests or colonization,
agriculture, navigation, or even on various natural phenomena, which has
arbitrarily decided to give the pre-eminence to some particular water-
course over the other rivers of the same system. It is now too late to try
to change the hydrographical nomenclature.
But, even were it possible, this alteration would be almost entirely inef-
ﬁcient, for the vitality of nature will not accommodate itself to the strict
classiﬁcations to which pedants would seek to restrict it. It is only by
pure abstraction that we come to consider a river as an isolated existence.
In reality, it is the aggregate of the streams and rivulets which ﬂow into
it from all the points of its basin; it unites the millions of rills which are
set free from the ice, or trickle from the crevices of the rocks; it is made
up of the innumerable springs which ooze out from the ground saturated
with rain or covered with snow. A river is in a constant process of
change, and every tributary takes its share in this work of transformation.
The entire drainage area, and not any particular aﬂiuent, ought, therefore,
to be considered as the real river. We must take into account the Mis~
ORIGLV OF NAAIES OF RIVERS. —RIVER SYSTEMS. 263
souri, the Ohio, and the Red River, no less than the Mississippi, extending
its long and constantly increasing peninsula of mud into the Gulf of Mex-
ico ; also the Tapajoz, the Rio Negro, and the Madeira, ﬂowing with the
Solimoes into the vast estuary of the Amazon. In like manner, to use the
language of the sailors of the Bay of Biscay, the “two seas” of Garonne
and Dordogne unite their waters to compose the “ Sea” of Gironde.
Those names of rivers which are formed by the contraction of the desig-
nations of their chief tributaries are, indeed, the only terms which are geo-
graphically correct. We may mention, as examples, the names of the
Somme-Soude, the Thames (Thame, Isis), the stream of Gyronde (Gyr,
Onde) in the Upper Alps, and,better still, that of the Virginian river Mat-
tapony (Mat, Ta, Po, Ny). The aggregate of the arteries of a river system
may be compared to the branches and twigs of an immense tree. The
Rhine and the Mississippi remind one of the oak by the majesty of their
shape and the magnitude of their branches, thrown out at right angles to
the parent stem. The Nile, with its long trunk devoid of lower boughs,
and crowned with its plume-like terminal branches, recalls to our mind
the palm-tree of the oasis. These comparisons, it is true, have no scientiﬁc
element in them, but still they do not fail to present themselves to the
eye, and geographers, as well as artists, must be to some extent struck by
them.
Almost all those portions of continents on which the humidity of the
atmosphere falls in the shape of snow and rain have their system of rivers,
into which all the water is emptied which is not, immediately after its fall,
absorbed by the earth or sucked up by the roots of plants. But when the
surface of the ground is almost or quite horizontal, the rain-water can not
ﬁnd a sufficient amount of slope to enable it to ﬂow down toward the sea,
and consequently spreads out in stagnant pools. Thus, in the pampas of
the Argentine Republic—where, however, the annual rainfall is greater
than that of France—the prairies are dotted over with lagunes having no
outlet, and the Vermejo, the Salado, and the Pilcomayo—the great rivers
descending from the mountains of the northwest—are not replenished by
a single tributary from the plains through which they pass.*
Lofty mountain chains, the peaks of which tower up into the sky, cross-
ing the very tracks of the clouds, collect in proportion a much larger
share of moisture than the plains, and consequently give rise to the most
abundant streams of water. Nevertheless, as low-lying countries, or those
possessing a moderately elevated vertical outline, embrace an area much
more extended than that of mountainous districts, these ﬂat regions are
the localities where rivulets spring from the earth in the greatest number.
In a general way, the ravines or dells in the plains in which the water of
river-sources is collected are representations in miniature of the deep
gorges and the hollows of erosion existing in high mountains. But among
the incipient river aﬂluents there are some which take their rise on level
plateaux, or in some triﬂing depression of the ground; there are others,
* Martin de Moussy, Conﬁ'de'ration Argentine.
264 THEEARTH.
especially in the great plains of Russia, which issue from lakes or marshes,
which spread out in vast sheets in the centre of the country. Thus the
watershed—that is, a ridge separating two slopes, or perhaps a mere ideal
winding line, on each‘ side of which the water ﬂows in an opposite direc-
tion—is developed under the most diversiﬁed conditions. A river basin
—that is, the area which is traversed by all its aﬂiuents—may be bounded
on one side by the jagged ridge of some mountain chain, on the other by
the gentle undulations of a range of hills, further on by an almost imper-
ceptible rising in some low-lying plain. In certain localities, indeed, it is
necessary to level the soil in order to. ascertain the exact spot where the
“divorce of the waters,” as the ancients used to call it, actually takes
place. Added to this, even in the mountains, the ridge line, or the highest
elevation, is very far from uniformlycoinciding with the watershed which
separates two drainage areas. Mountains exhibit such inﬁnite variety in
their original form, and the agents which denude them have hollowed out
their sides in ways so diversiﬁed, that some rivers actually take their rise
on the contrary side of the mountain to that which they are about to wa-
ter.
The most remarkable instance which is to be found on the earth of sud-
den interruption in a mountain system is probably the astonishing cut of
Riﬁihue, situated in the Chilian Andes, near the fortieth degree of latitude.


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According to the unanimous evidence of the aborigines and the Chilian
peasants of the country,'the stream of Huahuum, which takes its rise in
the. high pampas of Buen'os Ayres, empties its waters into the Paciﬁc
aftekhaving crossed the chain of the Cordilleras. Issuing from the lake
,Neltume, the stream then penetrates into a deﬁle, where it is known under
the name of the Caillitue. It is certain that further down it is replenished
BLFUR C'A TI ON OF RI VER- O'O URSES. 265
by a stream ﬂowing from the Andine lakes of Panguipulli and Cafalquen,
and that the combined liquid mass ﬂows on and empties itself into the
lake of Rifiihue, which is a tributary of the Paciﬁc Ocean. The Indians
assert that the whole extent of the Huahuum and Caillitue are navigable,
and are only interrupted by one single rapid. Unfortunately, the scien-
tiﬁc explorations of this region have not yet gone beyond the banks of
the lake Riﬁihue. It appears that in this part of its development the chain
of the Andes owes its form to the action of the subterranean agents, which
have raised cones of eruption at intervals along the volcanic line of
fault.*
Several river-basins exhibit rather a curious phenomenon. The water-
shed line, traversing high mountain chains, plateaux, and marshes, and
separating two hydrographical systems, is interrupted by breaches or gaps,
through which the water can ﬂow out of one basin into another. On
reaching this breach, the ﬂow of water, being attracted by two inclines,
forks out into two streams running in contrary directions, and sometimes
toward two different seas. Thus, in Columbia, the Upper Orinoco divides
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Fig. SS. Bifurcation of the Orinoco.
into two rivers, one of which empties into the Atlantic immediatelyto the
south of the Antilles, while ;the other, known bythe name of the Cassi-
quiare, runs to the southwest toward the Rio Negro, a tributary of the
Amazon. The river, therefore, which collects the waters of the upper ba-
sin of the Orinoco is a tributary of two seas at the same time; it assists
in turning the whole of the Guianas into a‘ great island, surrounded on
one sideby the ocean, on the other by a channel navigable along a double
incline, having its summit level at the foot of the high mountain of Duida.
* Frick,ll1ittheilungen von Petermann,ii.,1864. '
266 THE EARTH.
This phenomenon of bifurcation, which has been rendered famous by the
journey of Humboldt and Bonpland, is also found, although certainly on a
less magniﬁcent scale, in several other countries of the earth, some moun-
tainous, and others only slightly undulating. In some places, owing to
the kind of indecision which is produced in the liquid mass by the double
attraction of the two inclines, man has been enabled to regulate at his will
the course of the two diverging streams, or even entirely to do away with
the bifurcation by means of a dam, or some other hydraulic works. But
to make up for it, in a multiplicity of other cases human ingenuity has
been able to utilize the depressions of the surface so as to draw off later-
ally an arm of a river, and thus create an artiﬁcial fork.*
In Europe only, numerous instances may be mentioned of natural bifur-
cations. In Sweden a small lake, which is situated at a height of more
than 3300 feet at the foot of the lofty mountain of Sneehattan, simultane-
ously feeds the stream of Lougen, which descends toward Christiania, and
that of Romsdal, which empties itself into the Molde Fjord,between Ber-
gen and Trondjhem. Added to this, the marsh of Kol, on the plateau of
Hardanger, gives rise to eight rivulets, each diverging in its own particu-
lar directionf In like manner, on a rocky plateau situated at a height of
about 2640 feet to the east of Puy de Carlitte, in the Eastern Pyrenees, we
ﬁnd the little pool of Las Dons (the Two) emptying its waters simultane-
ously into an aﬁuent of the Tet du Roussillon and into the rivulet of An-
goustrine, a tributary of the Segre and, the Ebro. Central Italy affords a
still more curious instance of bifurcation. It appears unquestionable that,
at the time of the Romans and during the ﬁrst centuries of the Middle
Ages, the Arno was divided into two branches, one of Which emptied itself
directly into the sea, while the other, crossing on the south the valley of
Chiana, fell into the Paglia, a tributary of the TibenI When the river
Arno, gradually sinking its northern bed, ceased to ﬂow into the valley of
Chiana, the water which descended from the lateral ravines in this almost
horizontal depression ﬂowed to a very slight extent on one side into the
Tiber, and on the other into the Arno; but more often it stagnated in
wretched marshes, which were a constant source of fever. These marshes
have now disappeared, thanks to the splendid hydraulic works undertaken
since Torricelli’s time by the Tuscan engineers for the amelioration of the
valley. By means of the alluvium brought by the torrents on both sides
into the settling basins, an artiﬁcial watershed has been created in the mid-
dle of the valley, giving the water two very perceptible slopes, inclined in
contrary directions§ One of the tributarie of the basin of the Seine also
once offered an instance of constant bifurcation; at Moeurs the Grand
Morin divides into two streams, one of which ﬂows down to the Marne,
and the other feeds the Superbe, an affluent of the Seine. But lately, ow-
ing to the destruction of the woods, the sources have become diminished;
* Vide the chapter on “ The Labors of Man.”
_ 'l' Fritsch, llfittheilungen von Petermann, vol. xi., 1866.
i Salvagnoli Marchetti. § Simonin, L’Etrurz'c et Zes Etrusques.
RI VER-BASINS AND WA TERSHEDS. 267
the double communication of the water only takes place in an artiﬁcial
way by means of a dam.* '
Among phenomena of a like nature, we must also class the division of
the contents of a river into two branches, which, ﬂowing separately each
in its own valley, ultimately reunite at a considerable distance below the
point of bifurcation. It is not improbable that, at a recent geological pe-
riod, the Rhine was thus divided into two branches, embracing in its


€° "E. of Paris


Fig. 89. Bifurcation of the Valleys of the Rhine.
course an immense island of rocks and mountains comprehended between
the lakes of Wallenstadt, Zurich, and Constance, and the present conﬂu-
ence of the Aar and the Rhine. In the earth’s history the two valleys
may be looked upon as having an equal title to be considered the axis of
the river-basin, as they have both served as the river-bed, either simulta-
neously or in turn. Between Meyenfeld and Sargans, at a height of 1580
feet, the Rhine doubles round suddenly to the northeast, and, penetrating
a narrow deﬁle, runs down to the Lake of Constance, which it crosses, and
ﬂows on to join the waters of the Aar and the Limmat at about 93 miles
below Sargans. The latter town is situated on an isthmus of pebbles and
peat, which divides the present vbed of the Rhine from its former bed,
which tends toward the northwest. If this isthmus, which is only about
16 feet high,were to disappear, the river would again divide into a fork,
and one of its arms would ﬂow on to empty itself into the Lake of VVal-
lenstadt, and thence into the Lake of Zurich and the valley of the Aar.
'Various hypotheses have been propounded to explain the formation of
* I‘lessier, Formation des Plateaux et des Valle’es de la Brie.
268 THE EARTH.
this isthmus which has severed the river-basin into two parts, and forced
the whole body of the Rhine to ﬂow into the Lake of Constance. It is

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probable that this mass of pebbles is aportion of a slope of debris brought
down by the torrent of Seez from the recesses of the gorge of \Veiss-tan-
nen (White Firs), and deposited at the outlet of the lateral valley?‘ So
long as the river was able to clear a way through these heaps of stones, a
portion of it followed its old course toward the Lake of VVallenstadt; but,
being constantly impeded by the ever-growing barrier, it was ultimately
compelled to open a new outlet toward the north.
A great number of examples of this double ﬂow of portions of one mass
of water toward different basins are afforded by low and marshy plains.
The marshes of 'Pinsk, in Volhynia, serve as a common source to various
aﬂiuents both of the Vistula and the Dnieper, thus forming a link between
the Baltic and Black Seas. In spring, when the snow melts, and toward
the end of autumn, after the heavy rains, a series of lakes, wet marshes,
and temporary rivulets connect the inland Caspian withthe Sea of Azof
and the Euxine. The water of the Kalaous, coming down from one of the
rugged valleys of the Caucasus, divides, and forms a temporary channel
* \V. Huber, Report of the Geographical Society, February and March, 1866.
CHANGES IN THE 00 URSE 0F RIVERS. 269
between the twobasins, which were, indeed, once united in one and the
same ocean.


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The two principal river-systems of North America—p—those ofsthe'lMissis-
sippi and the St. Lawrence—are likewise blended together for a few days
after a prolonged rain-fall. Even before the construction ofthecanal
which at present unites the two rivers, small boats could sometimes pass
from the Chicago River into the Illinois, and thus cross the scarcelyéindi-
cated watershed which divides the basin of Newfoundland from that of
Mexico. In a recent period—that is, about 4500 or 5000 years ago—the
union of the two river-basins, which has now become but temporary, ap-
pears to have been of a permanent character. The calculations and ob-
servations of Sir Charles Lyell, Schoolcraft, and many American geolo-
gists, render it very probable that, at this epoch, all the upper afﬂuents
of the Mississippi and the St. Lawrence fed a lacustrine reservoir, the
vast sheet of which, situated about 600 feet above the level of the ocean,
stretched toward the north as far as the mouth of the Wisconsin, and on
the east joined the Lake Michigan, covering all the intervening peninsulas.
The centre of the continent was occupied by a sea as large as our Medi-
terranean, which emptied itself into the ocean by an immense delta, each.
arm of which was one of the greatest rivers of the earth.*
The bifurcations of water-courses do not, however, all take place on the
surface of the ground; and if the deeper layers could be disclosed to our
view, it is probable that we should ﬁnd the majority of river-basins would
afford instances of subterranean derivations. ' In a country like France, in
which geological exploration has seriously commenced, a considerable
number of these curious phenomena have been discovered, although they
* Humphreys and Abbot, Report on the Mississippi River.
270 THE EARTH. -

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Fig. 92. The Panto-Caspian Isthmus.
are in general but little noticed. Thus, in the Basses Pyrénées, the Gave
d’Ossau forms a fork at the foot of the high hill of the Sévignac. One arm,
running to the northwest, ﬂows on to join the Gave d’Aspe, and forms the
Gave d’Oloron; but the other buries itself under the rocks, and reappears
about ﬁve miles to the north, in two very strong springs, the stream re-
sulting from which, calledv the Neez, empties itself into the Gave of the
same name, not far from Pan. In like manner, in the centre of France,
the Haute-Vézere sends one of its arms under the ground, for a distance
of about three miles, to feed the stream of the Isle, which meanders through
its deep valley in long parallel windings.
ORDERL Y DISTRLB U TI ON OF RIVERS. . 2 1
CHAPTER XLV.
THE HYDROGRAPHICAL SYSTEMS OF VARIOUS PARTS OF THE WORLD.
THE great difference which exists between continents as regards both
their vertical outline and their extent of area gives to the water-courses
in each part of the world the most diversiﬁed directions and characteris-
tics. In every place the general plan of the hydrographieal system va-
ries in proportion to the height and bearing of the mountain chains, the
length and inclination of their slopes, the geological nature of the regions
which it waters, and the annual quantity and distribution of the rain-fall.
But, since the continental masses, both in their general outline and in
their different parts, present an evident equipoise in their forms; since
the‘ clouds and winds are in full obedience to constant laws; the result is,
that the rivers themselves are arranged on the surface of the earth with
a remarkable degree of order, which is all the more beautiful in that it so
considerably deviates from any symmetrical regularity. The graceful
windings of a river, its long and almost quivering curves, and‘F-the intri~
cate bends of its innumerable tributaries, prevent our noticing the rhythm
of its system, and how this system prevails from one end of theworld to
the other. On our earth physical laws are but rarely manifested in all
their inﬂexible simplicity. Owing to the vitality which pervades every
thing, they often assume a character of beauty, and through this very
beauty they not unfrequently evade the notice of man.
A study of the map, with regard to the distribution of rivers over the
surface of the earth, brings before our view, at a glance, this fact—that
the water-courses which are tributaries of the Atlantic exceed consider-
ably, both in number and importance, those which belong to the great
Paciﬁc Ocean. This sea, the greatest of all seas, receives directly only
ﬁve considerable rivers—the Cambodin, the Yantse-kiang, the Hoang-ho,
the Amoor, and the Columbia; but the comparatively narrow channel of
the Atlantic is the reservoir into which the most enormous rivers of the
earth pour their contents—the Uruguay and the Parana, the River of
the Amazons, the Orinoco, the Mississippi, and the St. Lawrence, without
reckoning the Congo, Niger, and Gambia, all the water-courses of West-
ern Europe, and, by the intervention of the Mediterranean, the Nile and
the Danube—the two great rivers of the ancients. This unequal distri-
bution of rivers is a result of the semicircular arrangement of the Andes,
the Californian mountains, and those of Kamtschatka and Siberia, all
round the basin of the Paciﬁc. The western side of South America is
excessively poor in rivers. All over this narrow-belt, which is on the
average not one tenth as wide as the opposite Atlantic side, and is, be-
272 THE EARTH.
sides, rarely visited with rain, there are at most but two or three rivers
which are navigable. The streams of Chili and Western Columbia would
scarcely merit the name of rivulets in the basin of the gigantic Maraﬁon.
In a hydrographical point of view, the continent of Asia may be di-
vided into three entirely distinct systems—those of the north, the centre,
and the south. The ﬁrst is the great plain of Siberia, which is gently in-
clined toward the Frozen Ocean, and the whole extent of which is crossed
by three parallel rivers, certainly among the largest, but also, perhaps,
the least used by man, of all the water-courses in the world. In the cen-
tre of the continent there are several closed basins, consisting of plateaux
more or less desert, the streams of which are lost in some lake, or evap-
orate during their course. The southern and eastern countries of Asia
are the portions of the continent which show a genuine vitality—thanks
to the sea which bathes them, the deeply indented shape of their penin-
sulas, the varied productions of their soil, and, above all, to the numerous
water-courses which traverse them.
The most remarkable of these rivers are arranged in pairs, so as to
constitute three groups of twin currents. These are the Tigris and En-
phrates, the Gauges and Brahmapootra, the Yantse-kiang and Hoang-ho.
In each of these pairs, the two rivers take their rise side by side in the
bosom of the same system of mountains, and, bending their course in op-
posite directions, each describes a vast semicircular line all across the
continent, and ultimately again unite before they empty themselves into
the sea through the same delta. There is another point which still far-
ther augments the analogy between these double ﬂuviatile arteries, viz.,
that each empties its waters into one of the three seas situated to the
east of the three southern peninsulas of Asia. The Shat-el-Arab ﬂows
into the Persian Gulf, to the east of Arabia; the Ganges into the Bay of
Bengal, to the east of India; the Chinese rivers into the Paciﬁc Ocean,
which stretches to the north and east of the Indo-Chinese peninsula.
In order to understand the general features of the river-system of the
Asiatic continent, there is a fourth group of allied rivers which we must
also notice—the Indus-Sutlcj. Certainly these two rivers of the western
regions of Hindostan unite their waters at a rather considerable distance
from their mouth; but their lower course has entirely the character of a
delta. The Indus and the Sutlej were probably once separated, and be-
came united in consequence of the alteration of their course, and the con-
siderable elongation of the delta common to both which received their
alluvium. In like manner, at the time of Alexander the Great, the mouths
of the Tigris and Euphrates were situated at a good day’s march from
each other; but at the present day the two river-arms coalesce at some
considerable distance from the sea, and form together the Shat-el-Arab.
The Indus and the Sutlej may, therefore, be classed among the double
rivers, as their sources lie very close to one another; their courses take
an entirely different direction, and they also have a common outlet. As
the waters of this fourth group of rivers descend from the same mountain
DIVERSI T Y OF RII’ER-S YSTEMS. 27 3
range which gives rise to the Gauges and the Brahmapootra, we might
even say that in the north of Hindostan there is a double system of al-
lied rivers which at their sources are almost joined. The four most con-
siderable currents of water in India, taking their departure from nearly
the same point, ﬂow away in opposite directions, and, after describing
enormous circuits, unite in pairs, as if to obey some double law of har-
mony and contrast—the Indus and the Sutlej to the east, the Gauges and
the Brahmapootra to the west. They are the four animals of the Indian
legend—the elephant, the stag, the cow, and the tiger—which spring
down from the same mountain peak into the green plains of Hindostan.
The contrast offered by Europe proper—so rich in mountains, peninsu-
las, and deep indentations of the coast—to the vast plain of an almost
Asiatic character which distinguishes Eastern Europe, shows itself equal-
ly in the river-systems of the two halves of the continent. In \Vestcrn
Europe the Alps and the other chains of mountains radiating from them
determine the characteristics of the water-system. In the Sclavonic
countries, inhabited as they are by peoples hardly emerged from barba-
rism, the great rivers, such as the Volga, the southern Dwina, the Niemen,
the Bug, and the Dnieper, all take their rise in the marshy or slightly
undulating regions which occupy the interior of Russia. Certainly they
roll down a very considerable mass of water; but in their historical im-
portance they are very inferior to the rivers which spring from the Alps,
and, ﬂowing in every direction, water the various countries of Western
Europe—the principal theatre of modern civilization. The Alpine group
of streams is that to which it is chieﬂy material to devote a separate
study. From the sides of the St. Gothard, the centre of the Alps, three
rivers, not counting the Reuss, take their rise--the Rhine, the Rh6ne, and
the Tessin—falling respectively into the North Sea, the Mediterranean,
and the Gulf of Venice. Two other water-courses, which do not pre-
cisely descend from the St. Gothard itself, take their rise in its vicinity. ‘
These are the Aar, the principal tributary of the Rhine, and the Inn, a
stream more important than the Danube—the name which it assumes be-
low the point of their conﬂuence. Here, then, are ﬁve rivers which radi-
ate toward four seas from one single group of the Alps; but as isolated
rivers, and not in the form of double systems, like those of India and
China. However, these distinct water-courses, especially the Rhine and
the Rhine, present some remarkable peculiarities. These two great riv-
ers, nearly equal in volume, ﬂow each in a diametrically opposite direc-
tion ; then, turning suddenly toward the north by an abrupt bend, and
crossing a lake of considerable dimensions—one the Lake of Geneva, the
other the Lake of Constance—cross the parallel chains of the J ura either
in rapids or cataracts, and, ﬁnally emerging from the mountainous regions,
ﬂow, the one directly to the north, toward the German Ocean, the other
directly to the south, toward the Mediterranean.*
Other groups of the same mountain chain, such as those of the Viso
* W. Huber, Bulletin de la Socie'té de Geographic, 1866.
S
274: 4' _ THE’ EARTH.

and the Levanna, near Mont Cenis,form secondary centres for the-radia-
tion of streams; but, as regards their hydrographical importance, none
of them .can be compared to the central group of the St. Gothard.
The great rivers of peninsular Europe which are not fed by the Alpine
‘snows. ﬂow .to thenorth of the almost continuous line of mountains which
is formed across the continent by the chains of the Pyrenees, the Co-
vennes, the J ura, the Alps, and the Carpathians. The rivers which descend
to the south are smaller, on account of the more contracted area which
is afforded them in Europe by the Mediterranean slope. But it must be
remarked that the line of summits does not exactly mark out the water-
shed where the waters divide, some ﬂowing to the north, the others to
the south; there is, in fact, a complete mutual invasion of the opposite
basins‘, and their respective interpenetrations ﬁt, as it were, one into the
other. . A river ﬂowing to the north receives afHuents from the southern
side of the mountains, and another ﬂowing to the south receives those
from the north. Thus, on the Tatra (Carpathians) the water-shed is far
from coinciding with the line of summits, and cuts across the chain of
mountains. The Arva, coming from the north, penetrates the mountain-
chain, and ﬂows on into the Thciss; while the Poprat, taking its rise in
I the south, hollows out a bed for itself through the gorges, and runs on to


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, join the Vistula.* In like manner, the Garon-ne rises in the glaciers of
the Maladetta, to the south of the principal chain of the Pyrenees, and
makesits Way into the district of Aran and the plains of France; but to
effect this it is compelled to cross the base of thearnountain of Poumero
through a subterranean gulf 4376 yards long. The? water, which disap-
pears on the Spanish side in the high valley of Essera, reappears on the
other slope of the mountain at a point 1980 feet lower down. The rising
- spring, the water of which thus pierces right through the rocks of Poumero,
was once held sacred; it is called the “ Goueil de J oueou” (Jupiter’s eye).
* Carl Bitter.
Q
NORTH AMERICAN RIVERS. 275
In North America the same radiation of rivers exists as in Europe, but
it spreads round three centres, two of which are mountain groups, and the
other a merely gradual and imperceptible rising of the plain. In the ter-
ritory of Idaho, between the 43d and 44th degree of north latitude, a
great peak towers up to'a height of 13,779 feet, to which Lieutenant Rey-
nolds has given the name of “ Union Peak,” because the water from its
melted snows, being soon increased and converted into important rivers,
ﬂows toward the Colorado on the south, the Missouri on the north, and
the Columbia on the west.* More to the south, but still in the angle
formed by the valley of the Colorado and those of the tributaries of the
Missouri, the Rio Grande del Norte takes its rise, thus completing the
system of radiation of large rivers round an elevated group of the Rocky
Mountains. Nine degrees farther north, in the vicinity of Murchison
Peak, several of the more important springs rise which feed the Fraser
River, the Columbia, the Saskatchevan, the Athapasea, and the Macken-
zie. According to Antisell, three of these rivers are fed by the snow of
the same mountain. The sources of the Mackenzie and the Columbia
take their rise at a distance of about 200 yards from each other; and in
fourteen paces or so a man may walk from the origin of the Columbia to,
that of the Saskatchevan. These, then, are the spots whence the radia-
tion takes place of the great rivers on the northwest of the continent.
The radiating centre of the rivers of the plain is situated a little to the
west of Lake Superior, in the vicinity of. the Red Lake, Lake Itasca, Lake
of the Woods, and several sheets of fresh water which are scattered over
the highest part of the lower plateaux of North America. Thence spring
forth the sources of the Mississippi proper, those of the St. Lawrence, and
the Northern Red River, a tributary of the great Lake Winnipeg, which
communicates with the Mackenzie River and the Frozen Ocean by a se-
ries of sheets of water. The radiating centre of the river-system of the
plains serves to link together the two centres of the Rocky Mountain
chain. It forms the complement of them.
The three regions of the American river sources are mutually linked to-
getherby the two principal aﬂiuents of one great river. Thus, the gigan-
tic development of the upper branches of the Mississippi connects the
lofty groups of the Idaho mountains with the marshy plains of the Min-
nesota; as the Missouri it is classed as a mountain current, and as the
Upper Mississippi it is a stream of the plains. The river, therefore, which
unites all these waters is essentially double in its character. The Mac-
kenzie River also presents this appearance of duality, although in a less
degree, as it receives aﬂiuents both from the lake region and also from
the chain of the Rocky Mountains. In like manner, the two principal
-branches of the Columbia, the Serpent River and the Columbia proper,
take their rise respectively in the two groups of summits, whcnce'the
streams radiate toward various points of the continent.
South America is par excellence the country of rivers. I There roll down
* Humphreys and Abbott, Antisell, etc.
276 THE EARTH.
the immense Amazon, navigable for-more than 3000 miles; the mighty
Parana, signifying by its name “ The River” pre-eminently; and the Ori~
noco, surnamed “the Father of Waters,” the drainage area of which is
not one third so extensive as that of the Mississippi, although the latter
river pours down a much less considerable body of water. On account
of the narrowness of the Paciﬁc slope, all the great water-courses of South
America ﬂow over the plains situated to the east of the continent; but
they do not all take their rise in the chain of the Cordilleras. The Orino-
co takes its rise in the mountains of Guiana, the Maraﬁon in the Andes,
the Parana and the greater part of its tributaries spring from the high
plateaux in the interior of Brazil. These rivers, therefgre, do not radiate
round the same centre; on the contrary, they belong to two basins which
are perfectly distinct, and, indeed, cross one another at right angles. The
basin of the Amazon tends, in fact, from west to east, while the plateaux
and plains in the middle of the continent, forming a basin in the direction
of the meridian transversal to that of the Amazon, are watered on the
north by the Orinoco and the Rio Negro, on the south by the Tapajoz,
the Madeira, the Paraguay, and the Parana. The distinguishing feature
of the river-system of South America is in the fact that the three princi-
pal rivers are interwoven by means of an almost continuous line of run-
ning water, which extends from north to south—from the mouth of the
Dragon to the estuary of the Plata. More than half a century ago Hum-
boldt placed the matter‘beyond all doubt that the Cassiquiare empties its
water both into the Orinoco and into the Rio Negro. The communica-
tions between the Tapajoz and the Paraguay are not so perfect, but they
nevertheless exist in several places. According to M. de Castelnau, the
proprietor of the Estivado farm irrigates his garden by turning the water
from an aﬂiuent of the Paraguay into the bed of the Tapajoz, and makes
the little channels ﬂow at his will toward either the northern or southern
side of the continent. In like manner, there is a stream near Macu which
at the time of inundations is divided into two currents, one forming a part
of the Plata system, and the other belonging to that of the Amazon.
Farther to the east, the Rio Guaporé, an affluent of the Madeira, and the
Jauru, a tributary of the Paraguay, take their rise in a plain which is
periodically inundated during the rainy season. At the foot of the Boli-
vian Andes a similar intermingling of basins takes place, as regards the
Marmoré and the Pilcomayo. Thus, the Caribbean Sea and the mouth of
the Orinoco are connected with the estuary of the Plata by a series of
rivers, streams, and marshes.
The numerous water-courses which proceed from the central plateau of
the continent are all set in an aspect parallel to the Tapajoz and the Madei-
ra. The chief aﬂ‘luents of the Orinoco, on the contrary, follow the same di-
rection as the River of the Amazons. We are, therefore, correct in saying
that the river system of South America comprehends two basins crossing
one another. The Rio Magdalena, the Atrato, and the other streams of
Guiana, are all rivers with distinctly limited basins; but it must be re-
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marked that they all ﬂow from the south to the north, in the same direc-
tion as the southern tributaries of the Amazon. ,
In that portion of the earth which is the most massive andethe least ar-
ticulated in its shape an harmoniouscorrespondence is found between the
water-courses and the continent itself. As long as the greatest part of
Africa was an unknown region, geographers were able to atti‘ibute to its
rivers all kinds of imaginary courses; they could, as their fancy dictated,
make the Nile, the Niger, and the Congo take their rise from one common
source, or 'inter'weave in a complete net-work all the tributaries of these
great rivers. But the discoveries of modern travelers will now warrant
us informing some’ general idea of the African river-systems. This land,
so devoid as it is of peninsulas and of deep indentations in its coasts, does
not, probably, present more than one centre of radiation for its waters,
‘which centre is situated about the middle of the continent. From this
point‘ descend the Chary, the Binué—a tributary of the Niger—various
streams falling into the Congo, and some important afHuents oi the Nile.
Still, the principal branches of the largerivers take their rise at enormous
distances from one another, and in the general features of their courses
exhibit only some transient and slight similarities. The basin of the Nile
is partly separated from that of the Niger by a great depression, the cen-
tre of which is occupied by the Lake Tchad. In like manner several lakes
and their aﬁluents are interposed between the three basins of the Nile,
the Zambesi, and the Congo; lastly, a small independent inland sea—the
Lake N’gami—having its own special system of tributaries, ﬁlls up the
space between the basins of the Zambesi, the Orange River, and the Lim~
popo. There is another point which distinguishes African rivers from
those of other countries; this is an absence of any extent of ramiﬁca-
I‘
278 THE EARTH. ‘
tions. In this characteristic‘ they resemble their mother-continent—a gi-
gantic trunk without peninsular branches. From Assouan to Rosetta, a
length of seven degrees, the Nile does not receive a single visible aﬂiuent;
nevertheless, it must necessarily be replenished by several underground
tributaries, for its liquid mass is much more considerable in Egypt than
in Nubia.*
Australia is even poorer in rivers than the east of the African continent
itself. With the exception of the Murray, its affluent, the Darling, and a
few other rivers that are navigable at all times, the greater part of the
water-courses in Australia can scarcely be said to exist except during the
rainy season, and in summer their beds are only indicated by pools of
stagnant water at intervals. Their special characteristic appears to be
periodicity.
The general features of the river-systems of each part of the world may
thus be shortly summed up :
Northern Asia is distinguished by rivers of simple character. In the
south and east they are allied.
Europe is distinguished by two centres from which the streams radiate
-—one situated in the midst of vast plains, the other .in the heart of the
highest mountains of the continent.
North America is characterized by a radiation of the rivers from three
centres, two of which, being elevated groups in a mountain chain, are
linked together by the third, occupying a marshy rising in the plains.
South‘America is characterized by the crossing of two mutually trans-
verse basins and the continuous union of the river-systems.
Africa is distinguished by the comparative independence of its water-
courses and their poverty in tributaries.
Australia, by the small number of its rivers and the periodicity of their
existence.
The form of each continent, and the phenomena of climate peculiar to
them, have thus determined the rise of rivers which are modeled on a par-
ticular type in each division of the world. As all continental masses dif-
fer one from another, the circulating system of each naturally harmonizes
with the general features of the regions which the running waters trav-
erse and vivify.
* Elia Lombardini, Essaz' sur l’Hydrologz'e du N i].
THE RIVER AMAZON. 279
CHAPTER XLVI.
THE RIVER OF THE AMAZONS.-—DIVERSITY IN THE CHARACTER OF WATER-
COURSES.-—UNITY OF THE LAW WVHICH GOVERNS THEM.——EQUALIZATION
OF THEIR SLOPES.—UPPER, MIDDLE, AND LOWER COURSES OF RIVERS.
IN like manner as the hydrographical systems of each continent pre-
sent in their special features the most marked contrasts, so the rivers of
each country and the various tributaries of each river. They are distin-
guished by the length of their system, the winding of their course, the
abundance of their water, the nature of the soil which they pass through,
the color and character of their alluvium, the general inclination of their
bed, and the shape and number of their meanderings. Thus, only men-
tioning the basin of one single river, we may reckon among the tributa-
ries of the Mississippi the Clear-water River, the Mud River, and the
Blue, Green, Yellow, Red, Black, and White rivers. Names designating
other physical properties besides that of the color or purity of the water
are also very numerous in the tributary valleys of the American rivers.
The same kind of names occur in most river systems; and, indeed, noth-
ing would be more easy than to give to every water-course ‘some name
relating to its general aspect, its characteristics, or some of the local cir-
cumstances which distinguish it, such as gulfs, cascades, or deﬁles. Like
the trees of a forest, so also an inﬁnite diversity is shown in all the run-
ning waters which moisten the surface of the earth. The chief cause,
however, for this inﬁnite variety in rivers must be sought for in the geo-
logical constitution of the soil through which they ﬂow. Thus, among
the old schistose and gneissose rocks, riversare more often characterized
by the abundance of their liquid mass and the winding of their bed.
In calcareous districts the water-courses are less richly supplied, more
rectilinear, and generally bounded on each side by steep escarpments.
Any sudden bend in the course of a river usually indicates some important
modiﬁcation in the geological nature of the strata. We may mention as
examples the elbows of the Rhine at Basle and Bingen, those of the
Rhone at Lyons, of the Danube at Ratisbon, of the Elbe at the outlet of
Saxon Switzerland. In South America all the great rivers ﬂowing into
the Atlantic describe a broad curv‘e toward the east when they leave the
valleys of the Andes and make their way into the tertiary formations of
the continent.*
The river par excellence, the glory of our planet, is the great stream of
the Amazons, which, next to the great upheaval of the chain of the An-
des, forms the principal feature of the Columbian continent. This mov-
* Ami Boué.
280 THE EARTH.
ing fresh-water sea, which takes its rise at a short distance from the Pa
ciﬁc, and empties itself into the Atlantic through an estuary measuring
186 miles from promontory to promontory, serves as a line of division be-
tween the two halves of South America, and, like a visible equator, sepa-
rates the northern hemisphere from the southern along a length of about
3000 miles. Every thing belonging to this great central artery is on a
colossal scale. In its immense basin, embracing an area of 2,700,000
square miles, it collects two or three thousand times as much water as
the Seine. In different parts of its course this immense river is known
under various names, as if it were composed of distinct streams set end
to end, and, together with its tributaries, its fares , or false rivers, its
igarapés, or lateral arms, offers scope for steam navigation of more than
30,000 miles. It is so deep that sounding-lines of 150, 200, or even 300
feet, have failed to measure its depths, and frigates can ascend it for more
than 1000 leagues. Its width is so great that in some places it is impos-
sible to see the opposite bank, and at the mouths of the Madeira, the
Tapajoz, the Rio Negro, and some other of its great aﬂiuents, the distant
horizon closes in upon the water just as in the open sea. It is replenished
by dozens of rivers which scarcely ﬁnd their equals in Europe, and many
of them, being yet unexplored, still belong to the realms of fable. In
several places its banks serve as limits to two distinct Faunas, and many
species of birds will not venture to cross the broad sheet. Like the sea,
it is inhabited by cetaceans; like the sea, too, it has its storms, and dur-
ing a tempest the waves will rise to several feet in height. When we
sail over the gray water of the estuary at the mouth of the river, we feel
tempted to ask, says M. Avé-Lallemant,* whether the sea itself does not
owe its existence to the enormous tribute which the rolling current is in-
cessantly bringing down to it. The difference in the motion produced
by the movement of the waves or by the force of the current is the only
thing which points out on which domain a voyager is sailing—that of the
fresh or salt water. Even in late years, the greater part of the inhab-
itants of the shores of the Amazon—white, black, or red men alike—are
in the habit of fancying that the great river surrounds the whole uni-
verse, and that all the nations of the earth are denizens of its banks’r
Certainly, the difference is considerable between the mighty South
American river and some slender stream; as, for instance, the Argens,
which is crossed by a bridge with a single arch, and can readily be waded
through by travelers. But whatever may be the comparative impor-
tance and the discrepancy of aspect in these rivers, they are none the less
governed by the same laws. The geographer can describe them all to-
gether by forming an outline of an ideal river, the course of which would
afford the combined phenomena of all the streams which traverse the
globe.
The function of rivers in the plan of nature is incessantly to renovate
* Reise durch N ord-Brasilien.
i‘ Bates, The Naturalist on the River Amazon.
ACTION OF RIVERS ON THE LAND. 281
the surface of continents, to convey the life and the alluvium of lofty
mountains down to the plains and the coasts of the ocean. It has often
been said that a landscape can not be really beautiful when it is destitute
of the rippling motion of a lake, or the presence of running water. The fact
is, that man, whose life is so short, and, in consequence, so restless, has a1
instinctive horror of immobility. To make him fully appreciate the vi-
tality of nature,it is requisite that motion and sound should bring it home
‘to his senses. Only by a course of long reﬂection can he duly estimate
the long-protracted movements of the terrestrial crust; he therefore needs
to view the rapid bounds of the water leaping down in cascade after
cascade, or the harmonious undulations of the waves. More than this, he
also demands the contrast between the stable and the unstable, between
restlessness and rest. This is the cause why a ﬁeld of snow as far as the
eye can reach, a desert without water, a sky without clouds‘, or a shore-
less ocean fail to excite in him any thing better than a gloomy or melan-
choly admiration. In the presence of these spectacles man feels himself
crushed, while in a narrow valley, with its streams of running water, he is
fully conscious-of his own vitality.
On our earth, water is, par excellence, the symbol of motion. It ﬂows
and ﬂows on forever, without rest and without fatigue. The lapse of
centuries can not dry up the slender rill of water trickling from the ﬁs-
sure of a rock, and fails to silence its soft and clear murmur. It leaps
down joyously, in cascade after cascade, to mingle with the impetuous
torrent; then, blended with the calm and mighty river, it ﬂows on, and
losesitself at last in the immense and mysterious ocean—that tomb in
which every water-borne fragment ﬁnds a temporary grave till the re-
solved elements enter again into the vast bosom of nature and reassume
fresh forms of vitality. Motion is only another word for action. Water
does not merely ﬂow through a bed hollowed out ready for it; it is inces-
santly eating away, undermining, corroding, washing away, and moving
the earth and the rocks which hem it in or oppose its course. Pebble by
pebble, and grain by grain, it is carrying the mountains into the sea. WVa-
ter, as Pascal says, is “not merely a road in motion, it is also a traveling
continental mass which, in the centuries of yesterday, was covered with the
eternal mountain snow, and will in the ages of tomorrow be ﬁxed on the
seashore, to augment the domain of man.” Rivers carry out the circula-
tion of solid as well as of liquid matter; they are like the blood, ever-ﬂow-
ing life-renewers. It is, then, requisite that we should study carefully the
mode of operation which rivers adopt in their renovating action on the
continents they traverse.
Every current of water is constantly tending to equalize its slope, to
increase it where it is almost imperceptible, and to diminish it where it
is too rapid. The whole course of the river, from its mountain source
down to its junction with the sea, may be compared to an avalanche fall-
ing from the heights of some snow-clad peak. The masses which sink
down into the valleys modify gradually in their fall the outline of the
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1282 - ~ ‘THE EARTH.
fcliffs. The projections are broken down, the ﬁssures are ﬁlled up,-a
gracefully curved slope of clébrz's abuts against the vertical walls, and ex-
tends in a gentle incline down into the plain. Owing to all these exca-
vations and ﬁllings up, the passage through which the avalanche makes
its way ultimately assumes an outline of considerable regularity. Al—
though less abrupt in its progress, less violent in its effects, and gliding
over a gentler slope than the avalanche, still the river adopts a very sim-
ilar course of action; it clears away the obstacles before it, and ﬁlls up
any depressions, appearing as if it endeavored to provide for itself a uni-
form incline down to the sea.
- The portions of a river’s course where this equalization of its incline
chieﬂy takes place are naturally those where the declivity of the bed is
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most rapid, and where the waters consequently attain their highest rate
of speed. _ It may be generally asserted that those portions of the river-
beds which are distinguished by the most abrupt incline are also the
most elevated; for in ‘almost all the countries of the earth the plains lie
round the circumference of the land, and the mountains rise far in the in-
terior. Most'rivulets and streams take their rise thousands of feet above
the level .of ‘the sea, and descend ﬁrst through a very steep bed, some-
times intersected by precipices, or even interrupted by lacustrine basins.
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Fig. 96. Slope of the P6, the Tessin, the Oglio, and the Mineio.
On reaching the lower plains, the running water, now converted into a
considerable river by the tributaries which have joined it on both sides
from. the valleys of the mountain-system, extends in long and peaceful
windings across the more or less sloping ground which serves as a ped-
00 URSES OF- RIVERS. 283
estal for the mountain chain. This is its middle course, during which
the river receives its principal aﬂiuents descending from other mountain
chains, or the high ground which commands it laterally. Then, below
the last hills, its lower course begins; the fresh water descends slowly
down to the sea, and, not far from the mouth of the river, is arrested in
its course twice every day'by the salt tide which meets it.
The Rhine is a magniﬁcent example of a river in which the three divis-
ions of its course are regularly developed.* The upper course, the whole
of which is included in the Alpine regions, bends round in a vast semi~
circle to Laufenburg and Basle, where the rapids cease. The middle
course, remarkable for its regularity, rolls on uniformly to a point below
Mayence, where the Rhine is compelled to open a passage across the
Odenwald and other hills; then, below the Siebengebirge, between two
low banks of alluvial origin, commences the lower course, which ulti-
mately terminates in the muddy estuaries of Holland. But for one river
where the three divisions of its course are marked with so much distinct
ness, how many there are which exhibit no marked difference between
the‘ various portions of their bed! How many there are, indeed, which
are even calmer and less inclined on the plateaux- of the interior than in
the vicinity of the sea! How many there are, especially, which-—as rep-
resented by some of their aﬂiuents—are entirely rivers of the plain,
While in other tributaries which descend from the mountains they ex-
hibit all the characteristics of torrents! These are differences essential
to the ﬂuviatile system and to its geological operations.
* Carl Ritter, Europa.
284 THE EARTH.
CHAPTER XLVII.
MOUNTAIN TORRENTS.-—INEQUALITIES ‘OF THEIR BEDS AND OF THEIR DIS—
CHARGE OF \VATER.—-TEMPORARY STREAMS.—FILLING UP OF LAKES.—
EROSIONS, GORGES, AND SLOPES.—TORRENTS OF THE FRENCH ALPS.
THE principal features which distinguish the mountain torrent from the
water-course in the plain is the irregularity of its bed, its mode of action,
its discharge of water, and its sedimentary matter. Among the gentler
features of the plain, the stream runs but slowly, and all the changes of
slope, curve, and level take place in gradual transitions; but, on the con-
trary, in narrow winding gorges it is violent, impulsive, and uncertain.
Rocky angles project abruptly across the water; the declivity is inter-
sected with precipices ; the liquid mass poured down by the torrent may
sometimes be compared to that of a river, but at other times it forms
only a slender rivulet, or even dries up altogether. Lastly, most mount-
ain streams are sometimes as pure as crystal, and at others are loaded
with so large a quantity of alluvium‘ that they are more like avalanches
of debris. The turns and twists of the gorges are so much the more sud-
den as the' rocks through which they are out are_ higher, harder, and
more irregular in their stratiﬁcation and ﬁssures. The water dashing
against some projection springsback at right angles on the opposite
rock, to be again driven back, and thus descends toward the valley in a
series ‘of zigzag falls. In ‘these rugged gorges, where the pathway seems
suspended from the ledges of the opposing cliffs, on either side overhead
may be seen the abrupt ﬁssures where the torrent has cut a passage;
and not only is this mass of water and foam incessantly cast from one
side to the other by the obstacles which hem it in, but it is very often
temporarily kept back by the barriers of debris which crumble down
across its course. When the dam, composed of stones and blocks of
rock, affords no interstices through which the water can glide, the latter
gradually rises in the form of a lake, and then makes its way as a cas-
cade over the wall of rubbish, which by degrees it hollows out down to
the level of its old bed. But usually the avalanche which pens back the
torrent consists of a mass of snow, dust, and broken stones; the water
kept back by this more plastic dam slowly converts it into a kind of ‘
pasty mass, and forces its way through a subterranean outlet. In the
spring, when a good many avalanches are falling from the sides of the
Alps, it is curious to trace the course of the torrent,,visible here and
there, in the gorges. The water may be seen diving down under some
grayish or dark mass, joining with its graceful curve the two opposite
sides of the ravine. The entrance of the gulf forms a kind of porch orna-
MOUNTAIN TORRENTS. 285
mented with icicles, down which the melted snow trickles or falls drop by
drop. Above the torrent which is roaring in the depths-below, the mass
of debris is intersected in some places with crevasses, and the closely-packed
snow presents a bluish edge, like ice; wells open in it at intervals, at the bot-
tom of which the foaming waves may be indistinctly seen eareering along.
In ravines and deﬁles where the slope is uniform the torrent-water af-
fords some degree of regularity in its volume; but when the declivity is
unequal and broken, and especially when, as is the case in most of the
calcareous districts, it is composed of horizontal layers intersected by
precipices, the liquid mass is incessantly changing in width and depth.
In the level or gently inclined portions of its bed the water, ﬂowing
slowly, spreads out into a wide stream, until, reaching the edge of the
cliff, it suddenly tumbles over, and, losing in volume what it gains in
speed, seems nothing but a slender thread of foam gliding over the face
of the rock. Below the fall a new basin opens out, often hollowed in the
shape of a tub, in which the water, now to all appearance unstirred by
the slightest current, reposes quietly as in a lake. A great number of the
valleys in the Alps, the J ura, and all mountainous countries, owe their
picturesque beauty to this succession of pools of quiet water and graceful
cascades. This series of gradations constitute the successive planes of
elevated valleys.*
The variations which are found in the discharge of a torrent stream
are really enormous, even in those mountainous countries where, owing
to the accumulation of the winter snow upon the heights, the water
never entirely dries up. During severe cold, when the snow above is
frozen on the ground, and numbers of rivulets are converted into solid
ice, the main stream of the valley sends down only an inconsiderable
liquid volume, and a traveler may easily cross it by jumping from stone
to stone; but on the arrival of the earliest warm weather, when the rain
and the sun, assisted by the south wind, melt the snow and cause it to '
slide down in avalanches, the masses of water which are discharged into
the torrent from all sides change it into a formidable river, running some-
times, Surell tells us, at a speed of 46 feet a second—more than 30 miles
an hour. It spreads out widely over its basins, ﬂows over the meadows,
and often washes away farm-houses, trees, and even the vegetable mould.
In the deﬁles, on the contrary, it is compelled to gain the requisite space
in height,- as it cannot ﬁnd it in width, and its level suddenly rises 60,
80, or even 120 feet. All this may easily be noticed inthe narrow Ital-
ian valley-streams fed by the snow from the Mont Blanc and Monte Rosa
groups. The Sesia, the Dora, and many of their atﬂuents, before they
empty into the plain, pass through dark gorges, where the liquid mass of
the ﬂood-water, ten times deeper than its width,_descends with the ra-
pidity of an avalanche. Looking forward to these rushes of Water, the
mountaineers, in many places, have dug out their paths more than 150
feet above the bed of the torrent.
"‘ See above, chapter on “Valleys,” p. 132.
28-6 THE EARTH.


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Fig. 97. Circle of the Valley of Lys.
The Var may be mentioned as an instance of this astonishing ﬂuctua-
tion in the discharge of its torrent-waters. At its outlet, the liquid mass
of this river varies from 37 to 5240 cubic yards, of water in a second;
this difference is as 1 to 143, and the proportion would be still larger if
the ﬂuctuations were measured above the conﬂuence of the Vaire, the
Tinée ‘and the Vésubie.* In the level countries of 'VVestern Europe,'the
difference presented between the high and low water levels is, on the av-
erage, scarcely one tenth of that afforded by the Var. In great rivers,
such as the Mississippi, the difference between high and low water is as 1
to 4 only. As a standard of comparison between the ﬂoods of a torrent
and those of a lowland river in the same climate, we may mention the
Upper Loire and the Somme. Above Roanne, the basin of the Upper
Loire, at its ﬁrst outlet from the mountains, ‘comprises an area of 2470
square miles, and the stream discharges during exceptional ﬂoods 9549
cubic yards of water a second—rather less than four yards for each mile
of surface. In its highest ﬂoods, the Somme sends down 117 cubic ‘yards
of water-'-—a quantity which, if it was spread over its drainage area, would
render the ﬂoods of the Upper Loire 84 times more considerable than
those of the Somme ;f and doubtless a comparative study 'of the inun-
' dations of all the water-courses in France would disclose still greater
* Villeneuve Flayose. - i T Belgrand, Aimoalesi des Ponts et €haussées,1854.
FL UOT UA TI ONS IN RIVERS.
variations between the system of torrents and that of the lowland
rivers.
In the tropical regions, where the rainy season is succeeded by the
season of drought, the greater part of the mountain rivers only run
during half the year; they are alternately considerable rivers and dry
ravines.
Thus some valleys—those, for instance, of the Sierra Nevada de Santa
Marta—exhibit a daily ﬂuctuation in the discharge of their streams, ow-
ing to the storms which the gusts of the trade-winds rarely fail every
afternoon to dash against the heights. In the evening all the gorges are
ﬁlled with masses of raging water, and the traveler ﬁnds himself com-
pelled to put a stop to his journey; he bivouacs on the edge of the river,
and is lulled to sleep by the noise of the cataracts roaring over the rocks;
when he wakes up at dawn next day, all he sees is a slender rivulet of
water, only visible here and there among the masses of gravel.
But the torrents which must be instanced as the most striking types of
the merely temporary water-course are the ouaclys in the Sahara and the
plateaux of Arabia, and the liquid masses which sometimes roll down the
qnebraclas of Bolivia and the Argentine pampas. All round the Red Sea,
embracing an extent of more than 1550 miles of coast-line, there does not
exist one permanent stream. All the ouarlys which, during heavy rains,
ﬂow into the sea, convey to it only the surplus of the surface-water which
the sand of the desert was not able to absorb. In a general way, before
the complete disappearance of these streams, most of which run over a
bed of subterranean rock, they ooze up imperceptibly through the sand,
and show themselves in pools stagnating in the passes of the deﬁles. In-
stances of streams thus converted into a chain of ponds are very numer-
ous in deserts all over the world—in Arabia and Algeria, in the Caspian
steppes, and in the North American solitudes.
In these regions the ground on the plateaux and in the plains is fur-
rowed with valleys exactly like those found in the country that is well
watered with rivulets, streams, and rivers. The river-system exists in
full force, and for hundreds of miles the traveler may trace wide hollows,
perfectly developed, which would contain rivers like the Danube or the
Rhine, and on either side debouch the stony stream-beds of the lateral
valleys. Nevertheless, these deep and winding depressions, hollowed out
by the temporary water-courses, generally contain nothing but pebbles
and sand; water is altogether wanting except during the season of the
periodical rains. One of these waterless rivers, the Roumah, which con-
nects its bed with the Euphrates, not far from the mouths of the Chat-el-
Arab, is not less than 750 miles in length. The only permanent ele-
ments, so to speak, of its vast drainage area are a few springs and rivu-
lets ﬂowing from the mountain sides round the circumference of its
basin.
In the upper part of their course, these torrent—waters assist, as we
have said, in modifying the relief of the terrestrial surface; but these
288 THE EARTH.
magniﬁcent operationsof erosion, which crumble away mountains, or, at
least, by enlarging the clefts, ultimately convert mere ﬁssures into open-
ings of such important dimensions both in width and depth, are not the
work of the torrents alone. The latter, in fact, are scarcely the chief
agents in the work; they do little else than clear away the stones and


Fig. 98. The Igharghar.
debris fallen from the heights above. All the meteoric phenomena of the
atmosphere—among which, however, snow and rain may certainly be con-
sidered as the real orign of torrents—contribute to the work of destruc-
tion, and ‘detach from the mountain-sides masses'of debris, which accumu-
late'atthe foot of the rocks in more or less inclined slopes. The torrent
ER OSIV'E "A (1T1 ON OF TORRENTS.
289
into which this débrz's crumbles down washes away all the sand and light-
er matter, until the time when, swelled by 1'
down toward the valley the great blocks of
ain and melted snow, it rolls
rock that have fallen into its
bed. It is diﬂicult to restrain a feeling of dread when we pass along the
bank of a ﬂooded torrent and hear, above all the uproar of the water, the
dull thunder of the masses of stone dashing
are hurried along under the rushing water,
it washes away.
one against the other as they
yellow with the earth which
Thus, year after year and century after century, the torrent clears
away
whole mountain sides which have crumbled'down into it rock by


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Fig. 99. Valley of Cogne.
rock, and this great work of erosion is inc
essantly going on. In some
mountain groups, where the rocks are easily shifted by the action of the
weather, nothing is left but a mere skeleton
which once towered up toward heaven. But
in the regions where the mountain strata
are of a compact formation, and the water
consequently takes some considerable time
to penetrate them, all that we notice 'in
the way of dilapidation are large holes
which the torrents have gradually hollow-
ed out in the body of the rock. Where
two mountain rivulets form a junction, it is
very seldom that the three headlands which
overlook the conﬂuence do not leave at their
base a small triangular valley, whence the
water leaps down into the lower gorge. In
of those former proud heights


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like manner, when two streams proceeding from directly opposite ravines
fall into the main stream of the valley at the same spot, the llttle plam
T
290 _ THE EARTH.
of erosion which is found at their conﬂuence generally assumes a quad-
rangular form. It must, however, be understood that the dimensions and
the outlines of these basins must vary inﬁnitely according to the force
of the torrents, the hardness of the rocks, and the energy of the agents
that attack them. Ultimately, the surface of the country, having been
carved out by the water for an unknown number of centuries, completely
changes its aspect; the mountains and the plateaux are swept down by
the rivers, and little else remains but the isolated landmarks of the an-
cient piles.
There is probably no country in the world where this devastation goes
on more rapidly than in the French Alps. The mountains of this region,
and especially those which inclose the basins of the Durance and its
tributaries, are in general composed of very hard rocks alternating with
other beds, which easily give way under the action of the water; in
every place we may notice immense cliffs resting upon bases without any
solid consistence. The marls, the disintegrated schists, and the other fri-
able matter are gradually washed away, and their fall precipitates that
of the compact layers at the summit, which suddenly fall down or glide
slowly into the valleys.* It is, however, the improvidence of the inhab-
itants, and not so much the geological constitution of the soil, which is
the principal cause of the devastating action of the streams. In the
mountains of Dauphiny and Provence, the slopes, most of which are now
so bare, were once covered with trees and various plants which kept
back the surface-water resulting from the rain or melting of the snow, by
absorbing a great, part of the falling moisture, and thus retaining the
coating of vegetable earth over the beds of crumbling rock. During the
course of centuries, the trees have been cut down by greedy speculators,
and by senseless farmers who wished to add some little strips of land to
the ﬁelds in the valleys and to the pastures on the summits; but when
they destroyed the forest they also destroyed the very ground it stood on.
The rain or snow, being new no longer kept back upon the slopes by
the roots of the trees, descends rapidly into the valley, driving before it
all the debris torn away from the sides of the mountain. The teeth of
the goat and the sheep helpslto lay bare the rootlets of the herbaceous
plants and the brush-wood; bit by bit, the whole of the thin coating of
vegetable earth is removed, the bare rock shows itself, and deep ravines
are hollowed out in the cliifs, and are traversed in the rainy seasons by
furious torrents which once did not exist. The water which, used slowly
to penetrate the earth, conveying fertilizing salts to the roots of the trees,
now serves no other purpose than that of devastation. When the forests
, are gone, great furrows of erosion may be noticed opening out at inter-
l, vals on the slopes; these furrows often correspond to ravines situated on
lthe other side of the mountain, and in a comparatively short space of
E time they ultimately sever the ridge of the mountain into distinct peaks,
I uniformly surrounded by a slope of rocks or fallen earth: summits of this
* Scipion Gras; Rozet; De Ladoucette; De Itibbc.
ER OSI VE A 0 TI ON 0F TORRENTS. 2 9 1
kind are being formed every year." In some localities there is not a sin-
gle green bush over a space of several leagues inextent; the scanty gray-

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Fig. 101. Valleys of Erosion of the Bourgogne.
colored pasturage is scarcely visible, here and there, on the 'slopes, and ru-
ined' houses blend with‘the crumbling rocks that surround them. 'The'
stream in the valley is generally nothing but a scanty rill of water wind-
292 THE EARTH.
ing among the heaps of stones; but these very heaps of shingle and rock
have been carried down by the torrent itself in the days of its fury. In
many parts of its course, the Haute Durance, which is generally not more
than 30 feet wide, seems lost in the midst of an immense bed of stones, a
mile and a quarter wide from bank to bank. The Mississippi itself does
not equal it in dimensions.
_ The devastating action of the streams in the French Alps is a very cu-
rious phenomenon in an historical point of view; for it explains why so
many of the districts of Syria, Greece, Asia Minor, Africa, and Spain have
been forsaken by their inhabitants. The men have disappeared along
with the trees; the axe of the woodman no less than the sword of the
conqueror have put an end to or transplanted entire populations. At the
present time, the valleys of the Southern Alps are becoming more and
more deserted, and the precise date might be approximately estimated at
which the Departments of the Upper and Lower Alps will no longer have
any home-born inhabitants. During the three centuries that have elapsed
between 1471 and 1776, the eigneries of these mountainous regions have
lost a third, a half, or even as much as three quarters of their cultivated
ground, and the men have disappeared from the impoverished soil in the
same proportion. From 1836 to 1866, the Upper and Lower Alps have
lost 25,090 inhabitants, or nearly a tenth of their population. At the
present time, in an area of 3860 square miles, embraced between Mont
Thabor and the Alps of Nice, there is not a single group of inhabitants
which exceed the number of 2000 individuals. Barcelonnette, the most
considerable place, has more than once been in danger of being carried
away by the stream, the bed of which is higher than the streets of the
town; the latter certainly would be still less .populous were it not that
the numerous functionaries necessary in every sub-prefecture tend to give
it an artiﬁcial life. Without the employee and the custom-house oﬂicers,
who almost consider themselves as exiles, the whole extent of a great
portion of these mountainous regions would be nothing more than a
,/ gloomy solitude. It is the mountaineers themselves who have made and
a are seeking to extend this desert, which separates the tributary valleys
‘of the Rhone from the populous plains of Piedmont. If some modern
Attila, traversing the Alps, made it his business to desolate these valleys
forever, the ﬁrst thing he should do would be to encourage the inhabit-
ants in their senseless work of destruction. Is it necessary that man
must ultimately rid the mountains of his odious presence, so that the latter,
left to the kind oﬂices of beneﬁcent nature, may again some day recover
their forests of ﬁr-trees and their thick carpet of ﬂower-studded turf?
Although the torrents lower the mountains, on the other hand they ele~
vate the plains; but their deposits, not being pulverized into clays and
sand, are oftep the means of bringing another disaster on the inhabitants,
who ﬁnd their fertile land covered beneath enormous masses of rocks and
pebbles. In fact, when a stream empties itself into a valley which has a
moderately inclined slope, and the former consequently experiences a sud-
TAH- 293
den check in its progress, it deposits over a long extent of descent all the
debris which it conveys in its water or rolls down before it. The masses
of rough alluvium accumulate on both sides of its course, so as to form a
rising, with regular slopes abutting against the escarpments of the mount-

lira.‘


Fig. 102. Talus of Débrzl's in the Valley of the Adige.
ain. Even in places where the stream once rushed down into the valley
in rapids or cascades, its tendency always is to conceal gradually every
irregularity in its old bed under the ever-increasing slope of rocks, peb-
bles, and sand. The deep ravine of the upper valley is succeeded by a
long embankment, which, continuing the incline, pushes out far into the
principal valley, and forces the stream to describe a considerable bend
round the base of the cone of debris. Some of these banks attain very
important dimensions; they accumulate to an enormous extent at the ;
outlet of each lateral ravine opening into the elevated valley of the Adige,?
to the south of the (Etzthal group. One, that of the Litznerthal, is 10363
\ ~ .
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Fig. 103. Talus formed by Torrents.


//


feet in height at the outlet of the ravine, and extends 4148 yards in length
as far as the Adige, with a mean slope of 4° 46'; the curve of the river
which winds roimd its base is not less than ﬁve miles in length.
When the streams empty their waters into a mountain lake, and not
into. a valley, the debris which they carry down accumulates at the upper
end of the lacustral basin, forming a slope much more abrupt than the
mass of stones deposited at the entry of a ravine. In fact, at the outlet
of the latter the water of the torrent continues to ﬂow over the masses
which it has heaped up; fresh materials are continually being brought
down, some of a small, others of a large size, which serve both to prolong
the slope and to render it more and more uniform with that of the plain
below. In lakes, on the contrary, a separation immediately takes place
in the various debris brought down by the current. The blocks of stone
and pebbles fall by their own weight into the depths of the water, and
form a kind of moraine, which incessantly pushes on into the quiet water.
294, THE EARTH.


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Fig. 104. Ancient Lakes and Deﬁles of Aluta.
The lighter alluvium, which is held in suspension by the liquid mass, is
partially carried on by the current toward the middle of the lake; but
the greater part of this matter is soon dropped on each side of the em—
bouchw'e, and ultimately extends in horizontal promontories above the
accumulated mass of heavier rubbish. Thus the bed of the stream, with
l


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Fig. 105. Lakes of Thun and Brienz.
FL UVIA TILE DEF osITs. 295-
its steep slope of stones in front, bordered by its layers of lighter allu-
vium, incessantly encroaches on the lake.
A large number of lakes have thus been gradually ﬁlled up altogether;
in several high mountain valleys, where lakes exist at intervals one above
another, all the basins have in turn been ﬁlled up. In other places the
upper pools only are choked, and the work is going on in one of the low-
er lakes, which, sooner or later, will ultimately be converted into a hori-
zontal plain. By very carefully measuring’the annual deposits of a ter-
rent, and ascertaining, by boring, the depth of the former lakes which
they have ﬁlled up, the number of centuries might ‘be approximatelyestt-
matedwhich‘ this immense ,work‘has, taken. , Also, sounding the depths-
of the basins which arewstill full of water would show the duration _7 of
ages which will be required to ﬁll up their abysses. At the foot of the
great group of the Bernese Alps, on the isthmus of Interlachen, so well
known 'to travelers, it would be comparatively easy to make the experi-
ments ngcessary for the solution of. this problem, which would also in-
form us approximately as'to the duration of the geologicalperiod' during
which the streams have 'ﬂoweddown from the mighty group over which
towers the Jungfrau. ‘For this calculation it would be necessary to
measure the present deposits of the furious Lutschine, andtofestimate
the enormous solid mass of the isthmus of Interlachen, whiclnhas been
thrown down by the stream as a kind of dam between the twin. lakes of '
Brienz and Thun, which once formed only one lacustrine basin.
2'96 . THE EARTH.
CHAPTER ,XLVIII.
I ' EROSION OF LACUSTRINE DIKESL—CATARACTS AND RAPIDS.
WHILE crossing the lakes situated at the bases of the mountains, the
waters of the torrent become tranquilized, and their course regulated;*
they emerge from thebasin ‘in streams of a‘less turbulent shape, and,
ﬂowing on to join other water-courses, descend with them quietly to the
sea.
But even the outlet-stream of the lake, although usually more peace-
able than the water-course above, accomplishes its special geological la-
bor, and is also employed in the-task of doing away ‘with the lacustrine
basin. The water, impelled by its own weight, constantly wears away
the layers which form the lower margin of the lake. The edge of this
margin being gradually destroyed by the liquid mass, sinks by slow de-
grees, and the average level of the water in the lake sinks also in the
same proportion. Thus, at the two extremities of the basin the river is


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carrying on two kinds of work, contrary in appearance, but which have
both an equivalent result in reducing the area of the lake which the rivers,
crosses. Up above, it gradually ‘elevates its bed, and gains on the, lake
by ﬁlling it up with alluvium; down below, it lowers the brink,‘ and, by
this constantly increasing waste-gate, gradually drains out the water.
The two stream-beds, the upper and the lower, will ultimately meet in
the middle of the lake, and the latter will cease to exist. This is the
double phenomenon which has been going on for ages in the Lake of Ge-
neva. This crescent-shaped sheet of water certainly once extended as
high up the stream ‘as the place where the town of Bex now stands, 11;};
miles from the end of the lake; it also extended down the stream in nar-
{ row basins as far as Ecluse, 91} miles from the outlet of the Rhone.
’ It must, however, be understood that the outlets of lacustrine reservoirs
are not the only places where the rapids and cataracts of a river crumble
away the rocks so as to lower the up-stream and elevate the down-stream
beds. However hard may be the strata which form the bed of a rapid,
the eddying waters ultimately penetrate the stone, and deposit the debris
'below the gulf that the furious shock of the torrent has hollowed out at
* Vide the chapter on “Lakes.” "
FILLHVG UT 0F LAKES. 297

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4° 7
Fig. 107. Alluvial Deposits of the Rhone and the Dranse.


the foot of the rocks. In like manner, cascades and cataracts incessantly
wear away the ledges from which the mass of their water pours down
to the bottom of the abyss, carrying the great stones with them in their
fall, and, destroying layer after layer, they continually retrograde toward
the source of the river, and tend to convert themselves into mere rapids,
which, in some thousands of years or perhaps centuries, are destined to
assume a perfectly uniform inclination. ‘This is the ideal, so to speak, of
every river—to do away with the irregularities of its course, and to ﬂow
down toward the sea, describing a regular parabolic curve. This ideal,
however, is never perfectly attained, on account of the diversity of rocks
in its course, the changes in its bed, the disturbances or elevations of the
ground, and other circumstances of various kinds which may cause a de-
viation in its current. But whatever may be the obstacles which oppose
the leveling of the declivity, still every river intersected by falls and rap-
ids is constantly at work in effecting the general uniformity of its slope.
In their magniﬁcent beauty, cataracts and rapids only yield the pre-
eminence to hurricanes and volcanic eruptions. Of the former, there are
some in Europe which are very remarkable: such as the falls of the Rhine
at Schaffhausen; the four cataracts of the Gotha-Elf at Trollhata (dwell-
ing of sorcerers); the Hjommel-saska (the hare’s leap), where the river
Lulea plunges over in a body from a height of 264 feet; and the Riu-
kan-fos (roaring cascade), which falls at the outlet of the Norwegian lake
Mjosvand in a single jet of 885 feet. The most celebrated water-fall in
the whole world is that of Niagara—-“ the falling sea”—the constant
thunder of which may sometimes be heard 12 milesoﬁ'. Above the cat-
aract the river, which discharges on the average 1300 to 1400 cubic yards
of water a second, breaks against the shore of Goat Island, and divides
into two rapidly inclined currents. Even at this point the mass of water
298: THE EARTH.

is impelled by such velocity ofmove-
ment that engineers have not yet
been able to sound its depth, and
they have similarly failed to do so
below the cataract. On reaching
1 the edge of the cliff, the two halves
of the river—one 655, and the other
.295 yards wide—take their, ﬁnal


. l e we,’ leap, and describe their vast para-
“tn-ha: "{ {in 5 ii} ' -
Fwiommdya bola, 147 feet and 160 feet 111 height.
‘;. ‘ >
furious gusts of wind, opens be-
tween the wall of rock and a sheet
of water, 18 to 33 feet in thickness,
which curves widely overhead like
an immense arch of crystal. Col-
umns of iridescent vapor spring
from the whirlpool of the roaring
waters, and half hide the two white
masses of the cataracts. At every
instant of the day, following the
path of the sun, the great rainbow
painted on the wavering and misty
spray shifts its position, and thus
modiﬁes the aspect of the fall. The various seasons, each in their turn,
add some feature of beauty-to the magniﬁcence of the spectacle- The
trees still left 011 Goat Island and the ‘cliffs contrast with-the whiteness
of the water—in summer by their verdure, in autumn by the more varied
colors of their foliage. In winter, stalactites, glittering in the sunlight
like immense strings of diamonds, hang down from all parts of the rock,
and serve as a frame-work to the two great plunging sheets of water. ‘ In
spring, when the‘ ice breaks up, a formidable spectacle is presented by the
blocks of ice, like mountain fragments, crowding together at the edge of
the cataract, and crashing against one another as they glide over the
enormous curve of water which is sweeping them along.
Other great water-falls in different parts of the earth afford similar phe-
nomena, and several of their number may even rival Niagara in their
beauty. Among these we may mention, in North America, the magniﬁ-
cent falls of the Missouri, the Columbia, and the Montmorency. Of like
beauty, also,‘ there is in Brazil, not far from Bahia, the wonderful cataract
of San Francisco, known by the name of Paulo Aﬂ'onso. At the foot of a
long slope over which it glides‘ in rapids, the river, one of the most con-
d
225
H
"a A gloomy passage, penetrated by
as
U


Fig. 108. Course of the Niagara.
siderable of theSouth American continent, whirls round and round as it '
enters" a kind of funnel-shaped cavity roughened with rocks, and, sudden- ~.
1y contracting'its width, dashes against three rocky masses reared up like A
towers at the edge of the abyss; then, dividing into. fourv vast columns .
FALLS OF THE ZAMBESI.
of water, plunges down into a gulf 246 feet in depth. The principal
column, being conﬁned in a perpendicular passage, is scarcely 66 feet in
width, but it must be of an enormous thickness,'as'it forms almost the
whole body of the river. Half way up, the channel which contains it
bends to the left, and the falling mass, changing its direction, passes .un-
der a vertical column of water, which penetrates through it from one'side
to the other, and, breaking it up into a chaos of surges, converts it'into
a sea of foam. Sometimes the white misty vapor may be seen,and the
thunder of the water may be heard, at a distance of more than ﬁfteen
miles."< »
This turbulent cataract is very different in character from the majestic
falls of the Zambesi, the existence of which Livingstone has made known

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Fig. 109. The Falls of the Zambesi.
to the world. Above the precipice the river is calm, and ﬂows over a
gently inclined bed; some islets, covered with cocoa-nut trees, are reﬂect-
ed in the clear water. A large island, called “ the Garden,” on account
of its rich vegetation, divides the Zambesi into two branches, and the
general features of the landscape are full of grace. All on a sudden,
without the least transition, the ground comes to an end beneath the
water, and the two liquid masses, one of which is 1858 and the other 546
yards wide, plunge down to a depth of 348 feet into the gaping ﬁssure of
a vast mass of basalt. They then escape by a narrow and winding chan-
nel, which the river itself has hewn out of therock during the lapse .of
many vcenturies. Ten columns of vapor, answeringto ten great projec-
tions on which the body of water dashes itself -_ tojpieces, rise ‘in eddies
* Avé-Lallemant, Reise durch Nord-Brasilien.
300 THE EARTH.
from the 'foot of the precipice, and ﬂoat, like the smoke of a conﬂagration,
far away above the surface of the river. They vary in height according
to‘the state of the water and the atmosphere; but, generally speaking,
they do not rise less than 1000 or 1150 feet above the brink of the gulf.*
On account of these clouds of spray and vapor, the natives have given to
the cataract of the Zambesi the name of Mosi-oa-Tozmya, or “Thunder-
ing Smoke.” >
With regard to rapids, we ﬁnd them on most rivers at different points


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Fig. 110. Rapids of Maypures- on the Orinoco.
of their course; either at spots where cataracts once existed, or at the
mouths of streams which carry down with them large quantities of at-
bris, and pile them up like dikes across the current. The American rivers
* Baines, Exploration in Southwest Africa.
FALLS AND RAPIDS.
are the principal localities where these rapids may be contemplated in
their full beauty. Humboldt was the ﬁrst to describe the raudales of
Atures and Maypures, where the Orinoco, changed into a mass of foam,
pours down innumerable cascades over a chaos of rocks and banks with
dark sides crowned with foliage and verdure. Each mass of granite,
resembling in its shape some ruined tower or castle, is surmounted by
a group of palms or densely-foliaged trees. Every stone below the level
which the river reaches during ﬂood-time is covered with alluvium, on
which the mimosa, with its delicate leaves, grows abundantly; also ferns
and orchids, with their charming ﬂowers. They are perfect little gar-
dens surrounded with foam, reminding one of the rocks covered with
ﬂower-studded turf which spring up in the midst‘ of some of the glaciers
in Switzerland. A cloud of vapor hovers over ‘the river, and the rainbow
shines through the verdant hues of innumerable bowers of foliage. This
is the lovely spectacle which the Orinoco affords for a distance of several
miles along each of its two rapids. The fall is not considerable, that of
the medal of Maypures being scarcely 30 feet; but still the slope is very
difficult to overcome, and in a width of 2841 yards the navigable channel
is sometimes not more than 18 feet.*
About the same time as that when Humboldt and his friend Bonpland
visited the rapids of Atures and Maypures, Azara examined the great
who of Maracayu, where the river Parana, which, just above, is 4590
yards wide, is suddenly contracted into a deep channel only 66 yards
across, and, sliding over an inclined plane of 60°, forms a fall of 56 feet of
, vertical height. The narratives of travelers have also made us acquaint-
ed with the rapids of the Madeira, the Huallaga, the Ucayali, and several
other rivers, down which the canoes of the savages used to glance like
arrows in the midst of the foam. In North America the most celebrated
rapids are those which the St. Lawrence forms at its issue from Lake On-
tario; but all-powerful steam has succeeded in overcoming them. The
European rapids are not so imposing, on account of the inferior quantity
of the river discharge, and also because the general relief of the continent
is much more gentle than that of the New World. We may, however,
mention the rapids of the Shannon, above Limerick, the porogs of the
Dnieper, and the Whirlpools (stmcleln) of Bingen, which were so danger-
ous before the rocks were blown ‘up which impeded the course ‘of the
Rhine. Among the most imposing rapids in France, both on accountof
their bulk and the fury of their foaming water, and also of the calm‘so-
lemnity of the surrounding landscape, are those of the Gratusse, formed
by the Dordogne, some miles above Bergerac. .
In surveying both falls and rapids, there is one point that especially
impresses the mind; it is that, in a general way, immediately the water
has emerged from its state of turbulent eﬁ’ervescence, it assumes an‘un-
broken surface, and spreads out into wide calm sheets, known in Spanish
America under the name of remcmsos. On one side‘ we look down on the
* Humboldt, Voyage aux Régions Equinoxiales.
302 THE EARTH
giddy chaos of the liquid masses dashing against one another as they
rush along; ‘ on the other we see a pool of water almost still, or at most
slowly rotating. Here the long gentle eddies seem unable even to move
the. straws and twigs which-incessantly ﬂoat round and round in the
same circle; higher up the. stream, the river in its impetuou's‘ career
sweeps away trunks of trees, tears up the stones of its bed, and notches
out the edge of the cliff over which it falls. This contrast becomes still
more strikingwhen we reﬂect that the cataract once descended ‘at the
' very spot where this tranquil sheet of water now lies, and that-during a
long course of agesthe fall has continually retrogaded. . The high ver-
tical rocks which hem in thetwo banks of the river belong to the same
geological formation, and‘the parallel lines of their strata exactly corre-


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‘spend on both sides. The traces of the current which has eaten away the
stone are still, visible, and themarks of the work slowly accomplished by
the water can be distinctly traced out by the eye. The immense cavity
which-extends like a dark passage below the fall has been hollowed out
1 by the cataract—scooped out, so to speak, grain by grain.
The rate ‘of speed at which the fall shifts its position might serve to
estimate approximately the age of the river itself If geologists had
studied this retrograde movement for a suiﬁcient' number of years, they
would know the exact degree of resistance afforded by the rocks through-
out the whole length of the cavity; they would be able to say with cer-
tainty how many centuries the present system has lasted with regard to
.every river which is interrupted‘in its course by a cataract. But this
comparative study of water-falls has scarcely commenced, except, perhaps,

WEARING AWA Y OF FALLS. 303
in the case of Niagara and some other of the great water-courses of North
America. According to Hall, Lyell, and other geologists, the Falls of
Niagara have receded three miles and a half in the space of about 35,000
years. The erosion of the edge of the precipice is now taking place at
the average rate of 12183 inches a year.* This is a tolerably rapid
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b. Clinton Group. \ d. Medina Sandstone.
Fig. 112. Proﬁle of Cataract of Niagara; after Maroon.
b


movement of retrogression, which, however, is explained by the nature of
the rocks; these latter are composed of calcareous strata ‘resting on beds
of soft and friable marl. The water penetrates intothese layers, and,
slowly undermining‘them, washes them away, thus throwing down. the
upper strata in massive blocks, which are carried away by the cataract.
The observations of M. Maroon have established the fact that the volume -
of water is constantly diminishing in the fall on the'American' side, and
that, in'consequence, the rocks there have scarcely been encroached upon
for some twenty years. To make up for it, the great cataract is rapidly
receding up stream, and even now it no longer assumes the graceful semi-
circular form which obtained for it the name of the “ Horse-shoe Fall.”
In an interval of time which may be estimated at eight or ten centuries,
the cliff of the cataract will probably be lowered as far back as the little
islets of the Three Sisters; the. whole liquid mass will then rush down
the current which runs along the Canadian shore, and the branch on the
American side, no longer receiving any water, will gradually dryup;
Goat Island will become united to the main-land, and the River Niagara,
constantly receding toward Lake Erie, will pour down the whole of its
water in one formidable fall. - . _ .
.It may likewise be presumed that the height of the cataract will tend
to increase; for the calcareous'strata which gave way under the weight
of the water gradually augment in thickness in the upstream direction.)t
But we are scarcely,warranted in estimating,_evenapproximately, the
time which the Niagara will take in receding to Lake Erie; for, as M.
Marcou remarks, the prodigious manufacturing activity of the Americans
may much modify matters in this respect.’ A canal, which is, in fact, a
* According to Lyell. Mr. Bakewell says that the annual retrogression of the falls has
been nearly a yard since 1790.
T Marcou, Bull. Soc. Géol. de France, 2d Series, vol. xxii. .
304 THE EARTH
perfect river, already turns a large number of mills on the American side;
and if the river is tapped by thirty or forty conduits of this importance,
the mighty Niagara will become nothing but a humble rivulet. “Arts.
and manufactures will have disarmed the thundering Jupiter.” But
Lake Erie itself, which,according to Ellet, contains at present more water
than the fall could run oﬁ‘ in six or eight years, will be perhaps ﬁlled up
with alluvium before Niagara has been able to wear away the lower
ledge of rocks which prevents the lake from rushing down bodily into
the basin of Ontario.
That which the future will perhaps accomplish as regards Niagara has
already taken place in the Mississippi. Nearly half way between St.
Louis and Cairo, the river penetrates a deﬁle which cuts through the
chain of the Ozark Mountains; rocks 300 feet in height rise between the
two banks, and on their perpendicular sides may be clearly distinguished
the lines of erosion which were once traced out by the current of the
Mississippi. In former days these rocks formed a barrier over which fell
' a cataract like that of Niagara, which, too, like the former falls, constant-
ly were away the strata which served as its bed. Above this barrier of
hills the water of all the upper tributaries united in a vast lake, which
extended north as far as the mouth of the Wisconsin, and, joining Lake
Michigan on the east, covered all the immense prairies of the intervening
peninsulas.* In liklekmstnner, the Rhine, the Danube, and a great many
other rivers, the course of which at the present day is tolerably uniform,
presented a succession of lacustrine ponds, placed in gradation one above
another, and united by cascades. The rocky barriers situated between
the ponds have been‘ gradually demolished and washed away by the wa-
ter; some of them have even been pierced through at their base, and this
is the origin of the natural bridges which throw their arches above a
great number of streams and rivulets. The Pont-de-l’Arc, which the wa-
ter of the Ardeche has slowly bored out during the course of geological
ages, has a span of not less than 177 feet. The famous natural bridge of
Virginia is only 111 feet in width.
By operations of this kind, rivers gradually regulate their slope and
effect a communication between plateaux of diﬁ'erent height, which sink
in successive gradations from the base of the mountains to the sea-coast.
Whatever may be the irregularities of the continental surface, running
waters cut out their beds in the form of inclined planes, and give them a
more or less regular slope, which is followed by merchandise, travelers,
and even civilization itself, in order to penetrate into the separate basins
of the river-system. Every cut made by a river across a chain of hills or
the side of a plateau may be considered as a gate opened through a wall
dividing two distinct regions. Thus, in studying the monography of
each river, it is necessary to study specially the apertures which the wa-
ter has made through the barriers which once opposed its free course.
By a succession of victories obtained over enormous masses of rock, the
* Humphreys and Abbot, Report on the Mississippi River.
THE “GREAT TOWER.” 305
river has succeeded in emerging from the lacustrine reservoirs where its
waters once lay dead, and has gradually constituted itself as a living in-
dividuality ever at work shaping anew with its waves, its alluvium, and
the bars at its mouth. The Danube obtained its hydrological impor-
tance from the time when its waters ceased to be lost in the former lakes
which have now become the plains of Hungary, Austria, and Wallachia.
Oftentimes, when the river thus cuts away a passage through a rocky
barrier, it leaves standing erect, as an evidence of the former state of
things, an islet of hard stone which it has failed in washing away. In
the most picturesque parts of their course, almost all large rivers exhibit
some of these solid masses which continue to resist the pressure of the
water some centuries after the destruction of the surrounding strata.
Thus, on the Danube, we ﬁnd those proud rocks, with their perpendicular
sides towering up, like enormous pillars, as high as the level of the rising
ground by the river-side, and crowned on their summits, some with a feu-
dal fortress, some with a hermitage, and some with nothing but a clump
of bushes or brush-wood. Thus, too, in the Mississippi, not far from the
spot where the whole body of its water once poured over a precipice in a
mighty cataract, we notice the ﬁne rock which, from its form and majestic
aspect, has obtained the name of the “Great Tower.” This rock still
bears, at a height of 132 feet, the circular line of erosion which was once
traced out by the current. But although we still ﬁnd a pretty consider-
able number of these natural water-girt “towers,” the greater part of
those which once existed have gradually disappeared under the action of
the elements, and their place is now marked only by hidden reefs or rocks
on a level with the stream.
U
306 THE EARTH
CHAPTER XLIX.
FORMATION OF ISLANDS.—~RECIPROCITY OF CURVES.-—WII\'DINGS AND OUT-
TINGS.-—-SHIFTING OF THE COURSES OF AFFLUENTS.
IT is therefore a fact that rivers, like all other natural agents, never
cease in their work of destruction, but they 'destroy only to reconstruct
in another place. They are continually eating away rocky islets,'and em-
ploying the débris in the formation of islands of sand. Wherever some
obstacle, exists iii mid-'eurrent,'such as a bank of rock, the trunk 'of a fallen
tree, or some construction 'of human industry, the water, arrested suddenly
in its course, divide'siinto two ﬂows as if before the cut-water of a ship,
which, gliding 'round the opposite sides of the obstacle, rush, one on the
right and the other on the left, either against the remainder of the water
ﬂowing regularly down the current, or in small streams against the banks
themselves._ From this results a double encounter; the two-curved ﬂows,
being more or less inﬂected and retarded by a thousand local circumstan-
ces, are thrown back toward the middle of the river, where they meet,
each having described its parabola. There, one portion of each of these
ﬂows continues to descend, describing a more elongated parabola, while
another portion ﬂows into the comparatively tranquil space which lies be-
low the obstacle, and gradually deposits on the bottom the sediment with
which it is charged. Thus is formed the ﬁrst islet, which is destined to
increase by degrees, and to serve as a starting-point for a series of other
islands and sand-banks which make their appearance in turn in the extent
of tranquil water embraced between the parabolas of the two curved
ﬂows. The Germans give these islands the name of “Werder” (from
werden, “to grow” [19]), to point out their slow and gradual mode of for-
mation.
In conformity to this same law of the scrz'atz'on of islands, banks of al-
luvium ought likewise to emerge regularly at the conﬂuence of two riv-
ers; for there, too, the masses of water come in collision, and,being mutu-
ally repelled, again approach one another in elongated curves. In fact,
the tongue of land which separates the two water-courses is often contin-
ued by a series of islets below the conﬂuence; but the force of the current
being considerably increased by the doubling of the liquid volume, and the
joint bed being always much less in width than the sum of the two beds
together, the stream must naturally gain in depth all that it loses in sur-
face. The water, being conﬁned in a narrower channel, hollows out the
bed with increased energy, and thus tends to prevent the formation of
sand-banks.* The alluvium is deposited in the interval between the two
* Von Hoﬂ“, Verz'z'nderzmgen der Erdoberﬂc‘z'clze, vol. iii.
FORMATION OF ISLANDS. 307
currents, and helps to lengthen, in a down-stream direction, the “bee” or
tongue of land which separates the two streams.


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Fig. 113. Series of Islands in the Western Scheldt.

These chains of sandy islets would always be deposited with the great-
est regularity if the river descended to the sea in a straight line. It is
true that every water-course, in obedience to the law of gravity, seeks to
scoop out for itself a rectilinear channel, so as to gain the ocean by the
most rapid incline. But the irregularities of its bottom and banks consid-
erably modify the direction of the river, and cause it to describe a series
of curves or windings, thus lengthening the total extent of its course.
Thus another law, that of the reciprocity of curves, is combined with the
succession of islands in beautifying the surface and contour of a river, and
in causing it to incessantly remodel the ground of the valley through which
it ﬂows by hollowing away the ground, sometimes on one side, and some-
times on the other.
Some lateral impulse communicated to the liquid mass is all that is re-
quired to throw the current of the river either to the right or to the left.
If the water strikes against a wall of rock, or any other obstacle placed
across the regular direction of the stream, the latter rebounds so as to form
an angle of reﬂection equal to the angle of incidence, and, induced both by
its impelling force and the general slope of the bed, it becomes more and
more inﬂected, and describes a parabolic curve toward the opposite bank.
There its current is again turned back, and again takes an oblique course
across the bed of the river. When the ﬁrst seriation is once brought
about, the current must necessarily form a succession of windings, in con-
formity with the law of the reciprocity of curves, which is, in fact, nothing
more than the law of the pendulum. Each oscillation calls forth an equal
308
THE’ EARTH.

ion in a contrary direction; each curve calls forth
If the ﬂuviatile econ—
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and isochronous oscillat
another curve of an equal radius and equal velocity.
omy was not constantly modiﬁed by the varied compos
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the immense diversity of the obstacles of every kind which it meets with’
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the river would ﬂow down toward the sea, always
zags as regular as the oscillations of a pendulum.
WINDLVGS OF RIVERS. 309
But the mass of the current does not conﬁne‘ itself to merely striking
against the two banks in turn; it also continually wears them away, and
modiﬁes their outline. When the water dashes against the bank with all
the impetus which is communicated to it by the current and the action of
centrifugal force, it tears away the earth, dissolves some of the solid par-
ticles, washes away the sand, and has a constant tendency to penetrate
farther. Being then driven back toward the opposite, side, there, too, it
destroys and washes away the soil before it is repelled afresh to continue
on each shore alternately its work of destruction. . Thus, by a law of equi-
librium, the current undermines each bank in turn, while its alluvium is, de—
posited at the points of the two bends. In consequence‘ of the succession
of bends and points, the windings are. sometimes almost ‘perfectly annu-
lar. A boat leaving the upper bend describes a long curve in following
the river, and when it arrives at last at the lower bend it issometimes ac-
tually in sight of the starting-point that it quitted long before. In the
greater part of its middle-‘course the Mississippi forms a series of windings
so exactly like one another that the Red Skin Indians and the earliest Eu-
ropean colonists were in the habit of estimating distances by the number
of curves which the river described. These windings, however, in a cer-
tain point of View, are of the very greatest utility for navigation. Every
bend has the effect of moderating the slope, and, thus retarding the veloc-
ity of the current, proportionately augments the mass and'the depth of
' the ‘water.


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Fig. 116. Meanderings of the Seine.
By dint of gradually washing away both the upper and the lower bend
in a contrary direction to one another, the river constantly tends to dimin-
ish the isthmus of necks which still connects the little peninsula with the
surrounding plains; thus the time will ultimately come when, the isthmus
having disappeared, the two bends will be united, and the winding of the
310 i ‘ THE EARTH.
stream will be converted into a perfect ellipse.- Then, unless the labor of
man oﬁ'ers any opposition, the whole liquid mass will ﬂow on in a straight
line along the rapid slope formed by the junction of the two bends, while.
the water still remaining in the‘ old beds will become‘ sluggish and dead on
account of the slight slope- which is afforded to it by theenormous curve
of the circuit in comparison to the newly-formed passage. The rapid wa-
ters of the upper bed striking against the still water in the former winding
are suddenly-arrested in their course, or‘ even driven back; they then‘de-
posit the earthy debris that’ they hold in suspension, and thus gradually
form-natural 'embankments of sand and mud between the two old beds of
the river. - It is not long before a similar embankment likewise separates
the two beds of the lower bend, so that the forsaken winding is ultimately
left without any‘ communication withthe'new current‘ of the river; its
water becomes‘ stagnant, and it is, in fact,converted into a lake. In the
basins of the Mississippi, the'Amazons, thevGanges, the Rhone, and the Po,
there are a‘ considerable number 'of these circular lakes.‘ We may trace

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Fig. 116. Meandering atiLuzech.


MIDDLE COURSE OF TIiE MISSISSIPPI
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WINDINGS OF RIVERS. 3 11
out with the eye, as it were, three rivers,one ‘of which, active and living,
ﬂows without interruption from its'source to the sea, while the‘ two others
on either side are become “ dead waters.” The remains of them, scattered


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Fig. 117. Old Channels of the Mississippi. I '
all along the existing river, still point out the spots where once extended
its ring-like windings._ In consequence of these alternate shiftings of po-
sition, the valley is always much wider than its river, and along its cir-
312
THE’ EARTH.
ins
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Fig. 118. Old Meanderings of the Rhine.
*Elia Lombardini, Dei Cangiamenti del Po.

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cuitous path windsthe continually changing bed offthe ex
In some parts of its course the Po only takes about thirty years in form
and destroying each of its meanders.*

The perforation of these river isthmuses is not always brought about
by the sole action of nature~;,_many channels uniting two river-beds.‘ have
been dug Out-by the hand of man, and,thanks to the currentsv which have
oorrnva 0F CHANNELS. 4 319
U
deepened them, they have ultimately’ replaced the former beds. Some en-
gineers have gone so far as to propose to carry out a systematic series of
operations as regards the whole line of the Mississippi, and thus to rectify
the bed of the river from Cairo to New Orleans. Since the colonization
of Louisiana, the labor of man, assisting the action of the currents, has al-
ready rectiﬁed several beds; in this way have been formed the “ cuts-off”
of Bunch, Needham, Shrieve, Point Coupée, and Fer-a-Cheval. Above
these different points the isthmuses are much more diﬁ‘icult to cut through,
on account of the strata of compact and hard 'clay which extend immedi-
ately below the superﬁcial bed of the modern alluvium, and are not easily
washed away by the water. Thus it was that in front of Vicksburg a por-
tion of General Grant’s army worked in vain for several months endeav-
oring to cause the current of the Mississippi to pass through a channel
cut across the narrow isthmus of the right bank. _
Nevertheless, all these “ cuts off” dug out by the hand of man can not
fail ultimately to become obliterated; for, in conformity with the law of
the reciprocity of bends, a river, when deprived of its windings, is not long
before it forms new ones. This was the case above Compiegne, where it
was vainly attempted to straighten the course of the Oise. In a very
short time the river made fresh windings, the development of which was
found exactly to equal those which had been done away with. It was
managed better in ﬁxing the course of the Midouze, in the Landes, for
there the ingenious idea was adopted—and followed by success—of giv-
ing to the river a series of meanders of perfect regularity. When man
attempts to meddle with nature, he can only succeed in permanently mod—
ifying its aspect by studying the constant laws of its phenomena, and by
making his work conform to these.
The idea of digging out and maintaining a straight channel between
two parabolic bends of the Mississippi is in no way more absurd than the
idea of constructing piles perpendicular to the current of the stream, in
order to limit the bed of the river, and to throw the waters into a regular
channel. By operations of this kind, contrary to every principle of hy-
draulics, our French engineers have entirely ruined the system of the
Loire, the Garonne, and several other water-courses. The Loire—a river
which is the despair of engineers, and still more of boatmen—is distin-
guished above all the streams in France by the inconstancy of its current,
and the continual shifting of its navigable channels. There is a very great
difference between the mass of water which a river rolls down in ﬂood-
time, and the slender rivulets which slowly maketheir way through the
. sand in the dry season. N ow, as a lateral shifting of the current takes
place at the time of every ﬂuctuation in the level, the result is that sever-
al temporary channels are formed, and obliterated in turn. Some mo-uil-
les, or comparatively deep holes, ‘are certainly to be met with almost con-
stantly at the concave extremity of the bends, where the partial currents
unite; but every where else the bed rises more or less over its whole ex-
tent, so as to form ridges (rdcles), and navigation becomesimpossible dur-
314 ' THE EARTH .


Fig. 119. Channel of Vicksburg.
ing a great part of the year. This fatal interruption to commerce, repre-
senting an annual loss of many thousands of pounds, would not take place
if it‘ was decided to adopt the system of “ guiding banks” proposed by M.
Edmond Laporte,* and subsequently by M." de Vézian. Instead of recti-
linear rows of piles constructed across the bed of the river, embankments
should be raised formed with'a parabolic curve, against which the princi-
pal current might strike at all seasons, so as to describe unhindered its.
regular. series'of serpentine'curves ; this is the only'plan'for insuring the
greatest possible depth to‘ the channel for navigation. The annexed plate,
borrowed from de Vézian’s work,f points out the position which the em- -
* Girona'e, September. 1864. _ ' - 'IAnnales duGe'nie Civil, May, 1863.
NAVIGATION CHANNELS. 315
bankments' ought to occupy, and the direction that they would communi-
cate to the current of the river. '


Fig. 120. Diagram to ShOW “Guiding Banks.” ‘
Even if the mass of water were to remain the same from year to year
and from century to century, it is certain that the mere action of the cur-
rent, striking each bank in turn, would in the long run be sufficient to alter
the curves'of the river, and gradually to remodel the ground in the valley.
But the liquid mass of every stream is incessantly varying from the com-
mencement of spring until the end of winter. It increases during the
rainy season and when the snow melts; ittdiminishes, on the contrary,
when the supply from the clouds, the snow, and the glaciers is not equiv-
alent to the water which is absorbed by the innumerable rootlets of the
vegetation by the river-side, and by the continual evaporation caused by
wind and heat. Under the inﬂuence of these various phenomena which
either increase or abate, the level of every river constantly ﬂuctuates be-
tween ﬂood and low-water. The current of the stream is consequently
shifted, ﬁrst to one side and then to the other, and thus every day con~
tributes'in a diﬁ'erent way to the erosion or consolidation of each of its
banks. The quantity discharged by the river during ﬂood-times being
ﬁve, ten, ﬁfty, or even a hundred times as much as at low-water seasons,
it is hardly to be wondered at that the erosion accomplished by the cur-
' rent should also vary in very considerable proportions.
By dint of manipulating the small particles which it has itself been the
means of conveying to the alluvial plains, the river ultimately succeeds in
completely altering the direction of its own tributaries. The short prom~
ontories which are situated at the conﬂuence of the principal river and the
streams which run into it are constantly lengthened in a down-stream di-
rection ‘by all the sandy or muddy debris which is deposited by the two
currents. The two masses of water, which are ultimately to encounter
one another, tend to take a direction more and more parallel on each side
of this increasing promontory, and, developing their windings on both sides
_ of their axis of descent, thus make their way side by side through the plains.
A magniﬁcent example of this inﬂection of river-beds may be noticed in
the valley of the Rhine between Basle'and ‘Mayence. All the aﬁluents
that the Vosges and Black Forest send down to‘ the great river bend to
the north as soon as'they have emerged from their natal'valley, and wind
through the plain, tending in the same direction as the current of the
316 THE EARTH.
Rhine. Above and below this wide plain of alluvium, in which nature
has aiforded no obstacle to the'free passage of the water, the'lateral rivers
do not double round in this way before they join the Rhine. Being kept


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back by the mountains or hills which command them, they fall directly into
the‘ litter. nearly at a right angle to it. '
FL UO T UA TI ONS IN RIVER LE WLS. 3 ]_ 7
CHAPTER L.
PERIODICAL RISING 0F sTREAMs—“EMBARRAs ” OF FLOATING TREEs—IcE-
FLOODS IN THE NORTHERN RIVERS.—INUNDATIONS.
A LARGE supply of rain-water being the principal cause of the swelling
of rivers, the rainy seasons must necessarily be the times when ﬂoods are
generally produced. In tropical regions, where the zones of clouds and
showers shift regularly from north to south and from south to north dur-
ing the course of the year, the ﬂuctuations in river-levels can be calcu-
lated and predicted beforehand, ust as the seasons themselves, according
to the passage of the sun over the ecliptic.* When the luminary shines
above the northern hemisphere,_and dry seasons prevail on the north of
the equator, the water-courses in the northern tropical zone become low,
and many are completely dried up. During the winter season, on the
contrary, when the sun has brought back to the north the rain-clouds and
tempests, then the rivulets, streams, and rivers again swell and ﬂow brim-
ful of water. The same phenomena take place in a contrary'order in the
southern hemisphere. Thus the level of running waters on the north
and on the south of the equator ﬂuctuates in turn, so as to form a kind
of annual tide, which in its regularity may be compared to thedaily tides
of the ocean. We must, however, add that in all tropical regions the
periodicity of the annual ﬂoods is variously modiﬁed both by the relief
of the ground and also by aerial eddies and other phenomena which have
an inﬂuence‘ on the falls of rain.
Among all the rivers of the intertropical zone, the ﬂoods of the Nile
have obtained the most world-wide celebrity. Herodotus and other his-
torians of Greek antiquity have told, with a sort of religious astonish-
ment, of this periodical swelling of the sacred river which conveys to
Lower Egypt the soil which nourishes it. To the agriculturists by the
river-side this beneﬁcent ﬂood seemed like a miracle, and their priests
never failed to take advantage of it, so as to increase their power among
the people. So long as the valleys of the Upper Nile and its tributaries
were unknown, it was really diﬂicult, when surveying the annual inunda-
tions of the river, not to consider it as a prodigy. The course of the
Lower Nile is not fed by a single tributary; it traverses an arid country
rarely watered by the rain of heaven; a burning sun evaporates "itlsiwa-
ter, and yet, all of a sudden, about the beginning of July, the river-level
rises, without any apparent cause, in its wide isle-studded bed. The wa-
ter rises, and goes on rising, and from August to October it covers the
sand-banks, ﬂows over its brink, and, inundating the banks, pours itself
* Vide the chapter on “ Clouds and Rain.”
318 ; V THE EARTH
out in strata no less regular than the annual rings in the trunks of trees.
At the very highest ﬂood the river often contains a mass of water twenty
times* as great as that which it conveys to the sea when at its very low-
est, and yet perhaps the Egyptian sky has not for several months yield-
ed a single drop of rain. This prodigy, incomprehensible enough to our
ancestors, may nowadays be easily explained. The enormous mass of
water, which serves to irrigate the cultivated districts of the delta, pro-
ceeds from‘ the snow and rain which the clouds so abundantly shed on
the mountains of Ethiopia and on the other countries of equatorial Africa.
There are many water-courses in ‘the intertriopical zone which afford
the phenomenon of periodical ﬂoodswith as much, regularity as those of
the Nile; but there are none which are more curious in this respect than
the great river of the Amazon basin; This “Father of .Waters” ﬂows
nearly under vthe equator, and receives simultaneously the aﬂiuents of
two hemispheres. Owing to this arrangement of its river system, the
ﬂoods of the northern rivers take place in summer and autumn, while
the southern tributaries overﬂow‘ during the winter. . The principal river
and the Madeira are mostly swelled by, the equinoctial rains,‘ and their
ﬂoods take place inspring and summer. An actual system of compen-
sation is thus establishedinthe lower bed of the'Amazon'between the
tributaries ﬂowing in on the right bank andthose .on the left. When
the Pastaza, the J apu-ra, and the Rio Negro are at low water, the Ucay-
ali, the Madeira, and the Tapajoz are running brimful; when the latter
begin to get low, the northern aﬂiuents increase their mass of water.
Jan. March. -.April. ‘May. June. July. Aug. Sept. Oct. Nov. Dec.

Tapajoz.
-._ Madeira.
'- Japura.
' ‘- Rio Negro.
‘ . Amazon.
‘= Rio Branco.


Fig. 122. Compensation of Floods in the Basin of the Amazon.
Beyond the tropical zone, rivers must necessarily manifest less regu-
larity in their annual ﬂoods, the rains'themselves being more irregularly
distributed among the various seasons. Nevertheless, an unquestionable
systemof order never fails to show itself each year in the fall of atmos-
pheric moisture, and this system is again met with inthe corresponding
ﬂuctuationrof the‘ river-levels. ; This is a fact which may be proved by
the study of various water-courses. - In regions like the north of France,
which are favored with rains in‘ winter, spring, and summer, the ﬂoods
* Elia Lombardini,'Essai sur l’Hydrologie c’a Nil.
5
PERIODICAL FL 0 ODS. 3 l 9
.generally take place between the 15th of October and the 15th of May,
and it is only due to the rapid evaporation which takes effect during the
hot weather that summer ﬂoods are so very rare.* In the Mediterranean
districts, where autumn rains predominate, the water-courses begin to
swell toward the end of the year. In those river-basins which, from the
vastness of their area, extend into several meteorological regions, the
ﬂuctuations of level, which succeed one another with more or less regu-
larity in each of the diﬂ'erent aﬂluents, are combined so as to form a
fresh series of ﬂoods as regards the principal artery, and the general
course of these ﬂoods may be easily foreseen. The most striking exam-
ple which can be mentioned is that of the Mississippi, a river which unites
in its vast bed the water coming from the great Western deserts and the
streams which ﬂow down the pleasant valleys of the Alleghanies. At
New Orleans the river commences to rise about the 1st of December,
and its mass of water increases until about the middle of January, which
is the time of the ﬁrst ﬂood. Then the level slowly sinks, and afterward
remains nearly stationary during the months of February and March. In
April and May the river swells afresh,‘ and in the course of the month of
June it forms the great ﬂood so dreaded by the planters. Immediately
after it sinks rapidly until the end of September, and its lowest level
coincides very generally with the commencement of November.
Several water-courses in the temperate zone exhibit, in the ﬂuctuations
of their level, a phenomenon of compensation similar to that of the Ama-
zon. These are rivers which are replenished simultaneously by streams
fed by rain-water, and also by torrents increased by the melting of snow
and glaciers. The variations of lowland streams being, as regards the
seasons, precisely contrary to the variations to which mountain tributa-
ries are subject, the level of the main river remains at a nearly regular
height. The rain-water tributaries diminish in bulk at the very time
when the aﬂluents, which have come down from the glaciers, are increas-
ing—that is to say, in summer; in winter and spring, on the contrary,
the glaciers supply very little water, while the plains are inundated with
rain, and their streams are ﬁlled to the brink. Thus the abundance of
one aﬂiuent balances the poverty of another. As an instance of this, the
Rhone and the, Saone have often been brought forward. During the
heat of summer the latter brings down only one ﬁfth of its winter dis-
charge. On the other hand, the Upper Rhone rises much higher during
the same season; but below its junction with the Saone the average
height of its water is nearly the same during every season of the year.
A compensation of a similar kind likewise takes place between streams
of surface-water and those which are fed by springs. The rivulets which
traverse the subterranean passages of rocks can not descend into the
plain so rapidly as the water-courses which ﬂow on the surface of the
ground.
The grandeur of the geological operations accomplished by ﬂood-wa'
* Belgrand.
320 THE EARTH
ters are best to be appreciated on the banks of rivers which have been
placed by the labor of man in a state of defense against the watery ene-
my. When the River Amazon overﬂows, it forms in some places, with
the marshes on its banks, a perfect sea of 100 or even 200 miles in width.
The animals seek a refuge in the tree-tops, and the Indians who live by
the sides of the river make a kind of encampment on rafts. About the
8th of July, when the river begins to sink, the water, returning to its
original bed, undermines the thoroughly soaked banks and slowly washes
them away. A sudden fall then takes place, and masses of earth, amount-
ing to.hundreds or thousands of cubic yards in bulk, sink down into the
water, carrying with them the trees and animals existing upon them.
The very islands are exposed to sudden destruction: when the entangled
masses of fallen trees, which serve as a breakwater to them, give way be-
fore the violence of the current, a few hours, or even a few minutes, are
quite suiﬁcient for their disappearance; they are literally washed away
by the ﬂood. They may be observed visibly melting away; and the In-
dians, who are quietly at work upon them collecting turtle-eggs or dry-
ing the produce of their ﬁsheries, are suddenly compelled to ﬂy for their
lives. Then it is that the current of the stream is encumbered with long
ﬂoating piles of entangled trees, which hitch together only to break away
again, and, accumulating round some headland, are heaped up one above
another all along the banks. All round these immense trains of trees,
which roll and plunge heavily under the impetus of the current like
great marine monsters or drifting wrecks, great masses of the plant Cem-
na Tana ﬂoat on the surface of the water, giving to some parts of it a
resemblance to broad meadows.* We may thus readily comprehend the
almost religious awe which has been experienced by travelers who have
made their way up the river of the Amazons, and viewing these whirl-
pools yellow with sand, have been eye-witnesses of their destructive
operations in tearing away the river-banks, throwing down trees, wash-
ing away islands in one place to form them again in another, and drifting
down the current long trains of trunks and branches. “The great river
was terrible to look on,” says Herndon, the American traveler, “as it
rolled through the solitudes with a solemn and majestic air. Its waters
seemed to wear a wrathful, malevolent, and pitiless aspect. The entire
landscape had the effect of stirring up in the mind a feeling of horror and
dread similar to that produced by the imposing solemnities of a funeral
at sea, by the minute-gun ﬁring at intervals, the howling of the tempest,
and the wild uproar of the waves, when the crew assemble on the deck
to bury their dead in the bosom of a troubled sea.”
The Mississippi presents a remarkable instance of a great water-course
which man has recently annexed to his domain, and has succeeded in
modifying considerably, as regards its geological action, during the course
of a few years. In 1782, and even at the time of the great inundation of
1828, the whole of the region embraced between the left bank of the Mis-
* Ave Lallemant, Reise in Nord-Brasilien.
ICE FLOODS. 321
sissippi and the course of the Yazoo—that is, an area of more than 30
miles in width on the average—was completely covered with water, as is
proved by the bones of wild animals which have subsequently been found
on the artiﬁcial mounds raised by the red-skin Indians. At the present
day the river is conﬁned on both sides by lateral embankments, and no
longer ﬂoods the whole basin of the Yazoo. Now it only tears away
narrow strips of the vast forests by the river-side; and even in the very
highest ﬂoods, the masses of trees which drift down the current do not
form, as before, long ﬂoating trains.
Even at the beginning of the present century, these ﬂoating trains, or
embarras, rendered the navigation almost impossible in some reaches of
the Mississippi and its tributaries. A great portion of the courses of the
Atchafalaya and the Ouachita were completely choked up by heaps of
trees. In many places a person might cross them without any idea that
he was going over a river. Bushes and even large trees grew upon some
of these ﬂoating masses.* One of these entanglements of drift-wood,
known by the Americans under the name of the “ Great Raft,” always ob-
structs the bed of the Red River. This immense agglomeration of trees,
under which the water disappears in a mass as if under a movable arch,
gradually gets higher up the course of the river as the trees at the lower
end break away, and the annual ﬂoods bring down fresh drift-wood to
the upper extremity. The obstruction was probably ﬁrst formed at the
conﬂuence of the Red River and the Mississippi, and has since gradually
advanced 391 miles from the mouth, gaining a mile or two every year.
In 1833 the Federal Government undertook some importantyoperations
for the removal of the obstruction, which had then attained a length of
124 miles; but while a ﬂotilla of boats was occupied in pulling out the
trees which formed the lower extremity of the “ raft,” the upper end was
constantly increasing by means of the fresh drift. In 1855, after twenty-
two years devoted to this “labor of Sisyphus,” the question was raised
whether it was not better worth while to abandon this ungrateful labor,
and to apply the funds at disposal to the improvement of the bag/ous,
or lateral channels. “The Great Raft,” being thus abandoned in the
marshes, which formed the old bed of the river, will he gradually con-
verted into a great peat-bed, destined perhaps to become coal at some
future geological period, unless human ingenuity should otherwise dis-
pose of it.
In cold countries, such as British America, Russia, or Siberia, the wa-
ter-courses carry down to the sea a far less quantity of vegetable debris
than the rivers in tropical countries; but, to make up for it, they are
loaded with enormous blocks of ice at the time of thaw, a period which
often coincides with the highest ﬂoods. It is a wonderful sight, especial-
ly in rivers adorned with cataracts like the Niagara, when the rocks of
ice, dashing against one another, and breaking up in the midst of the
watery columns, give one the idea of a cataclysm, in which lakes and
* Lyell, Second Visit to the United States.
X
322 THE EARTH
continent were all being simultaneously swallowed up in the abyss. The
icy sheet which extends over the surface is shattered with a sharp, grind-
ing noise, and the broken fragments are caught by the current, and
dashed violently against each other; their sharp angles are broken off in
the collisions, and they are whirled round and round in long eddies. In
the curves of the headlands, at the points of the islands and sand-banks,
and also in those portions of the river where the icy barrier still remains
ﬁrm, the broken masses gradaally accumulate, and, mounting up one
upon another, owing to the force of their impetus, butt against the banks
like battei'ingrams, and thus often clear away an outlet into the plains
for the ﬂood-water. Sometimes they rear themselves up like dams, and
drive back the body of the river up-stream again. For this reason, dikes,
embankments, and other hydraulic ramparts, built along the course of a
river subject to these annual breakings-up of the ice, must be construct-
' ed with the utmost solidity. Among other constructions of this kind,
we may mention the enormous buttresses with which the piles are fur-
nished to support the bridge of Montreal on the St. Lawrence, and the
defensive ice-breakers built in the Vistula on the upstream side of each
pier of the bridge of Dirschau. At St. Petersburg the granite quays
and the ediﬁces they protect would be all carried away by the ice-ﬂood,
if at the same time violent tempests from the west were to drive the
waves of the gulf into the mouth of the Neva.
In temperate Europe the breaking up of the river-ice is attended by
little or no danger; but the mere inundations are very much dreaded on
account of the towns, villages, and richly-cultivated districts with which
the banks are covered. The inhabitants on the edges of the Loire still
recall to mind with horror the disasters which have been caused by the
great though exceptional ﬂoods which in one year only (1856) carried
away roads and defensive embankments, causing damage to a most enor-
mous amount. In the same year the calamity was but little less disas-
trous in the valley of the Rhone, which was covered in some places, es-
pecially the Camargue, by an inundation almost like one of the ﬂoods of
the Amazon. The inhabitants of the banks of the rivers are now worse
off ‘in this respect than their ancestors. The extraordinary rains caused
by atmospheric changes are not all they have to dread. They have now to
look for greater irregularity in the action of the streams and still more sud-
den inundations, in consequence of so many of the marshes and pools being
drained dry, and the mountain slopes being cleared of wood by the axe of
the woodman, or laid bare by the feeding of the goats. They also have to
fear the immediate effects of the drainage channels which pour down the
rain-water so rapidly into the streams. Lastly, the surface-water is every
year precipitated into the plains more and more suddenly on account of
the increasing number of ‘ditches, which are carefully kept up along the
roads and paths, into which the boundary trenches of the various proper-
ties all empty?“ On the other hand, the extension of cultivation on the
* Becquerel, Comptes Readus de Z’Académie des Sciences. November, 1866.
INUNDA 17027.8. 393


.A‘
Fig.128. Limits of the Inumlation of the Rhone in 1840.
edge of a river, without the application of drainage, enables the earth to
absorb the water to a lower depth in the soil, and thus diminishes the
height of the ﬂoods. This fact is proved by the example of the Lake of
Aragua, in Venezuela. At the commencement of the century, when the
greater part of the neighboring plains were under cultivation, the level
of its water was comparatively low; but during the War of Independence
it gradually rose, owing to the devastation of the country by the con-
tending armies, and the consequent return of the plains to their original
condition of virgin forest. Latterly, fresh clearings have for the second
time sunk the water of the lake. I _ '
Under the action of all the causes whichsovariously inﬂuence the ‘ﬂu-
viatilc economy, some rivers, such as the Oder, since 1778, and the Elbe,
since 1828, have diminished in volume, although it is certain, from, the
meteorological registers, that the amount of rain falling into their basins
has not lessened. Other rivers, as the Rhone and the Loire, do not ap-
pearto have at all decreased in the quantity of their water; but, on the
other hand, their inundations aremuch more dangerous, than formerly.
The Seine, which, according to the testimony of the Emperor Julian,
poured through Paris, some ﬁfteen hundred years ago, nearly the'same
quantity of water in every season of the year, shows, at the present time,
a difference of about 33 feet between the high and low water levels.
Some rivers, indeed, such as the Garonne, appear to have been more for-
midable in days gone by than they now are. The highest inundation of
the Garonne which is on record is that of April, 1770. At Oastets, the
point at which the tide stops, the ﬂood-level attained a height of 42% feet
above the low-water mark. This is 6% feet more than in the largest ﬂoods
of the present century.*
"‘ Raulin, Geographic Girondine.
304 n-l
THE EARTH.
However this may be, some of these inundations assume such propor-
tions that they become perfect cataclysms for all the river-side districts.
The example of three little streams, the Doux, the Erieux, and the Ar-
deche, all three conﬁned to the limits of a single department, may give
an idea of the rapid swellings of these high ﬂoods. On the 10th of
September, 1857, the three water-courses, which usually ﬂow peaceably
enough over their rocky and pebbly beds, poured down into the Rhone
a combined mass of more than 18,000 cubic yards of water, instead of
the 20 to 25 yards which was their ordinary discharge in the same time.
This ﬂood was equivalent to the body of water which the Euphrates
and Ganges together pour‘ into the sea. Spreading over their respect-
ive valleys to a height of 50 to 60 feet above their low-water mark,
the ﬂooded rivers overthrew the houses, washed away the cultivated
ground, and uprooted the trees. So many thousand trunks of trees were
carried away in one day that, below the Erieux and the Doux, the whole
surface of the Rhone seemed nothing but a train of drift-wood, over
which, as it appeared, a bold man might well have ventured to cross the
river. Still, even these inundations have been exceeded, for, on the 9th
of October, 1837, the Ardeche rose, at the bridge of Gournier, to a height
of 70 feet above low-water mark, at least 10 feet higher than in 1857*
Above the Iron Gates some of the ﬂoods of the Danube have caused the
river to swell to a height of more than 60 feet above low-water mark.
It is a fortunate thing that, in most river-basins, it is very seldom the
case that the ﬂoods of the various afﬂuents exactly coincide, and that all
the tributaries are seen to swell at the same time. In fact, whenever a
rain-cloud passes through a valley, it discharges its moisture sometimes on
one side and sometimes on the other, and the various water-courses which
it swells overﬂow in turn after the rain-cloud has passed over. Thus, in
the valley of the Rhone, when the damp winds encounter the Cevennes,
the slopes of the Alps which are turned toward the river are sheltered
from the storm, and it is only gradually that the series of showers makes
its way from the Cevennes toward the mountains of Annonay. If all the
tributaries of the Rhone were to swell at one time, it would roll down a
most‘ formidabe mass of water, amounting to more than 130,000 cubic
yards a second. It would be another Amazon. Even when the Rhone
discharges into the sea only 16,000 to 20,000 yards a second, the havoc
which it makes upon its banks is most frightful.
* Marchegay, Annales des Ponts et Clzaussées, vol. i., p. 861.
.IIEANS OF PREVENTING FLOODS.
03
[O
O 1
CHAPTER LI.
MEANS OF PREVENTING FLOODS.—-NATURAL AND ARTIFICIAL RESERVOIRS.—
IRRIGATION CHANNELS—EMBANKMENTS, AND CRACKS IN THEM.
Iris evident that it would not do for man to remain constantly under
the apprehension of these inundations, and that it was necessary to ﬁnd
some means of preventing them. For hundreds and thousands of years,
and especially during this century of industrial activity, plenty of plans
of protection against river-ﬂoods have been both projected and put into
execution ; but too often these works have remained useless, or have even
produced entirely contrary effects to those which were expected by the
engineers and the inhabitants. The fact is, that in going to work they
did not always pay suﬂicient attention to the laws of hydrology. If man
wishes to become master of the forces of nature, and to make them work
to his advantage, the ﬁrst condition is, that he shall thoroughly under-
stand them. .
It must be remarked, in the ﬁrst place, that the mass of surplus water
forming a ﬂood is not actuated with the same speed over all its width.
The nearer the liquid particles are to the bank, the slower they move.
This phenomenon, caused by the friction of the ﬂuid against its banks
and the bottom of its bed, may, it is true, be observed to some extent at
low-water seasons as well; but it is when the level of the river is at the
highest that the various portions of the liquid mass present the greatest
differences in speed. The thread of the current, the mathematical line of
the greatest rapidity, which varies every day and in every stream, ac-
cording to the quantity of water and the section of its bed, exceeds by
about a ﬁfth the average speed of the river.* In ﬂood-times this line
gradually rises above the bottom, and by thus ascending toward the sur-
face of the river, so as to keep—according to the direction or forces of
thewind—sometimes on the surface of the river, sometimes a few feet be-
low, it leaves the solid walls which constitute the sides of the river, and
the medial part of the water, of which it is the ideal axis, and moves con-
sequently with greater facility. In great rivers, such as the Amazon, the
Mississippi, or the Rhone, the current sometimes descends with the speed
of seven or eight miles an hour. While the central part of the current
thus hastens down toward the sea, the water at the side, kept back by
the irregularity of the bed, remains behind, and ﬂows more slowly along
the banks. Thanks to this difference in speed, which increases accord-
ing to the height of the river, ﬂoods are sometimes lessened or even en-
tirely prevented. In fact, when mighty masses of water, descending ei-
* According to M. de Prony, it is 01835.
326 THE’ EARTH.
ther from the clouds or the mountains, fall simultaneously into the basin
of a stream, these liquid avalanches would certainly produce formidable
inundations if they were not immediately carried away by the centre of
the current, and did not distribute in succession a portion of their bulk
over all the points that they traverse. Forming, so to speak, a river in
the middle of a river, this rapid ﬂow weakens the ﬂood by dividing ‘it
over a vast length of' bank. In the river of the Ohio the mid-ﬂow has .
rolled ‘down for a distance of ﬁve miles,when, at a spot two miles and a
half from the very place where the rain fell, the high banks are scarcely
touched'by the rising water.
In consequence of the speed communicated to the mid-ﬂow of the ﬂood,
the liquid mass that it carries along is perceptibly higher than the mean
level of the river. ‘ It forms a kind of convexity, from the top of which
the water spreads out in'light sheets toward the two banks; but, on the
other hand, when the ﬂood-wave has disappeared, the middle of the river
exhibits a considerable depression, and the water which has'gradually ac-
cumulated near the two, edges has to ﬂow back toward the centre of the
current, so as to re-establish by degrees the ﬁuviatile level. It has been
.2 ' , /,
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Fig. 124. Growth by Floods. _ Fig. 125. Subsidences of the Waters. ,


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ascertained that on the Mississippi the central convexity of the ﬂood-wave
is on the average about three feet. When the river sinks, almost as con.-
siderable alteration of the level takes place in a contrary direction. The
wood-cutters of Maine and Canada are ‘not ignorant of this hydrological
fact. They are well aware that logs of timber thrown into the river in
ﬂood-time are thrown up on the banks, while they ﬂoat regularly down
the middle of the current when the river-level sinks.* .
The depression which is formed in the middle of the river during the
period of subsidence is, however, obliterated as soon as the liquid mass
ceases to diminish; the water then commences to bulge up again in_the
axis of the current, owing to the greater facility of movement possessed
by it in that part; The surface of" those great Russian rivers’which are
covered with ice for several months of the. year exhibits a remarkable in-
stance of the bulging up of the liquid mass in the central line of the cur-
rent. At the conclusion of .the .Winter, when the water from the melting
snow runs down oﬁ~ the banks towardthe bed of the river, and the sheet
of ice stretched over the river ‘is 'not'yet broken, it is' ascertained that the
surface-water collects in elongated pools on those portions of theﬁeld of
ice which are nearest to the edgesnvhilethe medial part'bulges up in an
arch“, above the current, and remains constantly dry. On the Volga, the
* Marsh, May, and N ature.
RESULTS OF FLOODS. . 327
difference of the level between the edges and the middle of the ice
amounts sometimes to more than three feet.*
The current is not the only regulating force which weakens the action
of ﬂoods, and gives more certainty to the height of the water. There are
other agents which assist in equalizing the discharge of a river by receiv-
ing the overﬂow during the rainy seasons, and afterward emptying it
into the principal current. These regulating agents are the surface or un-
der-ground reservoirs which exist on each side of water-courses which are
still left in a state of nature. Thus, according to Humboldt, the Upper
Maranon pours into the caverns of the pongo 'of Manseriche a portion of
its waters, and also all the drift-wood which it brings down from the
higher valleys. Many streams lose a considerable quantity of water by
the mere process of ﬁltration, through the spongy soil of their valleys.
It is stated that in some places the water of the Nile penetrates laterally
as far as ﬁfty miles from the bed of the river/r In like manner, during
ﬂoods, the Seine feeds the land-springs which extend under Paris, and all
the wells are then ﬁlled by the water of the river._’[ '
Next to lakes, which are the chief regulators of running waters,§ the
marshes lying close to the edges of a river take the principal share in
modifying its discharge. During inundations the lagoon andswamps on
both sidestemporarily store up a large quantity of ﬂood-water, which ‘is
only set free after the sinking of the river. The marshy regions through
which the Mississippi runs in its middle course affords a remarkable in-
stance of this fact. Thus, in 1858, the great American river, which be-
low the mouth of the Ohio sent down 52,039 cubic yards of water, only
discharged 45,915 yards at Baton Rouge, after it had received the con-
tents of the Arkansas, the Yazoo, and other less important rivers. A
mass of water, amounting to 6124 cubic yards a second—equivalent to
nineteen times the bulk of the Seine—must, therefore, have been lost on
the way." Just in the same way, the Rhone, in its great inundations,
makes its way over the side embankments opposite Ouloz, and, covering
the whole of the vast marsh of the Ohautagna, pours its surplus waters
into the Lake of Bourget. It has been calculated that during the ﬂood
of 1863 this reservoir absorbed from the Rhone a mass which altogether
amounted to 71,900,000 cubic yards of water, the effects of which would
have been most disastrous on the plains belowﬁl '
In places where the marshes beside a river have been drained by the
operations of man, the water-level of the stream rises to a much more con-
siderable height in ﬂood-time, and the plains around are. inundated. . But
the inundations themselves become new regulators. of the discharge of the
, water, and that, indeed, by means of their very irregularity. The liquid-
* De Baer, Bulletin de Z'Académie de St. Pétersbourg, vol. vii., No. 4.
'l' Marsh, Man and Nature. ' . _
I Delesse, Carte Hydrologz'que. § Vide the chapter on “ Lakes.”
ll Humphreys and Abbot, Report on the Illississippi River.
1]’ Gobin, Commission Hydrome'trique de Lyon, 1862.
328 . THE EARTH '
sheet which covers the ﬁelds is hindered in its ﬂow by the inequalities of
the ground and by clumps of trees. Being unable to follow the river in
its impetuous course, it remains behind, like a temporary lake, until the
river is low enough for it to return into its natural bed. Thus the ﬂow
of an inundation always decreases in height as it gets nearer to the sea,
and ultimately it completely disappears. The inundation of the Nile
diminishes as it ﬂows on from Assouan, where it is from 53 to 56 feet in
height, to Rosetta and Damietta, where it is not more than three feet in
height. A similar decrease in the ﬂood-wave may be observed on all
other rivers. We must not, however, lose sight of the fact that this
gradual waste of the water proceeds partly from several other causes,
such as the porous nature of the ground bathed by the river, the activity
of the vegetation growing by its side, and the amount of evaporation.
This. last cause of the exhaustion of the water is probably the most im-
portant in all hot countries like Egypt and Guinea.
It should be man’s part to complete the work of Nature by imitating in
his operations some of those means which she employs for storing up sur-
plus waters, and afterward distributing them equally over vast areas, thus
insuring a regular-discharge. Man should make it his task to watch the
drop of rain as it falls from the sky, to follow it in its course, to arrest it
in its progress when it would help to swell a dreaded ﬂood, and to em-
ploy it for the beneﬁt of agriculture, navigation, and manufactures. On
every mountain-side and elevated plateau he may avail himself of a pow-
erful remedy for the prevention of ﬂoods, by replanting them with trees;
for, as M. Becquerel’s experiments have proved, the quantity of water
which drops during heavy rain on wooded ground is only six tenths of
thatwhich falls on the bare soil.*. In a great number of the upper val-
leys reservoirs might be constructed, where the liquid mass would accu-
mulate in times of rain, and be subsequently emptied over the slopes in
innumerable irrigating conduits. On cultivated declivities, as Provence
and the Maritime Alps, man should enlarge and consolidate the ﬂat stages
which rise one above another along the mountain-sides, forming, as it
were, so' many staircases, each. step of which should keep back its share
of rain-water. In the valleys he should tap the river in order to feed ir-
rigationditches and mill streams. Finally, in the lowland plains, it would
be easy to line each side of the river with reservoirs, where the stream
might deposit the sediment .with which it is charged.
The streams, on the sides of which water-mills and manufactories have
been established, are, as it were, disciplined by means of the waste water
channels and the reservoirs where the water is stored up, and especially
through the mill-dams and other obstacles which convert the river or
stream into a regular canal, with its dammed-up levels. Inundations are,
therefore, very rare, or even quite unknown, in a great number of the
manufacturing valleys of England, Scotland, and the United States.
Still,the gratuitous‘ power afforded by water is not by any means gener-
* Comptes Rendus de Z’Académie des Sciences, November 5, 1866.
ad
‘LAKE .iuEEIs. 399
ally utilized at present; and even the inhabitants of manufacturing coun~
tries allow avery considerable quantity of available water-power to run
away to waste. Thus—to select an instance among the French streams
which turn the greatest number of mill-wheels—the Doubs itself, ﬂowing
through the manufacturing districts par excellence, scarcely does one quar-
ter of the work which might be obtained from it. From Vougeaucourt
to Besancon, a distance of 43 miles, the total fall being 248 feet, only
900,000 horse-power was utilized in 1860, out of the total amount of
3,400,000 horse-power which might have been employed.
Although manufacturing operations can only assist exceptionally in
moderatingand gradually doing away with ﬂoods, the agriculturalproc:
esses which are going on in. all the valleys inhabited by man ought to
exercise a direct and decisive inﬂuence in regulating the ﬂow of streams
and rivulets. The husbandman ought not to allow the waste of a single
drop of the beneﬁcent water, which, by a widely-extended system of irri-
gation, might double, or even increase tenfold, his crops, and convert a
wilderness into a garden. In the intelligent employment of running wa-
ter in the fertilization of a district, our agriculturists have much to learn
from the example of the ancients. As far back as the time of the early
Egyptians, works of irrigation of really colossal dimensions had been ac-
complished; and perhaps, among all the undertakings of this kind due to
modern industry, there is not one which, in boldness of plan or practical
utility, can be said to surpass the meri (basin), or Lake Mteris, which was
opened to the waters of the Nile in the reign of Pharaoh Amenemha 111.,
more than 4500 years ago, according to the chronology of M. Brugsch.
From the topographical details which have been left by ancient authors
as to this wonder of the world, we know that the site of Lake Mceris must
be looked for in the present province of Fayoum, the name of which is de-
rived from the Coptic, and signiﬁes sea. Now, a considerable lake exists
at the present time—the Birket el Keyroun—in the lowest part of the
province; and so long as the geography of this part of Egypt was but
partially known, it was very natural to look upon this lake as the ancient
excavation of the Pharaohs. A study of the localities has proved that
this is not the case. In fact, the Birket el Keyroun is situated in a deep
depression, nearly on the level with the sea, and 53 feet below the aver-
age waters of the Nile. This basin, therefore, can not be the one which
alternately received the surplus ﬂood-water of the river and emptiedit
out again through two wide gates, as Strabo tells us, into the plains by
the side of the Nile. Besides, the position of this lake differs much from
that which theancient geographers assigned to the Meeris.‘ According
to the discoveries of M. Linant dc Bellefonds, the engineer, the site of the
great reservoir was just in the very highest part of Fayoum, to the west
of the rocky gorge of Illaoun,through which ﬂows a natural side-chan-
nel of the Bahr Yousef, which probably, at some former geological period,
was the principal current of the Nile. , Fragments of a long dike, which
in some places is not less than 30 feet high and 200 feet wide, may still be
330 THE EARTH.
met with in the eastern part of Fayoum. It must once have constituted
a semi-circular rampart, spreading round the outlet of the great basin
of the Fayoum plains, and have penned back the water brought by the
Bahr Yousef. ,
M. Linant has calculated that, during the hundred days of ﬂood, this
branch of the river, which represents on an average about the twenty-
eighth part of the Nile, emptied into the basin a quantity of water equal
to 466 cubic yards a second, and that the total mass of water contained
in this gigantic reservoir, even after making allowance for evaporation,
could not have been less than 3,694,000,000 cubic yards. This was suf-
ﬁeient to diminish very considerably the dangers resulting from the in-
undations of the Nile, and subsequently to afford all the water that was


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requisite for the irrigation of 444,000 acres. According to the statement
of Herodotus, the surplus waters spread out to the ‘west toward the
Syrtes of Libya; that is to ‘say, after crossing the lake, which is called
Birket el Keyroun, it ﬁlled the bed of a channel now dried up, which car-
ried the waters of the Nile into the western deserts. At the present day,
Fayoum still possesses a magniﬁcent system of irrigation, which may be
compared to the ramiﬁcations of the arteries and blood-vessels of a liv-
'ing being; but forty-ﬁve centuries ago, Lake Maaris, which constantly
changed its level according to the needs of agriculture, was like a heart
from which the ﬂow of life was shed' out to nourish the great body of
Egypt as far as distant Memphis. Nothing new remains of Moeris but
the broken-down dikes, a few fragments of the two pyramids which were
IRRIGA TI ON CHANNELS. 33 1
built up in its waters to the glory of Amenemha, and a thick layerofal-
luvium deposited on its basis by the troubled waters of the Bahr Youseffi‘
Among European rivers, the P0 is that which may be best compared
to the Nile of the ancients, as regards the care with which its waters
have been utilized for the fertilization of the soil. So far back as 1863,
the Lombard agriculturists required for the watering of their crops
59,000,000 of cubic yards of water a day, equal to 681 yards a second;
that is, a liquid mass equivalent to the average discharge of the Seine
during the same periodfr Since the above date, the great Oavour canal
has been opened—a perfect artiﬁcial river—which requires for itself alone
144 cubic yards of water a second. Starting from Ohivasso, below Turin,
this river, which is not less than 55 yards wide at its commencement, -
spreads its fertilizing water on both sides in the already fertile plains of

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Fig. 127. Section across Fayoum.
Lomellina; it receives, en route, numerous streams—the Elvo, the Sesia,
the Agogna, the Terdoppio—and at Turbigo empties into the .Tesino
all that remains of its liquid mass, after having irrigated more than
494,000 acres. Next to the great canal of the Ganges, in Hindostan, it
is the most important operation of this kind accomplished in modern
times. There can be no doubt that the Po, once so dreaded on account
of its sudden ﬂoods, will ultimately become, in conjunction with the other
water-courses of Lombardy, a scientiﬁcally arranged system of agricul-
tural canals. -
Agriculturists should not only employ the water of torrents and streams
for increasing their crops and nourishing the soil, but they should also
make use'of the sediment and debris of all kinds which are washed away
by the water from their up-stream banks. As an instance, let us take the
Durance, a French river, which has been thoroughly surveyed and studied
to ascertain, the plan for utilizing its water and mud for the irrigation
and manuring of the plains by the river-side. The eighteen channels
which are fed by this stream can draw from it as much as 90 cubic yards
a second ; so that at any time when the whole of this liquid mass is being
* Linant de Bellefonds, Mémoz're s-ur Ze Lac Harris.
1‘ Elia Lombardini,.Politecnico, January, 1863, quoted by Marsh.
332 THE EARTH.
tak'en‘away. at once, only 30 cubic yards remain .in the bed of the Du-
rance in low water seasons, or about a quarter of its regular discharge.
According to the observations of M. Hervé-Mangon, which lasted from
the 1st of November, 1859,to the 31st of October, 1860, the mass of mud
brought down‘by the stream during the whole year represents a quan-
tity of near 18,000,000 tons. Some idea may be formed of the enormous
bulk of the mud which is washed away every year by the Durance from
the upper portion of its basin, by picturingthis mass in the form of a cube
242 yards on each side; if spread out uniformly on the ground this allu-
vium would cover in a year more than 108,000 acres, with a layer an inch
thick, containing in a form of combination most suitable to the plants
more azote than 100,000 tons of guano, and more carbon than 121,000
acres of forests Unfortunately, as these canals are constructed with
a view to irrigation only, nine tenths of the mud is lost for manuring pur-
poses; and the farmers purchase, at the cost of many thousand pounds a
year, the very elements of fertilization which their stream washes down
'into the Mediterranean, although they might so easily avail themselves
of them. .
As every river possesses its own special peculiarities, the regulating
. works which the engineers have to undertake for the purpose of doing
away with ﬂoods and distributing the water discharge, must be contrived
in different ways, according to the form and capacity of the upper mount-
ain hollows, the rapidity of the current, the suddenness of the ﬂoods, the
porosity of the ground by the river-side, and the extent of the forests
which clothe the hill-sides. The operation of regulating the discharge
of a water-course is certainly very diﬂicult to accomplish; in some river-
basins it would require the labor of several generations; but suﬁice it to
say, it is not impossible, and that it has already been successfully carried
out in many parts of the globe. Although the‘, greater part of the rivers,
in both Europe and the civilized portion of America, have up to the pres—
ent time remained free from man’s guidance, and still occasionally devas-
tate the cities and cultivated districts which lie upon their edges, there
are at least a few of which the ﬂoods have been rendered harmless,
thanks to the labor of the frightened inhabitants. Among the rivers
which were once most dangerous, and are now almost entirely subdued,
we may mention the Arno, which has been looked after for centuries by
the skillful Tuscan engineers. At one time this river was most formida-
ble, on account of its periodical inundations. From the year 1400 to
1761,no less than thirty-one disasters of this kind are recorded. Since
1761—the' date when the improvements of the river were carried out~—
until 1835, there has not been a single serious ﬂood.* The P0 itself—the
river which in ﬂood-time hangs suspended, so to speak, over the surround-
ing plains—is now much less to be dreaded than heretofore, thanks to the
irrigating channels which tap it, and also to the lateral embankments
which border the whole of its lower course below Cremona‘r
* Marsh, Man and AVature. , i‘ Vide p. 335.
EMBANKJLENTS. 333
In this stream, as in a’ great many others, the surplus waters of the
high ﬂoods come down too rapidly, and in masses too considerable, to
afford any possibility of storing them up, or of turning them off in a
lateral direction without devastating the plains. It is necessary that the
inhabitants should protect themselves by well-planned constructions

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against the threatening pressure of the water. The Egyptians dwelling
in the Delta built their cities on artificial hillocks above the level of the
annual ﬂoods. The inhabitants of some parts of Holland, wishing to fa~
cilitate the “warping” of the ﬁelds, elevate their habitations above the
ground, and the houses become so many islands in the midst of the ﬂoods.
In recently colonized countries, where man’s ﬁrst care is to protect his
habitation, all he does at ﬁrst is to construct a circular embankment
3 THE EARTH.
round the town or village. This was the procedure of the F rench colo-
nists after they had planted the ﬁrst ‘pile-work of New Orleans. The
Americans, too, adopted this plan of protection for the Californian city,
Sacramento, and the warehouses at Cairo, situated at the conﬂuence of the
Ohio and the Mississippi. In like manner, the towns on the banks of the
Loire are protected against the ﬂood-wave by walls. Added to this,
when the banks of a water-course are covered by cultivated ﬁelds, and
the inundation would prove fatal to them—as in Louisiana, Lombardy,
China, and many other countries in the thmperate zone—it is necessary
to raise longitudinal dikes on the‘ edges of the streams which at ﬂood-
time are higher in their level than the surrounding plains. Thus shut in
between their dikes, rivers are compelled to give up their wandering
course, and to ﬂow down to the sea through the channel which has been
traced out for them. These longitudinal embankments, which, at any
rate, are no ornament to nature, are sometimes a matter of absolute ne-
cessity; but if the constructors wish to prevent their dikes being broken
through, and to avert the disasters which are the certain consequence of
cracks, they must calculate beforehand the force of the liquid mass with
which they will have to contend during extraordinary ﬂoods; and they
must build their ramparts of materials suﬂiciently solid to resist without
difficulty the lateral pressure of the water. They must likewise carefully
protect their dikes against burrowing animals, for the embankments of the
P0 have several times been perforated by moles, and those of the Missis-
sippi by musk-rats. It is necessary, also, to give the embankments a gen-
tle bend, and to leave a sufficient width for the penned-in river. The
Loire, in front of Orleans, was once 3827 yards wide, but has been re-
duced by the embankments to a bed of 306 yards. At J argeau, it is only
273 yards wide at a place where it once had a lateral spread of 7650
yards. In 1856 the Loire burst twenty-three breaches through these
banks, which were said to be impenetrable ;* as soon as the height of the
ﬂood rose in the river to more than 16% feet, cracks became inevitable.
The losses occasioned by the breaking down of these too feeble ramparts,
over which the ﬂood-water rushed like a deluge, were so considerable
that the question was often asked whether it would not be better to
throw the dikes down entirely and to replace them with plantations of
trees. The water, ﬂowing without diﬁiculty through the open barrier of
the crowded trunks, would be distributed equally over the plains by the
river-side, and would consequently never rise to the formidable height
which it reached between the dikes. Added to this, its annual ravages
would be in' great-part compensated for by the fertile alluvium which
would be deposited by the sediment with which‘ the water is ‘charged.
It has been calculated that if the vast basin of the Saone, situated above
the gorge of Pierre-Encise, were protected against the ‘inundations of the
river by means of dikes, conﬁning the water to a bed 27 3 "yards wide, the
same as at Lyons, a liquid mass of 1,869,000,000‘cubic yards, which, during
* Champion, Inondaiz'ohs de la France.
EMBLYKMENTS 011* THE P0. 935
inundations like those of 1840, now spreads over the plains, would then
rush down upon the town in the space of a few days. On the other side of
Lyons the Rhone affords a remarkable instance of the inﬂuence which the
dimensions of the bed exercise on the height of the ﬂood. In 1856, in the
wide plain of Miribehseven miles and a half above Lyons, the ﬂood-wa-
ter rose only nine feet and a half; but it rose to 20 feet—that is, more
than double—in the narrow bed contained between Lyons and the Brot-
teaux.* In the valley of the Isere, the mean height of the ﬂood—waters
has undoubtedly risen since the construction of the side embankments,
which were, in fact, placed too close to one another. This has been
proved by the very exact observations of M. Dausse.
The embankments of the Po, more scientiﬁcally constructed than those
of‘ the Isere, were commenced many centuries ago, when the long night
of the Middle Ages still darkened the rest of Europe. At a point below
Cremona, where the continuous line of dikes commences, they are very
wide apart, but the space through which the ﬂood-waters can ﬂow is
gradually narrowed in down to the mouth of the river; from 6564 yards
_Eebr~ 1112211 April June Sqzgfnnber Octoberl-Iomber-Décenibe._


\3
J! m?
QMNN m&
Fig. 129. Mean Heights of the Isere.
it diminishes to 3000, 2000, and even 1000 yards. Ultimately each of
‘the branches of the delta is not more than 300 to 500 yards wide be-
tween the inclosing embankments. The fact is, that a great portion of
the mass of water, ﬁnding between its upper dikes so. considerable a
space over which it is able to spread freely, remains stored in the plains
above, and thus the ﬂood-watertcnds constantly‘ to diminish in a‘ down-
stream direction. The ﬂat districts that lie between the dikes are called
golenas. , Each land-holder may cultivate them and'embank them as he
likes; but on the condition that his dikes shall be always nearly six ‘feet
lower than the principal embankments, so as not to offer any serious ob-
* Gohin ; . Ti’l'lveille', Commission Hydrométrz'que de Lyon, 1863.
336 - THE EARTH.
stacles .to .high inundations. These golcnas, therefore, with their dikes
all round them, form so many settling reservoirs where the alluvium ac-
cumulates after each fresh ﬂood, and their level is much higher. than the
plains outside the dikes.* Owing to the care with which these embank-
ments are kept up by the syndicate of the river-side proprietors, cracks
inthem are very rare. Since 1705, the date at which a breach of more
than 50 miles took place below Cremona, the reconstructed portion of
this enormous rampart has not yielded at any point. Although lower

Hill
.11.
Fig. 130. Dikes by the Po, from Cremona to the Sea.
down the river extraordinary inundations still occasionally break through
the lateral embankments in some few places, any great disaster is in a
measure prevented by the side channels, opened on both sides of the
river, in the delta of the Po. Nevertheless, the system is not yet perfect.
M. Lombardini thinks it very important that in the lower part of the
river a considerable space should be left open to the ﬂood-waters, so that
the alluvium might be distributed on the plains on each side, instead of
throwing out a promontory into the Adriatic Sea, and consequently rais-
ing the bed of the river. '
Next to the embankments on the Dutch rivers, those of the Po form
the most remarkable system of protection against inundations that has
been devised in Europe; but they are inferior in importance to the em-
bankments which run alongv a great portion of the Mississippi, and which,
from their enormous size and length, form a source of admiration to
every traveler. On the right bank of the river, from Cape Girardeau
(Missouri) to the Pointe-a-la-Hache, situated below New Orleans, the em-
bankments form a wall of 1125 miles in length, only interrupted by the
mouths'of rivers and a few spots of rising ground. On the left bank, the
* Elia Lombardini, Dei Cangiamenti del Po.
EMBANKMENTS OF THE MISSISSIPPI. 337
base of the plateau, which the'Mississippi here and there touches, has
enabled the inhabitants to dispense with constructing any continuous
dike; but they have been compelled to resort to embankments for pro-
tecting all the plains which extend from Memphis to Vicksburg, and
from Baton Rouge to New Orleans. 7 The ramparts that have been raised
on the eastern bank are altogether more than 625 miles in length, and
some of them are of very considerable’ dimensions; that which has been
constructed at Yazoo-gate, in order to close a bag/014* of the Mississippi,
is no less than 42 feet in height, 42 feet in width at the top, and 317 feet
broad at the base. To these immense constructions we must add all the
embankments formed along the tributaries of the Mississippi and the‘
bag/ous of its delta; we must likewise take account of all the double and


Fig. 131. Golenas by the Po.
triple parallel dikes which have been raised in some of the spots which
are most exposed to the action of the river. The whole of the embank-
ments of the Mississippi must altogether reach a total length of at least
2500 miles. It is true that in many of these imposing ramparts there is
still much to be wished for in respect to solidity.
Every great ﬂood on the Mississippi which has been recorded has
formed one or more breaches in the embankments above New Orleans.
The water then rushes like a cataract into the plains which extend below
its levelto a depth of 10, 12, and even15 feet. It rapidly enlargesv the
opening by washing down “the dikes for an extent of one or more miles,
and then, digging deep into the. soil, hollows out‘for ‘itself a new bed
across the plantations. One of these temporary beds which the river
made in 1850, 1859, and 1862, near the hamlet of Bonnet-Carré, dis-
charged no less than 3930 cubic yards of water a second—that is, a sixth
Vide foot-note, p. 347.
338 THE’ EARTH.
‘ * ~ ’ * “ ~
the th of
its
ess 1n extent tha
age liquid mass of theMiSSiS'Sippi. If the inhabitants had not
. .110 it . _. ' .
of t e aver
‘ 1 e o o t
Mississippi. In like manner the Hoang-Ho, having burst through its em-
an ments emptied itself into the sea, partly to the north and partl to
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The ter itory ex ag
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consequence of the dikes being cut thr O'h.
DISAPPEARANOE 0F RIVERa ' 339
CHAPTER LII.
THE MOUTHS OF RIVERS.-—ESTUARIES.—LONG BANKS OF SAND.—DELTAS.
--NET-W'ORK OF BRANCHES OF‘ RIVERS IN ALLUVIAL PLAINS.
BELOW its conﬂuence with its last tributary a river can not fail to'di-
minish in volume,on account of the evaporation of its water, and also of
inﬁltration into the earth. There are, indeed, some. streams which, as we
have seen, gradually waste away without receiving any compensation‘from
tributaries to make up for their liquid loss, and ultimately entirely dry up.
Not only in the burning regions of the torrid zone, where rains are rare,
but also in the great plains of the temperate zone, wherever the surface ‘of
the ground is too level to afford an incline for the running away of the
- water, we ﬁnd many rivers ﬂowing down from the mountains, and then,
failing to make their way to the ocean or any inland sea,'they disappear
among the sands of the level country. Thus the Rio'Dulce,_the rivers
Primo, Segundo, Quinto, and several other water-courses in the Argentine
Republic, come to an end amid the pcmvpas in a series of lagoons, which
rise or fall, advance or retire, in the desert, according to the seasons ‘ofthe
year or the quantity of water. Farther up-stream these rivers are navi-
gable for boats, and sometimes cover the country round with their ﬂoods;
but'below their current becomes weakened, they break up into'pools, and
at last, becoming little more than liquid mud, they fail even in moistening
the soil of the prairie. In a similar ‘way the branch of the delta’ of the
Rhine, which retains the name of the river, disappeared ‘amid the sand-
banks previously to 1806, the date at which a canal was dug through the
dunes, and was protected against the sea by eﬁicient ﬂood-gates.
A river, however, can scarcely be considered to be worthy of its name,
and can play no important part in history, if it fails to send down its wa-
ter to the ocean in a constant and regular way. Only under these condi-
tions is it accessible to ships, and in a position to connect the inland fdis-
tricts with those of the sea-coast. Just as a tree, the trunk of which,
formed by the union of all its branches, brings into communication the at-
mosphere and the bowels of the earth, so the chief trunk of the river, in
which all its aﬁiuents combine their liquid mass, links the sea to the moun-
tains and to the plains. 'By its ever-moving ﬂow, by the junctions of its
own current of fresh water with the salt waves of the rising tide, it brings
together all parts of its basin, and gives life and energy to the earth, as
the blood quickens the ﬂesh which it moistens.
The oceanic portion of a river is characterized by the tides which twice
every twenty-four hours change the direction of its current, and cause the
water to ﬂow back tip-stream. In this small portion of its development,
340 i .- THE EARTH.
the action of a stream is completely modiﬁed; it is no longer a water-
course, nor is it the ocean. It is, in fact, a common bed where the two
elements meet and unite. The river-mouth is not only an entrance to a
continent through which navigators may pass; it also opens an outlet to
the sea-water, and enables it to ascend far inland, and to mingle with the
liquid'mass brought down by the river. That portion, therefore, of the
channel where the j unction, takes place between the salt and fresh water
constitutes a, geographical division which is perfectly distinct from all the
rest of the basin. ' a ' y ' '
Most water-courses, however winding their course may have been,
straighten as they approach the sea, and descend toward the shore by the,
shortest line possible, so as to form a right angle with the ‘coast. This
tendency may be partially explained by the fact that the steepest slope
of the ground is generally inclined in this direction; but another cause,
also, is the alternate action of the tide-wave, which takes place perpendic-
ularly to the shore, the to-and-fro motion of which ultimately governs that
of the river.
Added to this, a large number of rivers, when they reach the maritime
portion of their course, spread out their banks very widely so as to form
real .gulfs, in which it .would be impossible to trace out the precise limit
which marks the river-mouth. When these bays are'not original indenta-
tions of the coast, they owe their existence to the combined action of the
river and the sea, which gradually cuts away the banks, and ultimately
‘ deposits them on some distant shore. Thus ﬂuviatile estuaries are gen-
erally found on those-parts of the coast which are directly exposed to the
force of the tides and storms. Estuaries are very numerous on the coasts
of the ‘open ‘sea where-the tide rises to a great height, but they are com-
paratively less frequent in land-locked seas, which preserve an almost. un-
altered level, such as the Mediterranean, the Baltic, and the Caribbean
Sea. Nevertheless, the shores of several inland seas—among others, the
Euxine, so formidable for its winds—present river-estuaries similar to those
on the oceanic coasts; the most remarkable are the Zimans of the Dniester
and the Bug.
‘ Almost all the rivers of Western Europe spread out into estuaries in the
lower portion of their course. There are some among the number, as the
Thames, the Severn, and other riversof Great Britain, which are streams
of no great importance above the gulfs at their outlets, and owe all their
- consequence to' the powerful tide-waves of the Atlantic. In France, the
Seine, the Loire, and the twocombined rivers of the Garonne and the Dor-
' dogne, water basins which are‘ better proportioned in their area to the di-
mensions of their estuaries; nevertheless, the quantity of fresh water sent
down into‘ these advanced bays of the ocean forms but a very small por-
tion of the liquid mass which they contain. In the Gironde, which may
be taken as a type‘ of a marine estuary, the ‘salt water generally ascends
~ as far as 'Pauillac, 31 miles from the outlet; any one sailing on the river
may readily notice the shifting line where the various liquid masses, some
ESTUARES. . _ 341
green and transparent, and others yellow and muddy, mingle with one an-
other in long eddies.
At a point more than 10 miles from the sea-coast, the saltness of the
Gironde is scarcely diminished by the admixture of freshwater. At one‘
time, the low- ground by the river-side was intersected by salt marshes,
and the creek of Méchers,-on~ the north bank, hasv been utilized for some
years in the cultivation of oysters. The depth of the estuary is also very '
considerable. At Méchers, the Gironde, whichv at that place is 7%. miles
wide, is from 50 to 100 feet deep‘ even at low tide. At the outlet properly
so called, the estuary contracts, and is only 3% miles wide; but in mid-
channel, the sounding-line ﬁnds no bottom at 100 feet. This enormous
basin does not-look like a river. If a spectator contemplates it, not from
the point of a headland, but merely from the edge of the shore, at St.
George or Royan, he can not distinguish the whole extent of the opposite
bank; all that is visible is a few clumps of pines, separated by the white
line of the distant water, and these isolated clumps seem to form an archi-
pelago; the Gironde appears like a sea dotted over with isles and islets.
The color and the appearance of the water are continually changing; it is
as if several rivers, crossing one another in every direction, were ﬂowing
in one and the same bed. Sand-banks which show their white masses in-
distinctly under the green waves, the marine currents which meet and
mingle with the turbid water of the ebbing tide, the gusts of wind which
raise on the estuary a perfect net-work of winding ripples, the long trains
of foam which incessantly shift their place; lastly, the submarine counter-
currents which ﬂew up to the surface and there spread out inlsheets per-
fectly smooth—all these ever-changing phenomena are always modifying
the magniﬁcent spectacle afforded by the Bay of Gironde.
But what, after all, is this beautiful estuary of the French coast when
compared with the grand outlets of some of the American rivers, such as
the St. Lawrence, the current of the Amazons, and the Rio de la Plata?
This last estuary, into which pour the gigantic Parana and Uruguay, more
than six miles in width, is at the outlet no less than 155 miles across, and
occupies a space of more than 15,400 square miles. Within a recent geo-
logical period it stretched over a still wider area. At that time the Pa-
rana had not ﬁlled up with its ‘alluvium all the higher portion of the estu-
ary, and probably, also, the surface of the pampas was covered by the sea-
water. Even in the present day, the now diminished gulf is ‘nothing less
than a real sea. Its bed, which prolongs in a gentle slope the surface of
the Argentine plain, is hollowed out 66 to 100 feet belowthe level of the
ocean. Currents and counter-currents, like those in the‘open sea, traverse
the gulf in every direction. Furious winds, which seem to upheave the
whole liquid mass, give rise to tempests which are more dreaded than
those of the ocean, on account of the sand-banks and rocks which hem the channels. The highest ﬂoods of the Uruguay and the Parana have no
perceptible inﬂuence on the level of the Rio" de la Plata, and seem lost like
rivulets in the enormous estuary. '
342 , THE EARTH.
- Although the winds and tide have‘ such an effect in increasing the
mouths of rivers, into which the waves enter in a direct line, their mode
ofaction is very diﬁ'erent whenthey are diffused along a sandy shore,
Which'they meet at a very acute angle. In this case, the waves fromthe
open sea, being driven obliquely against the coast, wash away from it
large quantities of, debris, which they deposit in front'of the mouth of the
adjacent river. Under the enormous pressure of the ocean, the current of
the'river bends and gradually doubles round in the same ‘direction as the
marine current, allowingoa tongue of sand to form across its former bed.
In the course of time, a narrow peninsula, having a sea-shore on one side
and a river-bank on the other, divides the fresh water from the salt water
for a distance of several miles, sometimes breaking up into islands, accord-
ing to the various changes of the‘ atmosphere, the, current, and the tides.
Thus, on the coast of New Granada, extending from the Cape de la Vela
to the foot of the snow-clad mountains of Santa Marta, all the river outlets
are pushed toward the west by‘ the current which runs along the shore to-

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Fig. 183. Belts of the Senegal.
MO UTH OETEE SENEGAL. —LANDES. 343
ward the Gulf of Darien; mere embankments, ornamented here and there
with green vine-branches, and the violet corollas of a kind of bindweed,
protect the still waters against the onset of the breakers. “
' The River Senegal vexhibits one of the mostlremarkable examples of
these belts, formed along the shore by the marine currents, and running
across the outlet of: a river. , For a distaneelof more than-180 miles, the
great water-course-follows a direction perpendicular ‘to-the coast. , In this
way it reaches a point 15 miles from the sea, at which its course. is arrest-
ed by a chain, of’ dunes, and it is, compelled to ﬁnd an outlet through some
other partof the sea-shore. At one time the river, or at least one of its
branches, continued in itS direct path to the ocean, and on the spot where
its former bed may still be traced there'is a narrow marshy ﬂow, known
under the name of the__,l\Ia1-igot ofN’diadier. Being thus driven in a
southwest direction, the Senegalis compelled to approach the sea oblique-
ly. AboveSt. Louis the river is separated from the line of breakers by
nothing but thenarrow bank of the Guet-N’dar, on which the blacks have
built their faubourg. Farther down the coast, the embankment of sand
thrown up by the marine current running from the north continuesfor a
considerable length, altering its position every year, owing to'the double
actionof the ‘river-ﬂoods and the sea-waves. At the present time the
mouth. of the Senegal. opens 2%- miles south ‘of St. Louis, and is ascending
slowly'toward thyejtown'. In 1849 it ‘was 9 milesfart-her to the south,
but in'1825 it, was near Gandiole, a little farther up the stream. This
sandy rampart,-which extends, its graceful curve from north to south for
_more than 24-miles, is cut throughby the current. of the riser,» sometimes
at one spot and sometimes at another, but it never fails toform again,
‘ ‘sition along the sandy ‘dike.
owinglto'the actionof the sea-waves. ‘ _ Until the operations of man have
ﬁxed the‘place of the 'mouth'of the Senegal, it will continue to shift its po-
In a similar way, all thevarious streams which empty into the sea along
the low'coasts of the French Lcmcles bend round toward the south as soon
as they reach a pointat' a short distance from the ‘sea-shore. There is, in
fact, a current produced by the swell which runs parallel to the shore of
the Landeaa matter which is easily proved by noticing the drifting of
any ﬂoating substance, or the'bearing of shipwrecked vessels, which al-
ways point their sterns tojthe south.‘ This current-pushes before it‘mass-
es of sand, which are mixed with the breakers, and thrown up upon the
' beach. The sandy points, which are, constantly augmented the addi-
tions brought by the waves, are thus elongated toward; the south,<and
would ultimately reach the bases of the Pyrenean promontories if it were
not for the tendency'of the streams to, rise, so as tokilncrease their slopes,
and thus topress with increasing, weight on the-sands which. obstruct
them. Formerly the waste channels, or “ coumnts,” of the Lakes of Sous-
tons and St. Julian ﬂowed parallel to the, sea for a length of several miles
above their outlet, and fears were entertained that, injconseguence ‘of the
lengthening of these streams,‘ and the rise in their level, the lakes above
.2
344 THE EARTH
would spread over the surrounding country. In order to avert this disas-
ter, the inhabitants undertook to rectify the course of the waste channels,
and thus to lower the level of the lacustral waters. This plan succeeded
perfectly as regards the Soustons Lake. Its level was sunk 10 feet, to the
great advantage of the village near, which was enriched with a tract of
fertile alluvium. The Lake of St. Julian was likewise lowered several feet
by the alterations made in the “courant” of Contis; but the engineers
met with considerable diﬁiculty in mastering this water-course, and in pre-
venting it from ﬂowing in a southerly direction parallel with the‘coast.
They were several times compelled to lengthen the barrier which forced
it to ﬂow in a straight line down to the sea. As regards the more im-
portant stream of Mimizan, which serves as a waste-channel for several
considerable lakes, an attempt was often made to dig out for it a regular
bed in the direction of the coast, and to retain the ﬂow of water in it; but
the river would not be subdued, and, throwing down the barrier of piles
and fagots which was opposed to it, continued to run toward the south
and southeast. Miles of basket-work dikes, which were set up to guide
its waters, now lie buried under the dunes.
During the course of the Middle Ages, and probably also in the previous
historical era, the Lower Adour, which is now perpendicular to the coast,
‘extended in a line parallel to the chain of dunes and the sea-shore for a
length of about 12%— miles. The river then fell into the sea at a short dis-
tance'from the spot where the town of Cape Breton now stands. Toward
the end of the fourteenth century a violent tempest obstructed this outlet,
and the Adour, thrown back farther to the north, found no place of issue
nearer than a point 22 miles from Bayonne; a village called Vieux Boucau
(old mouth) marks the banks of the former river. At ﬁrst sight it seems
as if this ancient course of the Adour is to be explained in a similar way
as the curves described toward the southby the streams of the Landes;
but, if this were the case, the current of the sea-swell in this part of the
Gulf of Gascony ought to tend in a northerly direction. N ow the action
of the waves points, on the contrary, from north to south, as far as the
mouth of the Bidassoa, and consequently the sandy points are lengthened
with a southerly bearing. The belt of banks across the course of the
Adour was turned toward the north ,' it is therefore necessary to look for
the cause of this in the existence of a chain of dunes solidly based on the
nearest Pyrenean rocks, which presented an insuperable barrier to the
river on the western side. In 1578 this chain was broken through at a
point three miles and three quarters below Bayonne, by means of a trench
cut by Louis de Foix, the engineer, and still more by a formidable ﬂood,
which threatened to carry away the city. Since this date, the mouth of
the Adour, yielding to the coast-current, constantly tends to bend round
toward the south, and on this side the piers formed to maintain the river
are carried the farthest. At the end of the seventeenth century—at a
date when these latter works had not been commenced—the river, bend-
ing‘ gradually toward the south, emptied itself into the sea at the foot of
CHANGES IN RI VER-M O UTHS. 345

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Fig. 134. Old Course of the Adour.
the rocks of Chambre d’Amour, about two miles from Boucau Neuf (new
mouth). If the river had not been repelled on the right by the dikes con-
structed by Louis de Foix, it is very possible that it would again have
turned toward the north.* I
One of the most'wonderful phenomena on the face of the earth is the
formation of those long banks of alluvium which affect a considerable
number of streams, and, for a distance of hundreds of miles, protect a
multitude of river outlets against the waves of the sea. _A magniﬁcent
example of this formation exists on the coasts of Virginia and North Car-
olina. The rivers there, which ﬂow on the surface of the ground, counter-
poivsing the pressure of the ocean in the same way as the subterranean
waters of Yucataml have formed out at sea an immense breakwater. This
sandy dike-'—which is not less than 186 miles in length, bends round the
continent in gracefully-winding curves, and incloses within its limits per-
fect seas, with their bays, archipelagoes, and currents; behind this, the
Tar, the Alligator, the Neuse, and several rivers run into the sea. An idea
may be formed of the peculiarities presented by these. long' banks, com- '
* Vionnois, Annales des Ponts et Chausse’es, vol. xvi. i Vide above, p. 248, 249.
346 THE EARTH.
mon to several rivers, by comparing this dike with the altogether regu-
larly formed littoral bank which lies in front of the River Cape Fear, im—
mediately to the south.
A third arrangement of the mouths of rivers is that which the ancient
Greeks designated under the name of delta (A), on account of the triangu-
lar form so often assumed by the alluvial plain embraced between the
‘ branches of a river. This plain, which projects beyond the regular line
of the coast, is nothing but a former estuary, which has gradually been
ﬁlled up with mud and sediment of every kind. This alluvial plain can
not be formed to any great extent in places where the swell, the currents,
and the tides are constantly disturbing the outlets of the rivers. It is
necessary that the stream should be subject to conditions somewhat simi-
lar to those existing in still lakes, where deltas form without the least ob-
stacle. These conditions are found in almost inland seas, with a scarcely
perceptible current—such as the Mediterranean and the Baltic—which al-
low river-mouths to gradually ﬁll up with mud. The alluvium which is
brought down by the river is certainly soft, and has but little solidity;
it is often roughly handled by the water at ﬂood-times, and fails in pre-
venting the liquid mass from forming forks, or even from dividing into
numerous branches. But the sea, which assails these deposits, being con-
stantly at about the same level, ultimately has the eifect of consolidating
them by dashing against them with its waves. On the contrary, when a
river falls into a sea where the tides rise to a great height, and where the
coast is alternately traversed by the rapid currents of the ebb and ﬂow,
no time is left for the deposit of the river alluvium. This matter is ﬁrst
pushed back into the river by the ﬂow of the tide, and then, being seized
by the ebb, is carried out to great depths in the open sea. In this contest
between the river and the ocean, the latter gets the advantage on account
of the enormous mass of its waves, which, by their ﬂuctuating movement
of rising and falling, are incessantly scouring out the estuary through
which the fresh water ﬂows.
Among those rivers the deltas of which are incessantly gaining on the
sea, we may mention, as belonging to the ﬁrst class in this respect, the
great aiﬂuents of the Mediterranean, the Danube, the Nile, the Po, and the
Rhone; also, in the Caspian, the Terek, the Kouban, and the Volga. Other
rivers possessing deltas fall into the sea at the extremity of some gulf
well sheltered by a barrier of isles, and visited only by scanty tides. Of
this kind are the Hoang-ho, the Yang-tse-kiang, and other water-courses,
the alluvial shores of which continue to project more and more into the
shallow Chinese Sea and the Gulf Pe-tchi-li. The delta of the Mississippi,
which may serve as a type to all other formations of the same nature,
pushes its way into an almost closed gulf, Where the height of the regular
tide never exceeds three feet. The only instance which can be mentioned
of a great river delta existing at the extremity of a gulf Widely open to
the ocean is that of the Gauges and the Brahmapootra. But it must not
be forgotten that at the outlets of these rivers, the tide, ﬂuctuating be-
DELTAS. 3&7
tween 1 foot and 16% feet, never exceeds, on the average, 10 feet in height ;*
added to this, the delta, instead of pushing its way far into the sea, pre-
sents a ﬂattened shape, and extends its low shores from east to west, giv-
ing a width of at least 186 miles. There is no doubt that in a more pro-
tracted sea, the delta of these two combined rivers of Hindostan, which
bring down in their turbid waters so large a quantity of alluvium, would
have thrown out a long promontory of delta exhibiting very different pro-
portions.
In a cursory and rapid examination of a map, it would, however, be
easy to fall into error as to the real character of certain river-outlets, and
to look upon them as actual deltas, thrown out by the action of the river
itself, instead of collections of soil deposited under the shelter of isles of
marine formation. Thus Holland, which is placed at the angle of the
continent of Europe, appears at ﬁrst sight to be the combined delta of
the Scheldt, the Meuse, and the Rhine; but the outer shore is, in fact, an
ancient coast cut through by the waves of the ocean, and is composed of
a vast semicircle of dunes, stretching from the mouths of the Scheldt to
those of the Ems and the Weser. Far from having gone beyond this
original coast-belt, the greater part of the Dutch rivers have formed estu-
aries, and the wide sheets of the Bies-bosch, the Zuyder Zee, and the Dol-
lart constitute unquestionable testimony of the invasion of the sea-water.
The alluvial tracts of Holland do not, therefore, present the character of
a delta properly so called.
Deltas are not formed solely on the lower portion of a river’s course;
they also exist at all the points of the river Where former lacustrine basins
have been ﬁlled up by one or more several aﬂluents. At these spots, the
principal water-course and its tributaries divide into several branches,
radiating in a fan-like shape across the alluvial plain; sometimes they
even cross one another so as to form a complete net-work. About the
middle of its course, the Mississippi receives two considerable aﬂluents
from the west, the Arkansas and the \Vhite River. The principal river
and its two tributaries are united by a net-work of innumerable bag/021.9,]t
which at every inundation change their course and their depth, falling
alternately into one or the other of the three currents, according to the
respective height of their waters. When the Mississippi is very high, it
disgorges its surplus water into the system of bayous, and the latter
empty into the Arkansas and the White River. During the low-water
season, on the contrary, when the water poured by the Mississippi into
the marshes above has had sufﬁcient time to ﬂow from lagoon to lagoon
down to the White River, the latter feeds the net-work of bayous which
connects it with the Mississippi and the Arkansas. When the latter river
is swollen more than usual after heavy rains in the Western prairies, then
the pressure of its water drives back that of the Mississippi, and for a
* Beardmore, Manual of Hydrology.
T Derived from the French word baz'e, The Spaniards of La Plata give the name of baln'a
to natural channels of the same description.
348 THE’ EARTH.
time the Arkansas takes possession of the common delta. On the banks
of the Amazon River all these phenomena take place with much more
grandeur; at the mouth of the J apura especially, the principal current
forms with its aﬂiuent an inextricable net-work of false rivers, which seem
to ﬂow indiﬂ'erently in any direction, and, for a space of several thousand
square miles, direct their surplus waters from marsh to marsh through the
virgin forests. This system offuros, as they are called in South America,
resembles those congestions in the human body when the too great abun-
dance of blood gives rise to a system of false arteries and veins.
CHANNELS OF THE ‘MISSISSIPPI. ' ' 349'
CHAPTER LIII.
THE CHANNELS on THE MIss1ss1rP1.—“ wonxme nIvERs.”—sHIFT1Ne OF
THE roman on BIFURCATION.——BAISING on THE RIVER-BED ABOVE THE
DELTA.-—ALTERATION IN THE SITUATION on MOUTHS on RIVERS.
IN a geographical point of view, it is important not to confound appa-.
rent deltas with the real deltas of alluvial earth. Thus the basin of the
Mississippi, in which there is opportunity for studying so many other hy-
drological phenomena, exhibits several instances of emissaries which must
not be looked upon as branches of the delta. The Atchafalaya, in fact, is
not a branch of the Mississippi, as it is not fed by the latter; it is, on the
contrary, a continuation of the Red River, which sends down to the Atcha-
falaya a portion of its water directly, and another portion indirectly, by
using for nearly a mile the bed of the Mississippi itself The Plaquemine
and Lafourche bayous, which, during ﬂoods, receive a small portion of the
water of the Mississippi, are not regular ﬂuviatile beds, like the branches
of the Rhone, the Nile, and the Po; they are ‘mere channels 'Sommunica-
ting between the inland lakes and marshes, and have become united to the
Mississippi by an erosion of the banks of the river. It is, inﬁeed, owing
to the laborof man—that is, to the side embankments and tie drainage
of the marshes near it—that the Lafourche bayou has assumed the aspect
of a river for so large a portion of its course, and now no longer disap-
pears, as it once did, in a labyrinth of pools and marshes. The Manchac,
or Iberville bag/on, which used to reach the sea through the Amite River
and the Lake Maurepas, is now completely obliterated by the alluvium
and masses of entangled trees; but it has always been a mere ﬂow of no
great importance.* Thus the delta proper only commences at the “Head
of the Passes,” and this sheath-like bed, through which the Mississippi rolls
between two narrow banks of alluvium, one side of which is sea-shore and
the other river-bank, is, geologically speaking, the sole bed of the river.
Projecting from the continent like an arm, it pushes out for 62 miles into
the sea, and spreads over the water the branches of its delta, like the ﬁn-
gers of a gigantic hand. A Hindoo might well compare the extension of
the mouths of the river to an immense ﬂower opening over the ocean its
serrated corolla.
These narrow embankments of mud, brought down into the open sea by
the fresh water, present a striking spectacle. In several places these
banks are only a few yards thick, and during storms the waves of the sea
curl over the narrow belt of shore and mingle with the riVeP- The Soil
of the banksbecomes perfectly spongy; it is not ﬁrm enough to allow
* Humphreys and Abbot, Report on the Mississippi River, 1861 .
.350 . " THE EARTH.
even willows to take root, and the only vegetation is a species of tall reed
(Miegea macrosperma), the ﬁbrous roots of which give a little cohesion to
the ooze, and prevent its being dissolved and washed away by the succes-
sion of tides. Farther down the reeds disappear, and the banks of mud

91380‘
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k .50’ do’ 913 30'
Fig. 135. Mouths of the Mississippi.

form, are washed away, and form again, wandering, so to speak, between
the river and the sea, at the will of the winds and tide. On‘the left bank
of the southwest passage, which is used for the largest ships, the plank-
built huts of a small pilots’ village have been ﬁxed as delicately as possi-
ble. These constructions are so light, and the ground that carries them is
so unstable, that they have been compelled to anchor them like ships, fear-
ing that a hurricane might blow them away; still, the force of the wind
often makes them drag on their anchors. Below, the banks of the Missis-
sippi are reduced to a mere belt of reddish mud, cut through at intervals
by wide cross streams; still farther down even this narrow belt comes to
an end, and the banks of the river are indicated by nothing but islets,
which rise at increasing distances from one another, like the crests of sub-
marine dunes. Soon the summits of these islets assume the appearance
of a thin yellow palm ﬂoating on the surface of the water. Then all is
mud; the land‘ is so inundated with water that it resembles the sea, and -
LA YERS OF WATER. 351
the sea is so saturated with mud that it resembles the land. Finally, all
trace of. the banks disappears, and the thick water spreads freely over the
ocean. After getting clear of thebar, the sheet of water which was the
Mississippi preserves, during ﬂoods, the yellowish color by which it can
be distinguished for about twenty miles, but it loses in depth all that it
gains in extent, and, gradually depositing the earthy matters which it
holds in suspension, becomes ultimately perfectly mingled with the‘sea.

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Fig. 180. Channel of Loutre.

In calm weather, the union of the fresh and salt water presents an in-
teresting spectacle, affording some similarity to the meeting of the tide
and the river-current in an estuary. Gliding in layers of increasing thin-
ness over the weightier masses of the ocean, the muddy water, on escaping
from the mouths of the delta, swims like oil on the surface of the waves,
and the sailors are able to collect it without diﬁiculty by skimming the
surface. Ships, as they pass, break through this light yellowish sheet, and
leave behind them a long track formed by the blue and transparent water
of the sea. A contrast of the same nature is producedat the spot where
the Gulf Stream causes the belt of the water of the Mississippi to swerve
to the east; one might fancy that a straight line traced out by a ruler
352 THE EARTH
separated thetwo diversely-colored waters as far as the horizon. .Finally,
the sheet of fresh water, becoming very thin, is broken up into‘little tur-
bid islets, surrounded with salt water. They are often full of vegetable
debris—they are then edged with breakers in miniature, which give them
a border of foam.* The sounding-line let down to the bottom of the sea
off the mouth of the river ﬁnds the mud of the Mississippi as far as the
coral banks of the Florida coast. The accompanying plates show the dif-
ference in the depth of the sea between the axis of the Mississippi and
those portions of the gulf which are situated immediately to the south.
:sssasrzss 83 $8
were»: (Db-1010 ‘a 60
‘ Fig. 137. Depths of the Gulf of Mexico in the Axis of the Mississippi Current.
w‘ (7)
‘3' H
H

The ﬂuviatile tracts of alluvium which are constantly forming before
our eyes may be classed among the most important geological phenomena
in the history of the globe. Owing to the quantity of mud which the
masses of running water bring down to their outlets, the shore-line is in-
cessantly changing, and continents are increased in area. Carl Ritter has
given the name of “ working rivers” (ﬂezwes travailleurs) to these water-
' courses which deposit a large quantity of alluvium in deltas, and push their
shores farther and farther into the midst of the sea. Every river, indeed,
takes its share in this labor, but in great deltas the earth quite visibly
encroaches upon the ocean. At the mouths of several rivers the lifetime
of a man would be a period long enough for the salt bay to be converted
into a plain, and the ﬂoating sea-weed beds to become a magniﬁcent forest.


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‘giant, w a r‘ L ' : g , i ' i 1 I * *1 "l ,
//.. g /// ,,
/ . l i
/-I I /, ,"
I f/c/Z/A /
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Fig. 138. Depths of the Gulf of Mexico south of the Mississippi Current.
The deltas themselves, thevast plains which, as Herodotus says, are the
“gifts of rivers,” bear witness to the geological importance of running wa-
ters in the formation of continents. But the investigations which have
been made up to the present day enable us to estimate the progressive
course of these alluvial formations in but a small number of rivers. In
fact, the problem which has to be resolved is a very complex one. In the
ﬁrst place, it would be indispensable to prepare at intervals exact charts
* Kohl, Zeitsclzriftﬁr allgemez'ne Erdlcunde, September,1864.

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ALL UVIUM 0F RIVERS. 35 3
of the sea-coast and the depths of the sea in the vicinity; next, it would
be requisite to strictly apportion the quantity of sediment brought down
in each season of the year by the water of the river, and to ascertain the
amount of alluvium which is lost along the coast. Lastly, in the beds of
the delta itself, it would'be necessary to distinguish between the debris
washed away from the adjacent coast and the matter which is brought
" down by the river; for when a muddy point is formed, the currents along
the shore always drive upon it a constantly increasing bank of sand.
Some day, doubtless, more exact observations will enable us to trace out
the journey of the alluvium down the river that carries it along; we shall
ascertain the average time that elapses before the rock rolled down by the
torrent is broken up into pebbles, and then in succession reduced to grav-
el, sand, and impalpable mud; we shall learn the number of resting-places
that the débrz's avail themselves of in bend after bend from the river’s
source to the sea. Perhaps, even by the mere observation of the alluvial
layers, we shall be able to discover the age of the bed, as we ascertain the
age of a tree by its concentric rings. We must, however, confess that this
class of geographical observations is scarcely inaugurated, and that it
would require an enormous staff of savants, which does not at present ex-
ist. We are therefore compelled to form rather rough estimations as to
the results of the labor of rivers; this is the case as regards the Hoang-
ho, which is probably more loaded with alluvium than any river in the
Old World.
This river owes its name, Hoan g (yellow), to its muddy sediment, which,
far out at sea, soils the purity of the sea-water, and is carried by the cur-
rents as far as the coasts of Corea. The delta which it has formed during
the present period extends over at least 96,000 square miles, and consti-
tutes one of the most important provinces in China. The tracts of allu-
vium have joined to the main land the mountainous mass of Chantung,
which once stood alone in the midst of the sea. Fresh islets have slowly
risen from the bed of the sea, and the detritus is deposited in quantities
so great that, according to a calculation made by Staunton at the end of
the last century, they would be suﬂicient in the course of sixty-six days to
'form an isle a square mile in extent and 118 feet in depth. According to
the calculations of the same author, the whole of the Yellow Sea is' des-
tined to disappear entirely in about 24,000 years; but this period should
be at least doubled, for the waters of this sea are much deeper than Staun-
ton stated.
The English authors who have written on the subject of the lower re-
gions of the Sunderbunds—that prodigious mass of alluvium brought
down by the Ganges and the Brahmapootra, the terrible “ son of the Brah-
mah”—aﬂ'ord us but uncertain information as to the lengthening of the
mouths of the rivers. According to Rennell, the Ganges alone sends down
in its water from ﬁve to six cubic yards of mud a second; nevertheless,
the line of shore extending from the mouth of the Hoogly to the estuary
of Huringota, which consequently limits the Gangetic portion of the delta,
Z
3 54C 1 THE EARTH
appears ‘to have been subject to but very slight modiﬁcations during his-
toric times. The promontories and the islets of the eastern portion of the
delta encroach much more rapidly on the sea; for on this side the waters
of the Brahmapootra, which on the average are charged with twice as
much mad as those of theGanges, pour into the Bay of Bengal.* A great
quantity of the alluvium which is brought down bythe two rivers is lost
in the ‘immense depths of the marine depression, which lies about 31 miles '
from the mouth of theGanges, which is called the “ Great Swatch.”
The Nile—‘that typical~ river which was the subject of study to the
Egyptian hierophants thousands of . years ago—which spreads out the
graceful delta formed of its own alluvium, is incomparably better known
as regards its lower course than any river of Asia. This great water-
course, which may be compared in the length of its bed to the Mississippi

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Fig. 139. Delta of the Nile.
and the Amazon, scarcely surpasses rivers of the third class,such as the
Rhone or the P0, in the importance of its liquid mass, and ismuch‘ inferior
to them in the quantity of its alluvium. It has been calculated that if all
the mud brought down by the mouths of the Nile was thrown up uni?
formly on the coast, the latter would advance about 13 feet a year.
The
low points of alluvium which are deposited near the Rosetta and Damietta
mouths increase on
' * Ferguson, Zeits‘clmftfiir'Erdkunde, 1864.
the average—the one 34 acres, and the other 39 acres,
DELTA OF THE P0. 355
every year, which gives only three feet of annual progress for the front of
the delta, the convexity of which is 186 miles in length. If the advance
of the alluvial deposits was not more rapid during past ages than it is at
present, it must have taken the Nile no less than 74,253 years to deposit,
grain by grain, the triangular plain of the delta, comprising an area of
8610 square miles.*
The fact is, that the Nile leaves the greater part of its alluvium on the
plains by the river-side; added to this, the extension of the water over
the two banks, and the diminution of the current which results, necessarily
cause the fall of a certain quantity of sediment on the bottom of the river-
bed. The French savants of the Egyptian expedition found that the rise
in the bottom averaged 4'960 inches a century. This gradual elevation
of the bed doubtless corresponds with a similar change in the level of the
two banks of the river. By measuring the bed of alluvium in which the
statue of Remeses II. is buried at Memphis, Mr. Horner came to the con-
clusion that during the last 3215 years the soil of Egypt had risen 3'043
inches in each century. It is probable that in future the soil will be raised
more and more rapidly every year, owing to the “warpings” which are
incessantly carried on by the agricultural inhabitants on each side of the
river. Now that a vast system of skillful cultivation has appropriated
the banks of the Nile, and that steam-pumps are drawing off the water of
the river in every season, the liquid discharge and the mass of sediment
must diminish at the mouth; and if this impoverishment of the Nile con-
tinues to go on in the same proportion, we might perhaps calculate the
future date when the Nile, being exhausted by the irrigation canals, will
no longer send down to the Mediterranean either a drop of water or a
grain of sand. .
It may be readily understood that the best known river-delta must be
looked for in Europe, and in that country of Europe which, for so many
centuries, has devoted itself most earnestly to all questions relating to hy-
draulics and irrigation. The delta we speak of is that of the Po. Owing
to the testimony afforded by history,'the monuments left by the ancients,
and the operations of the engineers of the Middle Ages, we are enabled to
follow with the mind’s eye the progress made by the alluvium of the river
during the last twenty centuries. In some spots, especially round the. la-
goon of Comacchio, there are secondary deltas, the encroachments of which
may be measured with mathematical exactitude, for these tracts are, so to
speak, of human creation, and have been altogether deposited since the
opening of artiﬁcial channels and sluices. . ‘
Notwithstanding the shortness of its course, the P0 is one of the most
remarkable “ working rivers” in the whole world. The gradual subsidence
of the shores of the Adriatic, which is estimated by Donati‘at six feet at
least since the foundation of Venice, does not prevent the river encroach-
ing without intermission on the domain of the sea. Ravenna, which once,
like another Venice, stood in the'midst of lagoons, its outer rampart being
* Eli Lombardini, Essai sur l’Hydrologie du Nil.
356 THE EARTH

Li'ﬁrparia - - '


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.. \“5; :1} a
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_
Fig. 140. Mouths of the Po.
bathed by the Adriatic, is now situated far from the gulf’, .in a plain ﬁlled
with the alluvium of the Po. We also know that the townof Adria, the
ancient emporium of the Adriatic, to which, indeed, it gave its name, is
now 21 miles from the extreme point of the shore. This is a proof that
in two thousand years the annual average progress of the delta has. been
55 feet; but at the present day the advance of the alluvial tracts is much
more rapid. The patient investigations of M. Lombardini have established
the fact that the river brings down every year 15,015,600 cubic yards of
mud and ooze*—that is, about 1.781 cubic yards a second, and enlarges
the shore of its delta 76 yards. A chain of dunes, now left inland by the
encroachments of the alluvial deposit, still points out the direction of the
former sea-coast. The enormous amount of increase in the deposit at its
month, which is thus accomplished by a river of the third class, is readily
explained by the embankments, which compel the P0 to carry down to
the sea the whole of its alluvium, whilst the Nile and the Ganges, during
each period of ﬂood, spread over a great area of land, the level of which
they raise by their deposits.
The Rhone is the most active among the French rivers in the forma-
tion of a delta. The promontory deposited by its current in the open sea
projects much more decidedly beyond the regular line of coast than the
delta of the Nile, and advances every year with a rapidity which may al-
* According to M. Ch. Hartley, the Danube, which discharges ﬁve times as much water as
the Po, brings down to the sea only 46,500,000 cubic yards‘a year.
ALL UVIUM OF- THE RHONE. 3 57


A
Fig. 141. Delta of the Rhone in the Fourth Century and at the Present Time.


most be compared to that of the P0. In the fourth century the town of
Arles was only 16 miles from the sea, while at the present day it is 29
miles removed from it. The advance of the alluvium has, therefore, been
13 miles during the space of fourteen centuries, or about 52 feet a year.*
The annual average elongation of the shores of the principal branch of the
river is, therefore, about 164 feet. But this does not prove that the (Zébrz's
brought down by the river are increased threefold, in consequence of the
embankment of the land by the river-side; for the Rhone has frequently
shifted the position of its outlets by opening them alternately on both
sides of the banks of mud caused by its own deposits. In this way the
increase of the delta takes place at several points in succession; on one
side the alluvium encroaches rapidly, and in other places it remains almost
stationary.
In the Rhone, as in the Po, an endeavor has been made to estimate, by
means of the annual discharge, the quantity of matter deposited by the
river. This mass is about 22,000,000 cubic yards every year. It certain-
ly is a fact that, by direct measurements of the increase of the delta, and
by soundings made-on the bar, M. Reybert found that the total quantity
of matter brought down from 1841 to 1858 amounted to 419,000,000 of
cubic yards,>which would be equivalent to an annual increase of 25,000,000 2
a year; but this difference may be explained by taking into account the
enormous quantity of infusorz'a and small shell-ﬁsh which exist in all the
newly-formed soft banks. Some specimens of the mud taken from the
mouth of the Rhone contain, as M. Delesse has ascertained, as much as 30
* E. Desjardins, A perpu Historique sur les Embou-clzures du Rlzo‘ne.
358 _- THE EARTH
per cent. of carbonate of lime, proceeding, no doubt,’from the remains of
the shell-ﬁsh. It also appears that the proportion of the alluvium of the
Rhone which is brought down to the sea, and afterward carried away by
the currents to distant shores, is very slight. Almost all the mud is ab-
sorbed in the construction of the delta, and forms the toys or muddy islets
which make their appearance on each side of the mouth. The soil which
is thus brought down by the river is generally very fertile. The mud of
the Rhone is no less productive than that of the Nile, and sanitary and
irrigatory operations would soon render La Camargue another Egypt. In
this respect France has much to learn from the ancient land of the Pha-
raohs.
The delta of the Mississippi advances even more rapidly than that of
the Po. Among all the questions in respect to the great river of the New
World, the yearly prolongation of its alluvium has most of all excited the
curiosity of science. How many yards does the Mississippi advance ‘into
the sea during the course of each year? How many square miles does it add
to the main land in a century ‘3 How many thousands of years must it have
been at work in forming its delta, and depositing its enormous burden of
alluvium? Many geologists have, each in their turn, endeavored to an-
swer these questions by basing on data which are sometimes only hypo-
thetical the very diiferent results at which they have arrived. Thus M.
Elie de Beaumont, who at that time had not the necessary elements at his
disposal, estimated the progress of the delta at 382 yards a year. M.
Thomassy, comparing the‘ ancient French charts with the American sur-
veys,-has felt warranted in ﬁxing the annual conquest effected bythe Mis-
sissippi at about 110 yards. Messrs. Humphreys and Abbot, looking upon
the old chart as being too incorrect to serve as the base of a serious calcu-
lation, are satisﬁed with comparing the charts of Talcott and of the Coast
Survey, and judge the annual-prolongation of the delta to be 86 yards.
M. Ellet, one of the most conscientious investigators of the action. of .the
river, reduces the probable elongation of the delta to 22 feet, so as to make
allowance for the erosion exercised by the sea. Lastly, M. Kohl, whose
hypotheses it is very diﬁicult to understand, even if you have the maps
before you, maintains that the delta of the Mississippi remains .nearly sta-
tionary.* It must be confessed that the differences on the point would be
serious enough ‘to render doubt “ the best pillow for the wise man” if it
were not that the calculations of M. Thomassy and the learned explorers,
Humphreys and-Abbot, undoubtedly surpass all the others in scientiﬁc
value. The average advance. of the delta during the two last centuries
must therefore be estimated atfrom 86 to 110 yards.
This rapid progress in the alluvium is perhaps very much owing, to the
cutting down of the forests, which has rendered the soil of the banks much
more movable.)L To this cause for the growth of the delta must be added
the construction of high embankments on the banks of the Mississippi and
* Zeitschriftfiir Erdkunde, September, 1862. -
; ‘I’ Marcou, Bulletin de la Socie'te' dc Ge'ographie, July, 1865.
DELTAS. .359
its tributaries; for, as only asmall portion of the mud is able to settle at
the sides, a much more considerable'mass is ‘carried down to the mouth;
nevertheless, the delta is not increased in proportion. The more the points
of alluvium gain on the water, the deeper isithe spot in the gulf in which
the matter ,(estimatedat seven cubic yards apsecond) is deposited. ' At
the lower extremity of the delta of the Mississippi, the thickness of the bed
of sediment is not less than 98 feet; ‘and soundings have shown that the
river will soon reach the edge of the deep abyss through which the Gulf
Stream ﬂows. At 11 miles from the ‘southwest channel, the bottom of the
sea is 885 feet from the surface, and this depth rapidly increases to more
than 5000 feet. Being, of course, unable to ﬁll up these gulfs where the
rapid currents would carry the alluvium into the open sea, the Mississippi
must be content with obstructing the, lateralbays, or with extending to-
ward the east, in the direction of Florida. _ Some ‘daythe delta of this
river will be bounded on the southern side by a rapid slope, like that which
is formed by the Rhone in the'Lake of Geneva, and'bythe Congo in the
Gulf of Guinea. At the mouth of this latter water-course the sounding
lead falls'rapidly from 30 to 1600 or 2000 feet. , _ -
Whenthe river-outlets are left to themselves, the spot in the river where
the bifurcation takes place gradually shifts its position in‘ a down-stream
direction in proportion as the mouths advance toward the. sea. In fact,


Fig. 142. Height of the Layers in the Delta.
the current striking against the upper point of the delta must necessarily
wash away the two banks of the island which it has itself formed by the
deposit of its alluvium. A remarkable instance of this alterationin the
place of bifurcation of the river-outlet may be noticed in the Egyptian
delta. At the time of Herodotus, Memphis was the spot where the Nile
divided into two branches; it now forms its fork at Cairo, more than 1.8
miles from the spot where it took place 2400 years ago. The upper point
of the delta will henceforth remain stationary, owing ‘to the barriers con-
structed just at the beginning of the two principal branches of the river.
The elongation of the delta has a proportionate and constant tendency
to raise the bed of the river above the mouth. The calm‘and immense
river which empties itself into the sea obeys the very same laws as the
boisterous torrent pouring into a lake. In proportionas it pushes its
branches farther into the sea, it must form a slope considerable enough to
insure the discharge of the mass of water. This, slope can ‘only be pro-
duced by the gradual raising of the river-bed‘. ,VIt is evident that this rise
vwill be the more rapid the better the shores-'are-protected by-embank~
ments against inundations; for the alluviumlmust, in this case, all descend
to the sea, and lengthen the extreme points of thedelta. I _
The results produced on the action of rivers by lateral embankments
360 THE EARTH
have, however, been singularly exaggerated. Pessimists’ have often point-
ed to the example of the Po as a proof of the rapid heightening of the riv-
er_‘-level which is brought about by the construction of embankments;
“- but this oft-repeated assertion is not based on any real fact. Cuvier was
entirely mistaken in stating, according to a communication from M. de
Prony, that the surface of the water of the P0 is new higher than the roofs
of the houses in Ferrara.”* This, unfortunately, is one of those accredited
errors which it is diﬂicult to dispel, on account of the great names which
countenance them. Elia Lombardini has proved, by strict measurements,
that the mean level of the Po exceeds in but very few spots the level of
the ground in the adjacent country. In 1830, at the time of one of the
highest ﬂoods of the century, the surface of the P0 was scarcely ten feet
above the level of the pavement in front of the palace at Ferrara. The
mean height of the water over‘ the whole course of the river is considera-
bly below that of the neighboring plains. To make up for this, the streams
of the Reno, the Adige, and the Brenta, which empty into the delta of the
Po, have certain portions of their beds higher than the adjacent country.
The fact is, that, having so lately left the mountain gorges, theyv still retain
their characteristics as torrents, and, like all mountain. streams, raise a
bank of debris below the ravines of erosionq‘ The exceptional height of
theAdige, the‘ Reno,‘ and the Brenta must not, therefore, be attributed to
the dikes which border the lower portion of the course of these streams,
but to the impetuosity of the water above. The calculations of MM.
Humphreys and Abbot prove that the mouths of the Mississippi must
project 24 miles farther into: the sea for the river to rise only one feet
under the ramparts of Fort St. Philip, 81 miles above the southwest chan-
nel. '
If, however, rivers which are subject to high ﬂoods, such as the Nile, the
Po, and the Mississippi, are, during inundations, higher in levelthan the
plains by the river-side, this fact is owing to the lining of alluvium which
is gradually formed on the banks. During the period of ﬂood, the waters
which pour over the banks are retarded by a thousand various obstacles
——trunks of trees, bunches of plants, mounds, palisades, buildings—and con-
sequently they deposit on the ground much of the sediment which they
contain; before they leave the banks and ﬂow far and wide into the plains ‘*
they are comparatively puriﬁed. The effect of this is a gradual elevation
of the banks and the ground near them to a level somewhat‘above that of
the countrygenerally. Above New Orleans the natural inclination of the
soil is very marked; from the shores of the Mississippi to the marshes in
the interior the difference {in level is not less than 13 to 16 feet, and at
some points even this considerable slope is exceeded- The banks of the
islands scattered about in the'lower courses of rivers are likewise raised
by inundations to a‘ point above the level of the surrounding country. The
Lower Parana,1 the Volga,§ and a number of other large water-courses
* Discours sur les Revolutions del. Globe. ‘l' Vide abofe, _P- 293-
1 Martin de Moussy, Confederation Argentine. § De Beer, Kaspisclze Studien.
ELEVATION OF RIVER AB'O VE ALL UVIUM 361
present, near their mouths, multitudes of islands, the raised banks of which
circle round pools or marshes.
The elevation of the lower course of a river above the surface of the
surrounding plains explains in the most simple way the continual shift-
Hill
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ing of the outlets of the delta. As soon as a breach is made in the lining
of the bank, a considerable portion of the running water immediately
escapes through this opening, and descends to the sea over a new bed
which it hollows out for itself across the low-lying tracts, marshes, and
lagoons; these are natural crevices, similar to those which occur in em-
bankments raised by man’s labor. Thus, when the economy of a river
has not been modiﬁed by human agency, its outlets are of a changing
character, and move across the delta, depositing their sediment in the la-
goons, so as gradually to elevate the soil, and to bring it every where to
the level of the high ﬂoods. Every delta becomes modiﬁed, even during
the historical period, in- the number, direction, and importance of its
branches. Of the seven famous mouths of the Nile, ﬁve have now ceased
to exist except during ﬂoods; the two which still remain open—those of
Rosetta and Damietta—appear, according to Herodotus’s statement, to
have been dug out by the labor of man. During the last 3000 years, the
branches of the Lower Hoang-ho have undergone similar modiﬁcations in
their course, which are more remarkable on account of the immense ex-
tent of ground over which they have constantly wandered.* Still more
strangely, the Amou-Daria in Tartary, which now falls into the sea of
Aral, was in former days a tributary of another sea, and ﬂowed into the
Caspian; the traces of its abandoned bed may still be seen here and there
in the desert.
In consequence of the. incessant modiﬁcations to which the lower por-
tions of rivers are subject, it often occurs that two water-courses, which
were once perfectly distinct and independent of one another, become
united in- their deltas and principal outlets. We may mention the in-
stance of the Shat-el-Arab. In like manner, the Adige and the Po, which
communicate with one another by lateral branches, have a tendency to
join one another completely in a common bed, and nothing but extensive
operations has prevented, up to the present time, the perfect junction of
these two rivers. The Mississippi, so remarkable in all other respects,
presents, according to Ellet, the phenomenon of three former rivers united
in one. At one time the River Ouachita ran down to the sea throng hthe
Atchafalaya, which is now an overﬂow-channel of the Mississippi, but was
then a distinct river. The Red River, too, ﬂowed in the valley of the
Teche, where it has left numerous traces of its passage. The opposite
windings of the Red River and the Mississippi gradually approached one
* Vide above, p. 353.
362 ‘ . THEEARTH


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another and then united; the Ouachita-Atchafalaya has been, as it were,
cut into two parts, one. of which, the northern portion, is become an aﬂiu-
cut, and the other, the southern portion, an effluent ‘of the Mississippi.
Similar phenomena are observed in the delta common to the Gauges and
the Brahmapootra. There seems to be a real conﬂict between the branch-
es of these two rivers; they ﬁrst come together and are then mutually re-
pelled; they sever one another and ﬁll each other up.*
Thus, while in somecases distinct rivers unite, others, on the contrary,
which were once combined, are now separate, and take contrary direc-
tions. As a striking instance of this double series of hydrological phe-
nomena, we may mention the two rivers of Cilicia, once called the Sarus
andthe Pyramus,'now known as the Seih'oun and the Djihoun. These
streams, which project their alluvial deposits more than. six miles beyond
the outline of the‘ former coast, fall into the sea sometimes through two
distinct mouths, sometimes through one outlet common to the two rivers._
Since the, days of Xenophon, the two streams, which'then ﬂowed in beds
some distance from one another, have united three times, and three times
have again separated. In the space of twenty-three centuries, says M.
Langlois, six complete revolutions have taken place in succession in the
course of action of theiSarus and the Pyramus.
* Ferguson, Zeitsclirift Erd/cunde, 1864.
4)
BARS 0F RIVERS. 363
CHAPTER LIV.
BARS on RIVERS.—-OPERATIONS UNDERTAKEN FOR DEEPENING THE
MOUTHS on RIVERS.
NOTHING is more variable than the channels at the mouth of a river.
Thus—only to mention the Mississippi—this river has now ﬁve channels,
the southwest, the south, the southeast, the north, and the Loutre, which
is a ramiﬁcation of the one preceding. Sometimes one, and sometimes
another of these outlets becomes the real mouth of the river, and the
stream takes to them and abandons them in turn. The fact is, that the
Mississippi, having considerably elongated its principal outlet by the al-
luvium it has brought down, is compelled to seek some bed which is short-
er, and consequently more inclined, in‘ order to pour down its mass of
water; when this fresh outlet is likewise pushed out too far into the sea
to afford the requisite slope, the river turns either to the right or left to
clear for itself a third place of issue. At the time of the ﬁrst attempts at
colonization in Louisiana, the southeast channel was the principal one;
but this gradually became obstructed, and the northeast mouth was next
the most important. The mass of water in this channel diminished every
year; and in 1853 there was not more than'8 feet of water on the bar,
and small coasters were the only vessels which ventured over it. Since
1843, the southwest channel has become the real mouth of the river,
through which almost all large ships try to enter. In 1853 there were
16%» feet of water; but constant labor was necessary to maintain even this
depth, for the quantity of water constantly tends to diminish, while in the
Loutre Channel it is gradually increasing. Some hydrographers think
that this latter mouth will ultimately become the true Mississippi; it al-
ready has 13 feet of water on the bar; and, in order to avoid a considera-
ble circuit, nearly all the steamers running between Cuba, Mobile, and
New Orleans now attempt to pass through it.
However much they may shift their course, still most rivers are ob-
structed by a bar of sand or mud, to which mariners have given the name
of “bar.” These banks of alluvium are, for the most part, deposited in
the form of a crescent, off the mouth of the river, and, turning their con-
vex sides toward the open sea, mark the precise spot of the line of break-
ers which rise in rough weather. They may be deposited in different
modes, according to the quantity and impetus of the river-water, the
mass of sediment which the latter holds in suspension, the conﬁguration of
the'coast, and the general direction of the winds and currents out at sea.
There are, however, a few hydrological problems which have given rise to
lively discussions among geographers and engineers, for which, too, many
364 - _ THE EARTH.
various or contradictory solutions have been propounded. The fact is,
that the question is altogether a complex one, and presents itself under a
new aspect at'the mouth of each particular river. It certainly is the case
that, as regards all rivers, the collision of the two liquid masses ﬂowing in
\Vaves oi‘ theses
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contrary directions. is the primary cause of the formation of bars, bu the
materials which‘ are ' employed and the progress of the work vary singu-
larly.
At ﬁrst sight, the origin of a bar seems a matter easily to be under-
stood, especially in the case‘ of rivers with waters much charged with mud.
It is thought that thecurrent of freshwater, being suddenly arrested in
its career by the sea water, immediately lets drop on the bottom the mat-
ter which it held in suspension, and thus gradually forms the kind of sill
which rises between the bed of the river and the ocean. This, however, is
not the exact mode of formation. The. ﬂow of fresh water, being but lit-
tle retarded, continues its movement above the salt water coming in a
contrary direction. _ The sediment which is let fall by the current of the
river is taken hold of by the counter-current and borne up stream. At
the same time, the heavier alluvium, which makes its way to the sea by
gliding over the bottom of the river-bed, is arrested in its progress, and is
mingled with the sand and the innumerable organic remains driven in by
the waves. Thus an increasing cushion of mud is formed in front of the
rising tide ﬂowing to meet the river, and in this way the heaps of debris
which constitute the bar are gradually accumulated. This obstacle, being
produced by the shock of two opposing currents, shifts coincidently with
the scene of the conﬂict. During ﬂoods, the impetus of the mass of fresh
water be'comes‘suﬂiciently strong to remove the whole bar and to carry it
farther in advance ; but, on the other hand, when the water of the river is
low, the tide resumes the preponderance, and the bar is again driven back.
The barrier shifts its place, sometimes in one direction, sometimes in an-
other, ‘and is incessantly seeking to preserve its equilibrium between the
two opposed forces which impel it. _ -
The bars of the delta of the Mississippi may be quoted as an instance of
this mode of formation. Over the bar which obstructs the entry of the
principal channel, and the most practicable of all those on‘the'coast of the
Gulf,- there is an average depth of 16% feet. The alluvium‘ of the bed,
being kept in constant motion by the waves and the ‘current of the river,
BARS OF RIVERS. 365
is in an almost liquid state. Vessels have been known to cross the bar
without any other assistance than their sails, although their hulls were,
for more than half a mile, buried in the mud to a depth of six feet. Not-
withstanding the soft nature of the ooze, vessels may still incur consider-
able danger in crossing the bar. Those that do not avail themselves of a
steam-tug are sometimes taken athwart by the wind and driven irretriev-
ably upon the banks. It is often impossible to get them off again; the
motion of the keel stirs up and sends into the current the smaller particles
of the mud, but the heavy sand remains, and ultimately becomes cemented
round the bottom of the ship.
There are some bars which are almost entirely the work of the sea;
these are banks of sand or shingle which the waves throw up across the
outlet of a river, thus continuing the line of shore. Barriers of this kind
form in front of water-courses running into a sea agitated by violent
storms, or raised every day by a very strong tide. The ﬂow coming from
outside ascends far into the river-mouth, and forces the current meeting it
to deposit its heavier alluvium at some considerable distance above the
bar properly so called. The earthy particles held in suspension by the
current of the river can not be precipitated on account of the continual
agitation which is kept up at the entry by the breakers and the swell;
they remain mixed with the masses of water, and are driven up stream by
the ﬂow, or carried out to sea by the ebbing tide. Even the ﬁne sand
which the waves throw up on the bar is not allowed to remain there for
long; it is again stirred up by the water which brought it, and it ﬁnds a
resting-place only in these spots where the motion of the waves ceases.
The heavy sand, the shingle, and the stones which the waves drive before
them without carrying them along in eddies, are the only materials which
constitute the bar. Like the banks of mud in river-deltas, this line of de—
bris is incessantly shifting its place, sometimes up stream and sometimes
down stream, seeking the exact line where an equilibrium exists between
the ebb and the ﬂow. When the river is ﬂooded, the force of the water
running down carries the bar farther out to sea; on the contrary, when
the river is low, the tide gains the ascendency, and pushes the sand up
into the mouth of the stream.
In France, these phenomena have been best studied at the formidable
bar of the Adour. Thanks to the submarine charts which the engineers
prepare twice every month, we may trace out, so to speak, by the eye, all
the ﬂuctuations of the bank of clébrz's, and all the causes of its movements
can readily be taken into account. In this bar, however, there is every
evidence to show that the materials forming it are brought up by the
waves. The soundings that have been made in the bed of the Adour, as
far up as 15%- miles above Bayonne, uniformly show a bottom of mud or
ﬁne sand; but it is ascertained that the bank at the mouth is composed
of heavier sand and shingle, proceeding, no doubt, from the cliffs of the
Spanish coast.*
* Vionnois, Annales des Ponts et Clzausse'es, 3d series, vol. xvi.
366 THE EARTH
The bars of rivers, which have always been an obstacle and a source of
danger, are at the present time more troublesome to deep navigation than
they have ever before been. It certainly is the case that, thanks to the
steam-tugs, vessels with a light draught of water are able to follow the
direct channel, and can cross the diﬁicult part in the space of a few min—
utes; but, nowadays, commerce is no longer contented to employ the
small vessels of former times; it requires ships of heavy burden, carrying
large quantities of merchandise, and drawing a considerable depth of
water. Many a river-port, once the resort of whole navies, is now aban-
doned on account of the bar which cuts it off from the ocean, and is fre-
quented only by coasting vessels; commercial vitality has gradually left
it. Thus the deepening of their river-mouths is become a most important
question in some sea-coast towns. If they could only succeed in doing
away with the bar, these towns would increase suddenly in wealth, popu-
lation, and importance. If the bank of sand must remain ﬁxed across the
outlet of the river, the city is on its way to certain ruin. Every engineer
recommends his own special plan as being adapted to avert the danger;
each promises that he will correct these river-outlets which Vauban char-
acterized as “incorrigible.” But only too frequently, operations are un-
dertaken without taking account of the numerous causes which determine
the formation and ﬂuctuations of the bar. Amongst all the immense
works which have been carried out at the mouths of rivers, many have
become useless, or even absolutely injurious to navigation. Millions and
millions of money have been thus cast into the ocean and purely wasted.
The most simple means, and that, indeed, which is always resorted to
in the ﬁrst place, is dredging ,' but this plan is evidently merely provi-
sional, and in the present state of science can scarcely be considered as a
remedy of a lasting character. Moving an obstacle is not doing away
with it; besides, the ﬂotilla of dredgers which can be employed on a bar
in removing the alluvium is always insuﬁicient in number. Even if they
were constantly at work, there would be little or no result, for the inex-
haustible ocean would take up the task of providing the alluvium and
raising the bar; the obstacle would be merely shifted in place.
Instead of moving the mud, the more simple plan has often been tried
of sending it into the current by keeping the water in a constant state of
agitation. For a length of time it has been a recognized fact that, after
the passage of several ships, there is an increased depth of water on bars
composed of mud and ﬁne sand: the particles stirred up by the keels are
carried away by the current. This phenomenon may readily be produced
by artiﬁcial means. More than a century back a French company ap-
plied this re'medy in the principal channel of the Mississippi, by causing
heavy iron harrows to be dragged over the shifting bed of the river. Re-
cently, in 1852, the same plan was applied, and the federal government
employed on the bar a certain number of steam-boats, which kept the
mud on the bottom incessantly in motion by means of drags or harrows,
and thus prevented its precipitation. According to a popular tradition,
BARS OF RIVERS. 367
mentioned by M. Engelhardt, a Turkish pacha formed the same idea as
the American engineers. He obliged every vessel which left the Danube
to drag astern, while crossing the bar, a harrow attached to a heavy chain.
In both cases the agitation of the water seems to have produced a favor-
able result. The pacha succeeded in maintaining a channel of about 13
feet deep through the Soulina bar, where formerly it was not above half
this depth. By the same plan the American engineers obtained nearly
20 feet of water in the southwest channel. In a similar way, in order to
force the torrents to deepen their beds, the inhabitants of the Piedmontese
Alps used to plow up the tracts of pebbles which were brought down by
the ﬂoods.*
Unfortunately, this simple method of improving the condition of the
bar produces no lasting result, and the work always has to be begun over
again; for the bank forms again whenever the drags allow a moment’s res-
pite to the sediment held in suspension by the water. Besides, when the
water is low in the river, the operations must be suspended, or the sea
would drive back all the sediment in an up-stream direction, and thus
contribute to the silting up of the river-bed. It must also be remarked
that measures of this kind are only practicable in rivers where the bar is
composed of small particles, and is not subject to all the fury of the wind
and the billows. At the mouth of the Adour, for instance, what immense
harrows it would be necessary to use to move the beds of shingle driven
up by the storms!
A system of moles and jetties is, therefore, the plan that has generally
been resorted to by engineers in the improvement of the mouths of riv-
ers. This plan is somewhat similar to that of the embankments which
have been employed, with various degrees of success, on the middle
courses of rivers; but the marine dikes have not always Pl‘l‘iuued favor-
able results, and a great many experiments which seemed to offer good
chances of success have entirely failed. Among the undertakings of this
kind which have been the most costly and the most useless, we may men-
tion those which have been carried out in the delta of the Rhone. It was
hoped that, by conﬁning the mass of water in a narrower channel, and
compelling it to run into the sea through a single outlet, a current would
be produced which would be strong enough to clear out the passage to a
considerable depth, and thus to allow ships of a deep draught‘of water to
enter the river. In 1852, Surell, the engineer, closed up the' various
grausf through which the water of the Rhone found lateral outlets, and
lengthened the two banks of the principal month by means of dikes con-
verging one upon another, thus doubling the force of the current. The
water of the river did, in fact, accomplish the work of erosion, and cleared
out the channel; but fresh alluvium bein'g incessantly brought down by
the ﬂow of the Rhone, and thrown up by the waves of the sea, a new bar
* Chabrol, Statistique du Département de Montenotte. ‘
1' From the Latin gradus, a step, passage. In the‘ south of France this name is given to
the outlets of rivers, which connect the shore lakes with the sea and the mountain deﬁles.
368 THE EARTH.
formed across the mouth outside. Before the operations of banking were
begun, the average depth of the channel was 5 feet 10 inches; at the pres-
ent time it is the same, after having varied from 13 feet to 6% feet, and
3 feet 8 inches, according to the quantity of water sent down by the
current.*
A similar undertaking, attempted in 185 7, in the southwest channel of
the Mississippi, had not a more favorable result, a curvilineal jetty 1849
yards in length having been carried away by a tempest. However, the
commissioner appointed by the federal government to study the course
of action of the delta of the Mississippi recommended the reconstruction
of convergent jetties as being a plan which was likely to keep the chan-
nel clear. Looking forward to the constant increase of the alluvium of
the river in the now contracted channel, they advised, besides, as an indis-
pensable matter, that the jetties should be lengthened about 245 yards
every year, leaving it open to abandon a channel and choose a fresh one
when the dikes of the ﬁrst outlet should have attained any immoderate
length]L These operations would be enormous in their character; but if,
as was hoped, they would result in maintaining a depth of more than 19
feet in the channel, a tax might be imposed every year on the immense
commerce of the Lower Mississippi which would be amply suﬁ‘icient to de-
fray the costs of construction.
The Adour, which does not carry down to its mouth such large quanti-
ties of alluvium as the Rhone and the Mississippi, is one of those few riv-
ers where engineers have obtained, at least temporarily, favorable results.
Besides, it must be confessed that the works undertaken for the improve-
ment of the bar have lasted for a good many years; for it was in 1694
_ that Ferry, the engineer, constructed at the southern point a jetty which
was to ﬁx and deepen the channel, and since this date there has been no
cessation in this interminable labor. The lateral dikes have been carried
on to the sea, either in rock-work or by means of piles, and tending in va-
rious directions, which were adopted, in despair, after each successive fail-
ure. Finally, from 1855 to 1860, the jetties of the two points were slight-
ly bent round to the north, and continued, to an equal distance into the
sea, to a point 550 yards from the shore. The northern jetty, resting upon
a base of rocks hidden under the water, is constructed with openings along
all its length, and allows the current to ﬂow between the piles. The
southern jetty, which was to prevent the mouth from bending round to
the south, is solid for a length of 220 yards, and keeps the bar tending in
a direction leading to the coast. Since these operations were ﬁnished, the
' condition of the river-mouth has been subject to much change. In Febru-
ary, 1862, when the level of the water was very low, a bank of sand form-
ed exactly across the mouth, and compelled the water of the Adour to es-
cape laterally through the openings between the dikes. Nevertheless, the
general state of the channel exhibits a considerable improvement. The
* Minard, Des Embouchures des Riviéres Navigables.
'l' Humphreys and Abbot, Report on the Mississippi River.
BARS OF RIvRRs. 369
channel has taken a ﬁxed direction toward the west, and no longer spreads
out to the south; the bar has been driven far out to sea, but the average
depth of water on it is greater. Before the improvements were begun, at
low water it was covered with only 5 feet to 5 feet 10 inches of water;
the depth is now as much as 10% feet. This is an immense result, which,
according to the calculations of an author who is suﬂiciently skeptical in
matters of this kind,* represents a clear annual gain of forty thousand
pounds for the commerce of Bayonne. If, in the future, the bank of shin-
gle should attain to the same height as before, it would be necessary to
again lengthen the jetties of the Adour for several hundred yards into the
gulf, and, by means of the experience already acquired, the engineering
operations would again produce a considerable temporary improvement.
According to M. Bouquet de la Grye, whose opinion is a very valuable
one, it would be a very useful measure if the barriers were curved round
in a southwesterly direction, so that the waves from the oﬂing should not
beat directly in front of the current and ebbing tide. But the chances in
favor of any decisive amelioration of the bar must be much increased in
proportion as the jetties are lengthened. When these-artiﬁcial promon-
tories, like headlands, are surrounded by a deep sea, the débrz's which the
currents and waves deposit at their base will be no longer incessantly agi-
tated by the breakers, and thus raised into the form of a bar; they will
accumulate but slowly, and a long series of years, or even centuries, must
elapse ere they could seriously modify the submarine featuresf
The operations undertaken at Soulina—one of the mouths of the Dan-
ube—appear to have met with great success, but through an entirely
special cause. Mr. Charles Hartley, the skillful constructor of the Soulina
jetties, has taken care to push them out more than a hundred yards into
the sea, as far as a point where a current generally passes along the shore
tending from north to south. This current catches hold of all the alluvi-
um which glides down over the bottom of the bed of the river, and thus
hinders the formation of a fresh bani The average depth of the channel,
which was only 9 feet before the commencement of the works, is now
not less than 16% feet since the dikes have been constructed. It is cer-
tainly a fact that the gradual encroachments of the whole delta of the
Danube will have the effect of pushing the current itself farther out to
sea, and sooner or later a second mound of sand will obstruct the mouth
of the Soulina. According to an approximate calculation, based, howev-
er, on plenty of hypotheses, the works ﬁnished in 1860 will not become
completely useless until the year 1916.§
There are other mouths of rivers, especially those of the Oder in Prus-
sia, and the Meuse in Holland, which have been permanently improved
by engineering operations; we are not, therefore, entirely warranted in
* Minard, Des Embouclzures des Riviéres Navigables.
‘l’ Mongol-Bey, Percement dc Z’Isthme de Suez.
' I Zeitschriftﬁir Allgemeine Erdlcunde.
§ Engelhardt, Etudes sur les Embouchures du Danube.
A A
370 - THE EARTH


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Fig. 146. Mouths of the Danube. Arms of Kilia and Soulina.
repeating the words of Vauban, and characterizing all the bars of naviga-
ble rivers as “incorrigible.” The results obtained on the Clyde, in Sect-
land, may especially be classed among the most important triumphs of
engineering art. The water of that river was once so very shallow that
ships of a deep draught of water were compelled to stop 15% miles below
Glasgow, and the merchandise had to be reshipped in barges; at the pres-
ent time great three-masters easily come up close to the .quays. Besides,
in a great many cases it might, perhaps, be possible to divert the mouth
of a river in places where it was not possible to force a passage, and thus,
by indirect means, to obtain the depth of water necessary for large ships.
BARS 0F ‘RIVERS. 371


Fig. 147. J etties of Soulina.
A deepcanal, protected against alluvium by a system of sluices, would
then replace the natural channel. This plan, according to MﬁBesjardins,
is that which was adopted by the ancients in the case of the Tiber and
the western branch of the Nile, which was diverted toward vlexandria.
This plan, too, has been proposed by several American engineers-‘for insur-
ing to New Orleans a magniﬁcent port worthy of the river which bath'es
its .quays. Moreover, a work of this kind is being carried ‘out at the
mouth of the Rhone by the digging out of the canal of St. Louis. This
navigable channel is 2% miles long and 66 yards wide, and is intended to
connect the river with the Gulf of Fos—so called from a former navigable
canal dug out by Marius (fossce marz'cmce). Vessels drawing 24 feet of
water will thus be able to ascend as far as the port of Arles, which at the
present day has been almost abandoned by commerce, on account of the
deﬁciency of water in the channels of the Rhone. If the excavation ‘of
the canal of St. Louis meets with success—which scarcely seems a doubt-
ful point—this great undertaking will serve as a model for the subjection
of other 'mouths of rivers, which, up to the present time, have continued
rebellious to the operations of engineers. \ - "
372 THE EARTH.
CHAPTER LV.
ALTERATION IN THE POSITION OF WATER-COURSES IN CONSEQUENCE OF
THE ROTATION OF THE EARTH.-—MASSES OF WATER BROUGHT DOWN TO
THE SEA BY RIVERS—GENERAL CONSIDERATIONS.
THE sudden changes in river-beds produced by the rupture of their
dikes, as well as the movements, and even obliterations of their mouths,
constitute, generally speaking, catastrophes of a serious character, and it
may readily be conceived that the imagination of man has looked upon
these incidents as among the most important facts in the history of rivers.
Yet this is not the case. However great may be the inﬂuence of these
sudden modiﬁcations in the action of water-courses, they are but phenom-
ena of a secondary class in comparison with those more durable changes
which the rotation of the earth brings into the economy of every river
and the general physiognomy of its basin. The fact is, that the water of
rivers, like that of the ocean and the aerial waves, is subject to the inﬂu-
ence of all the great astronomical laws. Rivers, as well as the winds,
have a natural tendency to shift their course, so as to effect an arc of rev-
olution round the planet.
In fact, the running water which the earth carries round in its diurnal
movement is affected differently from the solid bodies which lie upon the
ground. .While the latter, just as the mere: inequalities in the terrestrial
surface, describe their daily orbit round the central axis, the ﬂuid parti-
cles which glide over the rotundity of the globe traverse in succession
various latitudes, and their movement consequently varies. The speed of
rotation being completely nulliﬁed at the mathematical points which act
as poles, and increasing gradually as far as the equatorial regions, where
it exceeds 1470 feet a second, every thing movable which tends from one
of the poles to the equator must necessarily remain in the rear of the in-
creasingly rapid terrestrial movement which carries it round, and must
consequently deviate toward the west—that is, to the right hand in the
northern hemisphere, and to the left in the southern. In like manner, any
movable body which takes its course from the equator to one of the poles
exceeds—owing to its acquired speed—the angular movement of the globe,
and inevitably deviates to the cast; that is, to the right in the northern
hemisphere, and to the left in the southern. These facts have been ren-
dered perceptible by the celebrated experiments of M. Foucault on the
pendulum of the Pantheon; and they can easily be veriﬁed by every one
by causing the rotation of two suspended globes, and by allowing some
colored liquid to glide over their surfaces.* The trade winds and all at-
* A. Herschel, Intellectual Observer, November, 1865.
DIRECTION OF RIVER-00 URsRs 3573
mospheric currents obey this law of deviation, as well as the Gull Stream
. and the other ﬂows of the ocean. Even balls rushing from the mouth of
a cannon are subject to this law; and sometimes the locomotives on our
railroads, when they run off the lines. This law applies equally to all
water-courses, and—provided that the conﬁguration of the ground allows
it, and that the oscillations of the terrestrial surface do not hinder it—it
causes running water to deviate regularly to the right in the northern
hemisphere, and to the left in the southern. With regard to those rivers
which ﬂow in a line parallel to the equator, there is no force which com-
pels them to eat away either one or the other of their banks; but they
are retarded in their course if they ﬂow to the east, and are, on the con-
trary, accelerated if they run toward the west.
This is the law which, for some time past, several geographers have
pointed out; which, however, M. de Baer has had the honor of completely
bringing to light. The only diﬂiculty is to make a choice among the nu-
merous rivers which may be mentioned as examples of water-courses mod-
ifying their course in the direction presupposed by this theory. South of
the equator there are the aﬂluents of the gigantic Rio de la Plata, which,
after having watered on the west the extent of the Pampas, are incessantly
wearing away their left banks. In the northern hemisphere there is the
Euphrates, which endeavors to pour itself bodily into the bed of the Hin-
diah, to the right of its own course ;* there is also the Ganges, which aban-
dons the town of Gour, in the midst of the jungles, and shifts in its delta
four or ﬁve miles to the west); There is the Indus, wearing away the
stony hills of its western bank, so as to move its delta for more than 600
miles in that direction. There is the Nile, leaving its ancient bed in the
Libyan desert, in order to carry its waters by the side of the Arabian
chain of mountains. In like manner, in Europe, the Gironde, the Loire,
and the Elbe wear away the escarpments of their right bank; and the
Vistula deepens its eastern mouth at the expense of that to the left. The
Rhine, in the plains of Alsace, is gradually increasing its distance from the
base of the Vosges, and is approaching the mountains of the Black Forest;
and so long as its course was not ﬁxed by the continuous rampart of its
embankments, it constantly gained on the territory of Baden, and bent
round to the west of the hills, along the foot of which it had previously
ﬂowed.I A still more remarkable fact is exempliﬁed by the Danube,
which passes in succession through a series of deﬁles, and always develops
its windings toward the right below each gate of rocks through which it
has to pass. The river shifts its place under the inﬂuence of the move-
ment of terrestrial rotation in the same way that a cord fastened at cer-
tain points would bend under the inﬂuence of a current.§ Thus, when
entering the plains of Hungary, which were once a vast lake, the Danube,
* Mittlzez'lungen van Petermann, vol. xi., 1862.
'l' Ferguson, Zeitsclzriftfiir Erdlcunde, April, 1864.
I Bourlot, Variatioas dc Latitude et de' Climat.
§ Von Siiss, Der Baden der Stadt Wien.
374 A . THE EARTH
instead or crossing ‘diagonally the level tract bathed by its waters, bends
suddenly to the south, and thento the east, so as to take the course of the
great central depression round the high ground on its right. ,
InEuropean and Asiatic Russia the normal displacement of rivers affords
an ‘especial opportunity for most interesting studies. In these countries,

I _ o’ u u u
j \ _ '. _ w“
~Kuan


- '1 - \d‘i
u_ , u “('1
Fig. 148. Middle Course of the Volga.

in fact, all those conditions are united which are most favorable to the
gradual encroachment of the rivers on their right banks; they have a
very considerable length of course, andthe liquid masses are powerful
enough to readily clear away any obstacles; there are enormous ﬂoods
which periodically increase the force of efbsion in the currents, and the
DIRECTION OF RIVER- 00 mars. 375
cliffs are composed of friable rocks; lastly, the sharp curvature of‘
globe is the cause of a rapid change inthe speed of rotation in the vari- ,
ous latitudes. Two centuries ago, the principalmouth of the Volga ﬂowed
directly to the east of .Astrakhan; since that time the great current‘ has
successively hollowed out for itself fresh beds“, tending more and more to
the right; and at the present day the branch navigated by vessels turns
to the south-southwest. Above the delta the river has every where shifted
its bed toward the west, and opposite Tcherno'i-Iar, the Achtouba, the
former bed of the Volga, now lies 12% miles from the principal current.
The twenty-three towns which have been built on the western bank, also
called the upper bank on account of its high cliffs, have been almost ‘all
demolished in detail, house by house, and street by street, and, being thus
undermined on one side, they have been compelled to advance on the other
into steppe-land. On the east, the plains once washed by the river are
scarcely raised above the'average level of the water: during inundations
they are converted into perfect seas; therefore the people have not been
able to build more than three towns on the eastern bank. One of these
towns—Kasan—was once situated at the conﬂuence of the Kasanka and
the Volga, but is now two miles from the latter river; it has, so to speak,
traveled to the east. In Siberia the water-courses move to the right still
more rapidly. The modern towns of Yakutsk, Tobolsk, Semipalatinsk,
and Narym have already been partially rebuilt. Along these water—
courses, the right bank, which is undermined by'the current, is almost in-
variably higher than the left bank bordering on the tozmdras, which once
served as the bed of the river. This is a fact of such a-general nature
that map-designers admit it as an axiom, and never fail to draw the right
bank as being the highest and the most escarped.
A large number of rapids and cataracts—among others, the magniﬁcent
falls of Trolhata—also afford examples of a continuous displacement pro-
duced by the rotation of the globe. Similar phenomena are likewise ob-
served in those river-like arms of the sea which are formed by the sea~
water passing through a narrow channel; thus the force of the current
is exercised mostly on the right-hand side in the Straits of Kertch and
\\ \\


Fig. 140. Left and Right River-banks;
the Bosphorus, and the greatest amount of erosion takes place on’ this
side. The law is of general effect, and applies to all the rivers which ﬂow
on the surface of the earth. The great rushes of water in former geolog-
ical periods have likewise in their ﬂow worn away the ground on the
37 6 ' THE EARTH.
right-hand side. In the north of the Pyrenees, the gases, which radiate
so remarkably round the plateaux of Lourdes and Lannemezan, all ﬂow
through valleys of erosion, commanded on the east .by high cliffs worn
away at their base, and on the west by long slopes of easy access, on
which the debris are deposited.*

a.
Fig. 150. Radiation of the “ Gaves,” North Pyrenees.
Among the important rivers which, in consequence of local circum-
stances, seem to contradict this law of the displacement of running water,
we may mention the Mississippi and the Rhone. Instead of gaining on its
right bank, and eroding the base of the heights which rise on the west,
the great American river impinges in ﬁfteen places against the cliffs of
the eastern plateau, and, throughout the whole of its course, constantly
tends toward the left. As soon as it enters the marshy plain of its delta
at a point below Baton Rouge, it ﬂows almost in a straight line toward
the southeast, to form the remarkable peninsula of mud through which it
falls into the sea. It must be remarked that the direction taken by the
water of the current of the Mississippi is exactly the same as that of all
the rivers which run into the Gulf of Mexico—the Rio Grande and its af-
ﬂuents, the Rio Pecos, the Nueces, the Colorado of Texas, the Brazos, the
* Leymerie.
DIRECTION OF .RIVER~ CO URSElS'. 377
Trinity, the N eches : these rivers, which uniformly tend toward the south-
cast, are parallel to the ridges of the Rocky Mountains. If it is a fact,
as many geologists seem to have established, that the western chains of
North America are undergoing a movement of upheaval, while the Caro-
linas, Georgia, and other neighboring regions are gradually subsiding, it
might very well be the case that the lower course of the Mississippi and
all the Texan rivers tends to the east, in consequence of the slow move-
ments of elevation and depression to which the North American continent
is subjected.*
With regard to the Rhone, the mouth of which likewise ﬂows in a south-
east direction, instead of tending to the right, as it once did, and follow-
ing the vast bed now adopted by the smaller Rhone, it is possible that its
course may have been modiﬁed during historic periods by the impet'uosity
of the .Mz'stral. However strange an assertion of this kind may appear
at ﬁrst sight, it perhaps merits‘ the attention of geographers. In fact, it
seems a matter beyond all doubt that, in consequence of the gradual cut-
ting down of the woods of the Cevennes and the central plateau of France,
the Mistral has continued to increase in violence since the ages of the R0-
man occupation. If this be so, this turbulent wind must necessarily impel
the waters of the Rhone toward the left bank in the direction theyare
taking at the present day. The aerial current beating down from the
Cevennes on the marshes of the Oamargue must necessarily have pressed
upon the current of the river, and marked out for it the line which it had
to follow in hollowing out for' itself a fresh bed. Every thing in nature
takes its share in eﬁ‘ecting modiﬁcations; every feature in the. planet owes
its form to the breath of the winds, the currents of the waters, and the
movements of the soil, quite as much as to the motion of the globe in space.
Rivers, taken as a whole, being merely the arterial system of continents,
renewing ‘the liquid mass of the seas, whence the waters return again to
the interior of the land in the form of clouds and rain, it is important to
know, at least approximately, the quantity of river-water which is ﬂowing
on-th‘e surface of the globe. For many years back, various hypotheses
have been regarded on this point; but any very precise data are still
wanting, and nothing but observations taken for a series of years will
render it possible to arrive at any accurate knowledge of this hydrologic-
al fact, so important in the economy of the globe. Buﬂ'on supposed that
the mass of water emptied out by the whole of the rivers running into the
sea would represent, in 812 years, a quantity of water equal to that of the
ocean; but the data on which he based his supposition are not of sufﬁcient
authority to render it of much use to discuss his opinion at the present day.
Among the most important calculations which have been recently made,
taking as their starting-point the quantity of rain falling annually on the
earth, we must mention that of Metcalfe. He estimates the total massof
water brought down by the rivers at 176,000,000,000 of cubic yards of
water every day. Keith Johnston considers that the daily average dis-
* Vide the chapter on “ Upheavals and Depressions.”
378 - THE EARTH
charge of the rivers of the earth is 229,000,000,000 of ‘cubic yards, or
more than 2,620,000 cubic yards asecond. -- '
This estimate is certainly much too high, for, by adopting another meth-
od, more in conformity to the rules of direct observation, and consequently
morescientiﬁc—that is, by adding up the masses ‘of water rolled down by
the rivers which have been already gauged in various parts of the world
by engineers and geographers—we ﬁnd that the total discharge ‘of a col-
lection of river-basins-comprehending an area of 4,246,000 square miles
does not exceed a little more than 72,000 cubic yards a second. Now
these basins, whichare those of the principal rivers of \Vestern Europe,
including the Danube,* as well as those of the Nile, the Chat-el-Arab, the
Ganges, the Hoangho, the Mississippi, and the Atrato, form a tenth part
Amazon 91,038.
a I a .Mississippi


‘I. I O 6,862.
. . . Danube 15,626.
. . . Rhone 8,405.
. . . RhIme 2,583. i
0 0 0 0 o o 7,388.
0 0 o Ganges 0 o o Ems-ho

Po 2,269
_. . . - Nile 4,816.
i ' Fig. 151,. Diagram showing the Comparative Discharge of Rivers, in Cubic Yards.
of the terrestrial surface,‘ the waters of which ﬂow down to the ocean.
If, therefore, the proportion of water which runs from the surface of the
ground into the sea were every where the same, the liquid mass of fresh
water combining with the salt waves would not be more than 850,000
cubic yards a second. We must, however, take into account the enor-
mous quantity of water discharged by certain rivers in the tropical'zone,
andespecially the Amazon, the delivery of which is probably 100,000 to
130,000 cubic yards]l , If, therefore, we add a third to the total river-dis-
charge obtained by the previous calculations, we shall have for the whole
mass a maximum of over 1,100,000 cubic yards a second. This is a quanti-
ty which represents an average fall of about 11 inches of rain over the en-
tire surface-of each basin, an average much larger than that of most of the
rivers which have been studied up to the present time. If we admit that
the average depth of the seas is 5400 yards, the quantity of water which
ﬂows down the surface rivers of the Continent would not equal that which
ﬁlls up the abysses of the ocean until after a lapse of ﬁfty millions of years.
This is evidently nothing but a provisional calculation, which will be
gradually rectiﬁed as the facts relative to the hydrology of the globe be-
* The discharge attributed to the Danube is probably too great; according to M. Hartley,
the real discharge is only 11,123 cubic yards a ‘second.
1' At the deﬁle of Obydos, the section of water which ﬂows every second to the sea is, ac-
cording to Spix and Martins, 23,113 cubic yards at low-water time; in ﬂoods, says Ave-Lal-
lemant, it is 319,476 yards at the same spot.
IS'EDDPIENT 0F RIVERS’. 37 9 ‘
come better known. When the mean discharge of all visible water-
courses is accurately gauged, when the force of subterranean streams has
been disclosed by the investigations of meteorologists as to the fall and
evaporation of rain, then it will be more easy to calculate, within a few
millions, the total mass of liquid which is annually poured into the sea by
the rivers of the continents. No doubt, within a period not very distant,
the measures which have been adopted with so much precision asregards
the Mississippi, the Po, the Rhone, and the Nile, willbe applied with equal
care to the other. river-mouths.
The investigations which have been simultaneously made as to the pro-
portion of sediment which exists in suspension in rivers will enable us also
to resolve the often-discussed question as to the actual importance of the
alluvium of rivers. Without mentioning here the streams which are lit-
erally liquid mud, or sometimes even avalanches of mud, there are some
rivers, like the Missouri, the waters of which are so charged with sediment
that the drift-wood, being completely penetrated with muddy particles, is
ultimately entirely submerged, and covers the bottom of the river.* There .
are, on the contrary, other rivers, such as the St. Lawrence, which send
down to the ocean waterwvhich is generally pure and transparent. Dur-
ing ﬂoods the Durance holds in‘suspension as much as 21 thousandths of
mud ;‘r the Garonne sometimes contains 10 thousandths;1 the vRhine 6
thousandths only.§ It will be readilyv understood that the quantity of
alluvium held in suspension must necessarily vary in differentrivers, ac-
cording to the more or less compact nature of the soils throughwhich they
pass; thus observations made on any particular water-courséhave noth-
ing more than a local value. The estimations made by various geogra-
phers as to the average quantity of alluvium contained in running water
differ prodigiously one from another. In the last century, Eustache Man—
fredi, who, taking account of the enormous deposits produced by the Po,
exaggerated the work of- this kind accomplished by other rivers, and esti-
mated the average proportion of muddy matter at Tim of the liquid mass
of rivers. But in this estimate he doubtless included the sand and mud
which are impelled by the current along the bottom of the bed, the bulk
of which is probably twice as large as that of the ﬂoating matter. Hart-
soeker, in his Traité dc Physique, admitted that the proportion of alluvi-
um was 1&6; while another author of the same epoch, thewriter of. the
Rec/terches Philosophz'gues sun Zes Amérz'caz'ns, was led by his observations '
and calculations to ﬁx the amounts of debris existing in the water of riv-
; ' l
913 at The diﬁ‘erences between the various estimates are naturally quite as
great when an endeavor is made to reckon approximately the time that it
* Continental Monthly, June, 1864.
‘t Payen. The average for the whole of the year is not more than one thousandth.
I Baumgarten. § Payen.
ll This question is treated on in detail in Von Hoif’s work, Verc'z'nderungen derErdoberﬂiic/ze,
vol. i. . . _
380 THE EARTH.
would take for the alluvium emptied out at the mouths of rivers to raise
the level of the ocean to a given point. Manfredi supposes that the de-
tritus carried down to the sea would be suﬂicient to raise its bed a yard
in 3300 years. Tyler thinks himself warranted, by his’ calculations as to
the alluvium of the Mississippi, in asserting that the deposits of rivers
would elevate the level of the ocean only two inches in 10,000 years, or
about a yard in 180,000 years. These are estimates of a very different
character; but when one reﬂects on the greatness of the sea, and on the lit-
tleness of rivers compared with the immense reservoir, even the last-named
estimate seems too high. If we admit that the average proportion of the
earthy matter carried down into the sea is about ﬁlm of the entire liquid
mass of rivers, and if we adopt, as the total discharge of running water, the
approximate quantity to which the critical examination of the known facts
of ﬂuviatile hydrography has led us, we shall ﬁnd that the mass of allu-
vium deposited every second at the mouths of rivers would be equivalent
in bulk to 436 cubic yards, or every year a body of matter equal to 4000
square miles in area, and a yard thick. This, however, would be an al-
most inﬁnitesimal quantity in comparison with the enormous abysses of
the ocean. *
Yet the earth belongs to all time, and during the course of ages any
geological work must ultimately be accomplished. These rivers, almost
imperceptible, so to speak, in comparison with the ocean, are gradually
eating away mountains and plateaux, and ﬁlling up the abysses of the sea
with their accumulated debris. These deposits have the effect of raising
the average level of the waters of the ocean, and of causing them to cover
low shores. There is, therefore, a double cause operating in the modiﬁca-
tion of the relief and outline of continental masses. If the only force in
action on the surface of the globe was tha-t of running waters, the elevated
parts of the earth would be constantly becoming lower, the sea would in-
cessantly encroach on the coasts, and, sooner or later, the planet would
become an immense globe, covered with a thin sheet of water. Owing,
however, to the geological movements of the earth’s strata, a transforma-
tion of this kind is not to be dreaded; but still, from the action of the wa-
ter of rivers, continents and seas are undergoing changes of the very high-
est geographical importance. The Baltic Sea has already become some-
thing between an inland sea and a chain of fresh-water lakes. The liquid
mass poured into it by rivers continues always the same, while the area
and depth of its basin are constantly diminishing. In the long course of
ages, its water will ultimately become perfectly fresh, and the straits of
the Sound will be only the European St. Lawrence.
Some day, Bory de Saint Vincent tells us, the Mediterranean itself will
become nothing more than a chain of lakes, and then a gigantic river.
The Sea of Azof is already being gradually converted into a stream, as its
shores are getting nearer and nearer together, while its bed remains per-
ceptibly the same.* The tracts of water which extend from the mouth
* Zeitsclzriftfiir Erdlcunde, May, 1862.
VALUE OF RIVERS. 381
of the Don to the Straits of the Dardanelles might be compared to the
Lakes Superior, Huron, and Michigan; the isles of the Archipelago will
some day overlook a labyrinth of lagoons similar to those which border
the Baltic Sea; the Gulf of Venice will be only an elongation of the val-
ley of the Po; and the two great basins of the Mediterranean, separated
by the Siculo-African bar, will become two lakes of increasingly contract-
ed dimensions, the waters of which will feed the greatest river in the
world. Then the Dnieper, the Danube, and the Po will be but mere trib-
utaries. Perhaps even the Nile, which is now of no great size at its mouth,
may lose all its water by means of evaporation before it reaches the Med-
iterranean Sea, and will become nothing but a water-course of an entirely
continental character, such as the Chary, the Houach, and the Jordan.
Certainly it would be diﬂicult to exaggerate the importance of the part
played by rivers in the history both of the earth and mankind. They dis-
tribute uniformly the snow and rain which fall at the various points of
their basins, and fertilize the whole territories by their innumerable rami-
ﬁcations. They powder up the rocks of the mountains, and spread the
matter which results in fertile alluvium over the plains, forming also new
tracts of land at their months. They equalize climates. Rivers coming
from the south warm with their vapor northern districts, while rivers
ﬂowing in a contrary direction moderate the heat in more southern lati-
tudes. Added to this, water-courses, those powerful workers, do not limit
themselves to carrying down water, alluvium, and climate ; they also roll
down in their ﬂow'the history and life of nations. The course of the riv-
er’s current is the path down which descended the canoe of the savage
warrior, and is now the highway for the ﬂeets of commerce bearing peace
and comfort. Steam has converted rivers into roads, which can be trav-
ersed both in a downward and upward direction, and a ﬂoating popula-
tion is constantly pervading their surface. Far from forming a barrier to
nations, rivers are the means of mobilizing them: they are continents set
in motion. Aided by rivers, the mountaineers of the Alps and Pyrenees
make their way to the Atlantic and the Mediterranean, while the inhab-
_ itants of the sea-coast ascend to the elevated districts in the interior of
the continent.
In the present day water-courses no longer assume, in the history of civ-
ilization, the high importance they once possessed, for now they are not
the only ways of communication between nations. No river can now be
all that the Nile was to the Egyptians, at once their father and their god,
the cause from which sprung both a race of husbandmen and also the
harvests which they gathered on the river-mud, warmed by the rays of
the sun. Another Ganges, with its sacred waves, will never again ﬂow
over the surface of the earth, for man is no longer the slave of nature.
He can now develop artiﬁcial roads, which are shorter and more speedy
than the roads formed by nature; and this second, and even more vital
nature, which he has created by the labor of his own hands, supersedes
his adoration of that ﬁrst nature which he has succeeded in regulating.
382 THE EARTH -
Nevertheless, rivers will be more important as servants than they have
ever been as gods. They bear upon their waters ships, and the products
with which they are freighted, and serve as arteries to vast organisms of
mountains, valleys, and plains, which are sprinkled over with thousands
of towns and millions of inhabitants. They vivify the earth by their mo-
tion, carve it out afresh by their erosions, and add to it by their ever-in-
creasing deltas. Some day, when the hand of man will be enabled to
guide rivers and to trace out for them their beds, he will employ these
potent workmen to carve out a nature in harmony with his own will; wa-
ter-courses will wear away the hills, ﬁll up lakes, and throw out promon-
tories into the sea in obedience to his orders: their eternal and mighty
vitality will become the complement of ours.
F ORM'ATI ON 0F LAKES. 383
CHAPTER LVI.
LAKES—FORMATION OF LAKES.——-THEIR INCREASE AND DIMINUTION. '—
THEIR FORM AND THEIR DEPTIL—LAKES LYING IN SUCCESSIVE GRADA-
TIONS OF ELEVATION.
CoLLEcTIoNs of water—ponds, pools, lakes, or inland seas—are formed
in every depression of the ground which receives a larger quantity of liq-
uid, either from rivers or directly from the clouds, than it can get rid of
through its aﬂluents, or transfer to the atmosphere in the form of vapor.
Hence arises that inﬁnite variety of lacustrine sheets of water which gives
so much grace or grandeur to landscapes, and exercises such a considera-
ble inﬂuence on the action of rivers, on climates, on the productions of the
soil, and‘ consequently on the development of mankind.
The liquid mass contained in any basin on the surface of the earth does
not increase to an indeﬁnite extent, even when considerable quantities of
water are constantly being poured into it by its tributaries. Either the
basin completely ﬁlls up, and the overﬂow is emptied out through the low-
est depression in its rim, or the lacustrine sheet, gradually enlarging in
area, ultimately presents a surface suﬂiciently extensive for evaporation
to establish an equipoise to the supply of water.
Perfect equality between the mass of water received and that which es-
capes does not, however, exist in any lake, and, consequently, the level
never ceases to ﬂuctuate ; sometimes it rises and sometimes it sinks, accord-
ing to the various seasons and years. After heavy falls of rain, or at the
time of the melting of the snow, some pools are changed into perfect lakes,
in the same way as, during long periods of drought, some lacustrine basins
entirely dry up. The great phenomena of the vitality of the globe—such
as the upheavals and sinkings of the ground, the growth of mountain-ridg-
es, the encroachments or retirement of the shores of continents, the alter-
nations of the winds and rains, land-slips, and the rupture of natural dikes
-all have the effect of either giving rise to and increasing, or of doing
away with or diminishing, the masses of water which are collected in the
interior of continents. Like every thing else which exists on the surface
of the globe, lakes have their periods of increase and decrease, and even
within the limited period during which man has begun to record the an-
nals of his planet numbers of fresh lakes have made their appearance,
while many others have entirely dried up, or have considerably dimin-
ished in extent.
In mountainous regions it is a well-known fact that the fall of rocks and
the advance of glaciers have often caused the formation of considerable
lakes. In like manner, some of the large lakes of the Landes have appear-
384 THE EARTH.
ed since the Middle Ages, owing to the cutting down of the trees upon the
dunes, and the shifting of the latter toward the east.* On the other hand,
instances of lakes which have disappeared owing to natural causes, with-
out being subjected to any human labor in the process of their exhaustion,
are likewise very numerous.
Thus the plain of Oisans, in the Alps of Dauphiny, having been sudden-
ly closed up in 1181 by a downfall of rocks which came from the sides of
the Voudene, the waters of the Romanche, the Olle, and the Vénéon accu-
mulated above the obstacle, and spread out into a lake of 61} miles in
length. Villages, vast plains, and whole forests were swallowed up under
a liquid sheet of an average depth of 33 feet, and the local employment
gradually became that of ﬁshing. The lake existed for thirty-eight years,
and then the barrier of debris suddenly yielded under the pressure of the
water, and the body of liquid rushed like a deluge over Grenoble, and all
the towns and plains on the banks of the Isere. At the commencement
of the fourteenth century, the former lake, which had received the name
of the Lake of St. Laurent, was completely dried up.
The formation of lakes of this kind above some dam of rubbish, and their
disappearance when these dams are broken down, may, however, be con-
sidered as accidental phenomena, and not dependent directly upon climate.
In this latter respect, the changes in level which are exhibited by some
great lacustral sheets, such as the lakes of Titicaca and Van, are much
more remarkable facts. Travelers assert that the area of the immense
Bolivian lake has always been diminishing since the commencement of the
historical period. Its water once bathed the walls of Tia-Huanacu, one of
the principal cities of the Incas; but this locality is now situated 12% miles
from the lake, and more than 130 feet above the level of its water. This
would be a remarkable proof of the increase of dryness on the high pla-
teaux of Boliviaf On the other hand, the height of the Lake of Van con-
tinues to increase—a fact which is conﬁrmed by travelers every year.
The inhabitants on its shores are frequently obliged to turn the sea-shore
roads farther inland; ancient villages have been swallowed up, and in
some spots the ruins buried by the water are still visible. Finally, the
town of Erdjisch, which was once separated from the lake by a great plain,
is nowadays invaded by the water, and the city of Van itself, which was
once far from the shore, is now quite close to it. A legend, which ex-
plains in its own way the constant swelling of the water, relates that some
capricious nomads, having obstructed an outﬂow of the lake, afterward
made useless eﬁ‘orts to re-establish‘the former outlet; but, since this date,
the irritated lake has never left off covering a fresh extent of plain every
year.,’[
As a simple process of reasoning must point out, lakes are most numer-
ous and most extensive in those countries where rain falls in considerable
quantities, and the surface of which, although but slightly undulated, is
* Vide the chapter on “Dunes.” ‘l Pentland; Bollaert, Antiquities.
I Otto Blau, Mittkez'lunyen von Petermann, vol. vii.,l863.
FORMATION OF LAKES. 885
nevertheless formed of compact rocks which do not allow the water to ﬂow
away into the depths below, and retain it as if in natural basins. Of this
kind are the regions of North America, in which lies the fresh-water Med-
iterranean crossed by the St. Lawrence, the YVinnipeg,Winnipegoos, Bear
and Slave Lakes, and several other sheets of water of less extent. In these
districts there is certainly less rain than in the tropical zone, and even than
in most of the countries of the temperate zone; for the depth of rain and
snow water does not attain to more than three feet in a year. But the
granitic soil retains in the shallower depressions the moisture which falls
from the atmosphere; evaporation does not take place actively, and the
slopes toward the different seas are not sufﬁciently inclined for the numer-
ous rivers to be able to pour down to the ocean all the surplus waters.
The island of Newfoundland is also in great part granitic, and is like~
wise covered by lakes maintained by the constant humidity which pre-
vails in those parts of the sea. In like manner, in Europe, the eastern val-
leys of the Scandinavian mountains and the plains of Sweden exhibit a
perfect labyrinth of lakes, some of which are very small, while others
stretch away and are lost on the distant horizon, save where they are dot-
ted over with archipelagoes, rocks, and islets, like the Lake of 'Malar, which


Fig. 152. Lakes ofFinlancI.
contains no less than 1260 islands. On the other side of the Gulf ofBoth-
nia, the granite plains of Finland are sprinkled still thicker with lakes than
B n
386 I THE EARTH
those of Scandinavia itself, so that the whole country may be considered
as an immense sheet of water intersected by innumerable isthmuses cross-
ing one another in every direction. ' 1 ~
Labyrinths of lakes of an altogether similar character are also found in
countries where the soil, although not rocky, lies ‘on a clayey or ochre-ous
subsoil, which is entirely impervious to water. Thus there used to exist
in the French lanclcs a great number of pools which the bed of allos re-
tained on the surface ;* these are at the present time mostly dried up. In
the same way Sologne, Brenne, and some other solitudes in central France
were dotted over with shallow pieces of water. La Dombes, a plateau of

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Fig. 153. The Dombes.
about 300 feet in height, which extends to the northeast of Lyons, between
the Rhone, the Saone, the Veyle, and the Ain, is also covered with a mul-
titude of pools, occupying ‘altogether an area of more than 47,000 acres.
It is a fact that in this part of France man has unfortunately lent his aid
*' Vale above, p. 83.
DIMENSIONS OF LAKES. 38"‘
to the work of nature. Most of the pools of the Dombes are of artiﬁcial
origin, and their being laid dry would cost even less than their construc-
tion. They serve as ﬁsh-ponds for the wretched inhabitants of the neigh-
boring villages, and then, being emptied and cultivated for cereals, they
are again ﬁlled up and stocked with ﬁsh.
The form of a lake always bears some relation to the general relief of
the ground in the depression of which its water is contained; its outline
and the proﬁle of its bed harmonize perfectly with the continental archi-
tecture. The water of alluvial, oozy soil is spread out in vast marshes, in
which it is diﬂicult to point out the precise spot where the dry ground
ends and the water begins. The liquid sheets, of low plains, deserts, and
level plateaux present generally more sharply-deﬁned outlines; but their
depth is but slight in comparison to their extent, and the least ﬂuctuation
in level considerably modiﬁes the line of their banks. The lakes of more
undulating regions are in general tolerably deep in proportion to their ex-
tent, and present bays and promontories of a more varied and picturesque


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,- Fig. 154. Altitudes and Depths ofLakes in Italy and Savov. '
character than the sheets of water in the plains.- But the place where
lakes exhibit all their beauty is round the bases of'lofty mountains. There
torrents run down into them, falling over in rapids and cascades ; green
glens slope down to their very. margin; the spurs of the mountain plunge
straight down into their waters, and the shores between the headlands
are traced out in gracefully-curved bays. By the harmony and variety
of ‘lines presented by their outline, these lakes seem almost a necessary
feature of the landscape, and their horizontal surface, by the contrast
which it affords, gives a more noble appearance to the surrounding moun-
tains. " I '
Lakes, like seas, are in general all thedeeper as the cliffs which over-.
hang them are the more steeply escarped; indeed the cavities which are
388 THE’ EARTH.
ﬁlled up by the water seem to correspond in their dimensions to the height
of the upheaved masses. Thus, tov bring forward no other instances than
those .of the Alpine lakes, the deepest of these lakes are found at the south-
ern base of the Alps, which on this side present their steepest slopes.
Lake Maggiore, the level of which is 652 feet above the Adriatic, is no less
than 2800 feet in depth; the Lake Como is 1981 feet deep in the lowest
u mumnmllllll
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7
Sea level
Fig. 155. Altitudes and Depths of Lakes in North Switzerland.
‘\ \}
part of its basin. The Lakes of Garda and Iseo are not so deep, but still
deep enough to descend far below the level of the sea. If we could sup-
pose the whole body of the Alps cut down to the level of the sea, the
abysses of the water in the Lakes of Maggiore, Como, Garda, and Iseo would
still be respectively 2149, 1318, 518, and 426 feet in depth; while, on the
other side of the Alps, the only lake which has a bed ‘below the level of
the sea-water is perhaps that of Brienz, if it be true, as Saussure asserts,
that it is 1968 feet in depth.* The two annexed plates represent the re-
spective altitudes of the principal lakes of the Central Alps in comparison
with the level of the sea. The results depicted in these plates have, how-
ever, unfortunately only an approximate value; for in the Alps, which
are, nevertheless, visited and studied by so many scientiﬁc men, accurate
sounding operations have not yet been made in some of the most impor-
tant lakes. In each of these plates the depth has been exaggerated a hun-
dred-fold in comparison with the breadth. In order that a clear idea may
be formed of the shape of the Alpine lakes, it is necessary to annex here
the actual outline of the depression of Lake Maggiore, the deepest of all
the lacustral basins in the Alps, and of the Lake of N euchatel, the prin-
cipal sheet of water in the J ura.


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Fig. 156. Lake Maggiore.
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Glancing at a map of the Alps, it is impossible to avoid remarking at
ﬁrst sight that the lakes are distributed in a certain order as regards
* Desor, Schweitzer Seen, in the Album dc Combe-Varz'n.


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Eng? by Erhard

‘ Drawn by Ayuillemm after—1 Seheda
assess. :x. savannas NEW voRx.


LAKES OF THE ALPS AND J URA. 389
the great groups‘ of mountains. Thus the Maritime Alps, those of Viso,
Provence, and Dauphiny, and also the Mont—Blane group, have but a very
small number of lakes, and even these better deserve the name of ponds.
On the east of Switzerland the various ranges of the Alps, which extend
as far as Turkey, are likewise almost devoid of lakes, except in Southern
Bavaria and the districts of Salzburg, where several masses of water ﬁll
up some narrow valleys which open nearly uniformly from south to north
between parallel chains of mountains. The noble lakes which form the


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glory of the Alps are all situated round the central group (of which the
Saint Gothard occupies the middle), and in the valleys and plains which,
under various names, form the western limit of the parallel ridges of the
Jura.
These lakes, which evidently owe their origin to the star-like form of
the chains which radiate round the Saint Gothard, and to the intersection
of the Alpine system by that of the J ura, have in general elongated ba-
sins, tending either from southwest to northwest, or, perpendicularly to
this direction, from southeast to northwest. The waters of the valleys of
the J ura—for instance, the Lakes of Joux and Saint Point—lie in the for-
mer direction, likewise the great bodies of water situated at the base of
the limestone mountains—the Lakes of N euehatel, Bienne, and Morat. The
Alpine lakes of Brienz, Sarnen, and those of Engadine also lie in this di-
rection; and even the lakes on the Italian side, Maggiore and Garde, are
nearly parallel to the lacustral basins and mountainous ridges of the Jura.
On the other hand, the great Alpine lakes of Constance, Zurich, Sempach, ,
Zug, and Thun all stretch in a contrary direction to those above named.
With regard to the two magniﬁcent inland seas of Switzerland, the lakes
of Geneva and Lucerne, they owe their admirable shape to a combination
of the two types. The Leman is a lake of the Jura in its lower part, and
an Alpine lake in its upper part; toward the middle the two sheets meet
and cross one another. In the Lake of Lucerne the two basins cross one
another at right angles, and thus give to the whole body of water the
shape of a cross.‘
It must likewise be remarked that the largest lakes are found on the
courses of the most plentiful rivers, which goes to prove that the same ge-
ological laws have presided in the formation of the valleys and in hollow-
ing out the lacustral basins. The Lake of Constance, the largest of all,
receives the Rhine, the largest river in Switzerland. The Leman is cross-
ed by the Rhone; the Aar ﬂows into the two lakes of Brienz and Thun;
the Reuss enters the Lake of Lucerne, the Linth that of Zurich. An ar-
rangement of this kind can hardly be fortuitous, but must depend on the
general structure of the great'groups of the Alps.
390 THE EARTH.
W In those mountains which possess an architecture of almost perfect reg-
ularity, as, for instance, those of the J ura, it is easy to classify the various
lakes according to the form of the depression which is ﬁlled by their wa-
ters. Thus the lacustral sheets which spread out in a valley between two
parallelridges of mountains generally exhibit outlines which are- scarcely
at all'broken' and disposed in a regular oval; the slopes of the bed‘are
gently inclined toward the'central part, the average depth of which is‘ not,
however, very. great. Here and there, and especially at the two ends, the
banks are marshy, and it is diﬂicult to determine the exact spot at which
the ﬁrm ground begins. Among these valley lakes we may mention those
of J ou-x, Saint Point, and Bourget. ‘
_ ,
Fig. 15s. Valley. Fig. 1'59. Cluse. Fig. 160. Cembe.


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In a similar. way, the combes ‘and cluses which serve as reservoirs to the
lake's confer on thejwater whichithey contain special ‘characteristics very
diﬂ'erent'from'those of the lacustrine basins in valleys. Thus the lakes in
clzises, lying? crosswise toa chain of limestone mountains, are generally
narrow, and the escarpments of the high cliffs whichcofmmand them de-
scend to a great 'dept'h'below the surface of the water. With regard to
the. lakes infcombes, the amphitheatre-likereservoirs 'which contain .them
give to the surroundings v'of'eaclibasin'a magniﬁcent aspect of grandeur
and majesty. Thewater in them is deeper than thatof the valleylakes,
but not so‘d'eep'. as thatof the lakes in ‘chases ,' and it is just in the lower
portion'of thelacustrine icavitythat the section‘ of water presents the
greatest thickness. -
It is, however, but seldom thaté—in the Swiss Alps and other moun-
tainouscountries with a deeply indented'vertical outline—we do not ﬁnd
lakeswhich present.characteristics of all the different types. In some
parts of their basins they are lakes of the valley, and.‘ in others they are
lakeslike those contained in "cluses or combes. For this reason, what a di-
versity of appearance they present in their shores, what picturesque beau-
ty.in the windings of their vbays and the succession of their headlandsl
1 Between mountain ridges which are not arranged‘in long parallel lines
like those of the'Jura, valley lakes are not mere oval sheets of water ;'they
extend-Tin long windings "like the Lakes :Maggio're, Come, and Lu-gano; or
in those valleys in which basins and contractions alternate in succession,
the lakes spread out‘and become narrow alternately. . Numerous instances
of this may be seen in the Scandinavian mountains. . In a general way,
however, theselakes are cut up into several pieces of water lying in gra-
dation, one above the other,'as if on enormous steps, and are connected by

FORMS OF LAKES. 391
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narrow deﬁles, down which the water of a torrent pours in cascades.
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Fie. 161. Stages of Lakes in the Valley of 00.

Lungern, Sarnen, and Alpnach, which are traversed by the River Aar,
may be mentioned; in the Pyrenees, the mountain lakes of Co and La Tet,
392 THE EARTH~
and the lakes of the valleys of Couplan, Aygues-Cluses, and Estom Sou-
biran, belong to the same class of lacustrine basins. In the Carpathians
they form those charming little pools of water to which the name of


Fig. 162. Lakes of Nors Elf.v
“meeraugen” (eyes of the sea) has been given; lastly, in Scandinavia,
lakes situated on graduated levels may be reckoned by hundreds.
FORMATION OF LAKES. 393


'3;
GI
:0
y .3
g 'a
0
m
m
W015i 5 L210:
' :5 G? Glacier a’ d'Estom soubimn
m 8; . a‘
. ‘2
‘Cascades


Fig. 163. Lake-stages of Estom Soubiran and Estom.
There, all the rivers, almost without exception, are, from their source
to their mouth, nothing but chains of lakes connected with one another
by rapids and cascades. They are, in fact, water-courses in process of
formation, which have not as yet hollowed out for themselves regular
beds, but ﬂow in all the natural depressions of the soil through narrow
channels which have been opened since the ground itself has risen above
the level of the sea. The land of Scandinavia having risen only at a re-
cent epoeh by a gradual movement of emergence, which at the present
time is still continuing, thev rivers have not yet had time either to ﬁll up
with débrz's the lakes that they meet with in their course, or to pierce
wide valleys through the rocks.* ‘
* Vide the chapter on “Upheavals and Depressions.”
394 THE EARTH.
CHAPTER LVII.
VARIOUS PI-IENOMENA IN LAKES—COLOR OF THEIR IVATERS—SEICHES—
CURRENTS AND TIDES.-——FORMATION OF ICE IN LAKES.
LAKES are not only distinguished from each other by‘ their shape and
the depth of their basin, they also vary in the appearance of their water,
i and even in this respect the diversity of the matters held in suspension or
solution in the liquid mass is notalways sufﬁcient to explain the remark-
able contrast presented by adjacent sheets of water. The color and trans-
parency of the liquid differ astonishingly in most mountain lakes. Some
are of an emerald green, others of a sapphire blue, a few even have a
milky shade. There are some, indeed, the water of which is transparent,
that have a brown or yellowish color. In every case, whatever may be
the natural hue of each of these lakes, they incessantly vary on account
of the-reﬂection of the rays of the sun, the clouds, or the color of the sky
and the refraction of the light. One lake, the water of which, not far from
thebank, is of a yellowish—green, owing to the rocky bottom just visible
' below the undulations of the surface, is of a deep blue above the invisible
abysses of its ‘central portion. Another lake presents a well-deﬁned dif-
ference of color between the tranquil water of its basin and that'which is
brought in by the rapid current of the'river which. crosses it. ‘ In other
places, again, the eddies light up the surface with reﬂections of a bronzed
or greenish hue; even the particles’ of sand or ooze, as well as the chem-
ical substances dissolved in the water, must necessarily, however inﬁnites-
imal their tenuity may be, tinge the liquid sheet with various shades.
Vegetable mould gives to lakes a color more or less shaded with red or
brown; clay gives them a yellowish tinge. As to the debris of rocks and
pebbles, these, according to Tyndall, are the agents which confer on the
Lake of Geneva and other mountain lakes their lovely azure color. The
most wonderfully transparent water, which, too, is the most devoid of all
impurity, is in general a sea-green hue. It is said that objects are some-
times visible in it'at a depth of 80 and even 100 feet.
All long and narrow lakes, over which atmospheric variations often take
effect in a sudden and violent manner, frequently exhibit abrupt oscilla-
tions of level, which can only be explained by a difference in the pressure
of the air. Such are the sez'ches of the Lake of Geneva and the Rulzssen
of the Lake of Constance, which are noticed sometimes at one point, some-
times at another. In these purely local swellings of the water, the latter
may rise all at once some inches or even a yard above the level of the sur-
rounding surface. The outbreak of ‘subterranean tributaries can not be
taken as an explanation of the cause of this sudden rise, for it takes place
SEIC'HES AND LAKES. 395
at the foot of mountains of a compact formation, which certainly do not
conceal any considerable streams in the depths of their rocks. Added to
this, on the surface of many lakes and inland seas the phenomena of seiclzes
have been observed around islets and more rocks.
Schulten has proved that the sez'c/zes of the Baltic, which are in every
respect similar to those of the Lake of Geneva, are in direct connection
with the height of the barometrical column. ‘Vhen the pressure of the
air diminishes the water begins to swell, and when the barometer again
rises up the surface of the sea sinks, only the'movements of the water are
always a few minutes earlier than those of the instrument, on account of
the greater mobility of the aqueous particles. Now, as the total varia-
tion between the different heights of the barometrical column at the level
of the sea corresponds to a variation of about a yard in a column of water,
it follows that the most considerable sez'c/zes can not exceed this height.
This has, in fact, been veriﬁed by observations in the Baltic as well as in
the Lake of Geneva, and in the great lakes of North America. In the
midst of the open sea seiches would likewise be produced, especially during
hurricanes; but the liquid mass being at full liberty, and able to spread
out freely all round the rising of the wave, the phenomena is there more
diﬂicult to. notice than in narrower lakes.* It is probable that the phe-
nomenon known by the Sicilians by the name of marubia (from mare abri-
aco,“ drunken sea”) is also a swelling of the water accompanied by the
.barometrical depression. It is observed on all the coasts of Sicily, but
especially off Mazzara, at the precise spot where the lllediterrancan, con-
tracting into the form of a strait, is severed into two basins. by a subma-
rine ledge which approaches the surface. Daubeny considers that these
movements of water are a sign of some volcanic vibration of the soil; yet
the description which he himself gives of the movements seems to indi-
cate that they are seic/zes similar to those in theLake of Geneva and the
Baltic. \Vhen the marubz'a occurs the air is calm and the horizon misty ; '
suddenly the water, stirred up in short waves, raises its level about 23
inches, and then, after an interval of from half an hour to two hours, the
south windwbegins to blow, and a heavy storm rises. '
Lakes, moreover, which are, indeed, inland seas of fresh or salt water,
must exhibit phenomena similar to those of the ocean. Lacustrine sheets
of water have‘ also their tempests, their swells, their breakers, and their
bores; and certain bays of Lakes Superior, Ladoga, and Baikal are not
less dangerous than the Black Sea and the Bay of Biscay. The waves
raised by the wind in the more conﬁned areas of lakes are neither so high
nor so rapid as those of the sea, because they have not so vast a ﬁeld on
which they c'an spread out, and because they do not moveover a suﬂi-
ciently great depth of water. They areshort, compact, and “ chopping,”
andfrom this very fact they are more formidable to any ship against
which they incessantly dash. Added to this, the water of most‘lakes being
fresh, and in consequence lighter ‘than that of the ocean, ‘it is also more
?" Anton von Etzel, Die Ostsee.
896 THE EARTH.
readily stirred up, and the wind has scarcely commenced to blow before
the surface of the lake is roughened with foaming billoWs.
With regard to the currents, it is evident that in lakes they can not be
developed with the same regularity as in great seas which lie open and
exposed from the poles to the equator; but currents are nevertheless pro-
duced in every spot where any perceptible difference in temperature exists
between two adjacent regions on the surface of the sea. There is, of ne-
cessity, a ﬂow of cold water toward the sides of the lake whenever the
superﬁcial liquid layers, heated by one cause or another, are comparatively
lighter, and suffer a greater loss from evaporation. Besides these lateral
currents, which are sometimes diﬁicult to be certain about, there are also,
in lakes as in the sea, interchanging currents ﬂowing between the upper
sheet of water and the masses underneath. Moreover, all the rivers which
cross an open lake or fall into a closed-up lake, like the Rhone, the Rhine,
the leuss, and the Jordan, determine the formation of local currents, from
each side of which the water of the basin ﬂows back in a contrary direc-
tion. Lastly, lacustrine basins also have their tides, although these phe-
nomena are generally nearly imperceptible, and are only discovered by a
long and attentive series of observations of the oscillations of the level.
In Lake Michigan the height of the tide reaches to about 3 inches.
One of the most curious phenomena in the lakes of the northern tem-
perate and polar zones is that of the formation of ice. In winter, when
the sheet of water is perfectly still, needles of ice, radiating one from the
other at angles of from 60 to 120 degrees, appear on the surface; then,
joining their net-work together, they soon form a level sheet of ice. On
the contrary, when the water is violently agitated by a storm, the ﬁrst
needles of ice, being incessantly bruised and rubbed against each other,
agglomerate in disks rounded by the friction, and the whole of the con-
gealed mass ultimately presents an uneven surface like that of rivers with
a rapid and violent current. The ice of lakes is generally much more reg-
ular and transparent than that of water-courses, in which the process of
crystallization is nearly always being disturbed. When a prism of this
pure ice is exposed to the inﬂuence of a ray of the sun concentrated upon
it by a lens, a multitude of little corollas, with six sepals arranged round
a glittering point, suddenly appear in the thickness of the prism. This is
one of the most charming sights which the beauties of nature can present
to the eyes of an observer.*
When the whole extent of the covering of ice is solidiﬁed over the
water, it does not remain immovable until the thaw; on the contrary, it is
constantly agitated by various movements, according to the state of the
atmosphere and the phenomena which are going on in the liquid mass be-
neath. If the temperature diminish, the lower side of the frozen crust is
immediately increased by a fresh layer of ice more expanded than the
water; the sheet must therefore necessarily rise and form a somewhat
curved surface. If the cold become less intense, the solid mass conse-
* Tyndall, Glaciers of the Alps.
THE’ 10E OF LAKES. 397
quently grows thinner, and forms hollows in some places. When the level
of the lake rises, owing to any larger quantity of water being poured into
it by its aﬂiuents, the arch of ice is upheaved unequally by the liquid
sheets which ﬂow beneath it. If the supply of water diminish, and the
level of the lake consequently sinks, the solid cover simultaneously gives
way, owing to its own weight, and splits up so as to follow the downward
movement of the water. Lastly, the long undulations which are produced
in the liquid mass by shocks received on the surface, the large quantity
of air which makes its way under the sheet of ice either in considerable
bodies or isolated bubbles, even the gas incessantly being evolved by the
respiration of the ﬁsh, all combine in producing the same result—that is,
the upheaval of the ice. The comparatively thin crust which separates
the hidden water from the great atmospheric ocean is constantly being
drawn sometimes in one direction, sometimes in another. Enormous crev-
ices, generally tending in the direction of the greatest length of the lake,
open suddenly with a terrible crash; the roaring of the air which penetrates
under the icy layer, or which escapes from it, is mingled with the crack-
ling of the breaking crystals; we have simultaneously noises like the roll-
ing of thunder and the rattling of musketry. On that part of the Lake
of Constance which is called the Untersee, M. Deiche has noticed cracks
in the ice which were six miles long and 13 to 16 feet wide.
In the great lakes of North America, and also in those of Siberia, espe-
cially in Lake Baikal, the phenomenon of the formation of ice takes place
in the most magniﬁcent way. During three months of winter, the mighty
Baikal, the inland sea in which seals live and coral-stems grow as in the
ocean, is covered by a ﬁeld ofice, presenting in some places a thickness of
6 to 9 feet. The vast sheet of water, extending over an area ofmore than
1400 square miles, and surrounded by mountains as high as the Alps, and
glittering with glaciers, is nothing but a solid mass, on which caravans of
travelers venture without fear. Sometimes, when the ice begins to form,
a sudden tempest reduces it to fragments, which, under the pressure of
fresh pieces of ice, brought by the waves and currents, are piled up one
on the other, intermingling in a kind of chaos which calls to mind the
séracs of the Alpine glaciers. Subsequently, when the water is entirely
covered with its heavy shell, the latter is occasionally rent asunder, ‘and
shrill whistlings, dull cracking noises, prolonged thunder-like rumblings,
mingled with innumerable partial crepitations, are heard while the ice is
bending and breaking. The water springs out from the ﬁssure in vertical
sheets, and, falling down again on the surface, forms risings on each side
of the crack which is sometimes more than a yard wide. Sometimes a
fragment of the broken layer of ice sinks below the general level; anoth-
er piece, being pressed on in every direction by the frozen masses, curves
perceptibly in the middle. All these movements of the solid crust pro-
duce long undulations in the water beneath. Travelers, borne along rap-
idly in their sledges over the ice of the lake, feel distinctly the shock of
the waves breaking against the lower side of the trembling ﬂoor beneath
398 THE EARTH.
them. On the sides of the cliffs which border on the lake may be noticed
heaps of solidiﬁed ﬂakes, sometimes resembling a cascade; this is the foam
which is jetted out at the time of the violent rupture of the ice, and has
hardened upon the rocks before it had time to fall.* In a general way,
Lake Baikal freezes so rapidly that, according to the statement of the na-
tives, the ice begins by adhering to the bottom of the lake, from which it
afterward becomes detached with a terrible noise, and rises to the surfaced
But this fact, which could not take place unless the temperature of the
deep water was much lower than that of the surface which is traversed by
freezing winds, has not yet been scientiﬁcall y veriﬁed. It is, on the con-
trary, very probable that the water on the bottom remains constantly liq-
uid. At the temperature of 39° Fahr. the aqueous particles acquire their
greatest density, and consequently their heaviest speciﬁc gravity. In obe-
dience to the law of gravity, the layers which are at 39° Fahr. of temper-
ature are those which must lie upon the bottom of the lake, and therefore
ice can only be formed on the surface. The direct observations which
have been made as to the temperature of the Swiss lakes conﬁrm this the-
ory. In the Lake of Geneva, the effects of meteorological variations are
not felt below a depth of 236 feet, and deeper still the constant temper-
ature is 42° Fahr. In the Lake of Constance the temperature is lower;
there it is only 39° Fahr., and in the Lake of Lausanne 39° 12’ Fahr. ; this
comparatively slight excess of heat is probably owing to the natural
warmth of the groundjj Added to this, in the environs of Boston, where
all the small lakes are regularly worked during winter, and furnish for the
demands of commerce more than 200,000 tons of ice a year, the solid layer
of ice has never been noticed to form in the ﬁrst place at the bottom of
the basin.
* Russell-Killough, Seize Mlle Lieues. 1‘ Carl Bitter, Erdlsuna‘e.
1 Buff, Plzysi/a der Erde.
REGULATIIVG ACTION OF LAKES. 399
CHAPTER LVIII.
LAKES ACTING AS REGULATORS OF THE RIVERS WHICH PASS THROUGH
THELL—FRESH-VVATER AND SALT-\VATER LAKES—THE CASPIAN SEA.
0
THOSE lakes which receive a superabundant quantity of water—and
these constitute the most numerous class—give rise to a river which car-
ries oil‘ the surplus of the liquid mass poured into the basin by the upper
afHuents. These lacustrine reservoirs may then be cbnsidered as expan-
sions, to some extent, of the ﬁuviatile valley; in this point of view, the
Lake of Geneva would be the Rhone, and become a hundred times wider
and deeper. The Lake of Constance would be an immense hollow of the
Rhine, containing in its reservoir nearly a hundred times as much water
as all the rest of the river. In like manner, the great inland lakes of North
America—Superior, Michigan, Huron, Erie, and Ontario—form the ﬁrst
part of the course of the St. Lawrence, a river of such slight importance
in comparison to the vast basins which feed it.
The large basins in which the water of a river is spread out before it
again takes its course down to the ocean, regulate the discharge of their
out-ﬂows all the more elﬁciently the more extensive the area over which
they extend. Very considerable inundations in a stream produce com-
parativel y but a slight rise in the level of a lake, because the water has to
be diffused over the whole surface of the basin, and loses in depth all that
it gains in breadth. During the season when the ice is melting—that is,
in spring and summer—the Lake of Geneva rises on the average six feet
above the low-water of winter, and consequently contains a surplus mass
of1,5 72,000,000 cubic yards of water. The gauges used at Geneva estab-
lish the fact that the discharge of the Rhone at its issue from the lake is
at its maximum 753 cubic yards; now, as the various aﬂluents of the lake
supply more than 1400 cubic yards during their highest ﬂoods, it is cvi- ‘
dent that the Lake of Geneva acts as a complete regulator. It keeps
back at least one half of the inundation-water, which it subsequently emp-
ties down gradually when its tributaries have retired to their usual level.
It is certain that, owing to the regulating action exercised over the dis-
charge of the river, the plains on the banks of the middle course of the
Rhone, from Geneva to Lyons, are comparatively protected against ﬂoods.
The equilibrium in the action of the river would be still more complete if
a dam were constructed at Geneva, with ﬂood-gates to regulate at will
the discharge of the water.*
Lakes which are crossed by rivers must be, almost without exception,
fresh-water basins, as the saline particles which are carried into the basin
* L. L. and E. Valle'e, Du Barrage de Genéve.
400 THE EARTH
by one or more aﬂluents are conveyed out of it with the surplus water.
Still, lakes of no great area, which are mostly fed by salt springs, discharge
brackish water through their out-ﬂows. As regards lakes without any
outlet, it is evident that the saline particles brought into them by tribu-
taries can not make their escape, and must consequently be deposited on
the edges, or must more and more saturate the liquid mass. Except they
are fed by afHuents entirely devoid of saline matter, lakes which are with-
out any communication with the sea must therefore more or less resem-
ble the ocean in the composition of their waters. Almost all the lakes
without outlet are ﬁlled with water more or less saline. It must, how-
ever, be understood that the proportionof salt varies in all inland basins,
and the transition is most gradual between the condition of water called
fresh, and that of brackish or salt water.
The largest inland sea devoid of any outlet—the Caspian—is the re-
mains of that great central sea which once extended from the Euxine to
the Frozen Ocean. It is probable that the slow upheaval of Siberia and
Tartary has gradually separated the Caspian from the Gulf of Obi and the
Sea of Aral, and that subsequently the rupture of the Bosphorus, by low-
cring the level of the water of the Black Sea, has laid dry the Ponto-Cas-
pian isthmus, which is now traversed by the waters of the Manytch. Be
that as it may, it is certain that by remaining isolated in the middle of
the land, the Caspian has lost by evaporation a larger quantity of water
than is supplied to it by its tributary rivers; for it has gradually dimin-
ished in extent, and its level has sunk more than 80 feet below that of the
Black Sea. If the Caspian. was again to ﬁll up the whole concavity of its
basin to a height corresponding to that of the adjacent open seas, it would
inundate the whole plain of the Volga below Saratov, and wouldcover the
surface of the steppes for an area of several hundred thousand square miles.
The Caspian Sea is divided into three distinct parts. The northern por-
tion—the bottom of which continues the almost imperceptible slope of the
steppe—is a "ast marsh, which is nowhere more than 48 to 50 feet deep,
which, too, several rivers are constantly engaged in ﬁlling up with their
alluvium. In the southern part of this sea of steppes lies the central ba-
' sin of the Caspian, which is bounded on the south by the promontory of
Apcheron, a prolongation of the Caucasus. The southern basin, mostly
surrounded by high mountains, the escarpments of which extend beneath
the water, is also the deepest. In some spots soundings have been made
of1772 and 2953 feet. , '
The saltness of the water is very unequal in different parts of the Cas-
pian. On the north, the Terek, the Oural, and especially the Volga, bring
down to the sea an enormous liquid mass, so much so that the total salt-
ness is only from 15 to 16 ten thousandths, and at many of the post sta-
tions, where there is a deﬁciency of springs, they drink the sea-water With-
out either dislike or danger. The central and southern basins, on the con-
trary, contain water which is completely salt. It is proved by the exper-
iments of M. de Baer that the average saltness is about nine thousandths:
'Ww-rw— “Ir—Yr—


C'ASPIAN SEA. 401
this is a degree of saltness about one third of that of’the waters of the At-
lantic Ocean.

Fig. 164. Caspian Sea.
Is the saturation of the Caspian diminishing‘ during the course of ages,
or is it, on the contrary, in process of increase? At ﬁrst sight one is
Go


402 THE’ EARTH.
tempted to admit the fact of the increase of the saltness as an evident
matter, since the soil of the surrounding steppes is gradually yielding up
to the sea the salt which it contains. The rain and snow water, when
penetrating through the surface layer of sand, carry with them the saline
particles, and concentrate them in the clayey subsoil. In every place
Where the ground is hollowed out by the ravines, so numerous on the
steppes, the saline clay is washed away by the water, and carries the mat-
ter with which it is charged into the Caspian Sea, either directly or through
the bed of a river. It appears, then, that the waters of the Caspian ought
to present an increasingly large proportion of salt.
Yet M. de Baer, who has devoted more study to this inland sea than any
other Savant, does not believe in any increase in the degree of saltness in
the waters of the Caspian; and, in his idea, if the proportion of salt be un-
dergoing any change at all, it is diminution. In fact, in the plains aban-
doned by the sea, banks of shells are here and there to be met with which
are identically similar to those of the shell-ﬁsh which now inhabit the Cas-
pian. The dimensions of these shells, being always proportional to the
quantity of salt contained in the water, ought to indicate the degree of
saltness of the former sea, and thus give a point of comparison. Now the
shells which are picked up in the vicinity of the Lakia of Elton, more than
200 miles from the present sea-shore, are as large as those of the molluscs
which now inhabit the open Caspian at a point 60 miles from the mouth
of the Volga. Near Astrakhan, where the sea-water, being mingled with
that of the river, must be comparatively fresh, the shells left by the retire-
ment of the sea indicate a degree of saltness equivalent to that of the wa-
ter in the central basin. Moreover, in the environs of Baku, on the sides
of the hills which overlook the water, amid the rocks, shells of molluscs
are found which are much larger than those of the same species now swim-
ming in the sea some yards lower down. This fact alone is suﬁicient to
afford considerable probability to M. de Baer’s hypothesis as to the de-
crease of saltness in the waters of the Caspian. The Black Sea, however,
with which the great inland sea of Russia formerly communicated, con-
tains proportionately twice the amount of salt.
How can this decrease be possible? How is it that the salt brought
down by the rivers and rivulets is able to escape from the vast basin which
has received it, and to separate itself from the sea-water with which it is
mingled? Nothing can be more simple; by the regular movements of its
waves, the Caspian—the same as all other seas—throws up banks of sand
in front of the shallow bays of its shores, and thus converts gulfs and
creeks into lagoons, into which the sea-water runs only through a narrow
channel. Evaporation, which is very active in these regions bordering on
the burning desert, is constantly tending to sink the level of these basins,
while the sea-water, charged with salt, ﬂows in without intermission to
maintain the equilibrium; in this way are formed perfect magazines of -
salt, which are incessantly being increased. When, after heavy storms or
a long continuation of dry weather, the channel which communicates be-
CASPIAN SEA. 403
tween the sea and the lagoon ultimately becomes dried up, the sheet of
water, now completely isolated, diminishes rapidly in area, or is even com-
pletely absorbed by the atmosphere, nothing being left of it but a layer of
salt of variable thickness, which is formed at the expense of the sea. Thus
it is that the lagoons recover from the Caspian the salt which the rivers
of the steppes carry down to it. The only question is to know if equality
exists between the incomings and the outgoings, or if, in conformity to
M. de Baer’s theory, the loss of salt is more considerable than the gain.
A long series of accurate observations could alone solve this problem.
The formation of these saline reservoirs may be studied all round the
circumference of the Caspian Sea. A former bay, situated not far from
Novo-Petrosk, on the eastern coast, is nowadays divided into a large num-
ber of basins, which present every degree of saline concentration. One
basin still occasionally receives water from the sea, and has deposited on
its banks only a very thin layer of salt. A second, likewise full of water,
has its bottom hidden by a thick crust of rose-colored crystals like a pave—
ment of marble. A third exhibits a compact mass of salt, in which glitter
here and there pools of water, situated more than a yard below the level
of the sea. Lastly, another has lost by means of evaporation all the water
which once ﬁlled it, and the strata of salt which carpet its bed are partly
covered by sand. The same facts are found existing farther to the south,
in the environs of the Bay of Alexander, and also quite at the extremity
of the northern basin, at the point where the arm of the sea lies, which is
known under the name of Karasu (black water). The saltness of the Ka-
rasu exceeds that of the Gulf of Suez, the saltest of all the seas which com-
municate with the ocean; in this part of the Caspian the proportion of
marine salt rises to nearly 4 hundredths, and all the salts combined form
57 thousandths of the water; animal life, therefore, must there be almost,
if not entirely suppressed.
Among the thousands of bays and lagoons in which the salts of the
Caspian are stored up, none is more remarkable than the Karaboghaz, a
kind of inland sea which probably connected the Hyrcanian Sea with the
Lake of Aral, and into which perhaps the Oxns emptied itself when this
river was still a tributary of the Caspian. This vast gulf communicates
with the sea by a narrow mouth, which, in its most contracted part, is from
150 to 160 yards wide; the bar will not allow vessels to enter which draw
more than 5 feet of water. A current coming from the open sea is always
running through the strait with a speed of three knots an hour. The west
winds accelerate it, and the winds which blow in an opposite direction re-
tard it, but it never ﬂows with less rapidity than a knot and a half. All
the navigators of the Caspian, and all the Turkoman nomads who wander
or? its shores, have been struck with the unswerving, inexorable advance
of this river of salt water, rolling over the shoals toward a gulf which even
recently none had ever ventured to navigate. In thé view of the natives
this ir‘and sea could be nothing but an abyss, a “black gulf,” as is express-
ed by the name Karaboghaz, into which the waters of the Caspian dive
4:04, THE’ EARTH.
down in order to ﬂow through subterranean channels into the Persian
Gulf or the Black Sea. It is, perhaps, to some vague rumors as to the ex-
istence of the Karaboghaz that we must attribute the statements of Aris-
totle about the strange gulfs in the Euxine, in which the waters of the
Hyrcanian Sea bubble up after having ﬂowed hundreds of miles through
the realms of Pluto.
The existence of this current, which conveys the salt waves of the Cas-
pian into the vast Gulf of Karaboghaz, is nowadays most satisfactorily
explained. In this basin, exposed as it is to every wind and the most in-
tense summer heat, the evaporation is considerable; the water is there-
fore constantly diminishing, and the deﬁcit can only be supplied by a
continual fresh ﬂow. Investigations, which can readily be made in the
narrow and shallow channel of the Karaboghaz, have failed to ascertain
the existence of a submarine counter-current conveying back to the Cas-
pian the salter water of the gulf. It is therefore very probable that it is
the atmosphere only which absorbs the water brought by the Caspian
current; but, though deprived of its water by evaporation, the immense
marsh retains the salt; the saline matter is more concentrated in it, and
the water is more and more saturated with it every day. Already, it is
said, no animal can live in it; seals which used to frequent it are no longer
found there, and even its banks are devoid of all agitation. Layers of
salt begin to be deposited on the mud at the bottom, and the sounding-
line, when scarcely out of the water, is covered with saline crystals. M.
de Baer has made the attempt to calculate approximately the quantity of
salt of which the Caspian is every day deprived for the beneﬁt of the
“ black gulf” Taking only the lowest estimates of the degree of saltness
of the Caspian water, the width and depth of the channel, and the speed
of the current, he has proved that the Karaboghaz receives daily 350,000
tons of salt—that is, as much as is consumed in the whole Russian empire
during a period of six months. If, in consequence of‘ violent storms, or
the slow action of the sea, the bar should close up between the Caspian
and the Karaboghaz, the latter would quickly diminish in extent; its
banks would be converted into immense ﬁelds of salt, and the sheet of
water which might remain in the centre of the basin would become only
a marsh. Perhaps, indeed, it would disappear altogether, like that sea
which _used to lie between Lake Elton and the River Oural, the former
existence of which is made known only by a depression in the ground of
about 79 feet below the level of the Caspian, and 151 feet below that of
the Black Sea. Like a tree letting fall its fruit upon the ground, the Rus-
sian Mediterranean detaches from its bosom the bays and gulfs on its
coasts, and scatters them over the steppe in the form of lakes and pools.
The comparative observations which have been made as to the averzfge
level of the Caspian Sea are not yet numerous enough to warrant us in
admitting, with certain geographers, as a proved fact, that there is a con-
stant diminution of the water in this inland sea. _ We are likewise ignorant
what foundation there may be for the opinion of some of the inhabitants


THE Bueoas OF THE CASPIAN SEA
105 ram of Penn
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OASPMN SEA. 405
of the coasts, mentioned by Humboldt in his Asz'e Centrale, according to
which the Caspian Sea experiences a succession of rises and falls every
twenty-ﬁve to forty-ﬁve years. It seems, however, probable that the
oscillations in its level are of no great importance, and that the quantity
of water removed by evaporation is on the average exactly replaced by
the liquid mass accruing from rivers and rain. An equilibrium is nearly
established between the supply and the loss.
There is one point which is certain, that at the epoch when the Caspian
Sea was separated from the Euxine, its level sank in a comparatively
rapid way on account of the excess of the evaporation. A proof of this
fact may be seen on the sides of the rocks which were once washed by the
waves of the Caspian. At the height of 65 to 80 feet above the present
level of the water, these former shoal-rocks have been furrowed out into
tooth-shaped points and needles; lower down, on the contrary, the rocks
bear no trace of the erosive action of the water, evidently because the
level of the sea sank too rapidly to allow the waves suﬂicient time to at-
tack successfully the cliif walls.
The innumerable indentations which cut into the shore between the
mouths of the Kouma and those of the Oural, and principally south of the
Volga, constitute another ‘striking instance of the rapidity with which the
level of the Caspian must have sunk after the sill of the Isthmus of
Manytch emerged from the water. For a space of more than 248 miles
the shore is gashed with very long and narrow channels, twelve, twenty,
and even thirty miles in length, and throws out into the sea a multitude
of peninsulas, which are prolonged for a great distance into the water by
isles likewise disposed in parallel ranges and separated by long channels.
These tongues of land form a kind of chain, which is interrupted here and
there by the sea-water, and sink by successive falls from isle to islet, and
from islet to marsh. The thousands of channels which separate these
narrow embankments of land are an immense labyrinth, unexplored even
by ﬁshermen; it requires a map of the most detailed character to give
any idea of this strange swarm of isles, islets, channels, and bays.
The buyers, or chains of hillocks which run between the parallel bays,
and farther inland, are connected with the level ground of the steppes,
are in general very narrow, their length varying from a hundred yards to
three or even four miles. They usually rise to the unpretending eleva-
tion of 26 to 30 feet; but some attain double this height. Seen from a
balloon, the ensemble of the bugors would resemble a tract of marshy land
turned up by a gigantic plowshare. Immediately to the west of the
Volga, the limans, or furrows which separate the buyers, are always
changed into rivers. During the inundation of the river, the current
pours into these channels the overﬂow of its waters charged with mud;
then, after the ﬂood is over, the sea again penetrates them, and there is
thus produced in these channels a‘ constant backward and forward motion
between the sea and the Volga. Farther to the south, the narrow valleys
of the limans, not being so often ﬁlled up by the ﬂood-waters, do not, in
406 THE EARTH
general, present a continuous sheet of water, but only a chain of lakes,
separated from each other by sandy isthmuses. ,
If we compare the whole of these ranges of hillocks to a border of fringe
attached to the continent, we shall observe that these fringes spread out
somewhat like a fan, on one side toward the north, on the other toward
the south. They are like the extremities-of radii diverging from a com-
mon centre which would lie in the depression of Manytch, on the ledge
which separates the slopes of the two seas. How can this arrangement
be explained except by the fact of the rapid sinking of the level of the
Caspian waters hollowing out in the soft soil the narrow furrows which so
astonish us? Thus, on the muddy banks of a reservoir when the sluice-
gate is opened, small limans are formed, separated by buyers in miniature.
A very remarkable fact, which again tends to conﬁrm the result of M. de
Baer’s investigations, is that all the bugors of the Caspian shore are strati-
ﬁed, and the superimposed beds assume the form of concentric arches.
The strata of the strongest clay are, as it were, the nuclei round which
are deposited the earth that is more mingled with sand. This distribu-
tion of the strata is owing to the action of the currents of water which
gave to the buyers their present appearance. It may, in fact, be readily
understood that the strata of clay and sand, being undermined laterally by
the water runnin g down the channels, bent over on both sides toward the
currents which washed their bases; hence arise these stratiﬁcations in the
form of an arch. '
DEAD SEA. 407
CHAPTER LIX.
THE DEAD SEA.-—THE SALT LAKES OF ASIA MINOR AND THE RUSSIAN
STEPPES.-—-THE GREAT SALT LAKE.——THE MELR’IR.
ALTHOUGH the Caspian is the largest of all the inland seas, the Asphal-
tite Lake is in some respects the most curious on account of its position in
a deep ﬁssure of the earth, many hundreds of feet below the level of the
Mediterranean. Since Schubert discovered, at the beginning of the cen-
tury, this single instance of a similar depression, it has been ascertained by
exact measurements that, over an area of nearly 186 miles, the whole val-
ley ascending toward the base of Lebanon and lying parallel to the sea-
shore of Palestine is lower than the ocean. Below the small Lake of
Houleh, the River Jordan, which traverses the valley, ﬂows into a cavity
which deepens by quickly recurring steps below the ideal sea-line. The
level of Lake Asphaltites, in which the waters of the river are lost, is 1286
feet lower than that of the sea. The greatest depth reached by the
sounding-line exceeds 984 feet, and is, therefore, 2270 feet below the level
of the Mediterranean. Thus the depression into which the Jordan falls is
deeper than the whole extent of the Adriatic and several other marine
basins in communication with the ocean. Lake Asphaltites, however,
does not merit the name of sea from its depth and its intense saltness
only; it also possesses its principal current, ﬂowing from north to south,
and continuing the course of the Jordan, and its counter-currents ﬂowing
on both sides parallel to the shore.* The surface of the Dead Sea exceeds
460 square miles; but, as is proved by the horizontal layers of gypseous
marl and the beds of salt deposited in stages on the slopes of the sur-
rounding mountains, the level of the lake was formerly much higher than
it is at present ;1 and probably the water ﬁlled all the elongated space
comprehended between the foot of Lebanon and the entrance to Arabah
at the north of the Red Sea. The drying up of the ancient sea of the Sa-
hara, and the consequent diminution of rains and increase of evaporation
is, perhaps, the cause which gradually lowered, century after century, this
ancient sea, called so appropriately to this day, the “Dead Sea.”
In fact, the landscape thoroughly presents an aspect of death. The
rocks are bare; nearly every spot on the shores is sterile; the waters
themselves nourish with diﬂiculty but a few living beings of the lowest
order; the ﬁsh, crustaceans, and insects brought down by the Jordan and
the surrounding mountain torrents immediately die; aquatic plants are
unable to grow. Off the mouth of a rivulet, the Wady-Mojeb, small ﬁsh
* Vignes, Voyage d’ExpIoratz'on a la Mer Morte.
T Lartet, Bulletin de la Socie'te' Ge’ologique de France, vol. xxii.
408 THE EARTH.
are carried as far as a point in the lake where the density of the water is
1115, but beyond this spot they inevitably perish. The only animals that


Fig. 165. The Dead Sea and the Jordan.
have been found in the mud at the bottom are some species of foraminifera,
classiﬁed by Ehrenber , the micrographer. ' This almost complete absence
of living organisms was formerly attributed to the enormous proportion
' DEAD SEA. 409


i
a
W- a‘? @- §§g ,3 .2: E.
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‘2 ﬁe "1 *ée'gE-e‘ﬁa a
'ggﬁmé .'§'n"a<'_§ .5
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- Fig. 166. Section of Palestine from West to East.
1 g, 22.08


of sea-salt which is found in the water of the Dead Sea. This proportion
is, in fact, very considerable, for it is twice as great as that in the Mediter-
ranean ; but there is, on the border of the lake, a small pond, the water of
which is not less salt than that of the Dead Sea, and yet a large quantity
of small ﬁsh live in it, which are immediately killed. by an immersion for
a few moments in Lake Asphaltites.* It is, then, probably chloride of
magnesium and bromine which render the waters of this inland sea so
completely destructive to animal life.
Chemical analyses have shown that the matters contained in the Dead
Sea differ greatly from those of sea-water, not only in proportion, but also
in number. Thus chloride of magnesium is found in this lake in much
greater abundance than sea-salt itself; the proportion of bromine is also
most extraordinary, as it varies from less than15 to more than 67 then—
sandth parts of the water. On the other hand, iodine, a substance the
presence of which is so characteristic of the waters of the ocean, appears
to be completely wanting in the water of the Dead Sea; neither are phos-
phorus, silver, caesium, rubidium, nor lithium found in its water. It must
be concluded that the Lake Asphaltites has never, since its formation, con-
stituted a part of the sea, and that it is not, as was long supposed, an an-
cient prolongation of the Red Sea, separated from the rest of this gulf by
the upheaving of the entrance of Arabah. Ehrenberg, however, had al-
ready come to'this conclusion by ascertaining that notone of the forami-
nifera found in the mud of the Dead Sea belongs to any species discovered
in the Red Sea. M. Lartet thinks that the chemical substances contained
in the water of Lake Asphaltites proceed from thermal springs spouting
out on the shores, and especially from the bed of thelake. One fact which
tends to conﬁrm this hypothesis is, that the quantity of bromine increases
with the depth of the water; it is at 984 feet from the surface that the
largest proportion of this substance is found. <' The fragments of bitumen
which ﬂoat on the surface of the water, and have gained for the basin the
name of Lake Asphaltites, also proceed from the springs in its bed. As
regards the saltness properly so called, it must have naturally increased
by the gradual concentration of the water. When the latter extended
over a larger surface of the country, the proportion of sea-salt dissolved in
' * Lartet, Bulletin de la Socie'te' Geoilogigue de France, vol. xxiii.
410 THE EARTH.
the liquid mass must have been much less. When the sea retires, it of
course leaves a saline sediment; but this sediment is conveyed into it
partly by streams and by the Jordan itself, which empties into the lake
about 90 cubic yards of water a second (‘5’), containing 6% bushels of sea-
salt. At the present time the water of the Dead Sea, the speciﬁc gravity
of which is in some places from 1'230 to 1'250, has almost reached the
point of saturation ; it deposits saline crystals at the bottom, and only dis-
solves to a very triﬂing extent the base of a cliff of rock-salt which over-
looks the western coast.
All the great lakes of Asia Minor, situated at different altitudes be-
tween the two great depressions of the Dead Sea and the Caspian, are
likewise rich in chemical substances. Lake Van, which covers an area of
1544 square miles, especially contains sulphate of soda, which, during the
dry season, when the waters are low, kills all the ﬁsh brought into it by
the tributary streams. Lake Urimiyeh, still more extensive than Lake
Van, is chieﬂy remarkable for the enormous quantity of sea-salt which it
holds in a state of solution; in this respect it is only equaled by the la-
gunes of the deserts and steppes, where the salt is so concentrated that it
is deposited upon the bottom in thick beds. Of this kind is Lake Elton,
to the northwest of the Caspian. The bed of this sheet of water consists
of immense layers of salt, to which each day adds a fresh sediment. In
winter, the rivulets which empty themselves into this small closed basin
bring a certain quantity of brine, which afterward evaporates during the
heat, leaving upon the soil a bed of crystals several inches in thickness.
In summer, when the shores are not covered with water, they appear to
extend as far as one can see, like an immense ﬁeld of snow. Every year
more than 220,550,000 lbs. of salt are extracted from Lake Elton, and yet
the saltness of its waters has not perceptibly diminished.
The Great Salt Lake of America is another Dead Sea, into which falls
another Jordan, and, by a strange historical coincidence, the Mormons
have established themselves upon the shores of this very lake; for this
sect call themselves the successors of the Jews, and the chosen people of
the New IVorld. This inland sea, the real shape of which has only been
known since 1850, by means of the explorations of Stansbury, is one of the
most remarkable lacustrine sheets in the world; it is not less than 248
miles in circumference, but its depth is inconsiderable, and does not ex-
ceed 32 feet; the average is only about 6 feet.
The degree of saltness of the Great Lake varies according to the seasons
and the duration of rains and drought; but it is always much more intense
than that of the ocean. In ﬁne weather, one might go to sleep on the
waves of the lake without fear of being drowned; nevertheless, it is very
diﬂicult to swim in it on account of the effort which must necessarily be
made in order to keep the legs below the surface. A single droplet fall-
ing into the eye causes the most cruel suﬁ'ering, and the Water, when swal-
lowed, causes paroxysms of spasmodic coughing. Stansbury doubts if the
most experienced swimmer could escape death if he were exposed far
from the shore to the violence of the waves and wind. Although the
GREAT SALT LAKE. 411
Great Lake only contains a very small proportion of those salts so destruc-
tive to animal life which are found in the Dead Sea, yet neither ﬁsh nor
molluscs exist in it; life is only represented by sea-weed of the .Nostoc
tribe, and by a small worm which here and there burrows in the sand of
the shores. The trout which are carried into its waters by the Jordan
perish immediately. Nevertheless, the surface of the lake affords hospi-
tality to innumerable ﬂocks of gulls, wild geese, swans, and ducks. Whole
armies of young pelicans, tended by their old lame guardian-birds, contem-
plate the waves from the top of all the ledges of rock, while the parents
go to ﬁsh in the Bear, Weber, and Jordan rivers, all of which abound in
ﬁsh. Not a tree grows upon the shores of the lake nor in the adjacent
plains; the only vegetation to be seen far and wide is tufts of Artemisz'a, and
other plants which delight in a soil impregnated with saline substances.
The line of separation between the water and dry ground is generally
undecided; it is impossible to tell where the shore begins or where the
lake ends, as so much of the shore presents muddy banks upon which the
water spreads in thin sheets and drifts about its ﬂaky foam. Higher up
the shore the mud dries in the sun and peels off in scales, which have the
appearance'of leather; sulphureous exhalations escape from cracks in the
soil, and diffuse an intolerable odor in the air. On the western side, vast
plains, nearly as level as the surface of the water, extend between the lake
and a range of distant mountains. During some of the summer months,
these plains, which are crossed by rivulets loaded with chemical substances,
arecovered by an immense sheet of crystalline salt split up into innumer-
able furrows produced by contraction of the soil. Whenever rain falls, or
even when the air is simply charged with moisture, the salt becomes deli-
quescent, and nothing is to be seen but an expanse of blackish clay, into
which beasts of burden sink at every step they make.
Formerly the Great Salt Lake, like all other inland seas saturated with
salt, spread over a much more considerable area. The parallel basins of
the plateau of Utah, and the lateral valleys which run into them, were the
gulfs, bays, and straits of the inland sea. At a great height above the
present level of the lake, the former alluvial shores and cliﬂ's surround the
valleys withtheir concentric rings traced upon the sides of the mountains.
Even in the plains some distance off, the surface of which exhibits a thin
bed of vegetable earth, the substratum is lake-clay saturated with seassalt
and the sulphates of lime and magnesia. Agriculture, therefore, is nearly
impossible upon these ancient lacustrine beds. In the earliest years of
colonization the damp and virgin earth still produced crops to some ex-.
tent, but subsequently the vegetable soil has'lost its nutritive elements,
and the clayey substratum, coming in contact with the roots of the plants,
withers them up by means of its acrid properties. ‘
Similar causes to those which led to the contraction of the Caspian and
the Dead Sea have constantly tended to diminish the waters of Lake Utah,
and also to saturate them with an enormous quantity of salt. The Great
Basin is separated from the Paciﬁc by high mountains .of comparatively
recent formation, which arrest the progress of the clouds, and prevent them
412 . THE EARTH.
from pouring upon the plateau the moisture derived from the sea. On
the other hand, the evaporation is very considerable upon these high,
rocky, and bare plains, and the winds which traverse them are but little
impeded from carrying the vapors outside the basinv of Utah. _ In conse-
quénce of this constant loss, the level of the Great Lake is become lower,
the streams are dried up, the springs are exhausted, and the salt has con-
centrated more and more in the water. It is probable that, at the present
time, an equilibrium is at length established between the annual fall of
snow and rain and the mists which rise from the surface of the diminished
lake. . Since the establishment of the Mormons in the territory of Utah,
the level of the lake has alternately risenand sunk.*
The various phenomena which take place in the waters of the Great Salt
Lake, as well as in those of the Caspian, Lake Uri'miyeh, and the Dead Sea,
are also produced in a multitude of other lacustrine basins of less impor-
tance, with all the variations caused by the difference of climate, the na-
ture of the soil, and the composition of the water. But as a great num-
ber of these lakes are situated in regions destitute of rain, and owe their
saltnpss to the copious evaporation which has abstracted so large a part
of their Waters, they are, in consequence of this diminution, of very small
area, and have become converted into lagoons and marshes. Sometimes,
indeed, they are reduced) to surfaces which are alternately muddy and
white with salt, when they have been either wetted by some casual rains
or dried up by the solar rays. As a type of these salt-tracts may be men-
tioned the steppes of Huiduck in the Polite-Caspian isthmus,and the Chott


Fig. 167. Lakes of Huiduck.
Melr’ir, a range of marshes which stretch from east to west, over a length
of more than 186 miles to the'south of Djebel Aouress, formerly commu-
nicating with the Gulf. of Great Syrtes by the Strait of Gabes, at present
choked up by sandq‘ These marshes are separated one from another by
isthmuses and islets of dry ground, and extend ‘at unequal levels to 95,
118, 128, 213, 249, and even 27 9 feet below the seal During the rainy
season they are sheets of shallow water, which spread far and wide into
the plains; during the dry season they are ﬁelds of salt, over which the
mirage throws its illusions.
* Fremont, Stansbury, Jules Remy, Engelmann.
1' Vida below, the chapter on .“ Upheavals and Depressions.”
i Dubocq, Me’moire sur Ze Ziban et l'Oued-R’z'r.
MARSHES. . 41 3
CHAPTER LX.
MARsHEs—swxnrs OF NORTH AMERICA.-—PEAT-BOGS.— UNHEALTHINESS
OF MARSHES: '
MARsHEs proper are shallow lakes, the waters of which are either stag-
nant or actuated by a very feeble current; they are, at least in the tem-
perate zone, ﬁlled with rushes, reeds, and sedge, and are often bordered by
trees, which love to plunge their roots into the muddy soil. In the trop-
ical zone a large number of marshes are completely hidden by multitudes
of plants or forests of trees, between the crowded trunks of which the
black and stagnant water can only here and there be seen. Marshes of
this kind are inaccessible to travelers, except where some deep channel,
winding in the midst of the chaos of verdure, allows boats to attempt a
passage between the water-lilies, or under some avenue of great trees with
their long garlands of creepers waving in the shade. Whatever may be
the climate, it would, however, be impossible to draw any distinction, even
the most vague, between lakes and marshes, as the level of these sheets of
water oscillates according to the seasons and years, and as the greater
number of lakes, principally those of the plains, terminate in shallow bays
which are perfect marshes. Some very important lacustral basins, among
others Lake Tchad, one of the most considerable in all Africa,~are entirely
surrounded by swamps and inundated ground,which prohibit access to the
lake itself, and prevent its true dimensions from being known.
In like manner, a portion of the course of many rivers traverses low re-
gions in which marshes are formed, either temporary or permanent, the
uncertain limits of which change incessantly with the level of the current.
The borders of great water-courses, when left in their natural state, are
the localities in which these marshy reservoirs principally exist, which, in
the absence of basins and artiﬁcial weirs, are of very great importance to
the regulation of the ﬂuviatile discharge. The most remarkable marshes
of this kind are perhaps those crossed by the Paraguay and several of its
tributaries; they consist of wet prairies and interminable sheets of water,
which stretch away like a sea from one horizon to the other. They have
received the names of Lakes Xarayes, Pantanal, etc. Farther south, cer-
tain tributaries of the Parana, the Maloya, the Batel, and the Sarandi,
which cross the State of Corrientes from northeast to southwest, are noth-
ing but wide marshes, the water of which overﬂows slowly across the grass
on the imperceptible slope of the territory. There is, indeed, one of these
marshes, the Laguna Bera, which drains simultaneously into the two great
rivers of Parana and Uruguay. These permanent inundations, however,
can not fail to disappear, sooner or later, before the encroachments of cul~
tivation.
414 THEE'ARTE


Fig. 168. Salt Marshes of Paraguay.
In the same way as the low river-shores are frequently converted into
marshes, vast extents of the sea-coasts when but slightly inclined ar' also
covered over by marshes, which are generally separated from the main sea
by tongues of sand gradually thrown-up-by the waves. In'these marshes,
mostof which once formed a part of the sea vand still mark its ancient out-
line; the water presents the-most-varied proportions- of saline admixture.
In! somerpd'aces,when evaporation is very active,‘the liquid ismuch more
salt than the sea itself; but in other spots'the‘ marsh, fed .byfresh water
‘which comes from the interior, is scarcely brackish. The saltness of the
water, however, constantly changes in all parts of the marsh, according to
'the alternations of ﬂow and ebb, and of rainy and dry weather. Thesehalf
dried-upbays are vrarely deep enough to allow of large vessels sailing in
them, and their banks ‘are generally overrun by the most luxuriant veg-
etation. The shore constantly keeps gaining upon them, and thus tends
to the increase of the main land.
The coasts which surround the Caribbean Sea and the Gulf of Mexico,
and also the Atlantic shores of North America from the point of Florida
to the mouth of the Chesapeake, are bordered by a very large number of
marine ‘marshes, forming a continued series over hundreds and thousands
of miles in length. In this immense series of coast-marshes all kinds of
vegetation seem to ﬂourish, and threaten to get the better of the mud
and water, and to convert them into terraﬁrma. To the south, upon the
shores of Columbia and Central America, the mangroves and other trees
of like species plunge the terminal points of their aerial roots deep into
the mud, crossing and recrossing in an arch-like form, and retaining Fall the
clébris of plants and animals under the inextricable net—Workoftheir'natu-
ral. scaffoldings. The shores of the Gulf of Mexico, in Louisiana, Georgia,
. S WAMPS.— Q UAKING-BO GS. 41 5


. ‘I Fig. 169. Marshes of Corrientes.
and Florida, are bordered by cypress swamps, or forests of cypress ( Cu-
pressus distz'cha); these strange trees, the roots of which, entirely buried,
throw out above the layer of water which covers the soil multitudes of
little cones, the business of which is to absorb the air. For millions of
acres nearly all the marshy belt along the sea-shore is nothing but an im-
mense cypress swamp, with trees bare-of leaves, and ﬂuttering in the wind
their long hair-like ﬁbres of moss. Here and there the trees and muddy
soil give place to bays, lakes, or quaking-meadows, formed by a carpet of
grass lying upon a soil of wet mud, or even upon the hidden water. In
Brazil these ouoyant beds of vegetation are frequently met with, and the
signiﬁcant name of tremendal has been given to them: in Ireland these are
vcalled “ quaking-bogs.” The least movement of the traveler who ventures
upon them makes the soil tremble to some yards’ distance.
To the northof Florida, in the Carolinas and Virginia, the belt of cypress
swamps continue; but in consequence of the changeof climate and vege-
tation, the quaking-meadows are gradually converted into peat-mosses.
416 THE EARTH.
Evaporation being much less active in these countries than in those situ-
ated farther ,to .the south, and the dry season being much less prolonged,
the water arising from rain and inundation remains—as if in the pores of
an immense sponge—in all the interstices of the entangled mass of mosses,
Sphagnum, Uonferoce, and other aquatic plants. The whole marsh swells
toward the centre, because the droplets, divided by innumerable stalks,
can not spread out laterally, and are drawn by capillary attraction into
the fresh beds of plants which are formed above the older ones. The sur-
face of the marsh is incessantly renewed by a carpet of green vegetation,
while below, the dead plants, deprived of air, carbonize slowly in the
moisture which surrounds them: these are the beds of peat which form
upon the ground just as the layers of coal were formed in previous geo-
logical epochs.
On the southern side, the ﬁrst great peat-bog of a well-deﬁned character
is the “Dismal Swamp,” which extends along the frontiers of North Car-
olina and Virginia. This spongy mass of vegetation rises 10 feet above
the surrounding land. In the centre, and, so to speak, upon the summit
of the marsh, lies Lake Drummond, the clear water of which is colored
reddish-brown by the tannin of the plants. A canal, which crosses the
Dismal Swamp to connect it with the adjacent streams, is obliged to make
its way along the marsh by means of locks. To the north of Virginia
peat-bogs proper become more and more numerous; and in Canada, Lab-
rador, etc., they cover vast expanses of country. All the interior of the
island of Newfoundland, inside the inclosure formed by the forests on the
shore, is nothing but a labyrinth—a great part of which is still unknown
—of lakes and peat-bogs; even on the sides of the hills there are marshes
on so steep an incline that the water from them would disappear and run
off in a stream if it was not stopped by the thick carpet of plants which it
saturates. Many a large peat-bog which may be crossed dry-shod contains
more water than many lakes ﬁlling a hollow of the valley with deep water.
Opposite Newfoundland, on the other side of the Atlantic, Ireland is
hardly less remarkable for the enormous development of its peat-mosses or
bogs. These tracts of saturated vegetation, in which Sphagnum palustre
predominates, comprehend nearly two and a half millions of acres—the
seventh part of the whole island. The inhabitants continue to extract
from them, every year, immense quantities of fuel. The spaces left by the
spade in the vegetable mass are gradually ﬁlled up again by new layers.
After a certain number of years, which vary according to the abundance
of rain, the depth of the bed of water, the force of vegetation, and the slope
of the soil, the turf “quarry” is formed anew. In Ireland it generally
takes about ten years to entirely ﬁll up again the trenches, measuring '
from nine to thirteen feet in depth, which are made in the bogs on the
plains, when a fresh digging of turf may be commenced. In Holland,
crops of this fuel may be gathered, on an average, every thirty years.
In other peatmoss districts the period of regeneration lasts forty, ﬁfty,
and even a hundred years. In France, on the borders of the Seugne
FEAT-Bees. 4,17
(Charente-Inférienre), it has been ascertained-that ditches 5' feet deep-and
nearly 7 feet wide are completely obstructed by vegetation after the lapse
of twenty years. As for the beds of peat-which carpet the sides ‘of moun-
tains, they take centuries to form afresh. ‘ '
As every thing in nature is continually changing and modifying, peaty
marshes, like lakes, are all either in a period of increase. or a‘period of
decay—some form while others disappear. Independently of the ‘action
exercised by the labor of man, the vegetation of peat-bogs may cease to
be produced in any basin either because the water ﬂows away naturally
through some wide outlet after the heavy rains, or because some river, by
changing its course, has exhausted or immoderately swollen the mass of
water necessary to the nourishment of the peat; or, again, because the
rain, becoming either more rare or more frequent, has dried up the basin,
or converted it into an inundated marsh; lastly, the sinking or upheaving
of the soil may also, according to the various conditions of the relief of
the country, be the cause of the disappearance of the Flora of the peat-
bogs. The same causes, acting in contrary directions, give rise to and
increase these enormous masses of plants swollen with water. In Ireland,
the Low Countries, the north of Germany and Russia, heaps of trunks of
former forest-trees—oaks, beech, alder, and other trees—are frequently dis—
covered, which by their decay have made way for the peat-mosses. The
Sphagnum, too, often takes possession of ground of which man had pre-
viously made himself master, and in many places roads, remains of build-
ings, and other vestiges of human labor are found below the modern bed
of vegetation by which they are now covered. Certain peat-bogs in Den-
mark and Sweden may be considered, on account of the curiosities which
have been found in them, as perfect natural museums, in which the relics
of the civilization of ancient nations have been preserved for the servants
of our own day. .
The air above the peat-mosses of Ireland and other countries in the world
is not often unhealthy, either because the heat is not sufficient to develop
miasma, or else because the vegetation, by absorbing the water into its
spongy mass, impedes the corruption of the liquid, and produces a consid-
erable quantity of oxygen. Farther south, the peat-mosses, which are in-
termixed with pools of stagnant water, and especially marshes properly
so-called, generate an impure air, which spreads fever and death over the
surrounding country. Unless marshes are surrounded with dense forests,
which arrest the dispersion of the gases, the latter exercise a most injurious
inﬂuence'on the general salubrity of the district; for during dry weather,
a vast area of the bed of the marshes becomes exposed, and the heaps of
organic debris lying on the bottom decompose in the heat and infect the
whole atmosphere. The average of life is much shorter in all marshy
countries than in the adjacent regions which are invigorated by running
water. In Brescia, Poland, in the marshes of Tuscany, and in the Roman
plains, the wan and livid complexion of the inhabitants, their hollow eyes,
and their feverish skin, announce at ﬁrst sight the vicinity of some centre
D n
413 THE EARTH.
of infection. There are some marshes in the torrid zone where the de-
composition of organic remains goes on with a much greater rapidity
than in temperate climates; no one can venture on the edges of these
districts without peril to his life. As Frcebel ascertained in his journey
across Central America, the miasma is occasionally produced in such abun-
dance that not only can it be smelt, but a distinct impression of it is left
upon the palate. One of the most important works of civilization is to
deal withthese unwholesome regions, which are still, as it were, unde-
cided between land and water, and to renderthem ﬁt for cultivation and
to be the abode of man.
PART IV.
SUBTERRANEAN FORCES.
CHAPTER LXI.
ERUPTION OF ETNA IN THE YEAR 1865.-—-MUTUAL DEPENDENCE OF ALL
TERRESTRIAL PHENOMENA.
THE Greek mythology, harmonizing in this respect with the ideas of
most nations which were acquainted with volcanoes, attributed to these
mountains an origin altogether independent of the forces which are in ac-
tion on the surface of the ground. According to the views of the Hel-
lenes, water and ﬁre were two distinct elements, and each had its separate
domain, its genii, and its gods. Neptune reigned over the sea; it was he
that unchained the storms and caused the waves to swell. The tritons
followed in his train; the nymphs, sirens, and marine monsters obeyed
his orders, and in the mountain valleys, the solitary na'i'ads poured out to
his honor the murmuring water from their urns. In the dark depth of
unknown abysses was enthroned the gloomy Pluto; at his side Vulcan,
surrounded by Cyclops, forged thunderbolts at his resounding anvil, and
from their furnaces escaped all the ﬂames and molten matter the appear-
ance of which so appalled mankind. Between the gods of water and of
ﬁre there was nothing in common, except that both were the sons of
Chronos, that is, of Time, which modiﬁes every thing, which destroys and
renews, and, by its incessant work of destruction, makes ready a place for
the innumerable germs of vitality which crowd on the threshold of life.
Even in our days, the common opinion is not much at variance with these
mythological ideas, and volcanic phenomena are looked upon as events
of a character altogether different from other facts of terrestrial vitality.
The latter, the sudden changes of which are visible and easily to be ob-
served, are justly considered to be owing principally to the position of the
earth in respect to the sun and the alternations of light and darkness, heat
and cold, dryness and moisture, which necessarily result. As regards vol-
canoes, on the contrary, an order of entirely distinct facts is imagined,
caused by the gradual cooling of the planet or the unequal tides of an
ocean of lava and ﬁre. Certainly, the eruptions of ashes and incandes-
cent matter have not revealed the mystery of their formation, and in
this respect numerous problems still remain unsolved by scientiﬁc men.
Nevertheless, the facts already known warrant us in asserting that volcan-
4:20 THE EARTH.
ic crises are connected, like all other planetary phenomena, with the gen-
eral causes which determine the continual changes of continents and seas,
the erosion of mountains, the courses of rivers, winds, and storms, the
movements of the ocean, and all the innumerable modiﬁcations which are
taking place on the globe. If, some day, we are to succeed in pointing
out exactly and plainly how volcanoes likewise obey, either partially or
completely, the system of laws which govern the exterior of the globe,
the ﬁrst and most important requisite is to observe with the greatest
care all the incidents of volcanic origin. When all the premonitory signs
and all the products of eruptions shall have been perfectly ascertained
and duly classiﬁed, then the glance of science will be on the point of pen-
etrating into, and duly reading, the secrets of the subterranean abysses
where these marvelous convulsions are being prepared.
The last great eruption of Etna, that central pyramid of the Mediterra-
nean, which the ancients named the “Umbilicus of the world,” is one of
the most magniﬁcent examples which can be brought forward of volcanic
phenomena; and as it has, moreover, been studied most precisely and
completely, it well deserves to be described in some detail.
The explosion had been heralded for some long time by precursory
signs. In the month of July, 1863, after a series of convulsive movements
of the soil, the loftiest cone of the volcano opened on the side which faces
the south. The incandescent matter descended slowly over the plateau
on which stands the “ Maison des Anglais ;” and this building itself was
demolished by the lumps of lava which were hurled from the mouth of
the crater. In some places heaps of ashes several yards thick covered the
slopes of the volcano. After this ﬁrst explosion, the mountain never be-
came completely calm; numerous ﬁssures, which opened on the outer
slopes of the crater, continued to smoke, and the hot vapor never ceased
to jet out from the summit in thick eddies. Often, indeed, during the
night, the reﬂection of the lava boiling up in the central cavity lighted
up the atmosphere with a ﬁery red. The liquid, being unable to rise to
the mouth of the crater, pressed against the external walls of the vol-
cano, and sought to ﬁnd an issue through the weakest point of the crust
by melting gradually the rocks that opposed its passage. Finally, in the
night of the 30th to the 31st of January, 1865, the wall of the crater yield-
ed to the pressure of the lava; some subterranean roaring was heard;
slight agitations affected the whole of the eastern part of Sicily, and the
ground was rent open for the length of a mile and a half to the north of
Monte Frumento, one of the secondary cones which rise on the slope of
Etna. Through this ﬁssure, which opened on a gently—inclined plateau,
the pent-up lava violently broke through to the surface.
The ﬁssure which opened on the side of_ the mountain, and could be
easily followed by the eye to a point about two-thirds of the height of
Monte Frumento, in the direction of the terminal crater of ZEtna, seems
to have vomited out lava but for a very few hours. Being soon obstruct-
.ed by the snow and the debris of the adjacent slopes, it ceased to retain
ER UPTION OF .E'TNA IN 1865.
its communication with the interior of the mountain, and now resembled
a kind of furrow, as if hollowed out by the rain-water on the side of the
cone. On the 31st of January all the volcanic activity of the crevice was
concentrated on the gently inclined plateau which extends at the base of
Monte Frumento, in the midst of which several new hillocks made their
appearance. On the lower prolongation of the line of fracture, all the
phenomena of the eruption properly so-called were distributed in a per-
fectly regular way. Six principal cones of ejection were raised above the
crevice, and gradually increased in size, owing to the debris which they
threw out of their craters; these, gradually mingling their intervening
slopes, and blending them one with another, absorbed in succession other
smaller cones which had been formed by their sides, thus reaching a
height of nearly 300 feet. Soon after the commencement of the eruption
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the two upper craters, standing close together on an isolated cone, vom-
ited nothing but lumps of stone and ashes, while jets of still liquid lava
were emitted by the lower craters, which were arranged in a semicircle
round a sort of funnel-shaped cavity. In consequence of the speciﬁc
gravities of the substances evacuated, a regular division of labor took
place between the various points of the crevice. The projectiles which '
had solidiﬁed the triturated debris, and the more or less porous frag-
ments which ﬂoated on the top of the lava, made their escape by the
higher oriﬁces; but the liquid mass, being heavier and more compact,
could only burst forth from the ground by the mouths opening at a less
elevation. , ~
Two months after the commencement of the eruption, the cone which
was the nearest to Frumento ceased to send out either scoriae or ashes.
The pipe of the crater was ﬁlled up with debris, and the internal activity
was revealed by vapors either of a sulphurous character or charged with
422 THE EARTH
hydrochloric acid. These rose like smoke from the slope of the hillock.'
The second cone, situated on a lower part of the ﬁssure, remained in di-
rect communication with the central ﬂow of lava; but it was not in a
- constant state of eruption, and rested after each effort as if to take breath.
A crash like that of thunder was the forerunner of the explosion; clouds
of vapor, rolling in thick folds, gray with ashes, and furrowed with stones,
darted out from the mouth of the volcano, darkening the atmosphere, and
throwing their projectiles over a radius of several hundreds of yards
round the hillock. Then, after having discharged their burdens of debris,
the‘ dark clouds, giving way before the pressure of the winds, mingled far
and wide with the mists on the horizon. The lower cones, which rose
immediately over the lava-source, continued to rumble- and to discharge
molten matter outside their cavities. The vapor which escaped from the
seething wall of lava crowded in dark contortions round the oriﬁce of the
craters. Some of it was red or yellow, owing to the reﬂection of the red-
hot matter, and some was variously shaded by the trains of debris ejected
with it; but it was impossible ,to follow them with the eye, so rapid was
their ﬂight. An unintelligible tumult of harsh sounds simultaneously
burst forth; they were like the noises of saws, whistles, and of hammers
falling on an anvil. Sometimes one might have fancied it like the roar-
ing of the waves breaking upon the rocks during a storm, if the sudden
explosions had not added their thunder to all this uproar of the elements.
One felt dismayed, as if before some living being, at the sight of these
groups of hillocks,roaring and smoking, and increasing in size every hour,
by the debris which they vomited forth from the interior of the earth.
The volcano, however, then commenced to rest; the erupted matter did
not rise much beyond 100 yards above the craters, while, according to the
statement of M. Fouqué, at the commencement of the eruption it had been
thrown to a height of 1850 to 1950 yards.
During the six ﬁrst days the quantity of lava which issued from the
ﬁssure of Monte Frumento was estimated at 117 cubic yards a second,
equivalent to a volume twice the bulk of the Seine at low-water time.
In the vicinity of the outlets the speed of the current was not less than
20 feet a minute; but lower down, the stream, spreading over a wider
surface, and throwing out several branches into the side valleys, grad-
ually lost its initial speed, and the fringes of scoriae, which were pushed
on before the incandescent matter, advanced on the average, according to
the slope of the ground, not more than 1?} to 6 feet a minute.* On the
2d of February the principal current, the breadth of which varied from
300 to 550 yards, with an average thickness of 49 feet, reached the upper
ledge of the escarpment of Colla-Vecchia, or Colla-Grande, three miles
from the ﬁssure of eruption, and plunged like a cataract into the gorge
below. It was a magniﬁcent spectacle, especially during the night, to see
this sheet of molten matter, dazzling red like liquid iron, making its way,
* These ﬁgures, borrowed from the account of the Professor Orazio Silvestri, are the re-
sults of measurements made by Viotti, the engineer.
ER UPTION OF ETNA LV 1865. 403
all
in a thin layer, from the heaps of brown scoriae which had gradually ac—
cumulated up above; then, carrying with it the more solid lumps, which
dashed one against the other with a metallic noise, it fell over into the
ravine, only to rebound in stars of ﬁre. But,this splendid spectacle
lasted only for a few days; the ﬁery fall, by losing in height, diminished
gradually in beauty. In front of the cataract, and under the jet itself,
there was formed an incessantly increasing slope of lava, which ultimately
ﬁlled up the ravine, and, indeed, prolonged the slope of the valley above.
From the reservoir, which was more than 160 feet deep, the stream con-
tinued to ﬂow to the east toward Mascali, ﬁlling up to the brink the
winding gorge of a dried-up rivulet.
By the middle of the month of February, the ﬁery stream, already more
than six miles long, made but very slow progress, and the still liquid lava
found it difficult to clear an outlet through the crust of stones cooled by
their contact with the atmosphere ; when, all of a sudden, a breaking out
took place at the side of the stream, at a point some distance up, not far
from the source. Then a fresh branch of the burning river, ﬂowing to-
ward the plains of Linguagrossa, swallowed up thousands of trees which
had been felled by the woodman. This second inundation of lava did
not, however, last long. The villages and towns situated at the base of
the mountain were no longer directly menaced ; but the disasters caused
by the eruption were, notwithstanding, very considerable. A number of
farm-houses were swept away; vast tracts of pasturage and cultivated
ground were covered by slowly hardening rock, and—a misfortune which
was all the worse on account of the almost general deforesting of Sicily
—a wide band of forest, comprising, according to the various estimates
that were made, from 100,000 to 130,000 trees—oaks, pines, chestnuts, or
birches—was completely destroyed. When seen from the lower part of
the mountain, all these burning trunks borne along upon the lava, as if
upon a river of ﬁre, singularly contributed to the beauty of the spectacle.
As is always the case in the events of this world, the misfortune of some
proved to be a source of gratiﬁcation to others. During the earliest pe-
riod of the eruption, while the villagers of Etna looked at it with stupor,
and were bitterly lamenting over the destruction of their forests, hun-
dreds of curious spectators, brought daily by the steamboats from Cata-
nia and Messina, came to enjoy at their ease the contemplation of all the
splendid horrors of the conﬂagration.
The aspect of the current of lava, as it appeared covered with its en-
velope of scoriae, was scarcely less remarkable than the sight of the mat-
ter in motion. The black or reddish aspect of the cheire was all rough-
ened with sharp-edged projections, which resembled steps, pyramids, or
twisted columns, on which it was a dif‘ﬁcult matter to venture,‘ except at
the risk of tearing the feet and hands. Some months afterthe commence—
ment of the eruption, the onward motion of the interior of the molten
stone, which, by breaking the outer crust in every direction, had ulti-
mately given it this rugged outline, was still visibly taking place. ‘Here
424 - , THE EARTH.
and there cracks in the rock allowed a view, as if through an air-hole, of
the red and liquid lava swelling up as it ﬂowed gently along like some
viscous matter. A metallic clinking- sound was incessantly heard, pro-
ceeding from the fall of the scoriae,-which were breaking under the press-
ure of the liquid matter. Sometimes, on the hardening current of lava,
a kind of blister gradually rose, which either opened gently, or bursting
with a crash gave vent to the molten mass which formed it. Fumerolles,
composed of various gases, according to the degree of heat of the lava
which gave rise to them, jetted out from all the issues. Even on the
banks of the river of stone the soil was in many places all burning and
pierced with crevices, through which escaped a hot air thoroughly charged
with the smell of burnt roots. _ -
On the slopes of the Frumento, quite close to the upper part of the ﬁs-
sure, at a spot where the liquid mass had ﬂowed like a torrent, M. Fouqué
noticed a remarkable phenomenon; sheaths of solidiﬁed lava were sur-
rounding the trunks of pines, and thus showing the height to which the
current of molten stone had reached. In like manner, the streams of ob-
sidian which ﬂow rapidly from the basin of Kilauea, in the isle of Hawaii,
leave behind them on the branches of the trees numerous stalactites, like
the icicles which are formed by melting snow which has again frozen.
Below the escarpments of the Frumento, the torrent, which was there re-
tarded in its progress, had not contented itself with bathing for a mo-
ment the trunks of the forest trees, but had laid them low. Great trunks
of trees, broken down by the lava, lay stretched in disorder on the un-
even bed of the stream, and, although they were only separated from the
molten matter by a crust a few inches thick, numbers of them were still
clothed with their bark; several had even preserved their branches. At
the edge of the cheire, some pine-trees, which had perhaps been preserved
from the ﬁre by their moisture being converted ‘by the heat into a kind
of coating of steam, were surrounded by a wall of heaped-up lava, and
their foliage still continued green; it could not yet be‘ ascertained if the
sources of the sap had perished in their ‘roots. - ' -
In some places, rows of ﬁrs very close together were suﬂicient to change
the direction of the ﬂow, and to cause a ‘lateral deviation. Not far from
the crater of eruption, on the western bank of the great chez're, a trunk of
a tree was noticed which by itself had been able to keep back a branch
of the stream, and to prevent it from ﬁlling up a glen which opened im-
mediately below. This tree, being thrown down by the weight of the
scoriae', had fallen so as to bar up a slight depression in the ground which
presented a natural bed to the molten matter. The latter had bent and
cracked the trunk, but had failed in breaking it, and the stony torrent
had remained suspended, so to speak, above the beautiful wooded slopes
which it threatened to destroy completely.
Round the very mouth of the volcano, a vast glade was formed in the
forest; the ground was covered every where with ashes which the wind
had blown up into hillocks, like the duneson the sea-coast; all the trees
ER UPTI ON OF ETNA 11V 1865. 425
had been broken down by the volcanic projectiles, and burned by the
scoriae and small stones. The nearest trees that were met with, at un-
equal distances from the mouths of eruption,had had their branches torn
off by the falling lumps of stone, or were buried in ashes up to their ter-
minal crown. A spectator might have walked among a number of yel-
low branches which were once the tops of lofty pines. Thus, on the pla-
teau of Frumento and the lower slopes, every thing was changed both in
form and aspect; we might justly say that, by the effects of the erupted
'matter, the outline of the sides of Etna itself had been perceptibly modi-
ﬁed.
And yet this last eruption, one of the most important in our epoch, is
but an insigniﬁcant episode in the history of the mountain; it was but a
mere pulsation of Etna. During the last twenty centuries only, more
than seventy-ﬁve eruptions have taken place, and in some of them the
ﬂows of lava have been more than twelve miles in length, and have cov-
ered areas of more than forty square miles, which were once in a perfect
state of cultivation, and dotted over with towns and villages. In former
ages, thousands of other lava-ﬂows and cones of ashes have gradually
raised and lengthened the slopes of the mountain. The mass of Mount
Etna, the total bulk of which is three or four thousand times greater than
the most considerable of the rivers of stone vomited from its bosom, is, in
fact, from its summit to its base, down even to the lowest submarine
depths, nothing but the product of successive eruptions throwing out the
molten matter of the interior. The volcano itself has slowly raised the
walls of its crater, and then extended its long slopes down to the waters
of the Ionian Sea. By its fresh beds of lava and scoriae incessantly re-
newed one upon the other, it has ultimately reared its summit into the
regions of snow, and has become, as Pindar called it, the great “ pillar of
heaven.”
426 - . THE EARTH.
CHAPTER LXII.
SEA-COAST LINE OF VOLCANOES.——THE PACIFIC “ CIRCLE on FIRE.”—~voLcA-
NoEs OF THE INDIAN OCEAN; OF THE ATLANTIC; on THE MEDITERRA~
NEAN; OF THE CASPIAN; OF CENTRAL ASIA.
THE earth being generally looked upon as immobility itself, it is a very
strange thing to see it open to shoot out into the air torrents of gas, and
shedding forth like a river the molten rocks of its interior. From what
invisible source do all these ﬂuid matters proceed which spread out in
sheets over vast regions ? Whence come those enormous bodies of steam,
extensive enough to gather immediately in clouds round the loftiest sum-
mits, and sometimes indeed to fall in actual rain-showers ? Science, as we
have already said,has not completely answered these questions, the posi-
tive solution of which would be so highly important for our knowledge
of the globe on which we live.
According to an ancient popular belief, Etna merely vomits forth, in the
shape of vapor, the water which the sea has poured into the gulf of Cha-
rybdis. This legend, although clothed in a poetic garb, has in fact be-
come the hypothesis which is thought beyond dispute by those scwants
who look upon volcanic eruptions as being a series of phenomena caused
chieﬂy by water converted into steam.
The remarkable fact that all volcanoes are arranged in a kind of line
along the coasts of the sea, or of inland lacustrine basins, is one of the
great points which testify in favor of this opinion as to the inﬁltration of
water, and give to it a high degree of probability. The Paciﬁc, which is
the principal reservoir of the water of our earth, is circled round by a se-
ries of volcanic mountains, some ranged in chains, and others very dis-
tant from one another, but still maintaining an evident mutual connec-
tion, constituting a “ circle of ﬁre,” the total development of which is
about 22,000 miles in length. This ring of volcanoes does not exactly
coincide with the semicircle formed by the coasts of Australia, the Sunda
Islands, the Asiatic continent, and the western coasts of the New World.
Like a crater described within some ancient and more extensive outlet
of eruption, the great circle of igneous mountains extends its immense
curve in a westward direction across the waves of the Paciﬁc, from New
Zealand to the peninsula of Alaska; on the cast, it is based on the coast
of America, rising in the south so as to form some of the loftiest summits
of the Andes.
The still smoking volcanoes of New Zealand, Tongariro and the cone
of Whakari, on White Island, are, in the midst of the southern waters of
the Paciﬁc properly so called, the ﬁrst evidence of volcanic activity. On


ERUPTlONS OF ETNA PLXX.


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DIS'TRIB UTION OF VOL OANOES. 42 7
the north, a considerable space extends in which no volcanoes have yet
been observed. The group of the Feejee Islands, at which the volcanic
ring recommences, presents a large number of former craters which still
manifest the internal action of the lava by the abundance of thermal
springs. At this point, a branch crossing the South Sea in an oblique
direction from the basaltic islands of Juan Fernandez as far as the active
volcanoes of the Friendly group, unites itself with the principal chain
which passes round, in a northeast direction, the coasts of Australia and
New Guinea. The volcanoes of Abrim and Tanna, in the New Hebrides,
Tinahoro, in the archipelago of Santa Cruz, and Semoya, in the Salomon
Isles, succeeding one after the other, connect the knot of the Feejee's to
the region of the Sunda Islands, where the earth is so often agitated by
violent shocks. This region may be considered as the great focus of the
lava streams of our planet. On the kind of broken isthmus which con-
nects Australia with the Indo-Chinese peninsula, and separates the Paciﬁc
Ocean from the great Indian seas, one hundred and nine volcanoes are
vomiting out lava, ashes, or mud in full activity, destroying from time to
time the towns and the villages which lie upon their slopes; sometimes,
in their more terrible explosions, they ultimately explode bodily, covering
with the dust of their fragments areas of several thousands of miles in ex-
tent. From Papua to Sumatra, every large island, including probably the
almost unknown tracts of Borneo, is pierced with one or more volcanic
outlets. There are Timer, Flores, Sumbawa, Lombok, Bali, and Java,
which last has no less than forty-ﬁve volcanoes, twenty-eight of which
are in a state of activity, and, lastly, the beautiful island of Sumatra.
Then, to the east of Borneo—Ceram, Amboyna, Gilolo, the volcano of
Ternata, sung by Camoens, Celebes, Mindanao, Mindoro, and Luzon ; these
form across the sea, as it were, two great tracks of ﬁre.
Northward of Luzon, the volcanic ring curves gradually so as to fol-
low a direction parallel to the coast of Asia. Formosa, the Liou-Kieou
archipelago, and other groups of islands stand in a line over the subma-
rine volcanic ﬁssure; farther on, there are the numerous volcanoes of
Japan, one of which, Fusiyama, with a cone of admirable regularity, is
looked upon by the inhabitants of Niphon as a sacred mountain, from
which the gods come down. The elongated archipelago of the Kuriles,
comprising about a dozen volcanic oriﬁces, unites Japan to the peninsula
of Kamtschatka, in which no less than fourteen volcanoes are reckoned as
being in full activity. To the east of this peninsula, the range of craters
suddenly changes its direction, and describes a graceful semicircle across
the Paciﬁc, from Behring Island to the point of Alaska. Thirty-four
smoking cones stand on this great transversal dike, extending from conti-
nent to continent. Ounimak, which rises on the extremity of the penin-
sula of Alaska, the peak of which is 7939 feet in height, serves as the
western limit of the New \Vorld, and is also pierced by a crater in a
state of full activity.
Eastward of the peninsula, the volcanic chain extends along the sea-
428 _ THE EARTH
w
coast of the continent. Mount St. Elias, one of the highest summits in
America, often vomits lava from its crater, which opens at an elevation
of 17,716 feet. Farther to the south, another active volcano, Mount
Fairweather, rises to a height of 14,370 feet. Next comes Mount Edge-
cumbe, in Lazarus Island, and the volcanic region of British Columbia.
The whole chain of the Cascades, in Oregon, as well as the parallel ranges
of the Sierra Nevada and the Rocky Mountains, are overlooked by a great
number of volcanoes; but only a few of them continue to throw out
smoke and ashes: these are Mount Baker, Renier, and St. Helens, enor- -
mous peaks 10,000 to 16,000 feet high. In California and Northern Mex-
co, it is probable that the basaltic and trachytic mountains on the coast
'no longer present any outlets of eruption. Subterranean activity is not

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manifested with any degree of violence until we reach the high plateaux
of Central Mexico. There a series of volcanoes, rising over a ﬁssure
crossing the continent, extends over the whole plateau of Anahuac, from
the Southern Ocean to the Gulf of Mexico. The Colima, then the celebra-
ted J orullo, which made its appearance in 1759, the Nevado de Tolima, Is-
tacihuetl, Popocatepetl, Orizaba, and Tuxtla are the vents for the furnace
of lava‘. which. is boiling beneath the Mexican plateau. To the south, in
Guatemala and ‘the South American republics, thirty burning mountains,
much more active and terrible than those of Anahuac, rise ‘in two chains,
one of which is parallel to the sea-coast, and the other crosses obliquely
the isthmus of Nicaragua' Among these numerous volcanoes there are
some, the names of which have become famous on account of the fright-
ful disasters which have been caused by their eruptions. Such are the
mountains del Fuego and'del Agua, above the Ciudad-Antigua of Guate-
mala ; the Phare d’Isalco, which during the night lights up far and wide
the plains of Salvador withits jets of molten stone and its column of
red smoke; Coseguina, the last great eruption of which was probably
the most formidable of modern times; the Viejo, Nuevo, Momotombo,
VOL CANOES OF AMERICA. 42 9
and other mountains, which are almost worshiped from being so much
dreaded.*
The depressions of the isthmuses of Panama and Darien interrupt the
series of volcanoes which borders the coast of the Paciﬁc. The peak of
Tolima, which rises to the great height of 17,716 feet, is the most northern
of the active volcanoes of South America, and is also one of the-most dis-
tant from the sea among- all the ﬁre-vomiting mountains, for the distance
from its base to the Paciﬁc coast is not less than 124 miles. South of Toli-
ma, and the great plateau of Pasto, where there likewise exists a crater,

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stands the magniﬁcent group of sixteen volcanoes, some already extinct
and some still smoking, over which towers the proud dome of Chimbo-
razo. Occupying an elliptical space, the greater axis of which is only
about 112 miles long, this group, comprising the Tunguragua, Carahui-
zo, Cotopaxi, Antisana, Pichincha, Imbabura, and Sangay, is often looked
upon as but one volcano with several cones of eruption; it is the cluster
which, on the southern coasts of the Isthmus of Panama, corresponds sym-
‘ * Moritz Wagner.
430 THE EARTH.
metrically to the volcanic group of Anahuac. South of Sangay, which is
perhaps the most destructive volcano on the earth, the chain of the Cor-
dilleras offers no volcanoes for a length of about 930 miles; but in South-
ern Peru the volcanic series recommences, and outlets of eruption still in
action open at intervals among extinct volcanoes and domes of trachyte.
The three smoking peaks of the inhabited part of Chili, the mountains of
Antuco, Villarica, and Osorno, terminate the series of the great American
voleanoes;* the activity of subterranean action is, however, disclosed by
some other less elevated craters down to the extremity of the continent
as far as the point of Terra del Fuego. This is not all; the South Shet-
land Islands, situated in the Southern Ocean, in a line with the New
World, are likewise volcanic in their character; and if the same direction
he followed toward the polar regions, the line will ultimately touch upon
the coasts of the land of Victoria, on which rise the two lofty volcanoes
of Erebus and Mount Terror, discovered by Sir John Ross. Stretching
round the sphere of the earth, the great volcanic circle is extended toward
the north by various islets of the antarctic, and ultimately rejoins the
archipelago of New Zealand. Thus is completed the great ring of ﬁre
which circles round the whole surface of the Paciﬁc Ocean.
Within this immense amphitheatre of volcanoes a multitude of those
charming isles, which are scattered in pleiads over the ocean, are also of
volcanic origin, and many of them can be distinguished from afar by their
smoking or ﬂaming craters. Of this kind are some of the Marianne and
Gallapagos Islands, which contain several oriﬁces in full activity, and
more than two thousand cones in a state of repose. Among these we
must especially mention the Sandwich Islands, the lofty volcanoes of
which rise in the middle of the central basin of the North Paciﬁc like so
many cones of eruption in the midst of a former crater changed into a
lake. The Mauna-Loa and Mauna-Kea, the two great volcanic summits
of the island of Hawaii, are each more than 13,000 feet in height; and the
eruptions of the ﬁrst cone, which are still in full activity, must be reck-
oned among the most magniﬁcent spectacles of this kind. On the sides
of the Mauna-Loa opens the boiling crater of Kilauea, which is, without
doubt, the most remarkable lava-source which exists on our planet.
Round the circumference of the Indian Ocean the border of volcanoes
is much less distinct than round the Paciﬁc; still it is possible to recog-
nize some of its elements. To the north of Java and Sumatra, the volca-
noes of which overlook the eastern portion of the basins of the Indian
seas, stretches the volcanic archipelago of the Andaman and Nicobar Isl-
ands, in which there are several cones of eruption in full activity. On
the west of Hindostan, the peninsula of Kutch, and the delta of the Indus,
are often agitated by subterranean forces. Many mountains on the Ara-
bian coast are nothing but masses of lava; and, if various travelers are
to be believed, the volcanic furnace of these countries is not yet extinct.
The Kenia, the great mountain of Eastern Africa, has on its own summit
* Philippi, Mittkeilungcn von Petermann, vol. iv., 1861.
VOL OANOE'S OF THE ATLAN TI 0. 431
a crater still in action—perhaps the only one which exists on this conti-
nent. Lastly, a large number of islands which surround the Indian
Ocean on the west and on the south—Socotora, Mauritius, Reunion, St.
Paul, and Amsterdam Island—are nothing but cones of eruption, which
have gradually emerged from the bed of the ocean.
The volcanic districts which are scattered on the edge of the Atlantic
are likewise distributed with a kind of symmetry round three sides of
this great basin. On the north, Jan Mayen, so often wrapt in mist, and
the more considerable island of Iceland, pierced by numerous craters,
Hecla, the Skapta-Jokul, the Kotlugaja, and seventeen other mountains
of eruption, separate the Atlantic from the Polar Ocean. At about 1500
miles nearer the equator, the peaks of the Azores, some extinct and some
still burning, rise out of the sea. The archipelago of the Canaries, over
which towers the lofty mass of the peak of Teyda, continues toward the
south the volcanic line of the Azores, and is itself prolonged by the smok-
ing summits of the Cape de Verde Islands. All the other mountains of
lava which spring up from the bed of the Atlantic more to the south ap-
pear to have completely lost their activity, and on the coast itself there
is, according to Burton, only one volcano still in action—that of the
Cameroons. With regard to the “line of ﬁre” along the western Atlan-
tic, it is developed at the entrance of the Caribbean Sea with perfect reg-
ularity, like the range of the Aleutian Isles. Trinidad, Grenada, St. Vin-
cent, St. Lucia, Dominica, Guadaloupe, Montserrat, Nevis, St. Kitts, and
St. Eustatius are so many outlets of volcanic force, either through their
smoking craters or their mud-volcanoes, their sobfataras or their thermal
springs. North and south of the Antilles, the eastern coast of America
does not present a single vent of eruption. It is a remarkable fact that
the two volcanic groups of the Antilles and the Sunda Islands are situa-
ted exactly at the antipodes one .of the other, and also in the vicinity of
the two poles of ﬂattening, the existence of which on the surface of the
globe has been proved by the recent calculations of astronomers.* More
than this, these two great volcanic centres, which are undoubtedly the
most active on the whole earth, ﬂank, one on the west and the other on
the east, the immense curve of volcanoes which spreads round the Paciﬁc.
The Mediterranean is not surrounded by a circle of volcanoes; but
there, as elsewhere, it is from the midst of the sea, or immediately on the
sea-coast, that the burning mountains rise—Etna, Vesuvius, Stromboli,
Volcano, Epomeo, and Santorin. In like manner, the volcanoes of mud
and gas of the peninsula of Apcheron, and the summit of Demavend,
14,436 feet high, rise at no great distance from the Caspian Sea. With
regard to the volcanoes of Mongolia—the Turfan, which is said to be still
in action, and the Pe-chan, which, according to Chinese authors, vomited
forth, up to the seventh century, “ﬁre, smoke, and molten stone, which
hardened as it cooled ”f——their existence is not yet absolutely proved;
but even if these mountains, situated in the centre of the continent,
* See above, p. 14. T Ckroniques Chinoises. Humboldt, Tableaux de la Nature.
432 THE EARTH.
should be in full activity, their phenomena might depend on the vicinity
of extensive sheets of water, for this very region of Asia still possesses a
large number of lakes, the remnants of a former inland sea, almost as vast
as the Mediterranean.
What is the number of volcanoes which are still vomiting forth lava
during the present period of the earth’s vitality? It is difficult to ascer-
tain, for often mountains have seemed for a long time to be extinct;
forests have grown up in their disused craters, and their beds of lava
have been covered up under a rich carpet of vegetation, when suddenly
the sleeping force beneath is aroused and some fresh volcanic outlet is
opened through the ground. When Vesuvius woke up from its protract-
ed slumber to swallow up Pompeii and the other towns lying round its
base, it had rested for some centuries, and the Romans looked upon it as
nothing but a lifeless mountain like the peaks of the Apennines. On the
other hand, it is very possible that some craters, from which steam and
jets of gas are still escaping, or which have thrown out lava during the
historic era, have entered decisively into a period of repose, ceasing some-
how to maintain their communication with the subterranean centre of
molten matter. The number of vents which serve for the eruption of
lava can, therefore, be ascertained in a merely approximate way. Hum-
boldt enumerates 223 active volcanoes; Keith Johnston arrives at the
larger number of 270, 190 of which are comprehended in the islands and
the Paciﬁc “ circle of ﬁre ;” but this latter estimate is probably too small.
To the number of these burning mountains, standing nearly all of them
on the sea-shore, or in the vicinity of some great fresh-water basin, must
be added the salses, or mud-volcanoes, which are also found near large
sheets of salt water. With regard to the thousands of extinct volcanoes
which rise in various parts of the interior of continents, geology shows
that the sea used formerly to extend round their bases.
VOLCANOES
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ESCAPE OF STEAM FR OM ORA TERS.
CHAPTER LXIH.
TORRENTS OF STEAM ESCAPING FROM CRATERS.—GASES PRODUCED BY THE
DECOMPOSITION OF SEA-\VATER.-—-IIYPOTHESES AS TO TIIE ORIGIN OF
ERUPTIONS.—-INDEPENDENCE OF THE SEVERAL VOLCANIC OUTLETS.
ONE of the most decisive arguments which can be used in favor of a
free communication existing between marine basins and volcanic centres
is drawn from the large quantities of steam which escape from craters
during an eruption, and compose, according to M. Ch. Sainte-Claire De-
ville, at least 999 thousandths of the supposed volcanic smoke. During
the eruption of Etna, in 1865, M. Fouqué attempted to gauge approxi-
mately the volume of water which made its escape in a gaseous form
from the craters of eruption. By taking as his scale of comparison the
cone which appeared to him to emit an average quantity of steam, he
found this mass, reduced to a liquid state, would be equivalent to about
79 cubic yards of water for each general explosion. Now, as these ex-
plosions took place on the average every four minutes during a hundred
days, he arrived at the result, that the discharge of water during the con-
tinnance of the phenomenon might be estimated at 2,829,600 cubic yards
of water—a ﬂow equal to that of a permanent stream discharging 55 gal-
lons a second. Added to this, account ought to have been taken of the
enormous convolutions of vapor which were constantly issuing from the
great terminal crater of Etna, and, bending over under the pressure of
the wind, spread out in an immense arch around the vault of the sky. In
great volcanic eruptions it often happens that these clouds of steam, be-
coming suddenly condensed in the higher layers of the atmosphere, fall
in heavy showers of rain, and form temporary torrents on the mountain-
sides. According to the statements of Sir James Ross, the mountain Ere-
bus, of the antarctic land, is covered with snow, which it has just vomited
forth in the form of vapor. It has besides been remarked that the vapor
which issues from volcanoes is not always warm; often, according to Peep-
pig, it is of the same temperature as the surrounding air.
As was said long since by Krug von Nidda, a German saccmt,volca-
noes must be looked upon as enormous intermittent springs. The ba-
saltic ﬂows may be compared to streams on account of the water which
they contain. It is probable that most of the lava which ﬂows from vol-
canic ﬁssures owes its mobility to the innumerable particles of vapor
which ﬁll up all the interstices of the moving mass. Being composed in
great measure of crystals already formed, as may be proved by an ex-
amination of the chez'res, in the body of which may be noticed nodules
and crystals rounded by friction, the lava would be unable to descend
E E
- THE EARTH.
over the slopes if it were not rendered ﬂuid by its mixture with steam ;
and the gradual slackening in speed and ultimate stoppage cf the ﬂow
are chieﬂy caused by the setting free of the gases which served as a vehi-
cle to the solid matter. Owing to this rapid loss of their humidity, ba-
salts contain in their pores but a very slight quantity of water in com-
parison with other rocks.* Yet even old lavas themselves contain as
much as 10 to 19 thousandths of water at the edges of the bed,and 5 to
18 thousandths at the centre]t
The various substances which are produced from craters also tend to
show that sea-water has been decomposed in the great laboratory of lava.
Ordinary salt or chloride of sodium, which is the mineral that is most
abundant in sea-water, is also that which is deposited the ﬁrst and most
plentifully round the oriﬁces of eruption. Sometimes, the scoriae and ashes
are covered for a vast space with a white eiﬂorescence, which is nothing
but common salt; one might fancy it a shingly beach which had just
been left by the ebbing tide. After each eruption of Hecla, the Iceland-
ers are in the habit, it is said, of collecting salt on the slopes. The lava
from the eruption of Frumento, analyzed by M. Fouqué, contained about
13 ten thousandths of marine salt.
Almost all the other component parts of sea-water are likewise found
in the gases and deposits of fumerolles; only the salts of magnesia have _
disappeared, but still are found under another form among the volcanic
products. Being decomposed by the high temperature, just as they
would be in the laboratory of a chemist, they go to constitute other
bodies. Thus the chloride of magnesium is changed into hydrochloric
acid and magnesia; the gas escapes in abundance from the ﬁmzerolles,
while the magnesia remains ﬁxed in the lava.1
As M. Ch. Sainte-Claire Deville was the ﬁrst to ascertain with certain-
ty, four successive periods may be observed in every eruption, each of
,which periods assumes a distinct character, owing to the exhalation of
certain substances. After the ﬁrst period, remarkable especially for ma-
rine salt and the various compounds of soda and potash, comes a second
in which the temperature is lower, and'during which brilliantly colored
deposits of chloride of iron are formed-and hydrochloric and sulphurous
acids are expelled. When the temperature is below 392° (Fahr.),there
are ammoniacal salts and needles of sulphur, which are found in yellowish
masses on the scoriae of lava. Lastly, when the heat of the erupted
bodies is below 212° (Fahn), the famerolles eject nothing but steam, azote,
carbonic acid, and combustible gases. Thus the activity of the exhala-
tions and deposits is in proportion to the incandescence of the lava. At
the commencement of the eruption, the oriﬁces throw out a large quan-
tity of substances, from marine salt to carbonic acid; but by degrees the
power of elaboration weakens simultaneously with the heat, and the gases
* Poulctt Scropc, Volcanoes.
‘i Delesse, Bulletin de la Socz'été Géologz'que de France, 1859.
I Fouqué, Phe'noménes Chimz'ques de l’Eruptz'on de l’Etna en 1865.
.E'XHA LA TI ONS OF VOL CANOES. 435
ejected gradually diminish in number, and testify, by their increasing
rarity, to the approaching cessation of volcanic phenomena. In conse-
quence of the difference which is presented by the exhalations during the
various phases of eruptions of lava, observers .have, at ﬁrst sight, thought
that each volcano was distinguished by emanations peculiar to itself.
Hydrochloric acid was looked upon as one of _the normal products of
Vesuvius, and sulphurous vapors as more especial to Etna. It was stated
(with Boussingault) that carbonic acid was exhaled specially by the vol-
canoes of the Andes; and, with Bunsen, it was believed that combustible
gases prevailed in the eruptions of Hecla.*
In his beautiful investigations into the various chemical phenomena
presented by Etna and the neighboring volcanic outlets, such as Vesuvius
and Stromboli, M. Fouqué appears to have established as a fact which
must be henceforth beyond dispute, that the gradual series of these
emanations is just that which would be produced by the decomposition
of sea-water. Added to this, we also ﬁnd in lava iodine and ﬂuorine,
both of which we should expect to detect in it on account of their pres-
ence in sea-water. The salts of bromine, of which, however, only a slight
trace is found in sea-water, have not yet been detected in volcanic prod-
ucts, which, no doubt, proceeds from the diﬂiculty which chemists have
experienced in separating such very small quantities.
The other matters ejected by eruptions are of terrestrial origin, and
evidently proceed from rocks reduced by heat to a liquid or pasty state ;
they consist principally of silica and alumina, and contain besides lime,
magnesia, potash, and soda. Oxides of iron also enter into the composi-
tion of lava, to the extent of more than one tenth, which is a very consid-
erable proportion, and warrants us in looking upon the volcanic ﬂows as
actual torrents of iron-ore; sometimes, indeed, this metal appears in a
pure state. It is to this presence of iron that lava especially owes its
reddish color, and the sides of the crater their diversely colored sides.
Compounds of copper, manganese, cobalt, and lead are also met with in
lava; but, in comparison with the iron, they are but of slight importance.
Lastly, phosphates, ammonia, and gases composed of hydrogen and car-
bon, are discharged during eruptions. The presence of these bodies is
explained by the enormous proportion of animal and'vegetable matter
which is decomposed in sea-water. Ehrenberg found the remains of ma-
rine animalcula in the substances thrown out by volcanoes.
Is the composition of the lava, and especially that of the vapor and
gases, the same in those eruptions which take place at a great distance
from the ocean ‘? It is probable that, as regards this point, considerable
differences might be established between the products of volcanoes placed
on the sea-coast, such as Vesuvius and Etna, and those which rise far in
the interior of the land, as Tolima, Jorullo, and Puracé. This compara-
tive study, however, which would be calculated to throw light on the
chemical phenomena of deep-lying beds, has as yet been made at only a
* Fouqué, Revue des Dew: Mona’es, August, 1866.
436 THE EARTH.
few points. Eruptions are rare in volcanoes situated far from the coast,
and when they do take place, scientiﬁc men do not happen to be on the
spot to study the course of the occurrence. Popocatepetl, one of the
most remarkable continental volcanoes, produces a large quantity of hy-
drochloric'acid; the snow from it, which has a very decided muriatic
taste, is_ carried by the rain into the Lake of Tezcuco, where, in conjunc-
tion with soda, it forms salt.*
When the water, either of sea or rivers, penetrates into the crevices of
the terrestrial envelope, it gradually increases in temperature the same as
the rocks it passes through. It is well known that this increase of heat
may be estimated on the average, at least as regards the external part of
the planet, at 1° (Fahr.) for every 54 feet in depth. Following this law,
water descending to a point 7500 feet below the surface would show, in
the southern latitudes of Europe, a temperature of about 212° (Fahr.).
But it would not on this account be converted into steam, but would
remain in a liquid state, owing to the enormous pressure which it has to
undergo from the upper layers. According to calculations, which are
based, it is true, on various hypothetical data, it would be at a point more
than nine miles below the surface of the ground that the expansive force
of the water would attain suﬁicient energy to balance the weight of the
superincumbent liquid masses, and to be suddenly converted into steam at
a temperature of 800° to 900° (Fahr.). These gaseous masses would then
have force to lift a column of water of the weight of 1500 atmospheres;
if, however, from any cause, they can not escape as quickly as they are
formed, they exercise their pressure in every direction, and ultimately ﬁnd
their way from ﬁssure to ﬁssure until they reach the fused rocks which
exist in the depths. To this incessantly increasing pressure we must,
therefore, attribute the ascent of the lava into vent-holes of volcanoes, the
occurrence of earthquakes, the fusion and the rupture of the terrestrial
crust, and, ﬁnally, the violent eruptions of the imprisoned ﬂuidsfy But
why should the vapor thus pervade the subterranean strata and upheave
them into volcanic cones, when, by the natural effect of its overcoming the
columns of water which press it down, it ought simply to rise toward the
bed of the sea from which it descended ‘B In the present state of science,
this is a question to which it seems absolutely impossible to give a satis-
factory answer,f[ and geologists must at least have the merit of candidly
acknowledging their ignorance on this point. The discoveries of natural
philosophy and chemistry, which have been the means of making known
to us the enormous activity of steam in volcanic eruptions, will doubtless,
sooner or later, explain to us in what way this activity is exercised in the
subterranean cavities. But at the present time the phenomena which are
taking place in the interior of our globe are not better known to us than
the history of the lunar volcanoes. '
* Virlet, Bulletin de la Socz'été Géologique de France, May 1st, 1865.
'l' Buff, Briej‘e iiber die Pkysik der Erde.
i Otto Volger, Erdbeben der Schwez'z.
CONNECTION OF VOL CAN 0E8. 437
Be this as it may, the direct observations which have' been'made on
volcanic eruptions .have now rendered it a very doubtful point whether
the lavas of various volcanoes‘ proceed from one and the same reservoir
of molten matter, or from the supposed great central furnace which, is
said to ﬁll the whole of the interior of the planet. Volcanoes which are
very close to one another show no coincidence in the times of their erup-
tions, and vomit forth, at different'epochs, lavas which are most dissimilar
both in appearance and mineralogical composition. These facts would be


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Fig. 173. Line of Fracture between Etna and Vesuvius.
eminently impossible, if the craters were fed from the same source. Etna,
the group of the Lipari Isles, and Vesuvius, have often been quoted as be-
ing volcanic outlets placed upon the same fracture of the terrestrial crust;
and it is added, in corroboration of this assertion, that a line traced from
the Sicilian volcano to that of Naples passes through the ever-active fur-
nace of the Lipari Isles. Although the mountain of Stromboli, so regular
in its eruptions, is situated on a line slightly divergent from the principal
line, and, on the other side, the volcanic isles of Salini, Alicudi, and Feli-
cudi tend from east to west, it is possible, and even probable, that Vesu—
438 THE EARTH.
vius and Etna are in fact situated on ﬁssures of the earth which were once
in mutual communication. But during the thousands of years in which
these great craters have been at work, no connection between their erup- .
tions has ever been positively certiﬁed.
Sometimes, as in 1865,Vesuvius vomits forth lava at the same time as—
‘Etna; sometimes it'is in a state of repose when its mighty neighbor is
'in full eruption, and rouses up when the lava of Etna has cooled. There
is nothing which affords the slightest indication of any law of rhythm or
periodicity in the eruptive phenomena of the two volcanoes. The inhab-
itants of Stromboli state that, during the winter of 1865, at the moment
when the sides of Etna were rent, the volcanic impulse manifested itself
very strongly in their island by stirring up the always agitated waves
of the lava-crater which commands their vineyards and houses. A com-
parative calm, however, soon succeeded this temporary eﬂ'ervescence, and
in the adjacent island of Volcano no increase of activity was noticed. If
the shafts of Etna, Vesuvius, and the intervening volcanoes, take their
rise in one and the same ocean of liquid lava, all the lower craters must
necessarily overﬂow simultaneously with the most elevated. Now, as
has often been noticed, the lava may ascend to the summit of Etna, at a
height of 10,827 feet, without a simultaneous ﬂow of rivers of molten


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stone from Vesuvius, Stromboli, and Volcano, which are respectively but
one third, one fourth, and one tenth the height of the former. In like
manner, Kilauea, situated on the sides of Manna-Lea, in the Isle of Hawaii,
in no way participates in the eruptions of the central crater opening at a
point 9800 feet higher up, and not more than 12 miles away. If there is
any present geological connection between the volcanoes of one and the
same region, it probably must be attributed to.the fact of their phenome-
na depending on the same climatic causes, and not because their bases
penetrate to one and the same ocean of ﬁre. Volcanic oriﬁces are not,
therefore, “ safety-valves,” for two centres of activity may exist on one
mountain without their eruptions exhibiting the least appearance of con-
nection.* _
Isolated as they are amid all the other formations on the surface of the
earth, lavas appear as if almost independent of the rest. Basalts, tra-
chytes, and volcanic ashes, are the comparatively modern products which
are scarcely met with in the periods anterior to the Tertiary age. Only
a very small quantity of these lavas of eruption has been found in the
Secondary and Palaeozoic rocks. Formerly, most geologists thought that
the granites and rocks similar to them had issued from the earth in a
past-y or liquid state; they looked upon them as the “lavas of the past,”
* Dana, Proceedings of the American Association, 1849.
ORIGIN OF VOL CANOES. 4:39
and believed that these ﬁrst eruptive rocks were succeeded in age after
age by the diorites, the porphyries, the trap-rocks, then by the trachytes
and the basalts of our own day, all drawn from a constantly increasing
depth. They thought also that, in the future, when the whole series of
the present lavas shall have been thrown up to the surface, volcanoes
would produce other substances as distinct from the lavas as the latter
are from the granite. Granites, however, differ» so much from the tra-
chytes and basalts as to render it impossible for us to imagine that they
have the same origin; added to which, the labors of modern scwants have
proved that, under the action of ﬁre, granite, and the other rocky masses
of the same kind, would have been unable to assume the crystalline tex-
ture which distinguishes them. We are, then, still ignorant how volcanic
eruptions commenced upon the earth, and how they are connected with
the other great phenomena which have co-operated in the formation of
the external strata of the globe.
440 THE EARTH
CHAPTER LXIV.
GROWVTH OF VOLCANOES.-——THEORIES OF IIUMBOLDT AND LEOPOLD VON
BUCH AS TO THE UPIIEAVAL OF CRATERS.—DISAGREEMENT OF THESE
THEORIES \VITH TIIE FACTS OBSERVED.
CONSIDERED singly, each volcano is nothing but a mere oriﬁce, tempo-
rary or permanent, through which a furnace of lava is brought into com-
munication with the surface of the globe. The matter thrown out accu-
mulates outside the opening, and gradually forms a cone of debris more
or less regular in its shape, which ultimately attains to considerable di-
mensions. One ﬂow of molten matter follows another, and thus is grad-
ually formed the skeleton of the mountain; the ashes and stones thrown
out by the crater accumulate in long slopes; the volcano simultaneously
grows wider and higher. After a long succession of eruptions, it at last
mounts up into the clouds, and then into the region of permanent snow.
At the ﬁrst outbreak of the volcano the oriﬁce is on the surface of the
ground; it is then prolonged like an immense chimney through the cen-
tre of the cone, and each new river of lava which ﬂows from the summit
increases the height of this conduit. Thus the highest outlet of Etna
opens at an elevation of 10,892 feet above the level of the sea; Teneriﬁ'e
rises to 12,139 feet; Manna-Lea, in Hawaii, to 13,943 feet; and, more
gigantic still, Sangay and Sahama, in the Cordilleras, attain to 18,37 2 and
23,950 feet in elevation.
This theory of the formation of volcanic mountains by the accumula-
tion of lava and other matters cast out of the bosom of the earth presents
itself quite naturally to one’s mind. Most savants, from Saussure and
Spallanzani down to Virlet, Constant Prévost, Poulett Scrope, and Lyell,
have been led, by their investigations, to adopt it entirely; indeed, in
the present day it is scarcely disputed. It is true that Humboldt, Leo-
pold von Buch, and, following them, M. Elie de Beaumont, have put forth
quite'a different hypothesis as to the origin of several volcanoes, such as
Etna, Vesuvius, and the Peak of Tenerilfe. According to their theory,
volcanic mountains do not owe their present conformation to the long-
continued accumulation of lava and ashes, but rather to the sudden up-
heaval of the terrestrial strata. During some revolution of the globe, the
pent-up matter in the interior suddenly upheaves a portion of the crust
of the planet into the form of a cone, and opens a funnel-shaped gulf be-
tween the dislocated strata, thus by one single paroxysm producing lofty
mountains, as we now see them. As an important instance of a crater
thus formed by the upheaval and rupture of the terrestrial strata, Leo-
pold von Buch mentions the enormous abyss of the Isle of Palmayknown


FORJIA TI ON OF ORA T E135’. l
by the natives under the name of “ Caldron,” or Caldera. This funnel-
shaped cavity is of enormous dimensions, and is not less than four or ﬁve
miles in width on the average; the bottom' of it is situated about 2000
feet above the level of the sea. Lofty slopes, from 1000 to 2000 feet in
height, rise round the vast amphitheatre, and abut upon inaccessible cliffs,


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. Fig. 175. Isle of Palma.
the upper ledges of which reach a total altitude of 5900 to 6900 feet in
height. The highest point, the Pico-de-los-lliuchaclios, is covered by snow
during the winter months ; and although it penetrates into regions of the
atmosphere which are of a very different character from those of the rest
of the island, the slope that is turned toward the crater is so steep that


442 THE’ EARTH.
blocks of'stone falling from the summit roll down into the inclosed
hollow.‘
The prodigious cavity in the Isle of Palma was, perhaps, the most strik-
ing instance that Leopold von Buch could bring forward in favor of his
hypothesis; nevertheless, the exploration of this island, since carried out
by Hartung, Lyell, and other travelers, is very far from conﬁrming the
ideas of the illustrious German geologist. The lofty side-walls of the
hollow appear to be formed principally, not of solid lava, which consti-
tutes scarcely a quarter of the whole mass, but of layers of ashes and
scoriee, regularly arranged like beds of sand on the incline of a talus.
Basalts and strata of ashes lie upon one another in the greatest order round
the inclosed hollow, which would be a fact impossible to comprehend if
any sudden upheaval, acting in an upward direction with suﬁicient vio—
lence to break the terrestrial crust, had shattered and ruptured all the
strata, and, by a mighty explosion, opened out the immense Caldron of
Palma. Finally, if a phenomenon of this kind had taken place, star-
formed cracks, like those produced in broken glass, would be visible across
the thickness of the upheaved strata, and their greatest width would be
turned toward the crater. Now there are no ﬁssures of this kind, and
the ravines in the circumference of the volcano, which one might perhaps
be tempted to confound with actual ruptures of the ground, become
wider in proportion as they approach the sea. The enormous cavity in
Palma is, therefore, a crater similar to those of volcanoes of less dimen-
sions. It is, however, certain that the Caldera was once both shallower
and less in extent, for the ashes and volcanic scoriae are easily carried
away by the rain, which is swallowed vup in the bottom of the basin, and
has hollowed out for itself a wide drainage-channel in a southwest direction.
co! 9!
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Fig. 176. Section of the Island of Palma from Southeast to Northwest.
001 5*
anta Cruz
M. Elie de Beaumont, as his chief support of Leopold von Buch’s hy-
pothesis, brought forward the fact that most of the strata of lava a sec-
tion of which may be seen on the sides of Etna, in the immense amphi-
theatre of the Val del Bove—are very sharply inclined. The celebrated
geologist aﬁirmed that thick sheets of molten matter could not run down
steep slopes without being very soon reduced, in consequence of the ac-
celeration of their speed, into thin layers of irregular scoriae. If this were
really the case, the position of the thick ﬂows of lava in the Val del Bove
must ‘have changed ‘since the date of the eruption; it would then be
necessary to admit that vthey have been violently tilted up after having
been originally deposited on the soil in sheets, which were either horizon-

VOL CH'AVO OF J OR ULLA. 44 0
U
tal or very gently sloped. Nevertheless, the recent observations made by
Sir C. Lyell, those of Darwin on the cones of the Gallapagos Isles, and of
Dana on the lava ﬂows of Kilauea; lastly, the remarks of the Italian sa-
cants who studied on the spot the volcanic phenomena of Vesuvius and
Etna, have satisfactorily proved that, in modern times, a great number of
rivers of lava, and especially that of the Val del Bove, in 1852 and 1853,
have ﬂowed over steep slopes varying in inclinations from 15 to 40 de-
grees. It must, besides, be understood that the lava which poured OVGI‘
the steepest slopes was exactly that portion which, not having experi-
enced any cause of delay, or met with any obstacle, in its course, presented
layers of the most uniform consistence and the most regular action.


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One of the strongest arguments of scientiﬁc men in favor of the theory
of upheaval is, that certain volcanic mountains, especially that of Monte—
N uovo, of Pouzzoles, and Jorullo, in Mexico, had been suddenly raised up
by the swellings of the soil. N ow the unanimous testimony of those
who, more than three centuries ago, witnessed the eruption of Monte-
Nuovo is, that the earth was cleft open, aﬁ'ording an outlet to vapor,
ashes, scoriae, and lava, and that the hill, very much lower than some of
the subordinate cones of Etna, gradually rose during four days by the
heaping up of the matter thrown out. The total volume of this eruption
4 1 4 THE EARTH.
was no doubt considerable, but compared with the amount of matter
which ﬂowed down upon Catania in 1669, or with the rivers of lava from
Skaptar-J okul, it is a mass of no great importance. Added to this, if the
soil was really upheaved, how was' it that the neighboring houses were
not thrown down, and that the colonnade of ‘the Temple of Neptune,
which stands at the foot of the mountain, kept its upright position?
With regard to J orullo, which rises to a height of more than 1650 feet,
the only witnesses of this volcano making its ﬁrst appearance were the
Indians, who ﬂed away to the neighboring heights, distracted with terror.
We have, therefore, no authentic testimony on which we can base an hy-
pothesis as to any swelling up of the ground in the form of a blister.
Quite the contrary, the travelers who have visited this Mexican volcano
since Humboldt have discovered beds of lava lying one over the other, as
in all other cones of eruption; and more than this, they have also ascer-
tained that none of the strata in the ground overlooked by the mountain
have been at all tilted up.*
It is true enough that local swellings have often been observed in the
burning matter issuing from the interior of the earth ; in many places the
lava is pierced by deep caverns, and entire mountains—especially that
of Volcano—have so many hollows in the rocks on their sides that every
step of the climber resounds on them as if on a vault. Besides, the lava
itself, being a kind of impure glass, is so pervaded by bubbles ﬁlled with
volatile matter that, when acted upon by ﬁre, so as to expel the water and
the gas, it loses on an average, according to Fouqué, two thirds of its
weight. But these caverns, these hollows and bubbles, proceed from the
mixture of the lava with vapor which is liberated with difﬁculty from the
viscous mass, or are caused by the longitudinal rupture of the strata dur-
ing an eruption, and can in no way be compared to the immense blister-
like elevation which would be formed by the strata of a whole district
being tilted up to a height of hundreds, or even thousands, of yards, leav-
ing at the summit, between two lines of fracture, room for an immense
cavity.
None of these prodigious upheavals have been directly observed by
geologists, and none of the legends invented by the fears of our ancestors,
referring to the sudden appearance of volcanic mountains, have been since
conﬁrmed. Lastly, the very structure of the peaks which are said to
have risen abruptly from the midst of the plains testiﬁes to the gradual
accumulation of material that has issued from the bowels of the earth.
It is, therefore, prudent to dismiss deﬁnitively an hypothesis which marks
an important period in the history of geology, but which, for the future,
can only serve to retard the progress of science.
* Arnold Bosccwitz, Les Volcans et les Tremblements de T erre.
ARRANGEMENT OF VOL CANIC' O U T LE T S. 445
CHAPTER LXV.
NUMBER AND ARRANGEMENT OF VOLCANIC OUTLETS—FORM OF VOL-
CANIC CONES AND CRATERS.
As, when the burning matter seeks an outlet, the earth is generally cleft
open in a straight line, the volcanic oriﬁces are frequently distributed
somewhat regularly along a ﬁssure, and the heaps of erupted matter fol—
low one another like the peaks in a mountain chain. In other places, how-

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Fig. 178. Series of Craters, Hawaii.
ever, the volcanic cones rise without any apparent order on ground that
is variously cleft, just as if a wide surface had been softenedin every di-
rection, and had thus allowed the molten matter to make its escape, some-
times at one point,sometimes at another. From the town of Naples-—
which is itself built on halfa crater in great part obliterated—to the
Isle, of Nisida, which is an old volcano of regular form, the Phlegreean
Fields present a remarkable example of thisconfusion of craters. Some
are perfectly rounded, others are broken into, and their circle is invaded
by the waters of the sea: grouped, for the most part, in irregular clumps,
even encroaqhing upon one another and blending their walls, they give to
the whole landscape a chaotic appearance. As'Mr. Poulett'Scrope very
justly remarks, the aspect of the terrestrial surface at this spot reminds
446 THE EARTH.
one exactly of the volcanic districts of the moon, dotted over, as it is, with
craters.
As the type of a region pierced all over with volcanic oriﬁces, we may
~ also mention the Isthmus of Auckland, in New Zealand, where Dr. Hoch-


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Fig. 179. Auckland and its ‘Volcanoes.

stetter has reckoned, in an area of 230 square miles, sixty-one independ-
ent volcanoes, 520 to 650 feet in height on the average. Some are mere
cones of tuf'a; others are heaps ofscorise, or even eruptive hillocks, which
have shed out round them long ﬂows of lava. At one time the Maori
chiefs used to intrench themselves in these craters as if in citadels; they
escarped the outer slopes in terraces, and furnished them with Palisades.
At the present day, the English colonists, having become lords of the soil,
have constructed their farms and country houses on these ancient volca-
noes, and are constantly bringing the soil under cultivation.*_
The Safa,in the Djebel-Hauran, is also a complete chaos of hillocks and
r’
"' Ferd. von Hochstetter, Neu-Seeland.
DISPOSITION OF ORA TERS.
abysses. On this plateau of 460 square miles, which the Arabs call a
“ portion. of hell,” almost all the craters open on the surface of the ground,
and not on the summits of volcanoes scattered here and there on the black


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surface. In every direction there may be seen rounded cavities like the
vacuities formed in scorize by bubbles of gas,‘ only these cavities are 600
to 900 feet wide, and 65 to 160 feet deep. Some are isolated; some either
touch or are separated'by nothing but narrow walls-like masses of red or
darkish-colored glass. ' One hardly cares to venture on these narrow isth-
muses, bordered by precipices, and intersected here and there by ﬁssures.*
The normal form of the volcanoes in which" the work of eruption takes
place is thatiof a slope of debris arranged in a circular form round the out-
let. Whether the volcano be'a mere cone of ashes or mud only a few-
yards high, or rise into the regions of the clouds, vomiting streams of lava


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* Wetzstein, ZeitsclzrzftErd/tunde, 1859.
'-v_
443 THE EARTH.
over an extent of 10 or 20 miles, it none the less adheres to the regular
form so long as the eruptive action is maintained in the same channel, and
the debris thrown out falls equally on the external slopes.
The beauty of the cone is increased by that of the crater. The term-
inal oriﬁce from which the lava boils out well deserves, from the purity
ofits outline, its Greek name of “ cup,” and the harmony ofits curve con-
trasts most gracefully with the declivity of the slope. In some volcanoes
the symmetry of the architectural lines is so complete that the crater it-
self contains a cone placed exactly in the centre of the cavity, and pierced
by a second crater in miniature, from which vapor makes its escape.
Volcanoes in which the eruptive action frequently changes its position
—and these are the more numerous class—do not possess this elegance of
outline. Very often the upheaved lava ﬁnds some weak place in the walls
of the crater; it hollows them out at ﬁrst, and then, bringing all its weight
to bear on the rocks which oppose its passage, it ultimately completely
breaks down the edge of the crater, leaving perhaps only one side stand-
ing. Among the European volcanoes, Vesuvius is the best example of

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these ruptured craters: before A.D-79, the escarpments of La Somma,
which now surround with their semicircular rampart the terminal cone
FORM OF VOL CANOES. 449,
of Vesuvius, were the real ‘crater. The portion of it which no longer ex--
ists disappeared, and buried under its debris the towns of Herculaneum.
and Pompeii.


...M& m»
Fig. 184. Section of Vesuvius from South to North.
Active volcanoes, however, never cease to increase in all their dimen-
sions, and sooner or later the breach is ultimately repaired; the remains
of the former craters are gradually hidden under the growing slopes of
the central cone. Thus a former crater on Etna, which was situated at a
point three miles in a straight line from the present outlet, at the com-
mencement of the Val del Bove, has been gradually obliterated by the lava
of successive eruptions: prolonged explorations on the part of MM. Seyell
and Waltershausen have been necessary in order to ﬁnd it out. The nor-
mal form of Etna is that of a cone of debris placed upon a large dome with
long slopes, becoming more and more gentle, and descending gracefully
toward the sea. In fact, in most of the eruptions, the lava does not rise as
far as the great crater, and breaks through the sides of the volcano so as to
ﬂow laterally over the ﬂanks of Etna. These eruptions, succeeciiiwiine
\
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Fig. 185. Section of Etna from West to East.
‘\1‘


another in the course of centuries, bring about the necessary resultyof grad-
ually enlarging the dome which constitutes the mass of the mountain, thus
breaking the uniformity of the lateral talus. The same thing occurs with
regard. to Vesuvius on the side which faces the sea-coast. There, too, the
terminal cone stands on a kind of dome, which has been gradually formed
by the coats of lava running one over the other. If Vesuvius continues to
be the great volcanic outlet of Italy, and rises gradually into the sky by

FF
450' ' v . THE EARTH'
the superposition of lava and ashes, it can not fail, some time or other, to
assume a form similar to that of the Sicilian giant. 4
The volcanoes which present cones of almost perfect regularity are those
which have their terminal outlet alone in a state of activity, and vomit out
a large quantity of ashes or other matter which glides readily over the
slopes. Among this class of mountains, those which attain any consider-
able elevation are distinguished by their majesty from all other peaks.
Stromboli, although it is not more than 2600 feet inheight, is one of the
wonders of the Mediterranean. From its proud form, it will readily be
- understood that its roots plunge down into the sea to an enormous depth;


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Fig. 187.’ Proﬁle of Orizaba.
the slope of clébrz's may be seen, so to speak, prolonged under the water
down to the abysses of 3000, to 4000ifeet,whichithe‘sounding-line has reach-
ed at the bottom of the ZEolian'Seaf sight of it one feels as if suspend-
ed in the midst of the void, as if the ship was‘ sailing in theair midway up
the mountain. This feeling of admiration mingled with dread increases
FORM OF VOL OANOES. 1
when this great pharos of the Mediterranean is approached during the
night over the dark-waved sea. Then the sky above the summit seems all
lighted up by the reﬂection of the lava, and a misty band of clouds and va-
por may be dimly seen girdling round the body of the volcano. In the
daytime the impression made is of a different character; but it is none
the less deep, for the real grandeur of Stromboli consists not so much in
the immensity of the mass as in the harmony of its proportions.
Volcanic mountains of an ideal form are those which infant nations have
most adored. Among these sacred mountains are the sublime Cotopaxi
of the Andes, Orizaba of Mexico, Manna-Lea of Hawaii, and Fusi-Yama of
Japan. The volcanoes of Java, and chieﬂy those in the eastern portion of

106' 108 no u:


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Fig. 188. Volcanoes of Java.


the island, also present a very majestic appearance on accountoftheiriso-
lation. Those on the western side are based upon an undulating plateau,
which causes them to lose their appearance of height; but on the east all
the volcanic mountains rise up from verdant plains like islands above the
waves of the sea, and command the horizon far and wide with their enor-
mous cones. Between the Merapi and Lavoe mountains lies a depression,
the highest ledge of which exceeds the level of the sea by only 312 feet.
Between Lavoe and Villis the plain is 230 feet in height. Lastly, the
plains which separate the Villis and Keloeet mountains nowhere attain an
elevation of more than 200 feet above the ocean.*
In the external details of their conformation many of the volcanoes of
Java present a regularity of outline which is all the more striking, since
they owe it in great part to the monsoon rains, the most destructive
agents of the tropical regions. In beating against the mountains, the
clouds let fall their burden of moisture on the slopes composed of ashes
and loose scoriae. The latter offer but a slight resistance to the action of
the temporary torrents which carry them ‘away, and, crumbling down
into the plains which surround the base of the volcano, are deposited in
long slopes, like those caused by avalanches. In consequence of the fall
of all this (Zebra's, the sides of the mountain are cut out at intervals by ra-
* J unghuhn, Java, seine Gestalt and innere Bauart.
452 > THE EARTH.-
vines or furrows, which gradually widen from the summit to the base of
the mountains, and attain atdepth of 200, 600, and 660 feet. There are
some volcanoes, such as the Sumbing, in which these ravines assume so
perfect a regularity that the whole mountain, with its equidistant furrows
andits intermediate walls, resembles a gigantic ediﬁce based upon enor-
mous buttresses, like the nave of a Gothic cathedral.*
Formerly the beauty of the island and the fury of its volcanoes were
the cause of its being altogether dedicated to Siva, the god of destruction;
and in the very craters of the burning mountains the worshipers of Terror
and-Death were in the habit of building their temples. In many spots the
ruins of these sanctuaries are discovered inthe midst of trees and thickets,
which the Arab conquerors have left to grow in the formidable cavities
of the volcanoes. Semeree, the loftiest peak in the island, was the sacred
mountain par excellence ,' the Sumbing, which rises in the centre of the
island, was the “ nail which fastens Java to the earth.” Even in our own
time some faithful followers of Siva inhabit a sandy plain, more than four
miles wide, which was once the crater of the Tengger volcano ; every year
they proceed solemnly to pour rice on the summit of an eruptive cone,
into the roaring mouth of the monster. In like manner, in New Zealand,
the ever-smoking oriﬁce of Tongariro was considered as the only place
worthy of receiving the dead bodies of their great chiefs : when cast into
the crater, the heroes went to sleep among the gods.
But the volcanic divinities, like most of the other rulers invoked by na-
tions, did not content themselves with the fruits of the earth or the com-
panionship of a few warriors; they also’ demanded blood,both by their
subterranean roarings, by their thundering eruptions, and their devasta-
ting rivers of lava. Innumerable- sacriﬁces have been offered to volcanoes-
to appease their anger: impelled by a mingled feeling of fear and ferocity,
the priests of not a few religions have cast victims with great pomp into
the gaping hollows of these immense furnaces. Scarcely three centuries
ago, when the disciples of Christianity were exterminated over the whole
length and breadth of Japan, the followers of the new religion were thrown
by hundreds into one of the craters of the Un'sen, one of the most beauti-
ful volcanoes of the archipelago; but this offering to the offended gods
did not appease their anger, for, toward the end of the eighteenth century,
this very same mountain and the neighboring summits caused by their
eruptions one of the most frightful disasters of any that are mentioned in
the history-of volcanoes. Actuated by a feeling of dread very similar to
that exhibited by the'Japanes'e priests, the Christian missionaries in Amer-
ica recognized in the'burning mountains of the New World not the work
of a god, but that of the devil, and went in procession to the edge of the
craters to exercise them. A legend tells how the‘monks of Nicaragua
climbed the terrible volcano of Momotombo in order to quiet it by their
conjurations; but they never returned: the monster swallowed them up.
" ' ~ * Arnold Boscowitz, Volcans et Tremblements dc Terre.
_ COMPOSITION OF LA VAb'. 45 3
CHAPTER LXVI.
COMPOSITION OF LAVAS TRACHYTES; PUMICE'STONE ; OBSIDIAN BASALTS ;
BASALTIC COLON N ADES.
LAVA is the most important product of the volcanic ﬁres. The various
kinds of lava differ very much in their external appearance, in the color
of their substance, and in the variety of their crystals, but they are all
composed of silicates of alumnia or magnesia, combined with protoxide
of'iron, potash or soda, and lime. When the feldspathic minerals pre-
dominate, the rock is generally of a whitish, grayish, or yellowish hue,
and receives the name of trachyte. When the lava contains an abun-
dance of crystals of augite, hornblende, or titaniferous iron, it is heavier,
of a darker color, and often more compact; it then takes the generic for-
mation of basalt. Numerous varieties, diversely designated by geologists,
belong to this group. '
Of ‘all the lavas, trachyte is the least ﬂuid in its form. In many places
rocks of this nature have issued from the earth in a pasty state, and have
accumulated above the oriﬁce in the shape of a dome, “just like a mass
of melted wax.”* In this way were formed the great domes ofAuvergne,
the Puys de Dome and de Sarcouy. In this district the ﬂowsof trachytic
lava are far inferior in length to the basaltic eheires ,: the most important
do not exceed four or ﬁve miles in length. At the present day, eruptions
of trachyte are much more rare than those of other lavas; so much so,
that certain authors class all the trachytic rocks among the formations of
anterior ages. It is, however, ascertained that most of the American vol-
canoes and those of the Sunda Archipelago vomit out lava of this nature;
the last eruptions of the ZEolian Isles, Lipari and Volcano, likewise pro-
duced only trachyte and pumice-stone. '
This latter substance resembles certain white, yellow, or greenish sco-
riae, which issue like a frothy dress from the furnaces of our iron-works,
and is, like the compact trachyte,-of a feldspathic nature. Some moun-
tains are almost entirely composed of it; among others, the Monte Bianco
of Lipari, which, viewed from a distance, appears as if covered with snow‘.
Long white ﬂows, like avalanches, ﬁll up‘ all its ravines, from the summit
of the mountain to the shore‘of the Mediterranean; the slightest move-
ment caused by the tread of an animal or a‘ gust of wind detaches from
the surface of the slope hundreds of stones, which bound down to the foot
of the incline, and are borne away by the‘ waves which bathe the base- of
the mountain. In the southern part of the‘ Tyrrhe'nean Sea, and especially
in the vicinity of the Lipari (ZEolian) Islands‘, the water is sometimes cov-
* Poulett Scrope, Volcanoes: the Character of their Phenomena, etc.
454 THE 5.112111
ered with these ﬂoating stones, almost like ﬂakes of foam. In the Cordil-
leras the currents of fresh water convey‘the morsels of pumice to consid-
erable distances. The River Amazon drifts down large quantities of
pumice as far as its mouth, more than 3000 miles from the place where it
fell into the river. Bates says that the Indians, who live too far away
from the volcanoes even to know of their existence, assert that these
stones, ﬂoating down the river by the side of their canoes, are assuredly
solidiﬁed foam. '
The external appearance of various lavas differs even more than their
chemical composition. The more or less perfect state of ﬂuidity, and the
presence in them of a greater or less quantity of bubbles of vapor, give a
very different texture to rocks which are composed of the same elements.
Pumice-stone has the appearance of sponge; obsidian looks like black
glass, and sometimes even it is semi-transparent. It is entirely liquid,
and issues from the interior of the earth like a stream ﬂowing rapidly
over the steeper slopes, and coagulating slowly in large sheets in the low
ground and on the gentle inclines whither its own weight has drawn it.
The surface of obsidian—for instance, that of Teneriﬁ'e—shines with a vit-
reous glitter; the cleavage of the rock is clean and sharp.
Some less degree of ﬂuidity in the current of lava gives it sometimes
the appearance of resin; this is the stone which is called pec/zstez'n (pitch-
stone). When the rock, issuing in a state of fusion from the bosom of the
mountain, becomes still cooler, it contains innumerable perfectly-formed
crystals, and only owes its ﬂuidity to the particles of vapor in its pores.
The external layer of the lava is also immediately covered with scoriae
which ﬂoat in ﬂakes on the ﬁery stream. These scoriae, too, assume a
great variety of shapes; some are mammillated, others are exceedingly
rough and irregular. In the Djebel-Hauran, near the crater of Abu-Ga-
nim, there is an inﬁnity of needles of red lava, about a yard high on the
average, and bent in various directions toward the surface of the plateau;
one might often fancy them ﬂames half beaten down under the pressure
of the wind. According to M.Wetzstein, these strange stone needles pro-
ceed from an eruption of ﬂaky lava. In the Sandwich Islands, and in the
Island of Reunion, certain crystals of a ferruginous appearance are group-
ed at the outlet of the crater in herbaceous forms of the most curious and
sometimes elegant character. Some of the products of the volcano of
Mauna-Loa and Kilauea resemble the tow of hemp! These are the whit-
ish ﬁlaments which are sometimes carried away by the wind; the Kanakes
used to consider them as the hair of Pele, the goddess of ﬁre.
Among the old basaltic lavas there are some to which the name of
basalt is more specially applied, which present a columnar disposition with
wonderful regularity. These form the enormous monuments, much more
imposing than those of man, which seem as if they had been constructed
by giant builders, turning their mighty hands to the noble art of archi-
tecture, which is still practiced, though on a smaller scale, by us their
feeble descendants. These magniﬁcent colonnades of basalt‘are every
BASALTIO 00L UMNS. 455


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Flow of Vitreous Lava at Mauna-Loa.


where attributed to giants. In Ireland, on the coast of Antrim, the sum-
mits of 40,000 prisms, leveled pretty regularly by the Waves of the sea,
and resembling a vast paved quay, have received the name of the Giant’s
Causeway. In Scotland, the beautiful cave of the Isle of Staﬁ‘a, hollowed
out by the action of the waves between two ranges of basaltic shafts, is
celebrated as the work of Fingal, the demigod. In the Sicilian Sea, the
Faraglioni Isles, or Isles of the Cyclopes, situated not far from Catania, at
the base of Etna, are looked upon by tradition as the rocks cast by Poly-
phemus on the ships of Ulysses and his companions. Many of-these prisms
are from 100 to 160 feet high, and are not less than 6 to 10 feet in thick-
ness. Near Fair Head and the Giant’s Causeway some of the shafts con-
nected with the perpendicular cliff of the headland are nearly 400 feet in
height. In the Isle of Skye, some of the columns, according to M‘Cul-
loch’s statement, are still higher. On the other hand, there are also col-
onnades in miniature, each shaft of which is not more than three quarters
of an inch to an inch from the summit to the base,» instances of these are
found in the basalts of the hill of Morven in Scotland.
Some geologists have thought that basaltic columns could not be form-
ed except under the pressure of enormous masses of water; but a com-
parative study of these rocks in different parts of the world has. proved
that several beds of lava are arranged in columns at heights considerably
above the level of the sea. In this colonnade-like formation of lava there
is, however, no phenomenon which is entirely peculiar to basalt._ Trachyte,
also, sometimes assumes this ‘form, and M. Fouqué has discovered amagnif-
icent instance of it in the island of Milo, in which there is a cliff composed
of prismatic shafts 320 feet in height. Masses of mudwhen dried in the
sun, the alluvium of rivers, beds of clay or tufa, and, in general, all, matter
which, in consequence of the loss of its moisture, passes from a pasty to a
solid state, either in a state of nature or in our manufactories and dwell-
ings, likewise assume a columnar structure similar to that of the basaltic
456 > THE EARTH.
lava. In fact, the entire mass, when gradually losing the moisture which
swelled out its substance, can not contract so as to shift the position of
all its particles toward the centre; certain points remain ﬁxed, and round
each of these the contraction of‘ a portion of the mass takes place. In
basalt, in particular, it is the lower layer which assumesjhe columnar
structure, for these alone cool gently enough to allow the phenomena of
contraction to follow the normal course. The highest portion of the mass,
being deprived, immediately after its issue from the earth, of the calorie
and the steam which ﬁlled its pores, is almost immediately transformed
into a more or less rough and cracked mass. But this very crust protects
the rest of the lava against any radiation, and serves as a covering to the
semi-crystalline columns which, by the continual contraction of their parti-
cles, are slowly separated from the rest of the mass. When a section of a
bed of basaltic lava has been laid bare by the water of a river, the waves
of the ocean, or earthquake, the rough stone of the top layers may be seen
lying, with or Without any gradual transition, on a forest of prisms, some-
times rudimentary in their shape, but often no less regular than if they
had been carved out by the hand of man. Most are of a hexagonal form;
" others, which were probably subject to less favorable conditions, have
four, ﬁve, or seven faces; but all are deﬁnitely separated from one another
by their particles gathering round the central axis. Mr. Poulett Scrope
describes a fact which proves the enormous power of this contractile force.
The colonnade of Burzet, in Vivarais, contains numerous nodules of oli-
vine, many of which are as large as a man’s ﬁst; and, in spite of their ex-
treme hardness, have been divided into two pieces, each ﬁxed in one of
two adjacent columns. Although the two corresponding surfaces have
been polished by the inﬁltration of water,.it is impossible to doubt that
the two separate portions were not once joined in the same nodule.
As natural philosophers have veriﬁed by experiments on various viscous
substances, basaltic shafts are always formed perpendicularly to the sur-
face of refrigeration. Now, this surface being inclined, according to the
locality, in a diversity of ways, the result is, that the columns may assume
a great variety of directions in their position. Although most of them
are vertical, on account of the cooling taking place in an upward direc-
tion, others,‘ as at St. Helena, take a horizontal direction, and resemble
trunks of trees heaped upon a wood-pile. In other places, as at the Coupe
d’Ayzac in Auvergne, the columns of a denuded cliﬁ' are arranged in the
form of a fan, so as to lean regularly on the wall of the cliff as well as on
the ground-of the valley. At Samoskde, in Hungary, a sheet of columnar
basalt, very small at its origin, spreads out from the top of a rock like the
water of a cascade, and hangs suspended over a precipice, resembling a
cupola which has lost its base. Elsewhere masses of basaltic pillars radi-
ate in every direction like the weapons in an immense trophy of arms.
An exact prismatic form is not, however, the only shape assumed by the
cooling lava. The phenomenon ‘of contraction takes place in different ways,
according to the nature of the erupted matter, the declivity of the slopes,
BASALTIC ,COL UMNS. 457
and all the other surrounding circumstances. Thus, in consequence of the
sinking of the rock, most basaltic prisms exhibit at intervals a kind of
joint, which gives the columns a kind of resemblance to gigantic bamboos.
In some lavas these joints are so numerous, and the edges of the stone are
so eaten away by the weather, that the shafts are converted into piles of
spheroids of a more or less regular form. At the volcano of Bertrich, in
the Eifel, one might fancy them a heap of cheeses; whence comes the
name of “ Cheese Cave,” which is given to one of the caverns which opens
in the ﬂow of lava. Sometimes, too, crystals scattered about in the midst
-of the mass have served as nuclei to globular concretions formed of nu-
merous concentric layers. Lastly, many currents of molten matter pre-
sent a tabular or schistose structure, caused, like that of slate, by the
pressure of the superincumbent masses.
458 THE EARTH.
CHAPTER LXVII.
SOURCES OF LAVA; STROMBOLI; MASAYA; ISALCO; KILAUEA.-—-LATERAL
CREVICES IN VOLCANOES.——ERUPTION AND MOTION OF LAVA.
ALTHOUGH lava, when cooled, is easy enough to study, it is more difﬁ-
cult to observe with any exactitude the molten matter immediately on its
exit from the craters or ﬁssures; besides this, the opportunities for study
which are offered to scwcmts are sometimes very dangerous. Long years
often elapse before an inquirer can notice at his ease, and without fear of
sudden explosions, the mouths of Etna or Vesuvius ﬁlling up to the brink
with boiling lava.
Stromboli is the only volcano in Europe in which this phenomenon oc-
curs regularly at closely-recurring intervals, sometimes of only ﬁve min-
utes, or even more frequently. When an observer stands on the highest
edge of the crater, he sees, about 300 feet below him, the waves of a mat-
ter which shines like molten iron, and tosses and boils up incessantly;
sometimes it swells up like an enormous blister, which suddenly bursts,
darting forth eddies of vapor accompanied by solid fragments. For cen-
turies past the lava has never ceased to boil in the cavity of Stromboli,
and it is but very rarely that a period of even a few hours elapses without
molten matter overﬂowing. Thus the crater, which, during the day, is
white with steam, and during the night red with the glare of the lava, has
served as a light-house for mariners ever since the ﬁrst vessel ventured
upon the Tyrrhenian Sea.
In Nicaragua, to the north of the Great Lake, the volcano of Masaya
(or “Devil’s Mouth”) presents a spectacle similar to that of Stromboli, but
grander, and perhaps still more regular. After having remained in a state
of repose for nearly two centuries, from 1670 to 1853, the monster—which
has received the name it bears from the frightful turbulence of its burning
waves—resumed all its former activity. In this crater the enormous bub-
bles of lava, which ascend from the bottom of the abyss and throw out a
shower of burning stones, break forth in a general way every quarter of
an hour.
The volcano of Isalco, not far from Sonsonate, in the State of San Salva-
dor, is also one of the most curious on account of its regularity. Its ﬁrst
breaking out was noticed on the 29th of March, 1783, and since this date’“
it has almost always continued to increase in size by throwing outside its
cavity ashes and stones. Some of its eruptions, remarkable for their com-
parative violence, have been accompanied by ﬂows of lava; but, generally,
the crater of Isalco conﬁnes itself to hurling burning matter to a height
* M. Squier gives another date, the 23d of February, 1770, but it is probably an error.

Fig. 191. Crater of Manna-Lea.


czex TE'R OF 151m UEA. 4:61
of 39 46 feet above its'craterl': ' explosionsifollow oneia'n'oth'e'r at "inter!
vals, of every two minutes.* ‘The .total elevation-of the’- cone-er eléb'y‘z's' '
above‘the village of :Isalco being 7 35'jfe'et', and‘thesl‘op'eof the-side. of the
mass’bein g, on the average, 35"degrees,'li/I. von Seebach, one of the-'observ-'
ers'~ of the volcano, hasjbeen able to calculate approximately the bulk-‘and
regular increase of the'mount‘ain. I In 1865 the mass‘ of debris was "about
35,000,000 of cubic yards, giving an increase of about 491,000 cubic-yards
every year, or 56‘ cubic yards every'hour. The volcano, therefore, might
be'looke'd upon as'a gigantic hour-glassy ~ - - - - - ' ~


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Fig. 190. Craters of Kilauea.
Of all the craters'in the world, the one which-most astonishes thosegwho' I, .
contemplate it is the crater of Kilauea, in the island of Hawaii. This vol-‘- .
canicoutlet ‘opens at more than‘ 3900 feetof elevation on‘ the sides ‘of the
great mountam of Manna-Lea, which is itself ‘crowned by a magniﬁcent‘-
tunnel-shaped crater27 35 yards across from one'brink to the other." ~_'I‘he_‘
elliptical crater of Kilauea is noless than '3 'm'iles'ini‘leng'th and 77 miles'pin' _
circumference. 1 The hollow, of this abyss is ﬁlled by a lake of lava, the ' _
'level of which- varies from year to year, sometimes 'rising'a'nd sometimes "
falling like water in a well. ' In a general‘way, it'lies about 600‘to"~9‘00‘
feet below the outer edge, and, in order-‘to study its details, #it'is necessary?
toget ‘on to a‘ ledge of blackla'va which extends ‘round the‘ whole "cii'c'u'mi‘
ference of the gulf; thisfis the ‘solidiﬁed edge of a" former sheet of molten‘
matter, similar 'to' those circular benches of -'ice whieh,'in northern‘ counl"
tries, border the banks‘ of .a 'lake',‘a'ndiefven'> i'n'spring'stillmarkth'e level
the water has sunk from; The 's'urface'o'f t'he'sea" of ﬁre‘is’generally'c'ovi‘ '
ered by a‘ thick crust'o'ver its whole extent; here an'd’there the redlava'i
* Moritz \Vagner; Carl von Scherzer. 1' Zeitsclmlftﬁir Erdlcunde, i866-
462 THE EARTH.
waves spring up like the water of a lake through the broken ice. Jets of .
vapor whistle and hiss as they escape, darting out showers of burning
scoriaz, and forming cones of ashes on the crust 60~ to 100 feet in height,
whichare so many volcanoes in miniature. Intense heat radiates from
. the immense crater, and a kind of hot blast makes its way through all the
chinks in the vertical walls of the sides. In the midst of the hot vapors,
one feels as if lost in a vast furnace. During the night-time an observer
might fancy himself surrounded with. ﬂames; the atmosphere itself, col-
ored by the red reﬂection of the vent-holes of the volcano, seems to be all
on ﬁre.
Fig. 192. Section across the Craters of Kilauea.


’/
The level or the ﬁre-lake of Kilauea is incessantly changing. In propor-
tion as fresh lava issues forth from the subterranean furnace, the broken
crust affords an outlet to other sheets of molten matter and fresh heaps of
scori'ee, and gradually the boiling mass rises from ledge to ledge, and ulti-
mately reaches the upper edge of the basin. Sooner or later, however,
the level rapidly sinks. The fact is, that the burning mass contained in
the depths of the abyss gradually melts the lower walls of solid lava;
these walls ultimately give way at some weak points in their circumfer-
ence, a crevice is produced in the -outer face of the volcano, and the liquid
matter, “drawn off ” like wine from a vat, rushes through the opening
made for it. The ﬂow increases the oriﬁce by the action of its weight on
the sill of the opening, and by melting the rocks which oppose its passage,
and then, running down over the slopes, ﬂows into the sea, forming prom-
ontories on the‘ shore. In 1840 the crater was full to the brink, when a
crack suddenly opened in the side of the mountain. This ﬁssure extended
to a distance of 131 feet from ‘its starting-point, and vomited forth a
stream of lava 37 miles long and 16 miles wide, which entirely altered the
outline of the sea-coast, and destroyed all the ﬁsh in the adjacent waters.
Mr. Dana estimated the total mass of this enormous ﬂow as equal to
7,200,000 cubic yards—that is, to a solid body ﬁfty times as great as the
quantity of earth dug out in cutting through the Isthmus of Suez. The
enormous basin of Kilauea, 1476 feet deep, remained entirely empty for
some time, and the former lake of lava left no other trace of its existence
than a solid ledge like those which had been formed at thetime of pre-
vious eruptions. Since this date the great caldron of lava has been several
times ﬁlled and several times emptied, either altogether or in part.
Almost all the volcanoes which rise ‘to a great height, get rid,like Ki-
lauea, of their overﬂow of lava through ﬁssures which open in their side
walls. In fact, the column of molten matter which the. pressure Of'thG
gas beneath'raises in the pipe of the crater is of an enormous weight, and
LA VA-FLOWS. 453
every inch it ascends toward the mouth of the crater represents an expense
of force which seems prodigious. The more or less hypothetical calcula-
tions which have been made as to the degree of pressure necessary for the
steam to be able to act on the lava-furnace lead to the belief that the out-
let-conduits of volcanoes, and consequently the mass of liquid stone‘to be
lifted, are not.less than nine miles in depth.* Various geologists—among
others, Sartorius von Waltershausen, the great explorer of Etna—believe
that the volcano-shafts are of a still more considerable depth. The rocks
of the terrestrial surface, limestone, granite, quartz, orv mica, are of a spe-
ciﬁc gravity two and a half times superior to that of water, while the
planet itself, taken as a whole, weighs nearly ﬁve and a half times as much
as the same mass of distilled water; the density of the interior layersv
must therefore increase from the circumference .to thecentre. ‘ Withre-
gard to the proportion of vthis increase, it is established by a calculation,
the whole responsibility of which must rest upon its authors. Baron Wal-
tershausen has ascertained, by means of a great number of weighings, that
the lava of Etna and that of Iceland have a speciﬁc gravity of 2'911. The
presumed consequence of this fact is that the rocks thrown out by the
volcanoes of Sicily and Iceland proceed from a depthof 7 7 to 78 miles (?).
Thus the shaft which opens at the bottom of the crater of Etna would be-
no less than 7 7 miles deep, and. the lava which boils in this abyss would
be lifted by a'forc'e of 36,000 atmospheres, an idea altogether. incompre-
hensible by our feeble imaginations. There would, then, be nothing aston-
ishing in the fact that a mass of lava, which is suﬁiciently heavy to bal—
ance a pressure of this kind, should, in a great many eruptions; melt and
break through the weaker parts of its walls, instead of ascending some
hundreds or thousands of feet higher, so as to run out over the edge of
theupper crater. - _
WVhen the side of the mountain opens, and affords a passage to the lava,
the ﬁssure is always perceptibly vertical, and those which are continued
to the summit pass through the very mouth of the volcano. Ina general
way, these ﬁssures of eruption are of considerable length, and are sufﬁ-
ciently wide to form an impassable precipice. Before these ﬁssures be-
come obliterated by the lava or by other debris—such as the snow and
earth of avalanches—they may be traced out by the eye as deep furrows
hollowed out on the mountain side. In 1669 the lateral ﬁssure of Etna
extended over morethan two thirds of the southern side—from the plains‘
of N icolosi to the .terminal gulf of the great crater. In like manner, in
the Isle of J an Mayen, the volcano of Beerenberg, 7513 feet high, presents
from top to bottom‘ a long depression ﬁlled up with snow, which is noth-
i g else than a ﬁssure of eruption. On other mountains, especially in
\Montserrat, Guadaloupe, and Martinique, these ﬁssures. have assumed such
_ dimensions that the peaks themselves have been completely split in two.
Through outlets of this kind the lava jets out, ﬁrstmaking its appear-
ance at the upper part, where thedeclivity is generallysteeper, then
* Buff, Playsilc der Erde.
464, THE EARTH. .
springing out below on the more gentle slopes of the lower regions of the
mountain. . ‘
At the sourceitself the lava is altogether ﬂuid, and ﬂows with consids
erable speed—sometimes, on steep slopes, faster than a horse can gallop;
but the course of the molten stone soon slackens, and the liquid, hitherto
dazzling with its light, is covered by brown or red scoriae,» like those of
iron just come out of a furnace. These scoriae come together, and, com-
bining, soon leave no interstices between them. beyond narrow vent-holes,
through whichthe molten matter escapes. The scoriae then form a crust,
which is incessantly breaking with a metallic noise, but gradually consoli-
dates into a perfect tunnel round the river of ﬁre; this. is the c/zei-re,* thus
named on account of the asperities which bristle on ‘its surface. Any one
may safely venture 011 the arch-shaped crust, although only a few inches
above the mass in state of fusion, without any fear of being burnt, just
as in winter we trust ourselves .on the, sheets of ice which cover a running
stream. The pressure of the lava succeeds in breaking through its shell
only at the. lower parts of its ﬂow, in spots where the waves of burning
stone fall with all their weight. Then the envelope is suddenly ruptured,
and the mass springs out like water from a sluice, pushing before it the
resounding scoriae, and swelling out gently in the formof an enormous
blister; it, then again becomes covered with a solid crust,which is again
broken through by a fresh effort of the lava. Thus the river, surround-
ing itself with dikes which it constantly'bre'aks through, gradually de-
scends over the slopes, terrible and inexorable, so‘ long as theoriginal
stream does not cease to ﬂow. ‘The‘only means of-diverting the current
is to modify the incline‘ in front of it—eitherby opposing obstacles to it
to throw it to either side, or by preparing a road for it ‘by digging deep
trenches, or by opening up above some lateral outlet for the pent-up lava.
111.1669, at the time of the great eruption which threatened to swallowup
Catania, all these'various means were adopted in order to save the town.
On one side the inhabitants worked at consolidating the rampart, and
placed obstacles across'the path of the current ,to ‘turn it toward the
south. Other workmen, furnished with shovels and mattocks,'ascended
along the edge of the ﬂow, and, in spite‘ of .the'resistanceoﬁ‘ered by the
peasants, ‘tried to piercev thro‘ugh'the shell of scoriae, and thus, by tapping
the stream, to open fresh'outlets for the molten matter. These means of
‘defense partly succeeded, and the terrible current which, at its source
near Nicolosi, had been able to. melt and pierce through the volcanic cone
of Monpilieri at its thickest point (this conestanding in its path), was
turned from its course toward'the centre of Catania, and destroyed noth-
ing but the suburbs. - . - - I -
The radiation from thelava being arrested by the crust of scoriae, which
is a very bad conductor of heat, the temperature of the air surrounding a ,
ﬂow of lava rises but very slightly. The Neapolitan guides have no fear
* Or. serre, in Italian sciara : these are synonyms of the word scie (saw) in the French of
the present day. " ' '
LA VA-FLOWS. 465
in approaching the Vesuvian lava in order to stamp the rough medals
made of it, which they sell to foreigners. At a distance of a few yards
from the vent-holes in the chez're the trees of Etna continue to grow and
blossom, and some clumps, indeed, may be seen ﬂourishing on an islet of
vegetable earth lying between two branches of a ﬂow of burning lava.
And yet, by a contrast which at ﬁrst sight seems incomprehensible, it
sometimes happens that trees which are distant from any visible ﬂow of
molten matter suddenly wither and die. Thus, in 1852, at the time of the
great eruption from the Val del Bove, on the eastern slopes of Mount Etna,
vineyards and vines, covering a considerable area, and situated at a dis-
tance of more than half a mile below the front of the ﬂow, were suddenly
dried up, just as if the blast of a ﬁre had burnt up their foliage. In order
to explain this curious phenomenon, it is necessary to admit that some
rivulets of the great lava-river must have penetrated under the earth
through the ﬁssures of the soil, and have ﬁlled up a subterranean cavity
in the mountain exactly below the vineyards that were destroyed: the
roots being consumed, or deprived of the necessary moisture, the trees
themselves could not do otherwise than perish.*
On lofty mountains in a state of eruption, the masses of snow and ice,
which are covered by the ﬁery currents which issue from the volcanic ﬁs-
sures, do not always melt, and some have been preserved under the scoriae
for centuries, or even thousands of years. Lyell has discovered them un-
der the lava of Etna, American geologists under the masses thrown out
by the crater of Mount Hooker, Darwin under the ashes in Deception Isl~
and, in the Tierra del Fuego, M. Philippi under the ﬂows of the volcano
N uevo de Chillanfr which in 1861 erupted through a glacier. There every
bed of snow which falls during the winter remains perfect under the coat
of burning dust which is ejected from the outlet of eruption, and sections
made through the mass of debris show for a great depth the alternate
black and white strata of the volcanic ashes and the snow. In 1860 the
crater of the mountain of Kutlagaya, in Iceland, hurled out simultaneous-
ly into the air lumps of lava and pieces of ice all intermingled togethenI
In like manner, the immense ﬂow of lava in Iceland have left in a per-
fect state of preservation the trunks of the Sequoias, and other American
trees, which adorned the surface of the island during the ages of the Ter-
tiary epoch, at a time when the mean temperature of this country was
48° (Fahr.), that is, 42° to 44° above that which it is at present.§ ‘Al-
though the radiation from the lava is so slight that it neither melts the
ice nor burns the trunks of buried trees, yet, on the other hand, the heat
and ﬂuidity of the lava are maintained in the central part of the ﬂow for
a very considerable number of years. Travelers state that they have
found deeply-buried lava which was still burning after it' had remained
for a century on the mountain side. i
* Lyell, Philosophical Transactions, 1858.
1' Mittkeilungen ran Petermann, vol. vii., 1863. I Wallich,’Nortla Atlantic Sea-bed.
§ Carl Vogt, Nonlfa/zrz‘.
G G
466 THE EARTH.


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Although the lava covers up and often preserves the snow and the ice,
which are doubtless defended against the heat by a cushion of spheroidal
particles of humidity, it immediately converts into steam the water with
which it comes in contact. The liquid mass, being suddenly augmented
to about 1800 times its former volume, explodes like an enormous bomb-
shell, and hurls away, like projectiles, all the objects which surround it.
A serious occurrence of this kind is recorded, which took place in 1843, a
few days after the formation of a ﬁssure in Mount Etna, from which a cur-
rent of molten matter issued, making its way toward the plain of Bronte.
A crowd of spectators, who had come from the town, were examining
from a distance the threatening mass, the peasants were cutting down the
trees in their ﬁelds, others were carrying off in haste the goods from their
cottages, when suddenly the extremity of the ﬂow was seen to swell up
like an enormous blister, and then to burst, darting forth in every direc-
tion clouds of steam and volleys of burning stones. Every thing was de-
stroyed by this terrible explosion—trees, houses, and cultivated ground;
and it is said that sixty-nine persons, who were knocked down by the con-
cussion, perished immediately, or in the space of a few hours. This disas-
ter was occasioned by the negligence of an agriculturist, who had not
emptied the reservoir on his farm; the water, being suddenly converted
into steam, had caused the lava to explode with all the force of gun-
powder. '
The quantity of molten matter which is ejected by a ﬁssure in one sin-
gle eruption is enormous. It is known that the current of Kilauea, in
1840, exceeded 6550 millions of cubic yards. That which proceeded from
Mauna-Loa in 1835 produced a still larger quantity of lava, and extended
as far as a point 76 miles from the crater. Flows of this kind are certainly
rare; but there are some recorded in the earth’s history whichare still
LA VA-FLOWS. 467
more considerable. Thus the volcano of Skaptar-Jokul, in Iceland, was
cleft asunder in 17 83, and gave vent to two rivers of ﬁre, each of which
ﬁlled up a valley; one attained a length of 50 miles, with a breadth of 15
miles; the other was of less dimensions, but the depth of the mass was in
some places as much as 492 feet. A subterranean ﬁssure, 99 miles in
length, which cleaves in two the ground of Iceland, was doubtless ﬁlled
up with lava along its entire length, for hillocks of eruptions sprung up
on various points of this straight line. It has been calculated that the
whole of the lava evacuated by the Skaptar in this great eruption was not
less in bulk than 655,000 millions of cubic yards, a mass equivalent to the
whole volume of Mont Blanc; it would be a quantity sufficient to cqyer
the whole earth with a ﬁlm of lava 0'0393 inch in thickness. As to the
celebrated ﬂow from the Monti Rossi, which threatened to destroy Oatania
in 1669, it seems very triﬂing in comparison; it contained a mass of molten
stone which was estimated at 1310 millions of cubic yards. On how tri-
ﬂing a scale, therefore, are these ordinary eruptions compared with the
surface of the globe! They are, however, phenomena perceptible enough
to man, in all his inﬁnite littleness.
468 THE EARTH.
CHAPTER LXVIII.
VOLCANIC PROJECTILES.~— EXPLOSION S OF ASHES.-— SUBORDIN ATE VOLC- '-
NOES.—- MOUNTAINS REDUCED TO DUST.-—- FLASIIES AND FLAMES PRO-
CEEDING FROM VOLCANOES.
THE lava swelling up in enormous blisters above the ﬁssures from which
it ﬂows in a current over the slopes is far from being the only substance
ejected from volcanic mountains. When the pent-up vapor escapes from
the crater with a sudden explosion, it carries with it lumps of molten mat-
ter, which describe their curve in the air, and fall at a greater or less dis-
tance on the slope of the cone, according to the force with which they
were ejected._ These are the volcanic projectiles, the immense showers of
which, traced in lines of ﬁre on the dark sky, contribute so much during
the night-time to the magniﬁcent beauty of volcanic eruptions. These
projectiles have already become partially cooled by their radiation in the
air, and when they fall are already solidiﬁed on the outside, but the in-
side nucleus remains for a long time in a liquid or pasty state. The form
of these projectiles is often of an almost perfect regularity. Each sphere
is in this case composed of a series of concentric envelopes, which have
evidently been arranged in the order of their’ speciﬁc gravity during the
ﬂight of the projectile through the air. The dimensions of these projec-
tiles vary in each eruption; some of them are one or more yards in thick-
ness; others are nothing but mere grains of sand, and are carried by the
wind to great distances. _
In most eruptions, these balls of lava, still in a ﬂuid and burning state,
constitute but a small part of the matter thrown out by the mountain.
The largest proportion of the stones ejected proceed from the walls of the
volcano itself, which break up under the pressure of the gas, and ﬂy off in
volleys, mingled with the products of the new eruption. This is the origin
of the dust or ashes which some craters vomit out in such large quantities,
which, too, are the cause of such terrible disasters.
When the impetus of the gas conﬁnes itself to forming a ﬁssure in the
side of the mountain, the ﬁ'agments of rocks which are broken up and re-
duced to powder are comparatively small in quantity. They are projected
in clouds out of the ﬁssure, and, falling like hail round the oriﬁce, are grad-
ually heaped up in the form of a cone on the side of the mountain from
which they arose. In Europe the enormous circumference of Etna pre-
sents more than 700 of these subordinate volcanoes, some scarcely higher
than an Esquimaux hut, and others, like the Monti Rossi, Monte Minardo,
Monte Ilici, several hundred yards high, and more than half a mile wide at
the base. There are some which are entirely sterile, or covered only by a
EXPL OSIONS 0F ASHES. ALGQ
scanty vegetation of broom, and are marked out by a red, yellow, or even
black color on .the main body of Etna; those situated on the lower slopes
are covered with trees or planted with vines, and sometimes contain ad-
mirable crops in the very cavity on their summit. These cones of ashes,
springingup like a progeny on the vast sides of their mother mountain,
give to Etna a singular appearance of vital personality and of creative
energy. The same phenomenon occurs on the volcanoes of Hawaii, which
carry on their declivities thousands of subordinate cones.


In the formation of these hillocksa real division of labor takes place.
The rocks and heavier stones fall eitheron vthe edge of the crater or in the
gulf itself. ' The ashes and light dust are shot up to a much greater height,
and,burried along by the impulse of the wind, fall far and wide, like the
chaff of corn winnowed in a threshing-ﬂoor. Thus the slope of the cone
toward which the wind directs the ashes is always more elongated, and
rises to a greater height on the edge of the crater. On Etna, where the


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Fig. 196. Cone of - del Bove.
wind generally blows in the direction of west to east, the eastern slope of
the, hillocks is more developed than on the opposite side. It must, per~
l1aps,l)e attributed to the action of the wind blowing on the heights, and
470 THE EAR TH.
not, as Siemsen,* the geologist, supposes, to the obliquity of the shaft of
the crater, that all the scoriae and ashes fall to the north of the oriﬁce of
the volcano Nuevo de Chillan, in Chili.
The phenomena which take place when the ashes issue from the mouth
of the crater itself do not differ from those which are observed at the out-
lets in ﬁssures. In the former case, however, the mass of rocks reduced
to powder is so considerable that the rain of ashes assumes all the propor-
tions of a cataclysm. It has sometimes happened that,during a paroxysm
of volcanic energy, the whole summit of a mountain, for a depth of several
thousands of feet, has been hurled into the air, mingled with a cloud of
vapor and the smoke of burning lava. Thus Etna, if we, are to believe
ZElianus, was once much loftier than it is in our time, and on the north of
the present terminal cone there may, in fact, be noticed a kind of platform
which. seems to have been the base of a summit twice as high as the pres-
ent crest. The whole of the Val del Bove is probably an empty space ‘left
by the disappearance of a former cone. , I
With regard to Vesuvius, it is known that, in the year 7 9- of the present
era, the whole of that part'of the mountain which was turned toward the
sea was reduced to powder, and that the débrz's of the cone, nothing of
which now remains except the semicircular inclosure of La Somma, buried
three towns and a vast extent of plain. The ashes and dust, mingled with
white vapor rising in thick eddies, ascended in a column to a point far
above the summit of the volcano, until, having reached those regions of
the atmosphere wherethe vrareﬁedair could no longer sustain them, they
spread out‘i'nto a wide umbrella-like shape, the falling dust of which ob-
scured the sky.‘ Pliny the Youger compared this vault of ashes and
smoke to the foliage of an Italian pine curving at an immense height over
the mountain. Since this memorable epoch the height of the column of
vapor has been measured which has issued from Vesuvius at the time of
several great eruptions, and it has been sometimes found that it reached
23,000 to 26,000 feet; that is, six times higher than the summit of the vol-
cano itself
One of these explosions of entire summits which caused most terror in
modern times was that of the volcano of Coseguina, a hillock of about 500
feet high, situated on a promontory to the south of the Bay of Fonseca, in
Central America. The debris hurled into the air spread over the sky in a
horrible arch several hundreds of miles in width, and covered the plains
for a distance of 25 miles with a layer of dust at least 16 feet thick. At
the very foot of the hill the headland advanced 787 feet into the bay, and
two new islands, formed of ashes and stones falling from the volcano, rose
in the midst of the water several miles away. Beyond the districts close
round the crater, the bed of dust, which fell gradually, became thinner,
but it was carried by the wind more than 40 degrees of longitude toward
the west, and the ships sailing in those waters penetrated with ditﬁculty
the layerof pumice-stone spread out on the sea. To the north, the rain
* lllittlzez'lungen von Petermann, vol. vii., 1863.
ER WTI ON OF OOSEG UHVA. 471
of ashes was remarked at Truxillo, Honduras, and at Ohiapas, in Mexico;
on the south, it reached Oarthagena, Santa Martha, and other towns of the
coast of Grenada; to the east, being carried by the counter-current of the
trade-winds, it fell on the plains of St. Ann’s, in Jamaica, at a distance of
800 miles. The area of land and water on which the dust descended must
be estimated at 1,500,000 square miles, and the mass of matter vomited
out could not be less than 65,500 million cubic yards.


Fig. 197. Eruption of Coseguina.
The uproar of the breaking up of the mountain wasﬁheard as far as the
high plateaux of Bogota, situated 1025 miles away in a straight‘line.
While the formidable cloud was settling down round the volcano, thick
darkness ﬁlled the air. For forty-three hours nothing could be seen ex-
cept by the sinister light of the ﬂashes darting from the columns of steam,
and the red glare of the vent-holes opening in the mountain; To escape
[from this prolonged night, the rain of ashes, and the burning atmosphere,
the inhabitants who dwelt at the foot of Ooseguina ﬂed in all haste along
a road running by the black water of the Bay of Fonseca. Men, women,
children, and domestic animals traveled painfully along- a difficult-path,
through quagmires and marshes. So great, it is said, was the terror of all
animated beings during this long night of horror, that the animals them-
472 THE’ EARTH
selves, such as monkeys, serpents, and birds, joined the band of fugitives,‘
as'if they recognized in man a being endowed with intelligence superior
to their own.* ‘ a -
A large number of volcanoes have diminished in height, or have, indeed,
entirely disappeared, in consequence of explosions, which reduced their
rocks to powder, and distributed them in thick sheets on the ground ad-
jacent. Mount Baker, in California, and the J apanese volcano of Unsen,
have thus raised the level of the surrounding plains at the expense of a
diminution in their own volume. In 1638, the summit of the peak of Ti-
mor, which might be seen like a light-house from a distance of270 miles,
exploded, and blew up into the air, and the water collecting, formed a lake
in the enormous void caused by the explosion. In 1815, Timboro, a vol-

130°
s¢1;_':'_,v,~=_=.-i?"~"=——-'=-_=¥'" ' ' ‘
*‘= 55


@100“ n . . 1___0° J86‘
Fig. 198. Eruption of Timboro.
cano in the island of Sumbara, destroyed more men than the artillery of
both the armies engaged on the‘ battle-ﬁeld of Waterloo. In the island.
of Sumatra, 550 miles to ‘the west, the terrible explosion was heard, and,
for a radius of 300 miles round the mountain, a thick cloud 'of ashes,
which obscured the sun, made it dark like night even at noonday. This
immense quantity of debris, the whole mass of which was, it is said, equiv-
4 * Landgrebe, Namrgesr-llielate der Val/cane.
FLAMES FR 0.1! VOL CANOES. 4:73
alent to thrice the bulk of Mont Blane—that is, 2,358,000 millions of cubic
yards (?)—fell over an area larger than that of Germany. The pumice-
stone which ﬂoated in the sea was more than a yard in thickness, and it
was with some diﬂiculty that ships could make their way through it. The
popular imagination was so deeply impressed by this cataclysm, that at
Bruni, in the island of Borneo, whither heaps of the dust vomited out by
Timboro, 870 miles away to the south, had been carried by the wind, they
date their years from “the great fall of ashes.” It is the commencement
of an era for the inhabitants of Bruni, just as the ﬂight of Mohammed was
for the Mussulmans.
The friction of the steam against the innumerable particles of solid mat-
ter which are darted out into the air is the principal cause of the electrici-
ty which is developed so plentifully during most volcanic eruptions. In
consequence of this friction, which operates simultaneously at all points
in the atmosphere which are reached by the volcanic ashes and vapor,
sparks ﬂash out which are developed into lightning. The skies are light-
ed up not only by the reﬂection from the lava, but also by coruscations of
light which dart from amid the clouds. When the vast canopy of vapor
spreads over the summit of the mountains, numerous spirals of ﬁre whirl
round on each side of the clouds, which, as they unroll, resemble the foli-
age of a gigantic tree. Doubtless, also, the encounter of two aerial cur-
rents may contribute to produce lightning in the columns of vapor; yet,
when the latter are slightly mingled with ashes, they are rarely stormy?“
Although the evolution of electricity in the columns of vapor and ashes
vomited out by volcanoes has never been called in question, the appear-
ance of actual ﬂames at the time of volcanic eruptions was for a long time
disputed. M. Sartorius von Waltershausen, the patient observer of Etna,
has maintained that neither this mountain, nor Stromboli, nor any other
volcano, has ever presented among its phenomena any ﬁre properly so
called, and that the supposed ﬂames were nothing more than the reﬂec-
tion of the red or white lava that was boiling in the crater. On the other
hand, Elie de Beaumont, Abich, and Pilla positively assert that they have
seen light ﬂames on the summit of Vesuvius and Etna. It would,however,
be very natural to believe that inﬂammable gases might be liberated and
take ﬁre at the outlet of those immense shafts which place the great sub-
terranean laboratory of lava in communication with the outer air.
This question was, however, resolved in the aﬂirmative at the time of
the recent eruption of Santorin, and popular opinion was right in opposi-
tion to most men of science. All those who were able to witness, at its
commencement, the upheaval of the lava at Cape Georges and Aphroessa,
have certiﬁed to the appearance of burning gas dancing above the lava,
and even on the surface of the sea. All round the upheaved hillocks,
bubbles of gas, breaking forth from the waves, became kindled as they
came in contact with the burning mass, and were diffused over the water
in long trains of white, red, or greenish ﬂames, which the breeze alter-
* Arago, CE'uvres Completes, vol. i.
474 _ THE EARTH.
nately raised or beat down; sometimes a; smart puﬂ? of wind put out the
ﬁre, but it soon recommenced to run over the breakers: by approaching
it carefully, fragments of paper might be burnt in it, which lighted as they
dropped. On the slopes of the volcano of Aphroessa, ﬁre, rendered of a
yellowish hue by salts of soda, sprung out from all the ﬁssures, and rose
to a height of several yards. On the rather older lava of Cape Georges
the’trains of ﬂame were less numerous; there, however, bluish glimmers
might be seen ﬂitting about in some spots over the black ridges of lava.*
Added to this, are not the ﬂames at Bakou, on the coast of the Caspian
Sea, produced by the volcanic action of the ground? The “growing
mountains” in the neighborhood are mud-volcanoes, and we must doubt-
less attribute to the same subterranean activity the production of the hy-
drogen gas which burns in an “ eternal ﬂame” in the temples of the Parsifr
During some of the evenings in autumn, when the weather is ﬁne and the
sun has heated the surface of the ground, the ﬂames occasionally make
their appearance on the hills, and for several hours may be seen the mar-
velous spectacle of a train of ﬁre stretching along the country without
burning‘ the ground, and even without scorching a blade of grass.
* Fouqué,_Revue des Deux-Mondes, August 15, 1866; Dekigallas; Schmidt.
'l‘ Arnold Boscowitz, Volcans ct Tremblements de Terre.
ER UPTIONS OF MUD. 47 5
CHAPTER LXIX.
STREAMS OF MUD EJECTED BY CRATERS.—MUD-VOLCANOES.
NEXT to lava and ashes, streams of water and mud are the most con-
siderable products of volcanic activity, and the catastrophes which they
have caused are perhaps among the most terrible which history has to re-
late. By means of these sudden deluges, towns have been swept away or
swallowed up, whole districts dotted over with habitations have been
ﬂooded with mud or converted into marshes, and the entire face of na-
ture has been changed in the space of a few hours.
The liquid masses which descend rapidly from the mountain height do
not always proceed from the volcano itself. Thus the local deluge may
be caused by a rapid condensation of large quantities of steam which es-
cape from the crater and fall in torrents on the slopes. A phenomenon of
this kind must evidently take place in a great many cases, and it was
doubtless by a cataclysm of this kind that the town of Herculaneum, at
the foot of Vesuvius, was buried. As regards the lofty snow-clad volca-
noes of the tropical and temperate zones, and also those of the frozen re-
gions, the torrents of water and debris—the “ water-lava,” as the Sicilians
call them—may be explained by the rapid melting of immense masses of
snow and ice, with which the burning lava, the hot ashes, or the gaseous
emanations of the volcanic furnace have come in contact. Thus, in Ice-
land, after each eruption, formidable deluges, carrying with them ice, sco-
riae, and rocks, suddenly rush down into the valleys, sweeping away ev-
ery thing in their course. These liquid avalanches are the most terrible
phenomena which the inhabitants of the island have to dread. They show
three headlands formed of debris, which the body of water descending from
the sides of Kutlugaya in 1766 threw out far into the sea, in a depth of
246 feet of water.*
Other deluges no less formidable are caused by the rupture of the walls
which pen back a lake in the cavity of a former crater, or by the forma-
tion of a ﬁssure which affords an outlet to liquid masses contained in sub-
terranean reservoirs. It would be too diﬂicult to explain otherwise the
mud-eruptions of several trachytic volcanoes of the Andes—Imbambaru,
Cotopaxi, and Carahuarizo. In fact, the mud (lodozales) which comes
down from these mountains often contains a large quantity of organized
beings, aquatic plants, infusoria, and even ﬁsh, which could only have
lived in the calm waters of a lake. Of this kind is the Pimelodes cyclo-
pum, a little ﬁsh of the tribe of the Silurz'doe, which, according to Hum-
boldt, has hitherto been found nowhere except in the Andini caverns and
* Olafsen and Povelsen, British Quarterly Review, April, 1861.
476 THE EARTH.


‘
If '
//j,
j/ j J


Fig. 199. Crater of Scte Cidadcs-
in the rivulets of the plateau of Quito. In 1691 the volcano of Imham-
barn vomited out, in combination with mud and snow, so large a quantity
of these remains of vorganisms that the air was contaminated by them,
and miasmatic fevers prevailed in all the country round. The masses of
water which thus rush down suddenly into the plains amount sometimes
to millions, or even thousands of millions of cubic yards.
Although, in some cases, these eruptions of mud and water may be
looked upon as accidental phenomena, they must, on the contrary, as re-
gards many volcanoes, be considered as the result of the normal action of
the subterranean forces. They are, then, the waters of the sea or of lakes
which, having been buried in the earth, again make their appearance on
the surface, mingled with rocks which they have dissolved 01' reduced to
a pasty state. A remarkable instance of these liquid eruptions is that
presented by Papandayang, one of the most active volcanoes in Java. In
1792 this mountain burst, the summit was converted into (lust and disap-
peared, and the debris, spreading far and wide, buried forty villages.
Since this epoch a copious rivulet gushes out in the very mouth of the
crater, at a height of 7710 feet, and runs down into the plain, leaping over
the blocks of trachyte. Round the spring, pools of water ﬁll all the clefts
in the rocks, and boil up incessantly under the action of the hot vapors
which rise in bubbles; here and there are funnel-shaped cavities. in which
\
ER UPT I ONS OF WATER AND MUD. 477
black and muddy water constantly ascends and sinks with the same reg-
ularity as the waves of the sea; elsewhere, muddy masses slowly issuing
from small craters ﬂow in circular slopes over mounds of a few inches or
a yard in height; lastly, jets of steam dart .outof'all'the ﬁssures with a
shrill noise, making‘the'ground tremble with the shock. . All these .vari-
ous noises, the roaring of the cascades, the explosion of the gaseous springs,
the hoarsemurmur of the mud-volcanoes,the shrill hissing of the jimzerolles,
produce an indescribable uproar, which is audible far away in the plains,
which, too, has given to the volcano its name of‘Papandayan'g," orY“Forge,”
as if one could incessantly hear'the mighty blast of the ﬂames and the
ever-recurring beating of the anvils. . . . . _
In volcanoes ‘of a great height it israrely found- that eruptions of water
and mud are constant, as. in the Papandayang; but temporaryejections
‘ of liquid masses are frequent, and there ‘are, indeed, some volcanoes which
vomit out nothing but muddy matter. The volcano of Aqua. (or water),
the cone of which is gently inclined like that of Etna, and rises to. about
1 3,000 feet in height, into the regions of snow, has never vomited any thing
but water; and-it is, indeed, stated that lava and other volcanic products
areentirely wanting on its slopes?“ Yet in 1541, this prodigious inter-
mittent spring'hurled into the air its terminal point (corom'lla), and poured
‘over the plains at" its base, and over the town’ of Guatemala, so largea
quantity of water, mingled with stones and débrz's, that theginhabitants
werev compelled to ﬂy'with the greatest haste, and to reconstruct their
capital at the foot of the volcano of Fuego. This new neighbor, however,
showed that he was as much or more to be dreaded than their former one,
for the violent eruptions from the mountain compelled the inhabitants of
the second town‘ to again migrate, and to rebuild their capital at a point
20 milesto the northwest. ,
Several volcanoes in Java and the Philippines also give vent, during
their eruptions, to large quantities of mud, sometimes mingled with or-
ganic matter in such considerable proportions that they have been utilized
as fuel]L : In 1793, a few months after the terrible. eruption of Unsen, in
the island of 'Kiousiou,_’[ an adjacent volcano, the Miyi-Yama, vomited, ac-
cording to Kampfer, so prodigious a quantity of water and mud that .all
the neighboring plains were inundated, and 53,000 people were drowned
in the deluge; unfortunately, we have no historical details of this catas-
trophe. Of all the eruptions of mud, the best known is that of 'Tungura-
gua, a volcano in Ecuador, which rises to the south of Quito to 16,400
feet in height. In 1797, at the time of the earthquake of Riobamba,'a
whole side of the mountain sank in an immense downfall, with the vforests
which grew on it; at the same time, a‘ ﬂow of viscous'mud issued from the
ﬁssujr'es at its base, and rushed down into the valleys; One of these cur—
rents of mud ﬁlled up a winding deﬁle, which separated two mountains,
to a depth of 650 feet, over a width of more than 1000'feet, and, damming
* J uarros, Landgrebe, Natur Gescliichte der Vullcane’, vol. i.
‘l' Otto Volger, Das Buck der Ertle, v01. i. ‘ I Vide above, p. 452.
478 THE EARTH.
up the rivulets at their outlet from the side valleys, kept back the water
in temporary lakes: one of these sheets of water remained for eighty-seven
days.
The volcanic mud, therefore, has this point of resemblance with the lava
——that it sometimes ﬂows out through the crater, as on Papandayang;
sometimes through side craters, as on Tunguragua. Doubtless, when the
volcanic muds have been better studied, we shall be enabled to trace the
transition which takes place by almost imperceptible degrees between the
more or less impure water escaping from volcanoes, and the burning lava
more or less charged with steam. This transition is, however, already
noticed in the ancient matter which the water has carried down and de-
posited in the strata at the foot of volcanic mountains. These rocks,
known under the name of tufa, trass, or perperz'no, are nothing but heaps
of pumice, scoriae, ashes, and mud, cemented together by the water into a
species of mortar or conglomerate, and gradually solidiﬁed by the evapo-
ration 0f the humidity which they contained. Of this kind, for instance, is
the hardened stone which, for eighteen centuries, has covered the city of
Herculaneum with a layer of 50 to 150 feet in thickness. Among rocks
of various formations, there are but few which exhibit a more astonishing
diversity than the tufas. They differ entirely in appearance and physical
qualities, according to the nature of the materials which have formed
them, the quantity of water which has cemented. them,‘ the greater or less
rapidity with which their fall and desiccation take place; lastly, the num-
ber and distribution of the chinks which are produced across the dried
mass, and have been ﬁlled up with the most different substances. Many
kinds of tufa resemble the most beautiful marble.
The small hillocks, which are specially called mud-volcanoes, or salses,
on account of the salts which are frequently deposited by their waters,
are cones which differ only in their dimensions from the mighty volcanoes
of Java or the Andes. Like these great mountains, they shake the ground,
and rend it, in order to discharge their pent-up matter; they emit gas and
steam in abundance, add to their slopes by their own débrz's, shift their
places, change their craters, throw off their summits in their explosions;
lastly, some of these salses are incessantly at work, while others have pe-
riods of repose and activity. In nature, transitions merge into one another
so perfectly, that it is diﬂicult to discover any essential difference between
a volcano and a salse, and between the latter and a thermal spring.*
Mud-volcanoes exist in considerable numbers on the surface of the earth,
and, like the volcanoes of lava, the neighborhood of the sea-coast is the
principal locality where we ﬁnd their little cones. In Europe, the most re-
markable are those which are situated at the two extremities of the Cau-
casus, on the coasts of the Caspian Sea, and on both sides of the Straits of
Yenikale, which connect the Sea of Azof with the Black Sea. On the east,
the mud-springs of Bakou are especially distinguished by their combina-
tion with inﬂammable gases; on the west, those of Taman and Kertch ﬂow
* Humboldt, Cosmos, vol. i.
MUD- VOL OANOES. 479
all the year round, but especially during times of drought, pouring out
large quantities of blackish mud. One of these mud-volcanoes, the Go-
rela, or Kuku-Oba, which, in the time of Pallas, was called the “Hell,” or
Prekla, on account of its frequent eruptions, is no less than 246 feet in
height, and from this crater, which is perfectly distinct, muddy streams
have ﬂowed, one of which was 2624 feet long, and contained about 850,000
cubic yards.*
The volcanitos of Turbaco, described by Humboldt, and the maccalube
of Girgenti, which have been explored, since Dolomieu, by most European
scwants who have devoted themselves to the study of subterranean forces,
are also well-known examples of mud-springs, and may serve as a type to
all the hillocks of the same character. In winter, after a long course of
rains, the plain of the maccalube is a surface of mud and water forming a
kind of boiling paste, from which steam makes its escape with a whistling
noise; but the warmth of spring and summer hardens this clay into a
thick crust, which the steam breaks through at various points and covers
with increasing hillocks. At the apex of these cones a bubble of gas
swells up the mud like a blister, and then bursts it, the semi—liquid ﬂowing
in a thin coat over the mound; then a fresh bubble ejects more mud, which
spreads over the ﬁrst layer already become hard, and this action continues
incessantly until the rains of winter again wash away all the cones. This
is the ordinary course of action of the salse, sometimes interrupted by vi-
olent eruptionsf On the coasts of Mekran the mud-volcanoes are not only
subject to the action of the seasons, but also depend on the action of the
tides, although many of them are from 9 to 12 miles from the Indian
Ocean. At the time of the ﬂow the mud rises in great bubbles, accompa-
nied by a hoarse murmur, like the distant roar of thunder. The highest
cone is not more than 246 feet high, and stands 7 miles from the shorei
In a general way, the expulsion of mud and gas is accompanied by a
discharge of heat; but in some salses, like those of Mekran, the matter
ejected is not higher in temperature than the surrounding air, as if the
expulsion of the mud from the ground was an entirely superﬁcial phe-
nomenon. Occasionally, in peat-bogs, the ground cracks, and cold mud is
ejected from the ﬁssure; and then, after this kind of eruption, the spongy
soil sinks and ‘again levels down. Is this eruptive phenomenon similar to
that presented by the mud-volcanoes, and caused by the fermentation of
gases in the midst of substances in a state of putrefaction? This is M.
Otto Volger’s idea; and it would be diﬂicult to give any other explana-
tion of this phenomenon.
* Ansted, Intellectual Observer, January, 1866.
1' Arnold Boscowitz, Volcans et Tremblements de Terre.
I Walton, Nautical Magazine, February, 1863.
480 THE EARTH
CHAPTER LXX.
' ‘VOLCANIC THERMAL SPRINGS.——GEYSERS.—-SPRINGS IN NEW ZEALAND.—
FUMEROLLES.-—-SOLFATARAS.—CRATERS OF CARBONIC ACID.
VOLCANOES, both of lava and mud, all have, either on their sides or in
the vicinity of their base, thermal springs, which aﬂ‘ord an outlet to their
surplus water, gas, and vapor. Most even of those mountains which are
at present tranquil, but which were once centres of eruption, continue to
manifest their activity by vapors and gas, like furnaces in which the ﬂames
are extinct, but the smoke is still rising. Although lava and ashes no
longer make their escape from the crater or lateral ﬁssures, yet numerous
ﬁmzerollcs and hot springs, formed by the condensation of the steam, gen-
erally serve as a vehicle for the gas pent up in the depths of the moun~
tain. “We may reckon by hundreds and thousands the “geysers,” the
“vinegar springs,” and other thermal springs in countries once burning
with volcanoes, the ﬁres of which are extinct, or at least quieted down for
a period more or less protracted. Thus the former volcanoes of Auvergne;
the mountains of the Eifel, on the Rhine, the craters of which contain
nothing but lakes or pools; the Demavend,with its mouth ﬁlled up with

1 gr ‘ a "
. a,
,


Fig. 200. Lrater oi’ Demavend.

snow all still exhale here and there, through springs and fumerolles, as it '
were, a feeble breath of their once mighty vitality.
The volcanic regions of the earth where thermal springs gush out are
very numerous: in Europe we have Sicily, Iceland,'Tuscany, and the pen-
THERMAL SPRINGS. 481
insula of Kertch; in America—that land so rich in volcanoes—the springs
warmed by subterranean vapor are still more numerous, and there are
some on the sides of the volcano Nuevo de Ohillan which gush out through
a thick bed of perpetual snow.* A lateral gorge of the valley of N apa,
in California, called the “Devil’s Canon,” may be quoted as one of the
most striking examples of the active production of thermal waters. The
narrow ravine, ﬁlled with vapor rising in eddies, opens on the side of a red
and bare mountain, that one might fancy was scorched by ﬁre. The entry
to the ravine follows the course of a rivulet, the boiling waters of which
are mingled with chemical substances horrible to the taste. Innumerable
springs—some sulphurous, others charged with‘alnin or salt—gush out at
the base of the rocks. There are both warm and cold springs, and hot
and boiling; some are blue and transparent, others white, yellow, or red
with ochre. In a cavity which is called the “ Sorcerer's’ Caldron” a mass
of black and fetid mud boils up in great bubbles. Higher up, the “ Devil’s
Steam-boat” darts out jets of gaseous matter, which issue pufﬁng from a
wall of rock: ﬁtmerolles may be seen by hundreds on the sides of the
mountain. All these various agents either murmur, whistle, rumble, or
roar, and thus a tempest of deafening sounds incessantly ﬁlls the gorge.
The burning ground, composed of a clayey mud—in one spot yellow with
sulphur, and in another white with chalk—gives way under the feet of
the traveler who ventures on it, and gives vent to puffs of vapor through
its numberless cracks. The whole gorge appears to be the common out-
let of numerous reservoirs of various mineral waters, all heated by some
great volcanic furnaceq‘ .
The ravine of Infernillo (Little Hell), which is situated at the base of
the volcano of San Vincente, in the centre of the Republic of San Salvador,
presents phenomena similar to those of the “Devil’s Oaﬁon.” There, too,
a multitude of streams of boiling water gush from the soil, which is cal-
cined like a brick, and eddies of vapor spring from the ﬁssures of the rock
with a noise like the shrill whistle of a locomotive.‘ The most considera-
ble body of water issues from a ﬁssure 32 feet in .width, which opens un-
der a bed of volcanic rocks at~a slight elevation above the' bottom of the
valley. The liquid stream, partially hidden by the clouds of vapor which
rise from it, is shut out to a distance of 130 feet as if by a force-pump, and
the whistling of the water pent up between the rocks reminds one of the
furnace of a manufactory at full work. One might fancy that it was the
respiration of some prodigious being hidden under, the mountain.'
The hottest springs which ‘gush out on the surface of the 'ground, such
as those of Las Trincheras an'd Oomangillas, do not reach the temperature
of 212° (Fahr.) ;1 but we have no right to ‘conclude from this that the
water in the interior of the earth does not rise to a much more considera-
ble heat. It is, on the contrary, certain that water descending into the
* Philippi, Mittheilangen von Petermann, vol. vii., 1863.
1‘ Henry Auchincloss, Continental Monthly, September, 1864.
i Vide above, 235.
H II
482 , THE EARTH.
deepest ﬁssures of the earth, although still maintaining a liquid state, may
reach, independently of any volcanic action,a temperature of several hun-
dred degrees; being compressed by the liquid ‘masses above it, it is not
converted into‘ steam. At a depth which. is not certainly known, but
which various savants have approximately ﬁxed at 49,000 feet, water of a
temperature exceeding 750° (Fahn) ultimately attains elasticity sufficient
to overcome the formidable weight of 1500 atmospheres which presses on
it; it changes into steam, and in this new form mounts to the surface of
the earth through the ﬁssures of the -rocks.* Even this steam, passing
through beds of a gradually decreasing temperature, is again condensed
and runs back again in the form of water, still it heats the liquid which
surrounds it, and increases its elasticity; it consequently assists'the gen-
eration of fresh jets of steam, which likewise rise toward the upper re-
gions. Thus, step by step, water is converted into steam up to the very
surface of the earth, and springs out from ﬁssures in the shape of fame-
rolles.
In Iceland, California, New Zealand, and several other volcanic regions
of the world, jets of steam mingled with boiling water are so considerable
as to rank among the most astonishing phenomena of the planet. The
most celebrated, and certainly the most beautiful, of allthese springs is the
Great Geyser of Iceland. Seen from afar, light vapors, creeping over the
low plain at the foot of the mountain of Blafell, point out the situation of
the jet of water and of the neighboring springs. The basin of siliceous
stone which the Geyser itself has formed during the. lapse of centuries is
no less than 52 feet in width, and serves as the outer inclosureof a fun-
nel-shaped cavity, 75 feet deep, from the bottom of which rise the water
and steam. A thin liquid sheet ﬂows over the edges of the basin, and de-
scends in little cascades over the. outer slope. The cold air lowers the
temperature of the water on the surface, but the heat increases more and
more in all the layers beneath; every here and there bubbles are formed
at the bottom of the water, and burst when they emerge into the air.
Soon bodies of steam rise in clouds in the green and transparent water,
but, meeting the colder masses on the surface, they again condense. Ulti-
mately they make their way into the basin, ~and'cause the water to bubble
up; steam rises in different places from thelliquid sheet, and the tempera-
ture of the whole basin reaches the boiling'sp‘oint; the surface swells up in
foamy heaps, and the ground trembles and roars with a stiﬂed sound.
The caldron constantly gives vent to clouds of vapor, which sometimes
gather round the basin, and sometimes are cleared away by the wind. At
intervals, a few moments of silence succeed to the noise of the steam.
Suddenlythe resistance is overcome, the enormous jet leaps out with a
crash, and, like a pillar of glittering marble, shoots up‘ more than 100 feet
in the air. A second and then a third jet rapidly follow; but the mag-
niﬁcent spectacle lasts but for a few minutes. The steam blows away;
the water, now cooled, falls in and round the basin; and for hours, or even
' ‘ * Vide above, p. 436.
THERMAL bLPRINGS. 483
days, a fresh eruption may be waited for in vain. Leaning over the edge
of the hole whence such a storm of foam and water has just issued, and
looking at the blue, transparent, and scarcely-rippled surface, one can
hardly believe, says Bunsen, in the sudden change which has taken place.
The slight deposits of siliceous matter which are left by the evaporation
of the boiling water have already formed a conical hillock round the
spring, and, sooner or later, the increasing curb of stone will have so con-
siderably augmented the pressure of the liquid mass in the spring that the
waters must ultimately open a fresh outlet beyond the present cone.
From the experiments and observations made by Forbes as to the forma-
tion of the layer of incrustations round the jet, this spring must have com-
menced its eruptions ten centuries and a half ago, and they will probably
cease in a much shorter space of time. Not far from the Geyser, the
mound of deposits from which is not less than 39 feet in height, there are
a number of pools which once acted as basins for springs which gushed
up through them, but are now nothing but cisterns ﬁlled with blue and
limpid water, at the bottom of which may be seen the mouth of a former
channel of eruption. A shifting in the position of the centre of activity
takes place in the Geyser, just as in mud-volcanoes and incrusting springs.
Several springs lying on the same terrestrial ﬁssure as the great jet cl’eau,
the Strokkr, the Small Geyser, and some others, present phenomena which
are nearly similar, and are evidently subject to the action of the same
forces. The vicinity of the active volcanoes of Iceland warrants us, how-
ever, ih supposing that the water produced by the melting of the snow on
Blafell does not require to descend many thousands of yards into the earth
in order to be converted into steam. There is no doubt that, at no very
great depth below the surface, they come in contact with burning lava,
which gives them their high temperature. By reproducing in miniature
all the conditions which are thought to apply to the Icelandic springs—
that is, by heating the bases of tubes of iron ﬁlled with water and sur-
mounted by a basin—Tyndall succeeded in producing in his laboratory
charming little geysers, which jetted out every ﬁve minutes.
About the centre of the northern island of New Zealand the activity of
the volcanic springs is manifested still more remarkably even than in Ice-
land. On the slightly-winding line of ﬁssure which extends from the
southwest to the northeast, between the ever—active volcano of Tongariro
and the smoking island of Whakari, in Plenty Bay, thermal springs, mud-
fountains, and geysers rise in more than a thousand places, and in some
spots combine to form considerable lakes. In some localities the hot va-
pors make their escape from the sides of the mountains in such abundance
that the soil is reduced to a soft state over vast surfaces, and ﬂows down
slowly to the plains in long beds of mud. For a distance of more than a
mile a portion of the Lake of Taupo boils and smokes as if it was heated
by a subterranean ﬁre, and the temperature of its water reaches on the
average to 100° (Fahr.). Farther to the north, the two sides of the valley,
through which ﬂows the impetuous river of Waikato after its issue from
484: THE EARTH.
theLake Taupe, present, for more than a mile, so large a number of water-
jets,,that in one spot as many as seventy-six are counted. These geysers,
which rise to various h'eights,.play alternately, as if obeyinga kind of
rhythm in their successive appearances and disappearances. While one

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v
Fig. 201. Volcanic Region of New Zealand.
springs out 'of the ground, falling back into its basin 111 a graceful curve
bent by the wind, another ceases to jet 'out. In’ one’ spot a whole series
of jets d’eauqsuddenly become quiet, andthe basins of still water emit
nothing'but a thin mist of vapor. Farther on, however, the mountain is
THERMAL SPRINGS, 'ETCC, OF NEW ZEALAND. 485
all activity; liquid columns all at once shine in the sun, and white‘casl
cades fall from terrace to terrace toward the river. Every moment ‘the
features of the landscape are being modiﬁed, and fresh voices take a part
in the marvelous concert of the gushing springs.*
About the middle of the interval which separates the Lake of Taupe
from the coast of Plenty-Bay, several other volcanic pools are dotted
about, all most remarkable for their thermal and jetting springs. One of
them, however, is amongthe great wonders of the world.‘ This is- the Lake
of R-otomahana, a small basin of about120 acres, the temperature of which,
being raised by all the hot springs which feed it, is about 78° (Fahr.). Dr.
von Hochstetter has not even attempted to count the basins, the funnels,
and the ﬁssures from which the water, steam-mud, and sulphurous gases
make their escape. Here and there, indeed, he noticed, all together, salses,
soifatams,famcrolles, and springs. The most magniﬁcent of allthese- jets
is the Tetarata, about 82 feet above the eastern bank of the lake. The
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basin, from the centre of which the water and steam spout out,-is a kind
of crater, 286 feet in circumference, which is surrounded by ramparts of
red clay 32 ‘feet in height, resembling the'sides of a crater. The basin is
full of clear water, which has entirely covered the former with a coating
of silex, white as marble. The water ‘in this dazzling basin assumes'a de-
licious blue shade, which is rendered more-beautiful'by the reﬂection of
the steam unrolling its spiral clouds; The liquid'which ﬂows from ‘the
basin runs into another pool, likewise covered'by a coating of silex,'and,
falling from terrace to terrace, thus reaches the level of the lake. These
glittering‘ steps, over which the water spreads in thin sheets, and then'falls
in cascades, form a wonderful spectacle of splendor and'grace. Sometimes
—say the natives—the whole body of liquid in the upper basin issudden-
ly upheaved in an enormous column, and the pool empties 30 feet of its
depth ; in this case nothing can be wanting to' complete‘ the grandeur of
the picture. - a - a ‘ ‘ -- ~ I
Have these wonderful springs existed for any great length of time, and
are theydestined to-be preserved for centuries in all their beauty? These
are points as yet unknown. _ When the New Zealand springs have been
studied for a considerable number of years, it will perhaps‘ be possible to
describe the various modiﬁcations which are taking place in consequence
* F. von'Hochstetter, Neu-Seleland.
4.86 THE EARTH
of the increase or relaxation of the subterranean action in these regions.
In several parts of Europe thermal springs have gradually lost both their
heat and their mineral qualities, owing to the cooling of the furnace which
heated them, and are becoming more and more similar to ordinary springs:
of this kind, for example, are the springs of Bertrichbad, in Luxembourg.*
The gases which make their escape from the fumerolles situated above
hidden beds of lava do not differ from those produced by great volcanic
eruptions; they are'the- hydrochloric, sulphuric, and‘ carbonic acids, either
in a state of purity or in combination with alkaline, earthy, or metallic
bases, and, as in the moving currents of lava, they indicate by their com-
position the degree of intensity of the subterranean heat. The most pre-
cise indications on these points have been furnished by the analyses of
MM. Bunsen, Ch. Sainte-Claire Deville, and Fouqué.
When they issue from the earth, ftm'zerolles deposit on the edges of the
ﬁssure various substances, such as sulphur, alum, and borax, which have
been sublimated in the subterranean laboratory; the vapors then spread
out into wide eddies, and-are lost in the air. There is no spot in Europe
where these fumerolles can be better studied than in the former crater of
the Isle of Volcano. The cavity, at the bottom of which all these chem-
ical operations take place, is more than a mile in circumference, and its
southern sides rise to 980 feet in height; the bottom of the abyss may be
about 320 feet wide. Through the mist of vapor which ﬁlls the immense
caldron a spectator sees the lofty cliffs, red or golden yellow in color, and
streaked here and there with most varied hues. On the slopes leading to
the bottom of the gulf the crumbling stones give way under the tread,
and yet 'it‘ is necessary to descend at a‘ running pace, for in some places
the hollow soil is‘ burning like‘ an arch over an oven. Vapor creeps along
slowly over the slopes. The air is saturated with hydrochloric and sul-
phurous acid gases, and is diﬂicult to breathe. An incessant noise of dull
sobbings and whistlings ﬁlls the hollow, and on every side there are small
oriﬁces between- the stones, whence jets of steam spring eddying out.
This isv‘the spot‘ whither the workmen—who seem accustomed to live in
theﬁre, like the legendary salamanders—resort to gather the .stalactites
of gilded sulphur which still crackle from the effect of heat, and the ﬁne
needles of ‘boracic acid, white as swan’s-down. At night the masses of
vapor accumulated above the crater are colored with a red glare, as if
from the reﬂection of an immense ﬁre.
Sometimes the rain which falls into the amphitheatre forms there a tem-
porary lake; but a great part of the water makes its escape through the
ﬁssures in the ground, and ﬂows in a stream over the external slopes, the
remainder being rapidly evaporated by the heat of the mountain. Some
of the fumerolles, the gases of which were analyzed in 1865 by M. Fouqué,
attain a temperature above 680° (Fahr). Other jets of less heat make
their appearance in various parts of the island, and even in the waters of
the bay. From the edges of the great crater these vapors may be seen '
*' See chapter on "‘ Springs.”
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ISLE OF VOL cal-m. 487
at the base of the slopes rising from the bed of the sea, and developing
into wide, whitish-colored spirals, similar in hue to the mud of potters’
clay. Inicertain places the temperature of the sea-water heated by these
gases is so high that voyagers-can afford themselves the childish satisfac-
tion of boiling their eggs in it.
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The solfatam in the Isle of Volcano produces scarcely 10 tons of sul-
phur every year. This does not seem much; but if we were to calculate
by centuries and geological periods the quantities deposited by the fume-
rolles, it would seem really enormous. Thus the mines of Sicily, which
have been worked for some centuries, furnish every year to commerce no
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488 THE EARTH.
less than 300,000 tons of sulphur, and yet the mining operations in these
districts are altogether of a primitive character. A large number of beds
are unexplored, and nearly a third of the sulphur brought to the surface
evaporates in the furnaces or is lost in the debris. These almost inex-
haustible veins appear to have been all produced, like the deposits of the
‘Isle of Volcano, by jets of vapor saturated with sulphur.
Sometimes carbonic acid gas is the only gas which is discharged from
the caverns and craters of volcanoes. This ﬂuid,being much heavier than
the atmosphere, does not ascend, like the other gases, and become lost in
the air, but accumulates in weighty masses round the outlet. Plants
which are bathed in this mephitic air rapidly wither, and all animated
beings die from asphyxia, unless their heads rise up above the deadly at~
mosphere. In the island of Java there is a small crater called Pakereman,
or “ Valley of Death,” the amphitheatre of which, after the heavy tropical
rains, is entirely ﬁlled with carbonic acid gas. No plant grows in this
vast cavity. According to the statements of London, the ground is strewn
with the skeletons of animals. At one time there might have been seen
in it the remains of human beings who had been doomed to perish from
asphyxia in the poisoned air. In Europe there is no spring of carbonic
acid which can be compared to that of Java; those which have been
studied in Italy,-Auvergne, and on the banks of the Rhine are most of
them nothing but very inconsiderable emanations, ﬁlling, perhaps, a con-
ﬁned cave, or the lower part of a small cavity well sheltered from the
wind. Insects, and sometimes a few birds, are the only victims of this
destructive gas. The famous cave in the vicinity of Naples is well known,
into which, to satisfy the idle curiosity of travelers, the guides are cruel
enough to bring some wretched dogs, and, forcing them into the layers of
carbonic acid gas which hang over the soil, cause them to pant for breath,
and ultimately die. At one time the crater, which is now ﬁlled up by the
gloomy Lake of Avernus, which the ancients looked upon as the entrance
to the infernal regions, gave vent to so large a quantity of carbonic acid
gas that birds ﬂying over the lake fell as if struck by lightning; hence is
derived the Greek name of the lake, “without birds.”
Otis.
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S UBMARINE VOL CANOES. 4:8 9
CHAPTER LXXI.
SUBMARINE VOLCANOES.
THE bed of the sea is, of course, inaccessible to our observation, but still
there can be no doubt that the phenomena of submarine volcanoes resem-
ble those of the burning mountains which tower so high above the ocean.
Whenever the crest of an isle of scoriae rises above the waves, all that we
see of its eruptions suiﬁces to prove that they take place exactly in the
same way as those of the volcanoes on the main land. There exist, how-
ever, in several places, former submarine craters which, since their period
of activity, have been upheaved, with the plains surrounding them. The
history of these craters, written legibly in their strata, is just the same as
that of other volcanic outlets. Still, as would necessarily be looked for,
on account of the pressure exercised by the immense body of sea-water,
the cones of debris which have been formed under the pressure of the
waves are, without any exception, more ﬂattened than mountains of the
same nature which have taken their rise on the tcrraﬁrma. With regard
to the lava which issues from submarine ﬁssures, it sooner becomes solid-
iﬁed, and does not ﬂow to such great distances. Often, also, it is con-
verted, under the superincumbent weight of the Water, into basaltic col-
onnades. We can, too, readily understand that the vapor must rapidly
condense while passing through the mass of cold water. It is only when
the mouth of the crater is very close to the surface of the ocean that col-
umns of vapor are freely discharged and ascend into the air.
Most submarine eruptions which have been known in modern times have
taken place at no great distance from some of the great insular or conti-
nental volcanoes. The Sicilian Sea, the Greek Archipelago, the waters near
St. Michael in the Azores, the portion of the Caspian which surrounds the
Peninsula of Apcheron, the seas of Japan and of the Aleutian Isles, the
Gulf of Darien, and the coast of Iceland, form, probably, a part of the same
subterranean regions of activity as the volcanoes situated on the adjacent
shores. There is, however, one volcanic district which is exclusively sub-
marine; this is the narrowest part of the Atlantic, embraced between the
two extreme points of the coasts of Guinea and Brazil. In this tract of
the ocean the water is often agitated by violent shocks, and ships tremble
as if they had run upon a sand-bank. Smoke, as if from a conﬂagration,
rises above the waves, and pumice-stone and other light scoriae are ﬂoated
about by the current. Even islands of ashes have been noticed to emerge
from the midst of the sea, which, being washed away by the waves, have
diminished, and ultimately disappeared.*
* Daussy, Darwin, Poulett Scrope.
490 THE EARTH.
The [submarine cones proceeding from the bottom of the sea which resist
the action of the water are those which have their layers composed of lava.
The group of Aleutian Isles contain at least two mountains which have
emerged from the water within a recent period. According to the ac-'
counts of the Chinese and Japanese chroniclers, several volcanoes have
risen from the bed of the sea on the coasts of Japan and the Corea during
the historical period. In the year 1007 a roar of thunder announced the
appearance of the volcano of -Toinmoura, or Tanlo, on the south of the
Corea, and then, after seven days and seven nights of profound darkness,
the mountain was seen; it was no less than four leagues in circumference,
and towered up like a block of sulphur to a height of more than 1000 feet.*
More than this, the celebrated Fusi-Yama itself, the highest mountain in
J apan,~is said. to have been upheaved in a single night (‘2) from the bosom
of the‘ sea twenty-one and a half centuries ago. With respect to marine
volcanoes of a more recent epoch, we may mention all the isles of either


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* Stanislas Julien, Comptes Rendus, vol. x., 1840.
VOL C'ANO OF TAAL. 491
extinct or still burning lava which rise in pyramids like Stromboli, or ex-
tend in a graceful semicircle like the crater of St.Paul in the Indian Ocean.
Lakes also exhibit a number of volcanoes of the same kind. Such are
Momotombo of Nicaragua, and the Taal of the Lake of Bongbong, in the
island of Luzon.

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The sudden appearance of lava which has most impressed the popular
imagination for many years past, and has also been best studied by scien-
tiﬁcv men, is the formation of hillocks of lava in the Santorin group. This
circular archipelago is doubtless the remains of a great cone, 30 miles in
circumference, which once rose in the midst of the sea. In consequence of
the action of the waves, earthquakes, and subsidences, the sides of this cone
were broken in upon and ﬁnally'ruptured by the water. When the Hel-
lenes established themselves in the islands of the Egean Sea, the shattered
mountain was divided into three fragments: one fragment, assuming the
492 . THE EARTH.‘
form of a crescent, and comprehending the larger portion of the former vol-
cano, constitutes the island of Thera, or Santorin; on the west, the little
Isle of Therasia bends round in continuation of the ring of land; and, on
the southwest, a great rock, the Islet of Aspro, rises as if to bear witness
to the rampart of lava now disappeared. The outer slopes of Santorin and
Therasia, partially covered with pumice-stone somewhat resembling a coat-
ing of snow, are rather gently inclined toward the sea, but the escarpments,
turned in the direction of the basin, which was once the crater, are in some
places nearly perpendicular for a height of 650 and even 1300 feet. The
various 1ayers,.which correspond on the two sides of the gulf—on the sides
of Therasia and of Santorin—are vividly marked out in bands of a red,
yellow, blue, black, or white color.

23?.E de Paris
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Fig. 206. Santorin.
In the centre of this crater, afterv a series of upheavals and eruptions, an
islet‘ of lava emerged about the year 196 BC. It was named Hiera (Holy),
and on the summit a temple to Neptune was built. This islet, which was
ished.
* KAZMENI ISLES.-.—SANTORIN. 493
several times increased in the centuries‘which followed—in the years46,
713, 726, and 1427 A.D.-——is now known underthe name of Palaeo-Ka'i'meni.
Not far from this isle, another smaller one, Mikro-Ka'l'meni, rose in 1570 or
1573. At the commencement of the eighteenth century, from 1707 to 1711,
another mass of lava, Neo-Ka'i'meni, an island no less than four miles in cir-
cumference, emerged within the annular crater formed by the crescent-
shaped Santorin and the Isle of Therasia. In 1768 Neo-Ka'imeni was
shaken by a violent eruption. From this date to 1866 no visible change
took place above the water, but soundings proved that the bed of the sea
had gradually risen. At a point near Mikro-Kaimeni, a bank of rocks, sit-
uated in 1794 at a depth of 80 to 100 feet, was in 1835 only 13 feet from
the surface. “Such is the singular fecundity of Santorin,” says a histo—
rian of this volcano, “that isles seem to grow up round it like fungi in a
wood.”*
At the end of January, 1866, subterranean roarings, a gradual sinking
of the ground, and the coloring of the water, announced an approaching
eruption. The centre of the shock was felt just below the little village of
Vulcano, situated on the edge of a creek where ships used to cast anchor
in order that the water, mingled as it was with acid gases, might destroy
the molluscs and sea-weed attached to their keels. On the 3d of Febru=
ary a brilliantly black mass of lava was seen, which rose slowly from the
bottom of the water, and increased in size every day with ,perfect regu-
larity. This mound, designated by the name of Geo'rge’s Isle, attained in
a few weeks a height of 164 feet, and ultimately became nnitedto Neo-
Ka'imeni, having ﬁlled up the creek of Vnlcano. On the 7 tlfof February,
another mound, the Isle of Aphroessa, rose at a little distance, to the south,
and, gradually ﬁlling up the channel which separated it from Neo-Ka'imeni,
became converted into a promontory. Afterward other islets made their
appearance by the side of the two principal cones. All round them the
sea, agitated by the gases which rose in great bubbles, exhibited in turn
the most diversiﬁed hues. It was in succession reddish-colored, milk-white,
or shaded with green or a chemical blue; it was, besides, generally tepid
or hot. The ﬁsh, either asphyxiated or killed by the heat, ﬂoated in mule
titudes on the surface, and mariners avoided steering their ships any where
near the eruption for fear the pitch between their planks should melt in
the water heated to a temperature of 160° to 170° (Fahr.). The summit
of the crater of Neo-Ka'imeni was shaken by frequent explosions. On the
20th of February lumps weighing 220 pounds were suddenly darted out
to a distance of several hundred yards, showers of ashes fell upon the vines
of Santorin, and clouds of débrz's, making their escape from the crater, shot
up to a‘height of 6500 to 9800 feet. It was not before the end of the year
1866 that the cone of George’s Island opened out for itself a crater by an
explosion which destroyed the whole of the upper portion of vthe mound.
But the intensity of the eruptive phenomena" soon after gradually dimin-
Currents' of lava more than half a mile long were: in some places
* Pegues, Histoz're des Phénoménes 'du Volcan dc Santorin.
d’
494 THE EARTH.
more than 300 feet in depth. It is evident that the reason why the mol-
ten matter has thus formed in heaps close to the outlet, instead of ﬂowing
in long streams, as on the sidesv of Vesuvius and Etna, is that the lava,
soon becoming cool by its contact vwith the salt water, was necessarily
compelled to arrest its progress.it ‘ -

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The cones of shifting ashes which are thrown out by the eruptions of
submarine volcanoes are notable to resist the. action of the waves for any
length of time; and however great may be their dimensions, they are cer-
* Fouqué, Revue des Deax-‘Monde's, August, 1866.
ISLE’ OF JULIA. 49 5
tain ultimately to disappear, unless they are based on solid foundations
which have entirely emerged from the water. As an example of this we
may mention the celebrated Julia, or Graham’s Island, which appeared in

Fig. 208. Graham's Island, or Isle of Julia.
July, 1831, throwing up heaps of dark-colored scoriae about 25 miles south
of the shores of Selimonte, in Sicily. An English captain, proud of being
able to increase the British domains, hurried to hoist his ﬂag over the
smoking stones. The islet gradually increased round the crater, and be-
fore long it measured as much as four miles round. But, at the conclu-
sion of the volcanic eruption, the work of demolition commenced, and, in
conformity with M. Constant Prévost’s prediction, the slope of debris was
gradually undermined at the base by the waves and currents. In October
nothing remained but a little mound. Six months after, the newly-discov-
ered island, which was also claimed by the King of Naples through his di-
plomatists, was nothing more than an oval reef about half a mile long. A
few years later the sounding-line’ showed a depth of 787 feet. In July,
1863, the isle again appeared, and in a few weeks rose to the height of
200 to 260 feet; but it existed only for a short space of time, for it soon
again sank, being demolished stone by stone by the dash of the waves.
It appears, however, that, previously to 1831, the volcano had made its
appearance on one or two other occasions. It is said thatv a smoking isl-
and existed in this spot about the year 1801, and the shoal is pointed out
in old charts. This island, ﬁrst rising up above the waves and then sink-
ing down again into the depths of the sea, seems to recall the recollection
of that mysterious country mentioned in the “Arabian Nights,” which
plunged down into the ocean just at the moment when the voyagers were
going to land on it. - ' .
Near the island of San Miguel, one of the Azores, there is another sub-
marine volcano, which likewise vomits out at each of its great eruptions a
temporary cone of scorize, which rises above the level of the sea. In the
496 . THE EARTH .
years 1658, 1691, 1720, and181 2,a smoking islet made its appearance, and
on each'occasion it was destroyed after a few weeks of existence. Never-
theless, in 1812, an Englishman found time to‘ take possession of it in- the
name of his government, and to give it the name of “ Sabrina.” In 1867
a fresh eruption took place at about the same spot, but the volcanic cone
did not reach the surface of the sea, and M. Fouqué, the indefatigable ex-
plorer of volcanoes, noticed nothing but ﬂoating scoriae, gases thrown out,
“and ﬂames dancing over the water. In the Icelandic seas, the land of‘
Nynoe, which appeared in 1783 at a point 31 miles tothe southwest of
Cape Rekianess, enjoyed a much longer life, for it lasted a whole year.
There, just as in the seas of Sicily and the Azores, the ashes washed away
by the waves are deposited at the bottom of the water in vast layers of ,
tufa mingled with shells and other débris. Some day or other these beds
of volcanic stone will appear on the surface, just as the tufas of the Enga-
nean hills in the valley of the Po, and the Phlegraean ﬁelds at Naples, and
will tell the tale of the submarine eruptions of the present period.
PERI 01)] 6'1 T Y 0F ER UPTIONS.
CHAPTER 'LXXII.
PERIODICITY OF ERUPTIONS.—INFLUENCE OF TEMPERATURE ON VOLCANIC
PHENOMENA.-—EXTINCTION OF FURNACES OF LAVA.
ONE of the most important questions in respect to volcanoes is that of _
the order in which their phenomena take place. Every thing in nature
acts in sure conformity to regular laws of periodicity; but when this rule
has to be applied both over vast spaces and long intervals, it may readily
remain unknown to us for a very long time. The fact is, that the rhythm
of the great volcanic revolutions has not yet been discovered, and, up to
the present time, the whole of these events appear to us as if they were a
perfect chaos. Even in the volcanic region which is the best known, and
which savants have the best studied, that is, in the area which includes
Southern Italy, Sicily, and the Lipari Islands, the succession of movements
(except as regards Stromboli) has taken place with the greatest apparent
want of order. Etna and Vesuvius have remained in a state of repose for
centuries, and then suddenly, and after unequal intervals, they have expe-
rienced sometimes one convulsion only, sometimes a series of shocks more
or less violent and numerous. - Besides, as we have seen, there is no neces-
sary coincidence between the phenomena of the two volcanoes. Some-
times, indeed, it happens that a period of extraordinary activity in one
volcano is contemporary with protracted tranquillity in the other. True
enough, during the dark night of the Middle Ages, phenomena like this
were almost entirely lost sight of in' history, but documents collected since
the sixteenth century evidently prove that the geologist must limit him-
self to studying the symptoms of periodicity in each smoking mountain
by itself.
In this last respect there is no want of evidence which renders highly
probable the existence of some sympathetic tie between the eruptions of
volcanoes and the more or less regular phenomena of the surrounding at-
mosphere. This, indeeQ is a proverbial article of faith with mariners as
regards a large number of active craters. The ﬁshermen of Stromboli
have for centuries all agreed in ‘stating that the mountain serves as a ba-
rometer for them in pointing out the approach of winds and storms by a
great increase of violence in its eruptions. At the time of the autumnal
equinox, as well as in winter, the boiling lava in the crater runs out much
more often through the outlet, and sometimes opens out a way of issue in
the sides of the mountain, so as to ﬂow down to the sea. The. fact is, that
the atmospheric pressure above the column of lava being diminished dur-
ing stormy weather, does not act with the same energy on the compressed
mass; the molten matter rises more rapidly in the crater, and ﬂows out
in greater abundance. Added to this, as the ‘smoke of the volcano gen-
I I
498 THE EARTH.
erally mounts up a thousand yards above the level of the sea, and some-
times rises in a column to the higher regions of the atmosphere, the con-
tests which take place among the aerial currents may often be seen more
or less clearly; thus, by experience, a knowledge may be obtained before-
hand of the changes of weather which will gradually make their way down
from the sky above. “By the smoke of this volcano,” said Pliny, eighteen
centuries ago, “ the natives can predict the winds three days in advance,
which leads them to believe that these vapors are in obedience to Aﬂolus.”
The inhabitants of Lipari say, also, that the vapors from the crater of
Volcano form clouds of much greater volume when storms are brewing.
This, then, would be another gigantic barometer, regularly indicating the
diminished pressure of the atmosphere. According to both travelers and
natives, the epoch of the equinoxes, when the monsoons blow, is the time
when the eruptions of the Peak of Ternate, Taal, and other volcanoes of
the Indian Archipelago are most terrible. In like manner, in the Isle of
Chiloe, Fitzroy was told that the eruptions of Osorno always announced
the approach of ﬁne weather, and, in consequence, an increase in the weight
of the column of air. With regard to phenomena other than the oscilla-
tions of the aerial masses, these may also be foretold by means of the vol-
canic movements, if we are to put faith in the statements of those who
live at the very foot of the smoking mountains. Thus, in Japan, the vol-
canoes generally begin to vomit out lava about the time of the ﬂow of the
tide, and inundations caused by exceptionally high tides always take place
after eruptions and earthquakes.* In 1827, Scuderi, a Sicilian, tried to
prognosticate all the meteorological phenomena by the form and direc-
tion taken by the masses of vapor which were vomited out by the crater
of Etna]l
M. Emile Kluge, by classifying all the known eruptions in seasons and
months, has ascertained that these crises take place in summer especially,
and that earthquakes are more frequent in winter. According to this ge-
ologist, there is no doubt that the eruptions of volcanoes depend on the
changes of seasons. The melting of the snow and ice, the falls of rain, the
oscillations in temperature, and the weight of the air, are, in his idea, the
real causes of the subterranean ﬁres; the latter, too, being the mere result
of chemical reaction, and among the purely ex¢rnal phenomena of the
planet. Not, therefore, in the abysses of a sea of ﬁre, but at a depth of
six to nine miles at most, must we seek for the furnaces in which the burn-
ing matter is elaboratedl
Nevertheless, although we may be warranted in looking upon the year
itself, with its return of seasons and atmospheric phenomena, as a kind of
day in the life of volcanoes, we are none the less in complete ignorance
in respect to the great secular periods of Plutonic activity in the various
parts of the world. Like all terrestrial phenomena, that of the eruption
of lava and ashes is limited in its duration. The volcanoes which rise up
* Siebold, quoted by Perrey. 'i' Memoire dell’ Academia Gioem'a.
‘l’ Ueber die Periodicitz'z't vulcam'scker Aasbriishe ; Neues .Tahrb. f iir Mineral.,1862, part v.
EXTINCTION OF VOL UANOE’S. 49 9


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out oi the ground are extinguished either after a short existence or after
thousands of eruptions. ' Over the whole surface of the earth there are a
large number of former volcanoes the nature of which has been disclosed
to us by modern geology alone. Some date from an epoch so remote that
beds of modern formation have to a great extent covered their sides and
ﬁlled up their craters. Others, like the hills of Auvergne, are still visible,
withtheir cones of scoriae or their domes of trachyte, their ﬁssures and
ch'eires of lava, such as they once were when the plains at their bases were
arms of the sea. Among these well-preserved volcanoes there are, indeed,
some_--especially that of Denise, near the Puy-en-Velay—which were in a
state of full activity at an epoch when man had already established him-
self in the adjacent districts, for in the tufa of their eruptions skeletons
have been found of the ancient inhabitants of Gaul. Lastly, numerous
volcanoes which have burnt during the historical period are now extinct,
and perhaps forever. The cycles of these lava-furnaces are doubtless con-
nected with those of the continents themselves; the conﬁguration ‘of land
and sea must change before these furnaces can again be lighted up. Con-
tinents and oceanic basins must 'also shift their position on the surface of
the globe before they can be extinguished.
500 THE EARTH.
.-
CHAPTER LXXIII.
EARTHQUAKES.—VIBRATIONS OF THE GROUND.—-VARIOUS HYPOTHESES.
As volcanic eruptions sufficiently show, this planet is not the immova-
ble mass which our imaginations depict it when comparing it to the at-
mosphere which surrounds it, to the ever-mobile waves of the ocean, or
even to the animated beings which wander over its surface. On the con-
trary, the ground which we tread under our feet vibrates very frequently.
Without alluding to those great shocks which overthrow cities, bring
down the sides of mountains, and open vast cracks across plains, there are
other less violent vibrations, which have been recorded by the annalists
of geological history, and may be reckoned by thousands as regards civil-
ized countries and modern times alone. There can be, however, no doubt
that the great majority of slight earthquakes pass unnoticed, being blend-
ed, especially in towns, with the confused rumbling of noises and murmurs.
Various seismologz'cal instruments, recently invented or brought to’ perfec-
tion,,reveal a large number of oscillations which it would be impossible to
discover in any other way. An attentive observation of the levels of air-
bubbles and of micrometrical threads reﬂected on the surface of a bath of
mercury has, indeed, warranted M. d’Abbadie in asserting that the earth
is in a state of constant vibration. The intervals of immobility which he
has noted have never exceeded thirty hours.
What is the cause of these trepidations of the ground? A great num-
ber of sacants, who have accepted the hypothesis of a pg/Tz'phlegeton, or
central ﬁre, do not hesitate to look upon these vibrations of the earth as
the repercussion of the undulations of the great burning sea. Each of the
shocks which are felt on the surface of the earth would then take its rise
below the envelope of the planet, and would be at ﬁrst produced in the
form of a current or tide in the burning mass which is supposed to exist.
As Humboldt says, an earthquake would be “the reaction of the liquid
nucleus against the outer crust.” Added to this, most geologists who
base their arguments on the hypothesis of a central ﬁre admit that earth-
quakes must necessarily be in connection with volcanic phenomena, and
that they invariably proceed from the same cause. Following‘ out the
comparison which must always present itself to the mind, the mouths of
volcanoes are safety-valves, and, on account of the obstruction of these out-
lets, the pent-up lava or vapor shakes the superincumbent layers of the
terrestrial envelope, seeking to ﬁnd some way of issue. This theory has
the merit of being very simple, and,in a large number of cases, seems to
harmonize very satisfactorily with the facts that have been observed.
But we must never forget, however probable this hypothesis as to the vol-
.\
DIST RIB UTI ON 0F EAR TH Q UAKES. 5 ()1
canic action may be, it has not as yet become a certainty; and the duty
for the geographer still is to study events impartially, and to suspend his
judgment until a satisfactory conclusion evidently results from the whole
body of facts observed.
In the ﬁrst place, it is important to know if those regions on the surface
of the globe in which earthquakes take place with the greatest frequency
are distinguished from other parts by any peculiar features in the form of
their vertical outline, or in the nature of their rocks. The volcanic dis-
tricts in Europe, such as the environs of Vesuvius and Etna, the islands of
Santorin and Milo, and the south of Iceland, are not the only places which
are subject to severe shocks; the former districts, too, have never been so
‘violently agitated as the mountains of the Abruzzi and Calabria, the islands
of Rhodes and Cyprus, the limestone districts of Carniola and Istria, the
Alps of the Valais, the environs of Basle, certain plateaux in Spain, and
the hills at the mouth of the Tagus. The mountains of Scotland, and es-
pecially ‘those in the county of Perth, have also experienced repeated
shocks: out of two hundred and twenty-ﬁve earthquakes recorded in the
British Isles, eighty-ﬁve have taken place in this one county. In Africa,
the soil of Algeria, so rich in saline and thermal springs, but devoid of vol-
canic craters, is sometimes very severely shaken. The districts of the
Nile, which are likewise without volcanoes, have also suffered much from
subterranean movements. In Asia, the peninsula of Guzerat, a spot in
which astonishing modiﬁcations of the shape of the coasts were produced
during a great earthquake, is situated more than 1240 miles from the near-
est volcanoes, the Demavend and the burning mountains of Thian-Chan;
'but, on the other hand, the Philippines and Japan, which are volcanic ‘coun-
tries, are also frequently agitated by movements of the ground. Again,
the sea-coast of Syria, the towns of Aleppo and Antioch, the scenes of some
of the most destructive earthquakes that are recorded in history, no lon-
ger possess very-active volcanoes, and the lavas of the Djebel-Hauran, on .
the southeast, have long been extinct. In South America most of the
great shocks have taken place in the region of the Andes, or not far from
their bases. The Argentine town of Mendoza, which was overturned in
the violent earthquake of 1861, is comparatively not far from a lava-fur-
nace, since the volcano of Maypu rises at a distance of only 87 'miles. The
equatorial Andes are often convulsed by violent oscillations of the soil, and
are also the theatre of great volcanic activity, many of their summits be-
ing domes of trachyte, or craters still vomiting out ashes, mud, or smoke.
Nevertheless, according to the testimony of Boussingault, the most ener-
getic shocks experienced in Columbia—those which destroyed the towns
of Latacunga, Riobamba, Honda, Merida, and Barquesimeto, and were sim-
ultaneously felt over a very extended area—presented no coincidence
whatever with ‘any volcanic phenomena, and their centre of agitation was
situated at a considerable distance from the smoking peaks.* The plateau
of Caraccas, celebrated for the catastrophe of 1812, is situated more than
600 miles eastward of the Grenadini volcanoes of Huila and Tolima, and
* Annales de Chimie et de Physique, 1855.
502 THE EARTH.
at rather a less distance from the craters of the Antilles, from which it is
separated by wide arms of the sea. Finally, the region in North America
where oscillations of the ground are most frequent and most severe is the
alluvial plain of the Mississippi, far distant from any volcanic district, and
even from any great chain of mountains. Thus,‘ although the history of
earthquakes is known only for a few centuries, and over but a small por-
tion of the earth’s surface, it is certain that severe oscillations of the
ground are felt in countries the most diverse, which bear no resemblance
to one another either in their formation or their aspect. The only fact
which seems well established is, that shocks are more frequent in moun-
tainous than in ﬂat countries. Nevertheless, if, as Mr. Mallet thinks, all
earthquakes not followed by an eruption are “incomplete efforts to open a
volcano,” if they are produced by the endeavors made by the planet to get
rid either of gas or the molten matter within, the ground ought to be
most frequently agitated in continental plains, far from volcanoes and
mountains; for in those localities there would be no natural “ vent-holes"
through which to discharge the overﬂow of the interior ﬂuids, and there,
too, according to the common theory, the terrestrial layers must be the
thinnest.
Those who look upon every volcano as a safety-valve for the adjacent
regions put forward in favor of their theory certain facts which have at-
tained to the dignity of legends, although their reality is far from being
certain, as M. Otto Volger has more than suﬂiciently proved.* Thus it is
said that, at the time of the earthquake at Lisbon,Vesuvius, which'was
vomiting out a considerable quantity of vapor, suddenly sucked in the
cloud which it was throwing out, and that the current of lava issuing from
its sides was suddenly stopped. But these statements are founded solely‘
on a much less precise expression in the account which Kant the philoso-
pher devoted to the catastrophe at Lisbon. Humboldt tells us “that,
after having vomited out for three months a high column of smoke, the
volcano of Pasto ceased to throw out vapor at the exact moment when, at
a distance of 248 miles, the earthquake‘ of Riobamba and the mud-eruption
of Tunguragua caused the death of 30,000 to 40,000 Indians]l Even‘the
great name of Humboldt must not, however, lead us to forget that, on the
plateaux of the Andes, communication is both rare and diﬂicult, and that
the population scattered over that space of 248 miles ,does not afford all
the guarantees which would be considered requisite in scientiﬁc observa-
tion. Lastly, theassertion that Stromboli relaxed its incessant activity
during the Calabrian earthquake in 1783 is based on nothing but the
vaguest information. According to the pamphlets of that date, all the
Lipari Isles were to be swallowed up in the sea, leaving but a few shoals
to mark the places they once ﬁlled! As may be seen, the facts which
havebeen brought forward as the foundation of the theory that all earth-
quakes are caused by the movements of lava or vapors are deﬁcient in the
requisite authenticity, and can not be looked upon as exempting geologists
from the necessity of direct observations.
* Erdbeben in der Sc/zwez'z, vol. iii., p. 385. 'l' Tableaux de la Nature, vol. ii.
0A USES OF EAR TH Q UAKES. 503
CHAPTER LXXIV.
EARTHQUAKES OF VOLCANIC ORIGIN.—SUBTERRANEAN DOWNFALLS.—
EXPLOSIONS OF MINES AND POWDER-MILLS.
THERE are a certain number of cases in which, independently OI any
theory, we can without diﬂiculty substantiate a relation of cause and effect
between a volcanic eruption and an earthquake. Thus, when the sides of
a smoking mountain, such as Etna or Kilauea, are suddenly cleft asunder
to pour forth a stream of lava, and at the same time the ground is strongly
agitated, it is evident that the earthquake is caused by the fracture of the
volcano. This local phenomenon is precisely analogous to that produced
by the explosion of a mine or a powder-mill. When the ﬁssure is of a
considerable length and the fractured sides of the volcano present a great
thickness, the shock is a violent one, and reverberates in long oscillations
in all the adjacent districts. When, on the contrary, the rocks of the
volcano, having been diminished in thickness and partially melted by the
rising lava, yield more easily to the pressure which bursts them, the ex-
plosion is only felt in the immediate vicinity of the ﬁssure. Thus, at the
time of the last great eruption of Etna, the trepidations of the ground,
which coincided with the formation of the ﬁssure, were in general very
slight, and the sharpest of them—which was, however, perceptible in the
town of Aci Beale—was not felt beyond the Etnean region properly so
called.* History also affords several examples of volcanic eruptions dur-
ing which the ground was not perceptibly shaken. In May, 1855,Vesu-
vius vomited out a considerable quantity of lava without the least trace
of any motion of the ground being perceived either in the observatory on
the volcano or at Naples. . .
When the ground of a volcanic region is convulsed by shocks, and we
are unable to observe the least connection, either as regards coincidence
or immediate succession,between these phenomena and the eruption of a
cone of ashes or the emission of a current of lava, we evidently have no
scientiﬁc reason for asserting with any certainty that these shocks origi-
nate in the subterranean furnace of burning matter, or that they are caused
by vapor endeavoring to break through the terrestrial crust. For still
stronger reasons, a similar assertion would be contrary to all the rules of
scientiﬁc observation when applied to earthquakes which take place far
from any volcano. Certainly, according to the “ safety-valve” hypothesis,
oscillations of the ground ought to take place just in those very localities
of the planetary envelope in which there exists no oriﬁce communicating
with the lava. But how is it, then, that undulations'of the soil are not
* Mariano Grassi, Eruzione dell’ Etna. h
504 THE EARTH.
constantly produced at places far from these gigantic vent-holes situated
on the sea-coast? Why is it, too, that frequent eruptions of Vesuvius and
Etna did not precede the Calabrian earthquakes, and afford an issue to the
pent-up vapor and lava? '
The hypothesis that volcanic forces are the cause of earthquakes being
one that can not be justiﬁed in every case, we must have recourse, in re-
spect to many of these phenomena, to some other theory—one, in fact,
which in all time has suggested itself to the minds of various people, and
was taught by the Greek philosophers. Some two thousand years ago
Lucretius propounded this idea in magniﬁcent language—an idea which
has now been scientiﬁcally adopted by Boussingault,Virlet, Otto Volger,
and other. geologists.
“ Learn, now, the cause of earthquakes, and ﬁrst be assured that the in-
terior of the globe is, like the surface, ﬁlled with winds, caverns, lakes,
precipices, stones, rocks, and a large number of rivers, the impetuous waves
of which hurry along in their course numerous submerged blocks. The
shakings of the surface of the globe are occasioned by the falling in of en-
ormous caverns which time has succeeded in destroying. Whole moun-
tains thus sink in ruin, and the violent and sudden shock is spread far and
wide in terrible vibrations. Thus a chariot, the weight of which is not,
however, very considerable, makes all the houses near tremble as it passes,
and the ﬁery steeds, drawing behind them the iron-armed wheels, shake all
the places round. It might well happen that an enormous mass of earth
should fall by reason of decay into some great subterranean lake, and that
the globe should tremble in a series of undulations. In like manner, on
the surface of the earth, a vessel ﬁlled with liquid in a state of agitation
can not resume its equilibrium until the water contained in it has found
its level.”
Various savants have recently collected a large number of facts which
are in favor of the theory of earthquakes once propounded by Lucretius,
although only generally, and without the necessary proofs. In a vast
number of cases this theory is certainly the true one, for it is often possi-
ble to catch in the act, so to speak, the phenomena which give rise to the
oscillations of the ground and subterranean thunders. Thus great land-
slips, such as those of the Diablerets, Rossberg, and other mountains of
the Alps, have caused real earthquakes, the waves of which were felt at a
considerable distance from the scene of the catastrophe. Even the falls
of moraines, séracs, and avalanches of snow shake the ground very severely
over considerable areas, so much so that in the mountains of Allemont,
in Dauphiny, the inhabitants consider all the vibrations of the ground as
the reverberations of distant downfalls of snow or rocks.*
The subsidence of rocks or shifting soil is accompanied by similar phe-
nomena. In September, 1814, near Alais, for twenty-four hours a series of
detonations were heard like a cannonade, and then, after a formidable
cracking noise, the ground sank 13 feet for a breadth of more than 88
K * Fournet, Annales des Sciences Plzysiques de Lyon, vol. viii.,1845.
0A USES OF EARTH Q UAKES. 505
yards. Not far from the town of Wagstadt, in Silesia, in 1827, a tract of
more than two acres in area sank in a similar way with a great crash. In
Carniola, where earthquakes are not unfrequent, heaps of fallen rocks are
noticed in the numerous caverns, which heaps correspond with the funnel-
shaped cavities on the surface of the ground. These subsidences, which
man sometimes personally witnesses, either in districts hollowed out by
natural caves, or in mining regions pierced with subterranean galleries,
may cause local shocks, or, in proportion to the mass of rocks falling, give
rise to earthquakes felt simultaneously over vast extents of country. In
fact, certain rocky strata sometimes leave intervals between them of very
considerable depth, as may easily be noticed on the sides of mountains;
and they may, besides, be composed of substances which are more or less
easily dissolved and washed away by the inﬁltrated water. When these
voids extend so far that the rocks above, sometimes hundreds or even
thousands of yards in thickness, can no longer maintain their position by
means of their own cohesion, the whole mass must necessarily fall down
on the beds beneath. It is, indeed, impossible to imagine that it can be
otherwise ; the enormous quantities of salt, gypsum, lime, silex, and other
substances which springs bring up to the surface must of necessity leave
great voids in the depths below, and, in consequence, the subsidence of the
rocks above these vacant spaces becomes inevitable. Only imagine, if it
is possible, the potency of the shock produced by the sudden fall of sev-
eral millions of cubic yards.*
Earthquakes produced by artiﬁcial causes in no way differ from natural
shocks in the effects which they produce; they, indeed, furnish us with
excellent terms of comparison. The explosions of mines and the passage
of heavily-laden trains cause a motion of the ground over areas increasing
in extent as the initial pressure is more considerable and as the rocks pre-
sent a greater degree of elasticity. Cannonades, the reaction of which on
the earth is, however, triﬂing in proportion to the effect produced, are
heard at distances which seem prodigious, if the ear is applied to the sur-
face of the agitated ground. Vibrations of the layers of the earth—in
fact, real earthquakes—are thus prolonged for more than 250, or, indeed,
for 375 miles. Thus, in 1832,the bombardment of Antwerp was heard, it
is said, in the Erzgebirge, in the centre of Germany. Twenty-ﬁve years
ago, at the time of the explosion of the powder-mills of Mentz, a very large
area of ground was made to tremble. More than 10,000 lbs. weight of the
gunpowder exploded (the greater part) blew up in open vaults, and could
not, therefore, react on the ground; yet the shock was felt, either as a
slight trembling of the ground or as distant thunder, as far as 100 to 125
miles away—far beyond the districts to which the sound of the detonation
was carried by the wind. The shock was felt at several towns in Suabia,
at Wurzburg, at Kissingen, in Fulda and Meiningen, in Thuringia, near
Cassel, and at Wildungenf Doubtless the observations made on earth-
quakes in the various countries of the world, whether these phenomena
* Otto Volger, Erdbeben in der Schweiz. 1' Ibid,
506 THE EARTH.


k
Fig. 210. Area over which was felt the Explosion of Gunpowder at Mentz.
are produced with or without the intervention of man, will some day en-
able us to estimate approximately the force that is necessary for shaking
some given area of the earth’s surface. These would be comparative
studies which could be made without prejudice in favor of the hypoth-
esis of the central ﬁre or any other theory.
GREAT CA. TASTE OPHES. 507
CHAPTER LXXV.
GREAT CATASTROPHES.—EARTHQ,UAKE AT LISBON.-—AREA OF DISTURBANCE.
——EARTHQUAKES AT SEA.
As a natural consequence of the fellow-feeling which tends to unite all
men together, writers of the earth’s history have been prone to give to
earthquakes a geological importance bearing a proportion to the number
of persons overwhelmed and the quantity of the productions of human
labor destroyed. A shock which shakes a vast city ﬁlled with stone
buildings, in which thousands of individuals are assembled, may cause the
most terrible disasters, while a much more violent one felt by the inhab-
itants of a nearly desert country is soon forgotten and passed over by
history. According to Otto Volger, the earthquake at Lisbon was scarce-
ly more violent than was that of the valley of Viége, a hundred years
after (‘.P); but it remains memorable on account of the thousands of human
beings who perished in it, while the shock of Viége, which only killed two
poor mountaineers, was soon forgotten.
The sudden vibrations which overturn cities in a few seconds are, in
fact, the most frightful catastrophes that can be imagined by man. All
other disasters are announced by some precursory signs. The stream is-
suing from the volcano advances but slowly, and its progress across vil-
lages and cultivated land may be foreseen. The ﬂoods of rivers threaten
the embankments long before they break through them, and preparation
may generally be made for the irruption ‘of water. Even the hurricane is
preceded by atmospheric signs; but earthquakes generally happen sud-
denly and unexpectedly, and in an instant, without a single sign to ex-
plain the catastrophe, whole cities are'demolished, and the inhabitants
destroyed by thousands. The earthquake of San Salvador only' lasted
ten seconds, and this space of time was sufficient for the destruction of
the town. The successive vibrations which devastated Calabria in 1783
were felt during barely two minutes. The terrible movements of the
earth which destroyed Lisbon succeeded each other during the space of
ﬁve minutes; but it was the ﬁrst shock, lasting from ﬁve to six seconds,
which caused the greatest damage. The inhabitants sometimes make use
of the brief respite given‘ them by the intervals between the great shocks,
not in taking refuge in the open air, but in increasing still more their
chances of death: struck with terror, they rush into the churches, the
roofs of which fall in upon them. After some of these castastrophes the
corpses may be counted by tens of thousands: the shocks in Sicily in 1693,
and Calabria in 17 83, must have caused in each of these two countries the
death of 100,000 persons. Lastly, records of more or less credibility speak
508 . THE EARTH.
of earthquakes in Syria, Japan, and the Sunda Archipelago, which resulted
in a sudden loss of life still more considerable. In 526, more than 200,000
people met with their death at Antioch and the adjacent towns.
These undulations, which are so terrible in their consequences, are sim~
*ultaneously felt over vast areas. Thus the commotion which destroyed
Lisbon on the 1st of Novembér, 1755, and‘demolished the_greater part of
Oporto and several other places in Portugal, threw part of the walls of
Cadiz into the moats, and, it is said, on the testimony'of the Governor of
Gibraltar, that the greater part of thetowns of Morocco, Tetuan, Tangiers,
Fez, Mequin'ez, and even the capital itself, were overthrown by the earth-
quake. Kant, the philosopher, and Hoﬁ’mann, who were the historians of
the earthquake at Lisbon, mention a great number of other countries in
Europe, Africa, and even the New World, which must have‘participated
in the violent disturbance. ' The vibrations extended over an area‘ of
15,400,000 square miles; that is to say, about a twelfthpart of the terres-
trial surface. The statements upon which the various accounts of the
catastrophe are founded are not always of any great~ value; it is now
proved that the extent of the area over which the undulations of the earth
were felt on this occasion has been singularly exaggerated. In the whole
of Europe, popular imagination was so struck by this event, which, in the
course of a few minutes, and, indeed, on a day of festival, destroyed so
many thousands of persons under the ruins of a great capital, that it was
naturally led to look upon‘ the earthquake at Lisbon as a phenomenon "
without parallel, the scene‘ of which was, if not the whole world, at least a
great part of the terrestrial surface. All the oscillations which were felt
in Europe, either on the same day or about the same time, were considered
in a general way' as the result of the great commotion at Lisbon; and
gradually a sort of legend was established ‘attributing to the same cause
a considerable number of geological facts of an undecided date, such as
the downfall of rocks, the formation of lakes, the breaking up of ice, and
changes of temperaturein thermal springs. Thus a shock which, “by a
strange chance,” was felt at Turin alone on the 9th of November, a week
after the catastrophe at Lisbon, was attributed to this vast disturbance.
The movements of the soil described as having taken place at New York
on the 18th of November are also reckoned among the undulations which
were then spread far and wide. The Lake Ontario was also added to the
immense area of disturbance, because stong vibrations agitated its shores
during the month of October; that is to say, before the day of the disas-
ter. As a matter of fact, there is nolpositive proof that the terrestrial
wave spread farther than Morocco on the south, the Oastiles on the east,
or in a northerly direction farther than Angouléme and Oognac.* This,
however, constitutes an area of 1118 miles in length; and if, as the diame-
ter of the area of disturbance, the same distance is taken in the direction
from east to west, we shall ﬁnd that the area of the earth shaken by the
great terrestrial wave of Lisbon was more than 1,158,000 square miles, or
* Otto Volger, Erdbeben in der Schweiz, vol. i.
EFFECTS OF EARTHQ UAKES.
about six times the size of France. As a term of comparison, we will
mention the earthquake which was felt in France on the morning of the
14th of September, 1866, the undulations of which were propagated to the
north as far as Rouen, and to the south as far as Bordeaux. The area of
disturbance of this shock must be estimated at about 77,218 square miles,
or the ﬁfteenth part of the surface agitated by the earthquake at Lisbon.

7 r 1 I.

l


Fig. 211. Chart of the Earthquake of the 14th of September, 1866.
At the time of this latter event there was one fact which contributed
much to extend the apparent area of disturbance; this was, that a marine
wave, harmonizing with the shock of the earth, was spread across the At-
lantic in all directions. But the water, being more easily moved than the
soil, necessarily transmitted the wave to a greater distance than the com-
paratively rigid beds at the bottom of the sea. At the mouth of the Ta-
gus, the wall of water formed by the waves rose, it is said, to a height of
nearly 56 feet; then, ﬁlling up all the estuary that extends in front of Lis-
bon, swept over the quays of the city and rushed among the houses. At
Cadiz a wave of nearly equal size rushed above the ramparts, and caused
much more havoc than the earthquake itself On the coasts of Madeira
and of Holland, the mouth of the Elbe, the sea-shores of Denmark and
510 THE EARTH.
Norway, and, lastly, the whole circumference of the British Isles, the sea
felt the reaction of the shock communicated to the waves in the waters off
Lisbon, and its level underwent rapid ﬂuctuations. The undulations of
the wave, variously modiﬁed by currents and tides, struck even upon the
shores of the New World. At Barbadoes and Martinique, where the ﬂow
of the tide never exceeds 28 inches, the wave produced by the transatlan-
tic earthquake attained a height of 13, 16, and even 19 feet. Thus the ma-
rine wave resulting from the shock was carried to a distance of nearly 3728
miles in a straight line. In 1854, at the time of the earthquake of Simoda,
the wave which reached the coast of California had traversed 2485 miles,
the whole width of the Paciﬁc Ocean.
When violent shocks agitate the ground, towns situated on the sea-
shore have often suffered much more from the sudden irruption of the wa-
ter than from the shaking of the earth itself When the waves receive
the shock from the neighboring coasts, or else when the centre of disturb-
ance is at the bottom of the ocean, the masses of water rise to a formida-
ble height, and dash upon the shores as if during a hurricane. In 1783, at
the time when the shock in Calabria overthrew the towns'and villages on
the main land, a terrible bore, after having swept away at once 2000 per-
sons assembled on the coast of Scylla, rushed into the port of Messina,
sank all the ships, and undermined the base of the. superb row of palaces
which bordered the shore: more than 12,000 individuals perished, it is
said, under the ruins. On the 7th of June, 1692, at the time of the earth-
quake which shook Jamaica and the neighboring seas, the waves rushed
violently upon the town of Port Royal, and in the space of three minutes
covered more than 2500 houses with a depth of 33 feet of water. The
ships were thrown in every direction on to the land, and the frigate Swan
was stranded upon the roof of a house. In like manner, according to the
statement of Acosta, the terrible wave which destroyed Callao in the year
1586, and carried a great ship right up on to the Lima road at a point 52
feet above the mean level of the sea, must have been altogether 89 feet in
height. The Japanese, whose islands have often suffered from earthquakes
and sea-bores caused by submarine shocks, say that these frightful phe-
nomena are caused by the blows of the tail of a monster striking against
the shore. Thus the Greeks attributed the vibrations of the soil not only
to Pluto, the “shaker of the world,” but also to Neptune, the “agitator
of the waves.”
EARTH-W14 VEIS’. 511
CHAPTER LXXVI.
MOVEMENT OF TERRESTRIAL ‘WAVES—VARIATIONS CAUSED BY THE INE-
QUALITY OF VERTICAL OUTLINE AND THE DIVERSITY OF ROCKS—AREAS
OF DISTURBANCE.—NOISE OF EARTHQUAKES.—~FRIGHT OF MEN AND AN-
DIALS.
WHATEVER may be the nature of the ﬁrst shock, whether it proceed
from a sudden swelling up of lava or vapor, or whether it be caused by
the falling in of upper strata upon the subjacent beds, the effects produced
will always be the same as regards observers who are above the central
point where the phenomenon is produced. They will experience a shock
tending upward. Even when falling with the ground, they might well
fancy themselves raised, like the aeronaut, whose balloon is falling toward
the earth, sees the country mounting up toward him. Around the central
point of disturbance, where the shock takes place in all its violence, and is
felt vertically, in a manner more or less irregular, according to the num-
ber of shocks, the movements become more and more oblique, and are
propagated across the strata of the earth in a direction which ultimately
becomes perceptibly horizontal.* The phenomenon of undulation which
is produced in solid rocks is perfectly analogous to that which may be ob-
served in water when a stone falls into it: a series of concentric waves is
formed round the centre of the shock, and gradually disappears in the dis-
tance. _ ' ‘ . ‘
Terrestrial waves which are formed thus are very long and very ﬂat, on
account of the inﬂexible nature of the rocks through which the movement
is transmitted. There does not, however, exist a single authentic meas-
urement from which the dimensions of each wave maybe deduced. The
observer feels them ‘pass rapidly under his feet during an earthquake, and
is often able to notice the rocking of houses and towers, as well as the to-
and-fro motion of church-bells; but these movements are much more mark-
ed than those of the ground, and-the movements of the earth'have not
been clearly distinguished on any occasion. '
As to the direction followed by the waves, the tendency generally dif-
fers much, owing to the inequalities in the relief of the ground,from the ~
regular direction it would otherwise take. This direction is often very
diﬂicult to discover, owing to'thewant of necessaryinstruments, and all
the local circumstances which may modify the movement. It appears,
however, that in mountainous countries, like Switzerland and the Pyre-
nees, the great undulations are propagated in the direction of the valleys.
In striking against the tilted strata at the base of mountains, the corru~
* Robert Mallet, Observation qfEartlzquake Phenomena.
512 THE EARTH.
.gations of the soil act like the waves of a river dashing against the shores;
.they break up, and, changing their course, run along at the foot of the
heights in the same direction as the stream of the valley. After this ﬁrst
rupture in'its movement, the undulation is communicated to the rocky
masses of the mountain, and traverses their whole thickness. Beyond
these lofty groups which disturb the movement, without always opposing
to it any insurmountable obstacle, the vibrations corrugate the ‘soil of the
4 0 w

Fig. '21‘). Transmission of Earth-waves.
plains in a more regular way; but the intensity weakens proportionately
to the square of the distance, and ﬁnally ceases to be perceptible to man.
It must also be remarked that, at the periphery of the area of disturbance,
the various shocks are generally produced at longer intervals than at the '
centre of the ‘earthquake. The stronger the waves are, the more rapidly
are they propagated, and thus it follows that between the different undu-
lations, which generally become weaker and weaker, the interval always
increases with the distance. In the centre the shocks all seem to blend
together; toward the circumference they succeed each other like waves
of slighty-agitated water.
- Among the causes which contribute to disturb the regular movement
of terrestrial oscillations, the diversity of geological formations must also
be reckoned. The swiftness of the transmission of the movement varies
considerably, according to the composition of the rocks, the quantity of
water they contain, and the hardness and elasticity of their layers. In
order to explain the difference that exists between the various strata as
regards the propagation of terrestrial waves, Mr. Mallet makes a striking
comparison. If a person applies his ear to a railway-rail which is struck
with a violent blow at a point about a mile away, the compact iron trans-
mits to him nearly instantaneously'the wave of the sound; immediately
after, the observer will feel the‘ undulation which is transmitted through
the soil below the rail; then he will hear the noise transmitted by the at-
mospheric waves. If a-- canal ﬂows along ‘by the side of the railroad, a
man plunged in the water would perceive the sensation of the blow, but
not at the same time. In fact, the mean swiftness of the wave is 1138 feet
in the air, 4692' in the water, and about 11,040 in a bar of iron.
It is a long-established fact that, during earthquakes, the shocks are prop-
agated much more easily-through compact rocks than through formations
interrupted here and‘ there by faults, ﬁssures, caves, and soft ground. Mr.
Mallet has proved these facts by direct and oft-repeated experiments, made
EARTH-WAVES. ‘ 513
not far from the town of Holyhead in Wales. When mines of powder
were exploded, the waves of disturbance, which were the more rapid as
the charge was stronger, were propagated 951 feet a second in wet sand,
1283 feet in a rock of friable granite, and 1640 feet in a compact granite.
Subsequently Mr. Mallet, having made some direct observations as to the
speed of transmission of the waves during the earthquake at Calabria in
1857, found that it was about 820 feet a second. According to the same
geologist, the starting-point of the shock was nearly three miles below
the surface.
Without having made any exact investigations, the Hellenes and the
Romans, who inhabited a soil frequently shaken by earthquakes, had
found out the fact that caverns, wells, and quarries retarded the disturb-
ance of the earth, and protected the ediﬁces built _in their neighborhood.
The town of Capua was, it is said, saved from the effects of the earth-
quakes to a much greater extent than the adjacent cities on account of
the numerous springs in its gardens. Vivenzio also asserts that in build-
ing the Capitol the Romans took care to sink several wells in order to
weaken the effect of terrestrial oscillations, and this plan succeeded in
preserving the building from all damage. In like manner, the great con-
structions at Naples were built above vast caves, in which the force of the
subterranean commotion is lost. Humboldt has described this curious fact
—-that at St. Domingo the inhabitants of the town spontaneously formed
the idea, similar to that of the Greek and Roman naturalists, of digging
out deep cavities as the only means of securing the stability of their
dwellings.
Besides, as may readily be supposed, the longer, thicker, and lower the
walls of the ediﬁces are, the better they resist the shock. In all towns
partly destroyed by earthquakes, it is said that walls of this form were
rarely demolished. When the undulations of the soil are propagated
along the whole length of a block of low houses, there is hardly an in-
stance in which the latter have been shattered; in countries, therefore, in
which the movements of the soil generally assume the same direction, dis-
asters can nearly always be provided against by setting the principal walls
of the ediﬁce in the direction of the terrestrial undulations.
The buildings which always suffer the most are those which have vault-
ed roofs, elevated in the form of domes or cupolas. The thrusting action
of the heavy masses which crown the ediﬁce causes the walls to separate
when they are in a state of vibration from the effects of the subterranean
shocks; the dome falls down inside, while the walls give way in an out-
ward direction. A considerable area is covered with ruins all round the
piece of ground on which the foundations stand, and, in consequence, the
danger of being crushed becomes very great to any persons who are near
the scene of the catastrophe. It was the earthquakes, and not the barba-
rians, which, according to the evidence of Mr. Mallet, destroyed so large a
number of the palaces and temples of Rome during the period between
the ﬁfth and ninth centuries. In like manner, in more modern times, ca-
‘ K K
514: .THE EARTH.
thedrals and churches have often been overthrown, while other houses
were saved.’ This well-known fragility vof vaulted roofs, when shaken by
undulations of the soil, ‘will explain the cause of those frightful calamities
which took place in various churches at the time of the earthquakes of
Lisbon, Calabria, Caraccas, Mendoza, and San Salvador, when kneeling
multitudes were crushed in the ruins.
The difference presented by rocks, as regards the speed with which the
earthquake wave is propagated through them, and the various obstacles
which impede it, has the effect of giving to the areas of perceptible dis-
turbance shapes which are perfectly.‘ irregular. The movements, there-
fore, are not produced round the initial point with a regularity which can
be at all compared to that of the wavelets which surround with their reg-
ular circles the centre of agitation in a disturbed water. Some earth-
quakes, as far, at least, as it is possible to judge from incomplete observa-
tions, seem to be propagated in very elongated ellipses. Others appear
to have had for their area a space of a polygonal'shape; thus the great
paroxysm of the valley of Viége, which extended over 108,878 square
miles, was felt three times farther in a northern than in a southern di-


0' ‘2° 4’ 6‘ 8‘
r.—
Fig. 213. Area aﬁ‘ected by the ‘Earthquake of Vii-go in 1855.
EARTH-WAVES. 515
rection. Sometimes, outside the limits of the ground in a state of vibra-
tion, a region has been remarked which likewise shakes, like a kind of
trembling islet surrounded by immovable land. At other times vast
tracts have not experienced any apparent disturbance, while the ground
all round them was trembling. On the 25th of July, 1846, the shock of
which the severest impulse was felt below St. Goar, on the banks of the
Rhine, propagated its undulations in France and Germany over a surface
estimated at 24,207 square miles; but a belt about 100 yards wide, be-
tween Pyrmont (Westphalia) and the right bank of the Rhine, appears to
have remained immovable.* According to the testimony of Humboldt,
this fact of rocks not participating in the general movement of the sur~
rounding formations has been frequently noted at the time of earthquakes
in the Andes. The natives say of these intermediate zones, thus exempt-
ed from the vibrations of the ground round them, that they form a bridge
(hacen puente), meaning by this that the oscillations are transmitted at a
great depth below the inactive beds at the surface. It is diﬂicult toim-
agine how such phenomena could take place if the oscillations of the soil
were caused by the movement of the waves in a subterranean sea of ﬁre:
if it were so, the upheaved terrestrial crust would undulate like an object
ﬂoating on the surface of the water, and the burning waves, spreading
out in a circle, would also give a perfectly round periphery to the super-
ﬁcial area of the earthquake.
To the two kinds of movement which have been observed in earth-
quakes—the upward shock and the long undulations spreading in the
manner of marine waves—most of the savants since Aristotle ;also add the
rotating or gyratory movement (corticosum). The fact is, that in great
cataclysms, when the different shocks cross each other in the ground, it
has been thought that proofs of these twisting movements have been felt
and even seen. At Quintero, in Chili, three great palm-trees, says Hum-
boldt, twisted round one another like willow-wands, after each had swept
a small space round its trunk. \Otto Volger, who does not believe in the
existence of rotatory movements, mentions, however, the example of the
steeple of Graechen, which twisted during the earthquake in the valley of
Viége in 1855: it is true that this twisting may have been caused either
by a movement of the soil being communicated'to the ediﬁce, or by the
want of equilibrium between the different parts of the steeple. Mr. Mal-
let also explains, by a difference between-the centre of form and the cen-
tre of gravity, the gyratory movement which the stones of two small ob-
elisks underwent during the earthquake at Calabria in 17 83; he absolute-
ly denies that the rotatory movement of the earth could-take-pla'ce, as the
Italian naturalists had alleged.
As to the speed of the propagation of terrestrial waves, it was, even
recently, very diﬁicult to estimate, owing to the want of precision in the
transmission of intelligence and the irregularity of the clocks in the dif-
ferent cities. Since 1853,'the period at which the electric telegraph was
* Daubre'e, Comptes Renclns, 1847.
516 THE EARTH
applied for the ﬁrst time in describing the shocks of the earthquake of
Soleure, almost certain means are at our disposal for noting the passage
of terrestrial waves in different localities; but up to our time it has
scarcely been employed save in an exceptional way, and too often some
of the desirable conditions of exactitude have been neglected.
The incomplete information gathered by Otto Volger about the great
earthquake of Viége in 1855 has warranted him in ﬁxing approximately
the speed of the undulation; it was at the rate of 2861 feet a second from
the centre of vibration as far as Strasbourg, and 1398 feet only in the di-
rection of Turin. Robert Mallet, after having made his celebrated exper-
iments on the speed of transmission of shocks in the rocks at Holyhead,
instituted comparative investigations into the speed of the undulations of
the great earthquake at Calabria in December, 1857, and found the aver-
age rate 7 74 feet a second. Since that time English observers established
at Travancore, in the south of Hindostan, have estimated the movement
of the undulations of a local shock at about 656 feet. The result of the
calculations varying thus in propoltion of one to four, it is impossible to
indicate any average ﬁgure for the rate of transmission of terrestrial
waves; it is certain that the rapidity, as well as the force and direction
of the movement, diﬁ‘ers according to the nature of the rocks, and the po-
sition of the chains of mountains and valleys.
The noises which are heard during earthquakes differ in intensity still
more than the other phenomena, and are much more diﬂicult to classify,
owing to the deep sensation that is felt when the earth is heard to roar,
and the part which the imagination never fails to play when memory
seeks to recall the past. The sounds, besides, heard at the time of the sub-
terranean downfall sometimes exceed in their violence all known noises,
and it is in vain to seek for suitable terms in which to describe them. In
a general way, the noises of earthquakes may be compared to explosions
of mines, discharges of artillery, peals of thunder, the rolling of carriages,
the fall of avalanches, or the roar of cataracts. The diversity of these
noises is explained by the difference of the phenomena which may be tak-
ing place in the interior of the earth—the falling in and reboundings of
rocks, the overﬂow of subterranean water, the irruption of masses of air
through ﬁssures, and distant echoes reverberating far and wide in the
abysses. It is a strange thing that sometimes during one and the same
earthquake certain persons can not ﬁnd terms strong enough to express
the frightful noises that they have heard, while others think they have
only felt the shock unaccompanied by the least sound. According to M.
Otto Volger, this singular difference of sensation proceeds from the fact,
well known to natural philosophers, that the scale of sounds perceived by
the ear differs in different individuals; just as in a meadow some persons
do not hear the cry of the cricket—the note is too shrill for them, so,
when the ground is shaken, those who are shaken with it would not all be
able to hear the sounds produced by the cataclysm on account of nothing
but the deepness of their tone; the noises would be too deep for their
TERROR CA USED B Y EARTH Q UAKES. 5
ears. At a distance from the centre of the shock the noise gradually di-
minishes in intensity, but it always remains diﬂicult to distinguish clearly,
because the sound is transmitted with unequal speed both under the
ground and in the atmosphere. Through the terrestrial strata the noise
of the paroxysm travels with more rapidity than the shock itself; the
shock is heard before it is felt; then, when the wave has passed, the sound
is heard anew, being transmitted more slowly by the air. This inequality
in the passage of the sound through the different mediums results in a
great confusion of roaring and rattling, of which it is very diﬂicult to give
any just account. Observers have compared the noise of a distant earth‘
quake sometimes to the rumbling of thunder, sometimes to a stormy wind
or the ﬂapping of the wings of a large bird, and sometimes even to a dis
charge of musketry, the crackling of ﬁre, or the whistle of a locomotive.
One might fancy that in this manifestation of its mighty vitality nature
makes use of all the sounds known to the human car.
All this diversiﬁed uproar and these frightful noises sufficiently explain
the instinctive terror which takes possession of nearly every one during
the time of an earthquake, even when the shocks have not caused any fatal
consequences. Nevertheless, as Humboldt remarks, a feeling of insecurity
is the cause which generally most contributes to upsetting moral force.
The earth which we felt so ﬁrm under our feet becomes as ﬂuctuating as
the waves; one hardly dares to Walk a step for fear of being swallowed
up in the opening ground. All our ideas as to the nature of things be-
come confounded, and,by a sudden reaction of his physical or his moral
nature, the man who feels that he is being deprived of the earth he stands
on loses all conﬁdence in his own personal powers. _
It is a widely-spread opinion, which, however, is not as yet undeniably
conﬁrmed, that animals manifest the greatest uneasiness at the approach
of an earthquake. In certain countries, indeed, where these convulsions
of the ground frequently take place, care is taken to observe attentively
the ways of domestic animals, in order to detect the presentiment of the
coming shock and to prepare for the danger. It may perhaps be the case
that slight vibrations, perceptible only to the delicate senses of animals,
precede the subterranean downfalls; but very often it is probable that
remarks of this kind are made after the catastrophe, and that imagination,
excited by the fright, plays no inconsiderable part in the descriptions.
Be this as it may, it is said that, before an earthquake, rats, mice, moles,
lizards, and serpents frequently come out of their holes, and hasten hither
and thither as if smitten with terror. Even the crocodiles have ﬂed away
from their marshes and hurried toward term ﬁrma, roaring with fear.*
At Naples it is said that the ants quitted their underground passages
some hours before the earthquake of July 26, 1805, and that the grasshop~
pers crossed the town in order to reach the coast; also that the ﬁsh ap-
proached the shore in shoalsf A fact which is better attested is the fright
of animals during the catastrophe itself At the time of the earthquake
* Humboldt, Relation Historigue, vol. v. t Landgrebe, Naturgeschz'clzte derVul/cane, vol. ii.
518 TH’ EARTH.
which shook the valley of Viége in 1855, the wild birds which most dread
the fowler, such as owls, wondpeckers, and peewits, collected on the trees
close to the dwelling-‘Muses, and uttered plaintive eries, as if to demand
the succor of man; Birds of long ﬂight—swallows and others—at once
tdok wing, and ﬂew away to distant parts. For several days, also, the
frogs ceased their croaking.*
* Otto Volger, Erclbeben in der Sclzwez'z, vol.
SECONDARY EFFECTS OF SH 0 0K5’. 519
CHAPTER LXXVII.
SECONDARY EFFECTS OF SHOCKS.—-SPRINGS.—JETS OF GAS.-—FISSURES.-
DEPRESSIONS AND ELEVATIONS OF THE GROUND.
EARTHQUAKES very frequently exercise a considerable inﬂuence on the
discharge of springs rising to the surface of the ground. A great many
instances have been brought forward of springs, both thermal and cold,
which have suddenly dried up or have increased in volume, accompanied ‘
by either an augmentation or diminution of temperature. These phenom-
ena can be easily understood. After each downfall of rocks or fracture
of the ground, the conduits through which the subterranean rivulets ﬂow
may be either altogether or partially obstructed; the water must then
seek some other course, or must ﬂow in a diminished stream through the
old channel. Sometimes, also, the breaking down of some barrier which
penned back the subterranean water opens up a free passage to it, and the
spring is thus augmented in its discharge. Again, the waters of several
subterranean currents of various temperatures may become mingled in
consequence of some catastrophe, and the springs, therefore, are rendered
either warmer or colder. In August, 1854, on the occasion of a violent
earthquake in the central Pyrenees, the heat of a spring at Baréges was
raised from 64° to 82° (Fahr.), and its discharge, which was 2729 gallons
a day, increased to 6338 gallons.
The effect more generally produced on springs by the occurrence of an
earthquake is to render the water muddy by ﬁlling it with the cléln'is
which has fallen from the rocks disturbed, and been raised by the ascend-
ing body of water. During a series of observations made on the artesian
well at Passy in 1861 and 1862, M. Hervé-Mangon ascertained that at the
time of each of the subterranean shocks of Western Europe which were
recorded by M. Perrey during the above-named interval, the water in the
well was charged with sediment. On the 14th of November, 1861—the
day on which a great earthquake occurred in Switzerland—the sediment
in the well at Passy suddenly increased in quantity from 956 grains per
cubic metre to 2268 grains; the next day it decreased to 1404 grains.
This skillful chemist, by numerous processes, established several other strik-
ing coincidences between the impurity of the water and the vibrations of
the ground. It is not at all probable that these geological facts are de-
void of any mutual relation ; it appears, on the contrary, that the artesian
spring at Passy, and doubtless also most other springs gushing out to the
surface, might be looked upon as actual “ seismometers.” At the time of
earthquake shocks a kind of clearing out takes place of the natural or ar-
tiﬁcial conduits through which the spring water passes. According to the
observations of M. Francois, who devoted considerable study to the action
D
5 20 THE. EARTH.
of earthquakes on the mineral springs of the Pyrenees, the results of a
shock are rarely felt for any length of time ; after the lapse of two or three
days the effects are no longer perceptible.
In all countries frequently affected by earthquakes, the inhabitants nev-
er fail to tell numerous stories as to sudden eruptions of water, mud, gas,
or ﬂames. Phenomena of this kind may be, in fact, produced in many dis-
tricts, for shocks violent enough to close up or to enlarge the conduits of
springs may equally well open out fresh channels, and thus afford an out-
let to water pent up under deep layers of rocks. In like manner, the hy-
drogen gases which are formed in the ground by the decomposition of or~
ganic matter may ﬁnd an outlet by the breaking down of the rocks above
them, and burn spontaneously, like the gases at Baku. Nevertheless, these
curious eruptions, however probable they may appear, have not as yet
been scientiﬁcally observed, and no idea seems to have been formed as to
the real importance, they might have. Even Mr. Mallet, the great advo-
cate of the constant connection between earthquakes and volcanic phe-
nomena, has not ventured to look upon these sudden jets of water, mud,
and gas as facts on which science may depend. With regard to the sud-
den appearances of ﬂashes and sparks, these may be explained in many
cases by the collision of stones, which strike against one another as they
fall. _
Occasionally, during earthquakes, the ground is rent open for very con-
siderable distances. In 1783, at the time of the terrible shocks which dis-
turbed Calabria, the phenomena of ruptures of the ground ranked among
the grandest and most frightful effects of the catastrophe. Whole moun-
tain-sides, undermined by water, slid down en masse, and tumbled into the
plains below, covering all the cultivated ground. Cliffs fell down in a
body, and rocks opened, swallowing up the houses which stood upon them.
At the western base of the granitic chain of the peninsula, the ground af-
fected by the shock was cleft open for a length of more than 18 miles, and
in some places, especially near Polistena, the ﬁssure was several yards in
width. Elsewhere other clefts were opened, one of which, near Cergulli,
was no less than 131 feet in depth for a length of more than a mile, and
32 feet wide. In the environs of Rosarno, on the shore of the Gulf of Ni-
cotera, well-like cavities were hollowed out with circular margins, doubt-
less caused by the gushing out of springs. Finally, districts with a level
surface were cleft in every direction by cracks radiating in the shape of a
star; the ground was broken up in a similar manner to mud which has
_ cracked from the loss of its moisture. In February, 1885, on the occasion
of the earthquake at Conception, in Chili, similar phenomena were ob-
served: every where, says Fitzroy, contact ceased between the shifting
ground of the plain and the bases of the rocky hills.
Not only do ﬁssures sometimes form in the ground during earthquakes,
but after commotions of this kind the level of the terrestrial surface is oc-
casionally permanently changed. When the catastrophe is caused by
some subterranean downfall, it is perfectly natural that the surface layers,
Q
EFFECTS OF 'EARTIIQ UAKES. 521
being suddenly deprived of their supports, should be included in the sub-
sidence; and, in fact, several instances have been brought forward of these
sinkings in the level of the ground. In some countries it is said that phe-
nomena of a directly opposite class have been observed, and whole dis-
tricts have been suddenly upheaved a few- inches, or even several feet. If
the facts are certain (and there seems but little doubt about them), they
would go to prove that earthquakes, from which these upheavals result,
are caused by the pressure of conﬁned vapor.
Among shocks of this kind we must mention the great geological catas-
trophe, unfortunately but too well known, which, in the year 1819, changed
the shape of the country of Cutch over a vast area. A part of the Great
Runn sank down over an extent of some thousands" of square‘miles, ‘and,
in consequence of the inroads of the salt water, it became a tract of land
of an undetermined character—during drought a desert Without water,
and during the monsoons a salt lagoon. A rampart several miles in length,
164 feet broad, and 9 feet in height, was also raised in a straight line across
one of the former mouths of the Indus. This rampart is called by the‘ in¢
habitants of the adjacent districts “ God’s wall” (U llah Band), to distin-
guish it from the Ally and Mora barriers, which the sovereigns of the coun-
try had constructed farther up stream. According to Mr. A. Barnes, the
earthquake which produced this strange phenomenon of elevationand de-
pression was felt over an area of more than 95,500 square miles. " r


62 88 ‘ '89; :
Mam Band LE THURR cu E'rrr-ntssar __ Ally under ' ‘Ullali ‘ "
r * ‘ __
, 3"’: ,-


Fig. 214. The Rand of Catch and the Ullah Bund.
With regard to the‘ earthquake at Conception in 1835, the aﬂirmative
evidence on the point is so abundant, that the raising of the coast at this
5 22 THE EARTH.
place must be regarded as a positive fact ;* but it must .remain unknown
whether some enormous depression in the interior of the continent did
not compensate for the temporary upheaval of the sea-coast. Still more
recently, on the 23d of January, 1855, at the time of an earthquake which
violently shook New Zealand, and especially the two shores of Cook’s
Straits, the ground on which the town of Wellington stands was raised
23 inches, a cape in the vicinity was elevated nearly 10 feet, while a ﬁs-
sure of about 40 miles in length opened in the southern island on the oth-
er side of the straits, and the alluvial plain of a small stream sank consid-
erablyt Also, in 1861, the coast of Torre del Greco, at the foot of Vesu-
vius, was suddenly raised 3% feet for a length of more than a mile. All
these are extraordinary phenomena, and a just hesitation must at present
he felt in venturing to give any explanation of them.
There is another geological fact which has been little studied as yet,
which, however, must be perhaps attributed to oscillations of the ground:
this is the curious arrangement that is assumed in some plains by the boul-
ders, pebbles, and drifts of sand. Thus, in the Desert of Atacama, in many
spots regular ﬁgures are to be met with—circles, squares, or lozenges-—
composed of small fragments of quartz or other stoneI In the entirely
uninhabited plains of Safa, at the foot of the former volcanoes of Djcbel-
Hauran, M. Wetzstein likewise remarked a multitude of small ﬁgures
with regular angles, formed something like mosaics, over very considera-
ble are'as. Must we look upon these designs as some immense symbolical
work to be attributed to the ancient inhabitants of the district, or are
they, in fact, the sports of nature, and phenomena similar in character to
the ﬁgures shaped out by grains of sand agitated on vibrating plates?
This question remains to be solved by future observers.
* Vide below, p. .529. i F. von Hochstetter, Neu Seeland.
I Tschudi, Ergc'z‘nzungslzeft ,- Mittlzez'lungen van Petermamz, 1860.
PERI ODICITY 0F EARTHQUAKES. 523
CHAPTER LXXVIII.
PERIODICITY OF EARTHQUAKES.——THE MAXIMUM IN WINTEIL—THE MAX-
IMUM AT NIGHT.-—-COINCIDENCE WITH HURRICANES.—INFLUENCE OF
THE HEAVENLY BODIES. ' '
FROM time immemorial it has been asserted by the natives of the coun-
tries which are most frequently ravaged by earthquakes, that these com-
motions bear some intimate relation to the movements of the atmosphere,
and very generally coincide with certain meteorological conditions, such
as rainy seasons, numerous storms, warm and damp winds.* Neverthe-
less, most geologists, considering these oscillations of the ground to be
nothing more than the half-exhausted quiverings of a great ocean of ﬁre,
have even recently denied'the possibility of any such coincidence.
In 1834, Professor Merian, having classed, according to their appearance
in the various seasons of the year, 118 earthquakes which occurred at Basle
and in the countries round it, ascertained, to the surprise of the scientiﬁc
world, that these phenomena are much more frequent in winter than in
summer. This fact, which was at ﬁrst called in question, has since been
indubitably established by the investigations of Alexis Perrey and Otto
Volger. Only, in proportion as the list of shocks becomes more numer-
ous, the difference between the winter maximum and the summer max-
imum tends to disappear, for the simple reason that, in the two opposite
hemispheres, the seasons follow one another at six months’ intervals, and
that the various phenomena in connection with the seasons are thus
brought into a state of equilibrium on each side of the equator. ' It is
therefore necessary to study, in each region separately, the order in which
the occurrence of earthquakes is divided among the different seasons. The
comparative frequency of these phenomena during the winter season is
"'\ Fig. 215. Monthly Distribution of 656 Earthquakes in France.
/
\ , ‘ /
\vf"\\


Numbers.‘_83__ 6t 53 J 55 d__ tel 36 L7 to ‘so - 48 60 78__
Jan. Feb. March. April. May, June. July. Aug. Sept. Oct. Nov. Dec.

then much more easy to be observed. Thus the 656 shocks enumerated
in France by Alexis Perrey up to the year 1845 are divided in the pro-
portion of 3 to 2 respectively, ‘for the half years commencing in Novem-
* Luigi Greco; Ferdinand de Luca; Alexis Perrey.
524 THE EARTH.- . ' -
her and May. In the regions of the Alps,‘where there are no volcanoes,
the difference between the number of earthquakes in winter and summer .
is, on the other hand, enormous. By comparing the four months of May,
June, July, and August, with December, January, February, and March,
we see that the shocks are three times as numerous in‘ the second season
as in the ﬁrst. In Italy, according to the same author, the difference vwas
much less perceptible, since out of 984 earthquakes, 453 took place in the
summer season, from April to September, and 531 during the winter half
Fig. 216. Monthly Distribution of 1230 Earthquakes in Switzerland.
\\
‘ '\
\/
\/
\
Numbers.’ 150 :43 438 _ug 58 56 Lo #7 u] m 85 168
Jan. Feb. March. April. May.- June. July. Aug. Sept. Oct. Nov. Dec[

year, from October to March. Nevertheless, even in this region, where
most of the great subterranean movements are evidently in connection
with volcanic action, these phenomena are perceptibly more frequent dur-
ing the cold portion of the year.
If we limit ourselves to the study of some particular centre of shocks,
the difference observed between the. seasons in respect to the frequency
of subterranean shocks is still more considerable. As an instance of this
we may mention, on'the authority of Otto Volger, the remarkable region
of the Mid~Valais, where, out of a total number of 98 known earthquakes,
one only took place in summer, while 72 were felt in winter. The pro-
\ Fig. 217. Monthly Distribution of 98 Earthquakes in the Mid-Valais.
%\F\ . N/
Numbcrs~3z 16 klodojo'yi-Iolilﬁlb 26-
Jan. Feb. March. April. May._ June. July. Aug. Sept. Oct. Nov. Dec.


portion is nearly the same in “the region'of Hohensax, on the southern
slopes of Santis, not far ﬁ'om the former fork of the Rhine. ' < ' ¢
Not only are subterranean commotions more frequent in winter than
in summer, ‘at least in the'regions ofCentral-Europe and on the coasts of
PERIODIC’ITY OF EAR THQ UAKES- 525
Fig. 218. Monthly Distribution of 98 Earthquakes in Southern Siintis.
\“ﬁ ' ' J/
Numbers~£t n glxlllrflijolololz 20
Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dec. ’
the Mediterranean as far as Asia Minor and the Caucasus,* but this re-
markable fact has also been observed—that the shocks are felt more fre-
quently at night than in the day, and this holds good in all seasons of the
year. In all earthquake regions this is uniformly the case. In Switzer-
land, out of 502 earthquakes, the date and time of which are known, only
182 took place between six o’clock in the morning and six o’clock in the
evening; 320—that is, nearly double—were felt during the twelve hours
of the night. There is, therefore, for every diurnal period, a series of al-
ternations resembling those of the annual period; but there is, in truth,
Fig. 219. Switzerland: Distribution of 435 Earthquakes every other Hour.
/r\
\nW/wfk


f \


Numbersu ' 49 ' 55 43 3x 3: 36 1a 27 31 at La 4.8
\12-2 lair/e 164516-13 8-10 ‘IO-12‘ zz-z 2-6 ' 6-6 ' 6'8 giro ao-xzj
Night. . Day. - Night.
no reason for astonishment in this, as, in an entirely general point of view,
every day, in its rain, its storms, and all its meteorological phenomena,
may be looked upon as an epitome of the whole year. Looking at it in a
certain way, midday is summer, and midnight is the winter of each diur-
nal revolution. Have we not, then, a good right to infer, from the regu-
lar ﬂuctuation of subterranean agitations, these ﬂuctuations correspond-
ing with the lapse of seasons and hours, that‘ these great events depend,
at least in certain countries, on some external phenomena, and not on the
tr'emblings of a sea of lava? “Are they not,” as Volger says, “ connected
with the. whole body of laws which govern the return of light and dark-
ness, heat and cold, snow and rain, drought and,i'unningwater?” The
greater number of earthquakes would thus be facts essentially connected
with the conditions of climate.
It is also related that, during the hurricanes in the West’Indies, the
ground is severely shaken, as if the wind, which tears down trees, over-
throws buildings, and drives the waves into immense water-spouts, had
also laid hold of the layers ‘of the rocks, and 'had shaken them olrtheir
' bases. Is it the fact that the inhabitants, under the inﬂuence of terror,
fancythat the ground itself participatesin the immense convulsion?
‘Such hallucinations would not. seem very wonderful when we consider
that at each fresh fury of the. cyclone, nothing but death is expected.
* Moritz, Bulletin dc Z’A cade’mie St. Pe’tersbourg, vol. viii.
526 ' THEEARTHZ
Fig. 220. Monthly Distribution of 2249 Earthquakes in Europe. . J00
A‘ I .
\“\ AvAd/mo

200
100
Numbers. 363 298 284 254 280 227 238 258 238 287 352 320
Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dec.
Nevertheless, the evidence relative to this coincidence between hurri~
canes and earthquakes is so abundant and positive, that it is difficult not
to put faith in it. In 1844, on the occasion of a hurricane which de-
stroyed hundreds of vessels in the roads of Havana, a shock, which was
not connected with any volcanic phenomenon, agitated the ground of the
island.* Still more recently, during the cyclone of the 6th of September,
1865, which ravaged Guadaloupe, the Saintes, and Marie-Galante, the
earth suddenly shook at the most terrible moment of the tempest, and
several houses were thrown down. What is the cause of this coincidence
between earthquakes and cyclones? Does the electric storm itself pene-
trate into the depths of the earth‘? or do the torrents of rain produce
subterranean downfalls? These are questions to which, at present, it is
impossible to reply. '
However this may be, we must at any rate admit that there are at least
two classes of earthquakes; one class proceeding from the pressure and
eruption of vapor and lava, the other caused by the downfall of rocks;
both, however, producing the same impression on the senses of man, and
developing themselves in the same way over vast areas. Perhaps to these
two classes of shocks it may be necessary to add a third—those shocks,
namely, which originate in the relations existing between our planets and
the other bodies in space. Thus, according to Wolf, there is a constant
relation between earthquakes and the spots on the sun. Finally, the in-
vestigations carried on with so much perseverance by Alexis Perrey prove
unquestionably that ‘the successive phases of the moon exercise consider-
able inﬁuence on movements of the ground. Like the ocean, the earth,
too, has its tides. The frequency of earthquakes, even of those which‘ are
only revealed to us by the delicate instruments of M. d’Abbadie, augments,
like the height of the ﬂow of the tide, at the epoch of the syzygies. This
frequency increases when the moon approaches the earth, and diminishes
when it is farther away; in a word, the time when the sea oscillates with
the greatest force is also the time when the earth itself most frequently 1
trembles. “Our planet,” says M. Boscowitz, “is engaged in a constant
exchange of forces and-inﬂuences with the heavenly bodies, which, like it,
occupy ethereal space.” ‘
* Andre I’oey, Comptes Rendus de Z’Acade’mie des Sciences, 1865.

U PHEAVALS AND DEPRESSION S-
120
ll" .
I : ‘illllllir'
ll‘.


l
Upheavals -
. Drpn-ssions l
o t .i.__
80 ‘J-T'mmv a or 'vr.“ no
Drawn by A Vuillernm after Chllarwm

OSCILLATIONS OF THE’ GROUND. 527
CHAPTER LXXIX.
SLOW OSCILLATIONS OF THE GROUND.—-DIFFICULTIES PRESENTED IN THE
OBSERVATION OF THESE PHENOMENA.-—'CAUSES OF ERROR! EROSION OF
SHORES, SIVELLING AND SINKING OF PEATY SOILS.——INFLUENCE OF TEM-
PERATURE.-—LOCAL UI’HEAVALS.
THE solid ground, which people once considered as the symbol of im-
mobility, is, on the contrary, in a state of constant oscillation. The crust
of the earth, carved out incessantly by the various meteorological agents
on one side, drawn by the other bodies revolving in space on the other,
modiﬁed by water and pressed upon by vapors, gases, and molten matter,
never ceases to undulate as a raft rising and sinking on the waves of the
sea. At rare intervals there are great earthquakes; more often this un-
dulation of the ground consists in mere vibrations, which are scarcely per-
ceptible except by the aid of instruments. The terrestrial crust is not
only continually shaken by these transient shiverings; it is, besides, actu-
ated by uniform movements of incalculable force, which at some points
raise it, and at others depress it, as compared with the level of the sea.
While we are busy on its surface, the earth itself is shifting'under our
feet.
These swellings up and depressions, which recall to mind the phenom-
ena of organized bodies, often take place so slowly, that to verify them
with any degree of certainty, successive generations of observers would
require the lapsepf many years, or even centuries. The “patient earth”
seems to revolve inertly in space, and yet it is at work without intermis-
sion in modifying the form of its seas and its coasts. During each geo-
logical period, the continental surface, motionless in appearance, rises in
some spots to a great height above the ocean, and in others it sinks be-
neath the water; every where, indeed, the ancient relief and outline of the
ground are being slowly modiﬁed. Inaccordance with what law, in what
geographical order, and at what comparative rate of progress do these
gradual oscillations take place, which result, in the long run, in effecting a
change in the general aspect of the globe ‘3 Science is not as yet in a po-
sition to give a positive answer to these questions. But, in the mean
time, until geologists are able to estimate exactly the dimensions and prog-
ress of each wave of upheaval which is formed by the crust of the earth,
it is, at all events, possible to bring together the principal facts which bear
upon the subject of the oscillatory movements of continents and the bed
of the sea. '
Small broken shells, the scattered remains of polypes, almost invisible
grooves marked here- and there on the sides of rocks—all these signs,
528 'THE EARTH.
which most people would pass by with indifference, are become, thanks to
the patience and sagacity of observers, so many undeniable proofs of the
regular movements of the ground. It is, however, only on the sea-coast
and in the vicinity of seas that savcmts can positively verify these mani-
festations of the vitality of the globe. Considering the ocean as a ﬁxed
level-mark, which is almost motionless in relation to the elevated or de-
pressed masses of the land, they can easily prove the general elevation of
a region by noticing on the shore the parallel lines formed at different
epochs by the friction of the sea-water. But farther inland the marks of
the same kind which are traced out on their banks by rivers and lakes are
very seldom able to furnish incontestable evidence of vertical oscillations
of the soil. The more or less shifting level of lakes and running water
depends on several geological circumstances, and it is only when all these
circumstances are perfectly well known that the ancient terraces and slopes
of erosion which exist in ﬂuvial and lacustrine basins can be made to serve
as marks to measure the progress of terrestrial oscillations. As a matter
of fact, geologists are, therefore, compelled to limit themselves to bringing
under notice those oscillatory movements of the earth’s crust which are
taking place on sea-coasts.
In studying the oscillations of the earth, it is important to be very care-
fully on our guard against the numerous causes of error which arise from
the eternal combat which is always taking place on the shore between
the land ‘and the sea. Neither the gradual encroachments of a'lluvial
shores, nor the progressive erosions which, in so many places, the coast has
to undergo from the sea, are to be considered, without due examination,
as proofs of the upheaval or subsidence of a region. The sand which is
driven up by the waves of the sea, and the alluvium which is drifted down
in the currents of rivers, are deposited on most low coasts in suﬁiciently
considerable quantities for the belt of shore to increase constantly in
breadth. Even where this zone sinks slowly with the land adjacent, as is
taking place at the north of the Adriatic, the alluvium may nevertheless
form on the shore a kind of cushion, and may defend the plains of the in-
terior against the waves of the sea. ()n the other hand, there are a great
many steep beaches and cliffs which, being assailed in front by the waves
and the tide, and worn away obliquely by lateral currents, recede gradu-
ally before the inroads of the sea; but in cases of this kind it is usually
impossible to detect the slightest depression in the general level of the
country. Gentle geological elevation of the ground may, indeed, actually
coincide with a falling back of the shores. The coasts of Aunis and Sain-
tonge present an example of this apparent anomaly.
In movements of the soil it is necessary also to distinguish these which
are produced by the slow pressure of subterranean forces, and those which
are occasioned by temporary causes, such as the more or less quantity of
water contained in the surface layers, the activity of evaporation, and the
bringing into cultivation of the country. Thus, when peat-mosses form in
the low-lying lands of the valleys, taking the place of lakes and marshes,
Lo (1.4L OSO'ILLA TIONS. ‘529
they hold the water in their masses of moss just as an immense sponge,
and, gradually swelling, ultimately rise to a height of several feet above
the former level of the soil. On the other hand, those tracts of peat-moss
which have been dried by draining operations gradually sink; the mosses
wither, die, and are reduced to dust. One might fancy that the soil was
slowly sucked toward the interior of the earth by some secret force,
There is, however, no reason to be astonished at these alternate phenom-
ena of swelling and shrinking which are afforded by peaty soil, as a mere
variation of temperature is suﬂicient to produce similar results in the ‘com-
pact strata of mountains. In the daytime the particles of rocks dilate un-
der the inﬂuence of the solar rays;'in the night time they become cool,
and contract in consequence of radiation, and the total mass sinks to a
very slight extent, which is sometimes perceptible by means of instru-
ments. Thus Moesta, the Chilian astronomer, has been enabled to ascer-
tain that the National Observatory of Chili, situated on the hill of Santa
Lucia, near Santiago, rises and descends alternately in the space of twen-
ty-fourhours. The daily oscillations of the rock, which in turn dilates
and shrinks, are, indeed, considerable enough to render it necessary to in-
troduce this element of calculation into the mathematical formulae devoted
to the regular observations. Similar phenomena, but occasioned by dif-
ferent causes, are produced under the Observatory of Armagh, in Ireland.
After heavy rains, the hill on which the ediﬁce stands rises perceptibly;
then, after active evaporation has got rid of the extra water contained in
its pores, the hill again sinks. _ _
The shocks of greater or less violence communicated to the soil in vol-
canic districts produce alterations in the level which are much more con-
siderable than the slight oscillations ca'used by the heat of the sun or the
various atmospheric agents. But these alterations of level are none the
less merely local phenomena, and although they are doubtless connected
with the same class of facts as the slow upheavals and depressions, they
must be clearly distinguished from the long-protracted movements which
bulge up the crust of the earth under whole continents. As an instance
of the local undulations which are mere accidents in the history of the
planet, we may mention that which the earthquake of Conception caused
to take place temporarily in February, 1835, at the Isle Santa Maria and
the adjacent coasts of the Chilian main land. An enormous mass of earth
was suddenly elevated. The shore nearest the town was raised perpen-
dicularly a yard and a half, while the island, uprooted, so to speak, by the
violence of the subterranean shock, was upheaved obliquely 2%- yards at its
southern point, and 3%- yards at its northern extremity. Two months aft-
erward the shore at Conception was scarcely 23 inches above its former
level, and the island had also sunk in proportion. Finally, toward the
middle of the year, every trace of the upheaval had disappeared, and the
sea-water came exactly up to the same winding line of debris which it
washed before the catastrophe.* '
* Fitzroy, Voyage of tire “Adventure” and the “Beagle.”
IJ L
530 . THE EARTH.
The famous columns of the supposed Temple of Serapis, which rise on
the shore of the Mediterranean, not far from Pozzuoli, likewise bear on
their marble shafts proofs of purely local oscillations. Spallanzani some
time ago showed that these columns, the bases of which were surrounded
with rubbish, must at some formerdate have been immersed in the water
of the sea to a depth of about 21 feet; for up to this height the calcareous
cases of the serpulae may be noticed on the shafts, and also the innumera-
ble holes that the pholades have hollowed out in the thickness of the mar-
ble, which is eaten away circularly by the waves. The temple, having
been repaired in the reign of Marcus Aurelius, must certainly, at that time,
have been above the level of the sea. It is not known at what date it
sank, together with the hilldck on which it stands. It might, perhaps,
have taken place during the year 1198, in which year the Solfatara of
Pozzuoli produced an eruption. With regard to the emergence of the
colonnade from the water, it is probable that it happened in the year 1538,
at the time when the Monte Nuovo made its appearance. If these sup-
posed dates are the real ones, the lower half of the Temple of Serapis must
have been bathed for 340 years in the waters of the gulf. But this event
can only have been caused by some local agitation of the earth; for, dur-
ing the same period, the adjacent coasts of Naples have not altered their
level to any perceptible extent.*
* Lyell, Principles of Geology, vol. i.
UPHEA VAL OF SCANDINA VIA. 5 31
CHAPTER LXXX.
UPHEAVAL OF THE SCANDINAVIAN PENINSULA; OF SPITZBERGEN; OF TIIE
COASTS OF SIBERIA; OF SCOTLAND; OF WALES.
ON all those coasts where heaps of modern shells now left dry, and the
ledges cut out at different heights in the faces of the cliffs, furnish un-
questionable testimony of a progressive upheaval of the ground, savants
who desire to study the progress of the phenomenon must, of course, do
so both by direct measurements and by comparing the levels taken at
longer or shorter intervals. More than a hundred and thirty years ago,
Celsius, the Swedish astronomer, formed the idea of resorting to these
means, not with the intention of verifying the growth of the Scandinavian
peninsula—a fact which to him did not seem at all probable—but in order
to prove the supposed alteration in the level of the waters of the Baltic
Sea. He was aware, from the unanimous testimony of the inhabitants of
the sea-coasts, that the Gulf of Bothnia was constantly diminishing both
in depth and extent. Old men pointed out to him various points on the
coast over which, during their childhood, the sea used to ﬂow, and, be-
sides, showed him the water-lines which the waves had once traced out
farther inland. Added to this, the names of places, the position more or
less upon the main land of former ports now abandoned, and of ediﬁces
built once upon the shore; the remains of boats found far from the sea;
lastly, the written records and popular songs, could leave no doubt What-
ever as to the retreat of the sea-water. At this epoch, when savants still
believed in the immovable solidity of the rocky frame-work of the globe,
Celsius was naturally bound to attribute the constant growth of the seas
coast to the gradual depression of the level of the sea. In 1730 he felt
himself warranted, by comparing all the evidence he had collected, in pro~
pounding the hypothesis that the Baltic sunk about 3 feet 4 inches every
hundred years. Then, in the course of the following year,having, in com-
pany with Linnaeus, made‘ a mark at the base of a rock in the island of
Loeﬁ'grund, situated not far from J eﬂe, he was able personally to verify,
thirteen years afterward, that.the retreat of the Baltic Sea was taking
place quite as rapidly as he had supposed. The difference of level ob-
served during these thirteen years was '7 inches, or 4 feet 5 inches for a
century. From 1730 to 1839 the upheaval of Loeffgrund amounted to 2
feet 11 inches only.*
Celsius was accused of impiety by the divines of Stockholm and Upsal.
The Parliament, indeed,wished to.eut the matter short by a vote; the two
orders of peasants and nobility declared themselves incompetent in the
* Lyell; Robert Chambers.
532 THE EARTH.
matter, while the representatives of the clergy, followed timidly by the
burgesses, condemned the new opinion as an abominable heresy.* Never-
theless, the geologists who, since the last century, have visited the coasts
of Sweden, have been compelled to verify and complete Oelsius’s observa-
tions. They have, however, been‘forced to reject the ﬁrst hypothesis of
the gradual subsidence of the water, and to recognize as a fact that the
movement, attributed in error to the liquid mass of the Baltic, was that of
the continent itself As, indeed,had been already laid down by Antonio
Lazzaro Moro, an Italian meant, it was the earth, and not the sea, which
was the moving and shifting elementf In fact, if the sea-level was pro-
gressively sinking, as was once supposed, the water, the surface of which,
owing to gravity, must always remain horizontal,would retreat equally
all round the Scandinavian peninsula, and on all the sea-shores. But this
is not the case. At the northern extremity of the Gulf of Bothnia, at the
mouth of the Tornea, the continent is emerging at the rate of 5 feet 3
inches a century, but by the side of the Aland Isles it only rises 3%- feet in
the same time; south of this archipelago it rises still more slowly; and
farther down, the line of the shore does not alter as compared with the
level of the sea. The terminal point of Scania is gradually being buried
under the waters of the Baltic, as is proved by the forests which have
been submerged. Several streets of the towns of Tlielleborg,Ystad, and
Malmoe have already disappeared; the latter has sunk 5 feet 2 inches
since the observations made by Linnaeus, and the coast has lost, on the av-
erage, a belt 32 yards in breadth.
On the west coasts of the Scandinavian peninsula the phenomena prov-
ing a recent upheaval of the ground are just as numerous as on the eastern
shores; but the rapidity of the ascending movement has not yet been
measured, although it is certainly less considerable than in Sweden. The
terminal point of Jutland, bounded by an ideal line tending obliquely from
Fredericia toward the northwest, rises, according to Forchhammer, 11'70
inches a century. At Christiania the increase is perhaps still less, for, ac-
cording to Eugene Robert, the pavement of the ancient town appears to
have remained stationary for three hundred years. Lastly, farther to the
north, the present position of several ediﬁces situated in the island of
Munkholm, near Trondhjem, proves, as Keilhau the geologist says, that
during a thousand years the elevation of the ground has been less than 20
feet. This is all that is positively known. Nevertheless, a comparison
of the various lines of level, and an examination of all the other indications
of a slow upheaval, seem to show that, in spite of the numerous inequali-
ties in the rate of progress of the phenomenon, that portion of the coast
which is nearest to the pole is rising the most rapidly out of the water.
Elevated beaches, which can be traced by the eye like the steps of an
amphitheatre, are arranged in stages at various heights on the slopes of
the mountains. Heaps of modern shells are found at heights of 500 to
* Anton von Etzel, Die Ostsee.
‘l’ Von Hoff, Verc'z'nderungen der Erdoberzﬂc'iclze, vol. iii. , p. 31 8, 319.
UPHEA. VAL OF SCANDINA V1.4. 533
650 feet above the level of the sea, and the great branches of pink coral
formed by the Lophohelia prolifera, which lives in_ the sea at a depth
varying from 1000 to 2000 feet, are now raised up to the base of the eliﬁ'.*
The pine woods, too, which clothe the summits, are continually being up-
heaved toward the lower snow-limit, and are gradually withering away in
the cooler atmosphere; wide belts of forest are composed of nothing but
dead trees, although some of them have stood for centuries’;
The whole body of facts known on the subject of the movements of the
ground of Scandinavia will therefore warrant savants in comparing the
whole peninsula to a solid plane turning round a line on which it rests,
and raising one of its ends so as to lower the other in the same proportion.
The gulfs of Bothnia and Finland, like vessels tilted up out of the horizon-
tal, slowly pour their waters into the southern basin of the Baltic. Fresh
islets and ranges of islets appear in succession, rocks are laid dry, and if
the elevation of the bed of the sea continues to take place with the same
regularity as during the historic ages, it may be predicted that in three or
four thousand years the archipelago of Qvarken, between Umea and Vasa,
will be changed into an isthmus, and the Gulf of Tornea will be converted
into a lake similar to that of Ladoga. Later still, the Aland Islands will
become connected with the continent, and will serve as a bridge between
Stockholm and the empire of Russia. It is, besides, very probable, if not
certain, that the great lakes and innumerable sheets of water which ﬁll all
the granite basins of Finland have taken the place of an arm of the sea
which once united the Baltic to the great Polar Ocean. The erratic blocks
of granite scattered about all over Russia can only have been carried
thither by trains of ice which have made their way over the sea from the
mountains of Sweden. The shells belonging to polar waters, which are
~ found as far as the basin of the Volga, also testify in favor of the existence
of a former arm of the sea. The name of Scandinavia itself signiﬁes “ Isle
of Scand,” and the name of Bothnia (Botten) proves that these coast prov-
inces were formerly a marine bed.1 Here philology steps in to aid geol-
ogy and tradition.
This is not all. The Baltic Mediterranean also communicated with the
North Sea by a wide channel, the deepest depressions of which are now
occupied by the lakes Maler, Hjelmar, and Wenern. Considerable heaps
of oyster-shells are found in several places on the heights which command
these great lakes of Southern Sweden. On the rocks now laid dry, which
surround the Gulf of Bothnia, banks of these molluscs have also been dis-
covered exactly similar to those of Norway and the western coasts of Den-
mark. With regard to the celebrated Irjoeklcenmoeeldings of the Danish
islands, they are in great part composed of oyster-shells, which the inhab-
itants, in the Age of Stone, evidently used to collect in the bottoms of the
neighboring bays. It has been proved by the investigations of M. de Baer
* Carl Vogt, Norc‘lfalzrt. ‘
l‘ Keilhau, Bulletin de la Socie'te’ Gcologique de France, First Series, vol. Vii.
1: Von Maack ;' Eugene Robert,
534 THE EARTH
that the oyster can not live and grow in water holding more than thirty-
seven parts in a thousand of salt, or less than sixteen or seventeen parts

n I»
% lignoda'oﬁt'rrcﬁznrmoaw. '
Llgneduw‘fardnm R0003";
m Llymdaw'ta-‘Iigpakoaau
I n’ ' s ‘I


b ' Fig. 221. Elevation of the Bed of the Gulfof Buthuia.
, in a thousand. Now the Baltic Sea, into which its numerous tributaries
bring a large quantity of fresh water, does not contain, on the average,
ELEVATION OF SCANDINA VIA. ' ' 535
more than ﬁve parts in a thousand of salt; and, indeed, in some of the.
gulfs, the water, now devoid of all its former inhabitants, has become en-
tirely fresh. And yet—-_—the heaps of oyster-shells prove it—the Baltic Sea
and the inland lakes were once as salt as the North Sea is at the present
day. Whence, then, could this saltness proceed, except from some for-
mer strait which occupied the depressions in which theSwedish engineers
have dug out the Trolhatta Canal? Besides, when the sluices were being
constructed,there were found, not far from the cataracts, and at a height
of 40 feet above the Cattegat, various marine remains, mingledwith relics
of human industry—boats, anchors, and piles. According to M. de Baer,
it is not, at the most, morethan ﬁve thousand years before our century
that we must date the closing up of the straits which used to exist between
Southern Sweden and the great mass of the northern plateaux. ‘
Since Leopold von Buch has placed beyond all doubt the important fact
of the gradual upheaval of the northern portion of the Scandinavian pen-
insula, several geologists have ascertained that the elevation does not take
place in a mode that is perfectly uniform. During by-gone centuries the
movement has sometimes been accelerated and sometimes slackened, as is
proved by the inequality of the elevated sea-beaches which run along the
sides of the mountains on the coastsof Norway. Some of these steps or
shelves that the waves have carved out in the rock are wide and gently
inclined; others are abrupt, and can scarcely be distinguished'from the
slopes above them. Lastly, the measurements made by M. Bravais along
the lines of erosion of Altenf jord have proved that they are not parallel,
and that the rocky masses situated at the ends of the gulfs‘lia-ve' been
more energetically upheaved than the layers lying nearer the sea. Thus
the upper bank of Altenfjord has risen at the eastern end to a height of

risen 91 feet. In like manner, the lower shelf, throughout the whole of its '
immense circuit round the gulf, presents a slight inclination toward the
sea, being no less than 88 feet high on the ‘east, and only 45 feet at the‘
outer promontories. Thus the action of upheaval is evidently stronger in
the vicinity ofthe mass of mountains than it is on the coast; but this does
536 THE EARTH.
not afford any sufficient reason for saying that at a certain distance to the
west, under the bed of the sea, the movement of the ground entirely ceases.*
M. Carl Vogt has propounded an ingenious hypothesis .to account for
this inequality of elevation. According to his theory, rocks of various na-
tures—schists, sandstones, or limestone—which compose the mountains of
the Scandinavian peninsula, incessantly swell in consequence of the inﬁl-
tration of snow-water, and, owing to fresh crystallizations taking place by
means of moisture, are gradually converted into masses of stratiﬁed gran~
itc. This hypothesis, which has been much discussed by geologists, would
certainly explain the raising of the lines of erosion of the Norwegian coast
near the groups of mountains, but it would fail to account for the intervals
of comparative repose, and especially for the sinking of the ground, which
many geological facts prove to have taken place during the glacial period.
It is, therefore, necessary to admit that other forces have been in action in
the solid mass of Scandinavia.
Added to this, we must not lose sight of the fact that the upheaval of
this peninsula is not an isolated event, and that the other countries of the
north of Europe and Asia, notwithstanding the diversity of their rocks, all
appear to be actuated by a similar movement of ascension. The islands
of Spitzbergen exhibit generally, between the present sea-shore and the
mountains, former sea-beaches which are gently inclined, and half a mile to
two miles and a half in breadth, on which are found, up to a height of 147
feet, heaps of bones of whales and shells of the present period. These re-
mains, surrounding all the snow-clad slopes of Spitzbergen, prove that this
archipelago, like Scandinavia, is gradually emerging from the waves of the
Polar Ocean]L The northern coasts of Russia and Siberia are likewise
rising, as is attested by popular tradition and the evidence of learned
travelers. MM. Dc Keyserling, Murchison, and DeVcrneuil have found, at
points 250 miles to the south of the White Sea, on the banks of the Dwina
and the Vaga, beds of sand and mud containing several kinds of shells sim-
ilar to those which inhabit the neighboring seas, and so well preserved
that they have not lost their colors. In like manner, M. De Middendorf
states that the ground of the Siberian toundras is in great part covered
with‘ a thin coating of sand and ﬁne clay, exactly similar to that which is
now deposited on the shores of the Frozen Ocean: in this clay, too, which
contains in such large quantities the buried remains of mammoths, there
are also found heaps of shells perfectly identical with those of the adjacent
ocean. Far inland, be'sides, trains of driftwood are seen, the trees forming
which once grew in the forests of Southern Siberia; these trees, having
been ﬁrst carried into the sea by the current of the rivers, have been
thrown up by the waves on the former coasts, which are now deserted by
the sea. It .is this half-rotten wood which is called by the natives “ Noah’s
wood,” fancying that they have before them the remains of the ark of the
deluge. More than this, there are also direct proofs of the upheaval of
Siberia. The island of Diomida, which Chalaourof noticed in 1760 to the
* Bravais, Voyages en Scandinavz'e, vol. i.
'l' Malmgren, Mz'tt/zez'lzmgen ran Pctermann, vol. ii., 1863.
GRADUAL UPRISLNG OF LAND. 5
east of Cape Sviatoj,wa_s found to be joined to the continent at the date
of \Vrangell’s voyage, sixty years later. It is, besides, very probable that
this upheaval of the ground is prolonged to the east over a great portion
of the circumpolar land of North America, as far as northern Greenlandj‘"
for numerous indications of this phenomenon have been recognized in the
Arctic Isles scattered off the coasts of the continent. At Port Kennedy
MnIValker found shells of the present period at a height of 557 feet above
the sea; a bone ofa whale lay at a height of 164 feetj
The cliffs of Scotland also present phenomena similar to those of Scandi-
navia. Parallel water-marks traced oilt by the waves on the escarpments
' of rocks, and collections of shells peculiar to the neighboring seas, attest
the gradual elevation of this portion of Great Britain. The elevation, too,
must have been of a much more regular character than that of the coasts
of Norway, for, according to Robert Chambers, not the slightest variation
of level is noticed on the ancient terraces.
still continuing; for it has been ascertained that the marine cliffs which
were once situated above the estuaries of the Forth, the Tay, and the
Clyde contain not only organic remains of recent ages, but also heaps of
pottery of Roman origin. The former Roman port of Alaterva (Cramond),
the quays of which are still visible, is now situated at some distance from
the sea, and the ground on which it stands has risen at least 24% feet. In
other places the debris scattered on the bank show that the coast has risen
about 26% feet]: Now, by a remarkable coincidence, the ancient wall of
Antoninus, which, at the time of the Romans, served as a barrier against
the Picts, comes to an end at a point 26 feet above the level of high tides.
The general upheaval of the region may therefore be estimated at 01%
inch a year; but since 1810 the movement has become more rapid, as is
proved by the tide-meters at the port of Leith, and it is, at present, at the
rate of 0546 a year.§ Farther to the south, on the sides of the mountains
of Wales, there are numerous indications of the presence of the sea during
the present period.
don, at a height of 1357 feet, a bed of drift containing ﬁfty-four species of
shells of similar kinds to those still existing in the northern seas of Eu-
rope; the same soil was, however, found at a point 650 feet higher, but de-
void of shells. -
Thus, from Wales 'to Spitzbergen and the eastern coasts of Siberia, the
ground has continued to rise slowly during a portion of the Glacial period,
and also during the present epoch. The area of upheaval includes a por-
tion ‘of the earth’s surface which is not less than 160 degrees of longitude.
In the face of these facts, are we to consider the phenomena of upheaval
as mere local accidents produced by the swelling of rocks and volcanic
shocks, or must we look upon them as the results of some general cause
acting in various ways over the surface of the‘ whole planet ? The latter
hypothesis appears to us to be the more probable.
* Vicle below, p. 555. 1' Samuel Haughton, Natnral Llz'story/ Review, April, 1860.
I Arch. Geikie, Edinburgh New Philosophical Journal, New Series, xiv.
§ Smith, Geological M'ugazine, September, 18126.
This ascending movement is‘
Mr. Darbishire lately discovered, not far from Snow-I
~§
538 THE EARTH.
CHAPTER LXXXI.
UPHEAVAL OF THE MEDITERRANEAN REGIONS—FORMER LIBYAN STRAIT.
-—COASTS OF TUNIS, SARDINIA, CORSICA, ITALY, AND WESTERN FRANCE.
THE countries of the South of Europe certainly possess a more grace-
fully-indented outline than any other regions on the face of the earth.
The peninsulas which they throw out present the greatest variety of con-
tour and aspect, and they have thus become, as it were, imbued with vital-
ity, owing to their numerous articulations, similar to those of an organized
‘body. Correspondent with this multiplicity of external shapes are the
singular irregularities and exceptional contrasts in the movements of the
ground. A certain complication is here and there manifested between the
upheaved regions and those which are subsiding. Nevertheless, a suﬁi-
cient number of observations have been collected to warrant us in admit-
ting, in a general way, the elevation of most of the countries which sur-
round the basin of the l\[editerranean. These regions, which in several
places have been caused to oscillate by volcanic forces, constitute a con-
siderable area of upheaval, extending from the deserts of the Sahara to
Central France, and from the coasts of Spain to the steppes of Tartary.
The mountainous peninsula of Scandinavia is situated in the middle of the
upheaved regions of Northern Europe, and, by a kind of polarity, the long
depression of the Mediterranean occupies the centre of the vast areas in
the South of Europe and Northern Africa, which are gradually rising.
. This immense space was once bounded, toward the tropical zone,by an-
other sea, or at least by a strait several hundreds of miles in width, which
commenced at the Gulf of Syrtes, and, ﬁlling up the depressions of the
Berber Sahara, joined the Atlantic in front of the archipelago of the Ca-
naries. In 1863 MM. Escher von der Linth and Desor ascertained, accord-
ing to M. Charles Laurent, that the sands of these regions are entirely
identical with those of the nearest Mediterranean shores, and contain the
same species of shells. One of these witnesses of the past, the common
cockle (Ucm'dz'um ccl'ule), is found not only 011 the surface of the ground,
but also at some depth, and likewise up to a height of 900 feet upon the
sides of the hills. The Algerian Sahara has, therefore, risen to this extent
during a recent geological period. Various depressions, the surface of
which is lower than the level of the Mediterranean, have been gradually
separated from the sea, and, in the present day, they exhibit nothing but
marshy pools or interminable plains. At a recent, and perhaps historical
epoch, Lake Tritonis of the ancients, now the Sebkha Faraoun, into which
ﬂowed the Igharghar, has ceased to be a prolongation of the Gulf of
Gabes, and has become a mere marsh. It was the last remnant of the
O
L'PHEA VAL OF THE MEDITERRANEAN REGIONS. 5 39
arm of the sea which separated the mountainous regions of Atlas from the
African continent, both so distinct in their general character, as well as in
their fauna and ﬂora. To the existence of this African Mediterranean,
which is now replaced by white sands, beds of salt, and rocks devoid of
verdure, MM. Escher von der Linth and Lyell in great part attribute the
enormous extent of the former glaciers of Europe. It is, in fact, very nat-
ural to think that, before the drying up of this inland sea, the masses of
air blown to the north would become saturated with moisture while pass-
ing over the water, and, rising gradually to the higher regions, would con-
stantly convey fresh layers of snow to the summits of the Alps, instead of
melting the snow, as the fG/m now does, heated as it is by the reﬂection
from the burning sand of Africa?!‘ It is, however, possible that the Swiss
mountains have decreased in height since the Glacial period. The same
slow oscillation of the ground which emptied the Libyan Mediterranean
has, perhaps, by its reaction, lowered the foundations of the Alps, and
brought them nearer to the level of the seat
On the coasts of the Mediterranean, the indications which would lead us
to infer the fact of some upheaval of the ground are plentiful enough.
Thus the shores of Tunisia are constantly encroaching 011 the sea. The
ancient ports of Carthage, Utiea, Mahedia, Porto Farina, Bizerta, and oth»
ers, are now ﬁlled up.I The bays are done away with, the points advance
farther and farther into the sea; and these phenomena take place with a
rapidity suﬁicient to show that we are witnessing the effect of a vertical
impulse similar to that which once upheaved the beds of the Saharan seas.
In like manner, Sicily appears to be constantly elevated by the forces in
action under the beds of its surface. On the heights which command Pa-
lermo, caves have been observed at an elevation of 180 feet, which have
been hollowed out by the sea during a period characterized by existing
species of shell-ﬁsh.§ On the eastern coast of the island, Gemellaro has
recorded a recent upheaval of more than 42 feet. In Sardinia, not far
from Cagliari, M. De la Marmora points out, as existing at heights of 242
and 231 feet, deposits which contain remnants of pottery mixed with mod-
ern shells, which deposits, in his idea, were oh a level with the sea at a
date when the island was inhabited by man. Certainly M. Emilien Dumas,
an excellent observer, considers that these remnants of pottery and heaps
of shells are nothing but the remnants of the cooking of food, similar to
the Zjocklrcnmoeclclings of Denmark. If this be the case, there would be
nothing to prove that Sardinia was upheaved at any recent epoch. But
are the enormous banks of oyster-shells which cover the ground at the
Lake of Diana, 6 feet above the level of the sea, and are continued far un-
der the water, to be considered as nothing but the debris of Roman ban-
quets ? Such an idea does not, at least, appear at all probable to M. Au-
capitaine and a number of other observers.
* V Me the chapter on “ Winds.” '
‘l Lyell, Inaugural Address to the British Association at Bath, 1864.
1 Guerin, Voyage Arcllc'ologz'que 21 la Re'gencc cle Tunis. §.Lyell, Antiquity of Man.
540 THE’ EARTH.
The facts of upheaval brought forward by geologists as regards the
other regions of the coast of the Mediterranean are not as~ yet suﬁiciently
veriﬁed, and it can not be’ positively asserted that these shores have risen
above the sea during the present period. Nevertheless, the body of evi-
dence is of considerable importance, and merits serious consideration.
Thus, round the former island of Circe, now become a promontory of Tus-
cany, the rocks, which have much the appearance of a former sea-beach,
are pierced by pholades.* With regard to the discovery of banks of mod-
ern shells made by Risso near Villefranche, at the extremity of the Cape
of Saint Hospice, M. Emilien Dumas disputes its scientiﬁc value. N ever-
theless, it is plain that this coast, and the whole of the adjacent shore as
far as Spezzia, were covered by sea-water at a recent geological epoch.
All that is necessary to prove this is to examine the caves of Menton, of
Ventimiglia, and of the Cape of Noli, which were hollowed out by the
waves at some former date, and open like rows of arched doors and win-
dows along the facade of some palace.
The southern coasts of France do not afford any direct evidence of an
upheaval of the soil; but various indications possess a value which can
not be disputed. Astruc, of Languedoc, brings forward a great number
of facts, which prove that, at the time of the Romans and in the Middle
Ages, the marshes extended much farther inland. The ancient Roman
road from Beaucaire to Béziers describes a wide curve toward the north,
doubtless to avoid the plains on the shore, which were then entirely under
water. Ancient cities with Gallic names—as Ugernum (Beaucaire) and
.Nemausus (Nismes)—are found along the ancient road,while all the places
situated to the south bear Latin or Roman names—as Aigues Mortes,Fran-
quevaux,Vauvert, and Frontignan (Fl-ens stagm')—and appear, therefore,
to be of more modern origin. It is, besides, proved by various documents
that ancient ports have ﬁlled up, and have been converted into termﬁrma.
Astruc also points out the remarkable fact that the Romans, who highly
appreciated thermal springs, were not aware of the abundant wells of
Balaruc, although the eddies of steam could not have failed to point them
out if they had not been covered at that time by the waters of the Lake
Than. This is an important argument in favor of the hypothesis of a
gradual elevation of this part of France.
Beyond the Mediterranean basin this movement of general upheaval
appears to continue toward the north and west. Thus, at Seixal, opposite
Lisbon, they have been compelled to cease building ships of the line on
account of the increasing diminution of the water, which is attributed both
to the deposits of mud and also to the upheaval of the rocks. On the At-
lantic coasts of France a great number of phenomena of a similar nature
have also been. adduced. To many geologists, especially to M. Bravais, it
seems probable that the whole of France, agitated by a slight and almost
imperceptible tremor, is being slowly upheaved on the southern side, and
turns on a base-line passing through the peninsula of Brittany. At all
* Romanelli, Breislak, quoted by Biittger, Zlfzttelmcer.
UTHEA VAL OF_THE OOASTS OFEUROPE. 541
events, the coasts of Poitou, Aunis, and Saintonge appear to have risen
since the commencement of the historical epoch. Guérande, Croisic,
Bourgneuf', and Sables d’Olonne show upon their shores unquestionable
traces of recent elevation. The former Gulf of Poitou, the entrance of
which, two thousand years ago, was not less than 18 to 25 miles in width,
which, too, penetrated inland as far as Niort, has constantly contracted its
dimensions since the above-named date, and is now nothing more than a
small bay, known under the name of the Creek of Aiguillonfi‘ The con-
stant deposit of marine alluvium would scarcely be a sufﬁcient cause for
this rapid increase of the land; it is therefore probable that at this spot
the upper layers of the ground are regularly in a course of upheaval.
Farther to the south, La Rochelle, which owes its name to the position
which it once occupied on a rock almost isolated in the midst of the water,
now only communicates with the sea by a narrow channel, often choked
up with mud. Brouage, another fort which, in the Middle Ages, was a
town of important trade, is now nothing more than a ruin, some distance
from the sea. The district of Marennes, to which the name of “ Colloque
des Iles” was once given, is now entirely connected with the main land,
and the arms of the sea which cross it have been converted into draining-
channels, salt marshes, and oyster-beds. In like manner, the peninsula of
Arvert, situated between the mouth of the Seudre and that of the Gironde,
ceased to be an archipelago during the course of the Middle Ages. At
Rochefort it has, indeed, been calculated approximately how much the
ground has risen, the slips for ship-building, dug out in the time of Louis
XIV., having been gradually elevated more than a yard]L “ The bank is
pushing up,” say the inhabitants of the coast, who have long since ob-
served the gradual upheaval of the ground.
* De Quatrcfages, Les Cé‘tes de la Saintonpe.
1' Babinet, Revue des Deux—Mondes, September 15, 1855.
e91
H2.
k0
THE EARTH.
CHAPTER LXXXII.
COASTS OF ASIA MINOR—ANCIENT OCEAN OF HYRCANIA.-—COASTS OF
PALESTINE AND EGYPT.—THE ADRIATIC GULF.
PHENOMENA of upheaval are also very common in the islands and round
the edge of the eastern basin of the Mediterranean. Like Sicily and sev-
eral parts of the coasts of Italy and Greece, a considerable number of isl-
ands—as Malta, Rhodes, and Cyprus— are surrounded with circular ter-
races more or less elevated above the level of the sea, and composed of
calcareous or sandy rocks of recent formation.* The northern portion of
the island of Crete has risen more than 60 feet during the present geolog-
ical periodﬂr A study of the shores of Asia Minor proves that there also
the ground has continued, since-man inhabited that region, to rise with a
rather rapid movement. During historic times this part of the continent
has gained a considerable belt of land at the expense of the ZEgcan Sea.
It is not the alluvium of the rivers, or the matter washed up by the sea,
which has caused this increase of the land, for the Anatolian rivers are
very inconsiderable, and the water which bathes the coast can not, on ac-
count of its great depth, throwT up much sand. It must, therefore, be in
consequence of a slow upheaval of the earth’s crust that the ruins of Troy,
Smyrna, Ephesus, and Miletus have gradually become'more distant from
the coast, and appear to be receding still farther inland. From the same
cause so many islands in the AEgean Sea which were once separate are
now united, or are connected with the main land, and form headlands or
hills surrounded by low-lying plains. The testimony of ancient authors is
unanimous as to these encroachments of the shores. Thus it is said that
the two halves of Lcsbos, Issa, and Antissa have become united, that the
bays have been converted into inland lagoons, and that various islands
have joined on to the main land at Mindus, Miletus, the Parthenion Cape,
at Ephesus, also at points near Halicarnassus and Magnesia. At the time
of Herodotus, the mountain of Lade, not far from which the Ionian galleys
fought a battle with the Persian ﬂeet, was an island; at the present day
it forms part of the main land, and stands in the midst of the plain of the
Meander. Since the date of Strabo and Pliny, several other islands have
similarly become headlands. The former Latmican Gulf is converted into
a lake, known under the name of Akiz. The encroachments of term ﬁrmer.
on this gulf have added to the eastern coast of Asia Minor about 67 square
miles in less than two thousand years. This retirement of the sea took
place likewise in preceding ages, for the town of Priene (Samsoun), which
at the time of Strabo was 4% miles from the shore, had been built at a pre-
Vious date on the sea-coast. In like manner, the village of Ayasoulouk,
* Albert Gaudry, Revue des Deux-Mondes, November 1, 1861; Newbold.
T Raulin ; Leycester and Spratt. Vide p. 545.
ELEVATION OF ASIA JILYOR. 543
where the ruins of the ancient city of Ephesus may still be seen, is at the
present time two leagues from the coast, and the former estuary which
was commanded by the town is now converted into a marshy plain.
\Vould the little river Meander, the total length of which is not more‘than
341 miles, have been able, by nothing but its alluvial deposits, to ﬁll up
lakes and estuaries of so large an area, and to modify so considerably the
outline of the shore ? It is therefore important that the discharge of this
'river and its annual deposit of alluvium should be exactly measured, in
order that we may arrive certainly at the real cause of these encroach-
ments on the part of the Anatolian coast, where, according to the ancient
saying of Pausanias, “ all is unstable and changing.” According to M. De
Tchihatcheff, this portion of the coast of Asia Minor has gained, since his-
toric times began, an extent of about 185 square miles, equal to the area
of the Isle of \Vight.*
Similar phenomena are, however, likewise taking place on the southern
coast of Asia Minor. Near Adalia, the Lake of ' Capria, which was very
extensive at the time of Strabo, ﬁrst ceased to communicate with the sea,
and then gradually emptied, being new nothing but a marshy hollow:
the surface of the peninsula has thus been increased by an area of 154
square miles. On the north of Asia Minor a great number of signs prove
that there also the water has retreated before the shores and rocks of the
continent. During the present geological period the area of the Enxine
has been diminished, and, according to the traditions of the Crimean Tar-
tars, it is still diminishing. Banks of modern shells have been left by the
sea at considerable heights on the hills of Thrace and Anatoliafr round
the Crimea, salt lakes, stagnant marshes, now exist far inland in the place
of former gulfs. Certainly enough the Black Sea, before the opening of
the Bosphorus, received from its tributary rivers more water than the sun
and wind could evaporate, and must necessarily have much exceeded the
level to which it now reaches. But if the earth itself had remained sta-
tionary, and had not slowly risen, the sea—water would not have left the
marks of its presence at any point higher than the former Strait of Isnik,
the site of which is now dotted over with lakes which once formed a part
of the sea. It is, perhaps, in consequence of the upheaval of the ground
that this strait was closed, and the water of the Black Sea, gradually
accumulating in its basin, was compelled to open by force a new outlet
through the volcanic ﬁssures which have now become the Bosphorus.
A geological examination of Southern Russia and the plains of Tartary
will preclude us from entertaining any doubt as to the fact that the Cas-
pian Sea, the Sea of Aral, and all those innumerable sheets of water which
are scattered over the steppes, were separated from the Euxinc and the
Gulf of Obi by a gradual upheaval of the continent. The plains are still
covered with salt and marine remains. The inland seas and the scattered
lakes are still inhabited by seals, and their fauna altogether presents an es-
sentially oceanic character. Herodotus, Strabo, Ptolemaeus, and all the
* Asie Mneure. Von Hoff, Verd'nderungen der Erdoberﬂliclze.
1' De Tchihatcheff, Le Bosphore ct Constantinople.
544 THE EARTH.
authors of antiquity attribute to the ancient Hyrcanian Ocean an extent
far larger than that of the Caspian of our day; most of them, indeed, con-
sidered this inland sea as a prolongation of the Frozen Ocean. This lat-
ter opinion, no doubt erroneous as regards a date two thousand years ago,
would certainly have been true of some anterior epoch. After Humboldt’s
profound investigations on Central Asia, we shall not, at the present day,
show too great temerity in assuming that, during some portion of the
present period, a vast strait, like that which once ran along the southern
base of the Atlas, extended from the Black Sea to the Gulf of Obi and the
Frozen Ocean.* The vast depression of the Caspian plains which is below
the level of the sea, and, according to Halley, was produced by the shock
of some wandering comet, is, on the contrary, really owing to a slow ele-
vation of the ground.
The observations of level made on the coasts of the Mediterranean have
enabled us to ascertain not only that the larger portion of this inland ba-
sin of the ancient world, and many of the regions bordering on it, have
gradually risen,'but that they have, in addition, pointed out the limits of
the area of upheaval. They may be distinguished with some degree of
precision on the coast of Syria and Palestine; it may be noticed that in
this region the surface of the ground is corrugated like that of water, and
forms a series of waves and depressions ﬂuctuating in contrary directions.
The shores of the Gulf of Iskanderoun are regularly gaining in Width by
means of the elevation of the ground as well as of the matter thrown up
by the sea; but at Beyrout a tower is shown which is sinking farther and
farther into the water. More to the south, the former Isle of Tyre is now
connected with the continent, and several parts of the peninsula bear
traces of the sojourn of the sea during some recent epoch. Lastly, Kaisa-
rich and some other towns in Palestine are included in an area of subsi-
dence, as is proved by the remains of fortiﬁcations which are now visible
below the level of the Mediterranean.
On the east, all the Egyptian coasts were still rising at a comparatively
very recent epoch, for the Bitter Lakes and the banks of the Nile exhibit
former sea-beaches on which modern shells are found. But at the present
day the ground is sinking continuously and imperceptibly. Ruined towns
are situated in the midst of the marshy plain of Lake Menzaleh, which is
covered by the sea during the greater part of the year. Farther on, a for-
mer branch of the Nile, with the banks which bordered it, is entirely hid-
den by the waters of the Mediterranean. The same phenomenon occurs
on the other side of the Delta. In 1784 the sea made an irruption into the
interior of the land, and formed the Lake of Aboukir in the midst of a
plain on which important towns once stood. In like manner it may be in-
ferred, from the ancient descriptions of Alexandria and its environs, that a
considerable subsidence of the ground must have taken place there during
* In Captain Maury’s magniﬁcent studies, in which, however, imagination sometimes has
as large a share as science, he endeavors to prove, by very ingenious arguments, that the up-
heaval of the Andes, by modifying the system of winds and rain over the whole earth, was the
cause of the gradual drying up of the plains of the Caspian and Aral.
COASTS OF EG YPZl—THE' ADRIATIC. 545
the centuries of our era. Artiﬁcial caves and catacombs, dug out in the
days of the Ptolemies, and incorrectly known as “ Cleopatra’s Baths,” are
now invaded by the waves.’’‘: On the shores of the Red Sea, not far from
Suez, some sepulchral caves hollowed out in the calcareous rock have like-
wise been inundated, owing to the subsidence of the ground. Perhaps
this movement in the ground of Egypt is common to all that portion of
the Mediterranean which may be called the Egyptian Sea; for in the isl-
and of Crete the western point has constantly risen during the modern
epoch, but the side nearest to Egypt is gradually sinking under the water.
As Strabo himself expressly said, Nature is. seeking to destroy the Isthmus
of Suez, which she once formed between the two continents. Man, in his
operations of cutting through it, is only anticipating the geological labor
of centuries to come.
Along the shores of the Adriatic Sea, to the north of Zara and Pesaro,
geographers have noted other phenomena of depression which mark the
northern limit of the great Mediterranean area of upheaval. In the mid-
dle of the sixteenth century Angiolo Eremitano propounded the opinion
that the isles of Venice were sinking at the rate of about a foot a century,
and this hypothesis, which was based upon a comparison of the buildings
and the pavement of the streets with the water, has since been fully con-
ﬁrmed. In the Isle of St. George, Roman constructions are now found be-
low the level of the lagoons ; in other places paved roads are covered by
the water, and churches and bridges have sunk in comparison with the
surface of the sea. In 1731 Eustache Manfredi noted the same. subsidence
of the soil under the ediﬁces of Ravenna, but he, in error, attributed it to
the gradual elevation of the level of the Adriatic. In addition, an entire
town Conca—once situated not far from the Cattolica, at the mouth of
the Crustummio, has been entirely submerged for some centuries, and,
when the sea is calm, the remains of two of its towers may still be seen
under the waves. M. Giacinto Collegno thinks that all these alterations
of level are produced by the deposit of the alluvium brought down by the
Po and the other rivers descending from the Apennines and the Alps.
This is a cause which must certainly contribute in no small extent to the
general depression of the Venetian coasts of the Adriatic Sea, but proba-
bly it is not the only cause, for the opposite coasts-of Dalmatia and Istria
are also sinking, in spite of the compact nature of their rocks. At Trieste,
at Zara, and in the Isle of Poragnitza, various works of man—such as pave-
ments, mosaics, and sepulchres—may be seen below the level of the seal-
Moreover, as Lyell remarks, the artesian borings which have been made
in the delta of the P0 to a great depth below the sea have brought up
nothing but river alluvium, which unquestionably establishes the fact of a
gradual depression of the ground. The earth which is penetrated by the
boring-rod at the bottom of the artesian wells was once situate above the
level of the sea.
* LyelhAntiquity of Man; Pococke; Wilkinson; Schleiden.
'l' Donati,Hz'stoire Nalurelle de la Mer Adriatigue ,- Schleiden,Lu Plam‘e.
M M

546 THE EARTH.
CHAPTER LXXXIH.
SUBSIDENCE on THE sHoEE on THE CHANNEL or HOLLAND, on
SCHLESWIG, on rnussrx.
WHETHER it be that the whole of Central Europe participates in the
movement of depression to which the shores of the Adriatic are subject,
or whether the latter be merely a local phenomenon, it is nevertheless the
case that the southern coasts of the Channel and North Sea are also sink-
ing, although very slowly. On the coast of Brittany and Normandy, nu-
merous forests which’ have been'submerged, and buildings surrounded by
the sea-water, prove that the ground has sunk during the present period.
In 709, the monastery'of' Mount St. Michael was built in the midst of a
forest ten leagues from the sea; it now stands, like an island, in the
midst of sand-banks. The inroads of the sea are still continuing, especially
in the Bay of La Hougue and in the harbor of Carteretf‘< It appears, how-
ever, that various undulations, like those on the coast of Syria, also exist
on.these coasts, for in several places banks of sand and modern shells have
been discovered at heights from 40 to 50 feet above the level of the sea.
At some remote epoch, but nevertheless contemporary with man, the val-
ley of the Somme was also upheaved, but for thousands of years it has
been slowly subsiding, as submarine forests are found along the coast,
and the peat-bogs of Abbeville, the bottom of which is situated below the
Bay of Somme, afford no other debris but the remains of animals and veg-
etables which lived 011 the earth or in fresh water. When these peat-
mosses began to grow, the ground of the valley must have been higher
than the surface of the neighboring seas]L
In Flanders and Holland the phenomena of subsidence have been, if not
more considerable, at least more important in their results, on account of
the very low level of these countries in comparison with the sea. A mere
enumeration of the successive catastrophes brought about by this gradual
depression constitutes a terrible history. The plains of Dordrecht have be-
come a forest of reeds (Biesbosch). The Zuyder Zee itself—once a marsh,
next a lake, and then an arm of the sea—is still continuing to sink: at the
present time there is, it ‘is said, suﬁicient depth for ships of heavier burden
than those which used to‘navigate it in former centuries. Like a raft
gradually sinking under the waves, Holland would be slowly swallowed
up in the abyss if it were not that the inhabitants, accepting the contest
with the elements, have walled in their country by means ‘of dikes, and
laid it dry by immense operations of drainage, which will never cease to
be a subject of astonishment. Several savants, at the head of whom stands
* Bonissent, Congres ScientzI/z‘que dc C/zerbourg, 1860.
1' Lyell, Antiquity qf Man.
S UBAS'IDEATCE OF HOLLAND. '5 4:7


" on e RUIDENBERG is???
Fig. 223. Biesbosch.


the eminent geologist M. Staring, are of the opinion that the'gradual de-
pression of the land which is thusembanked is caused only by the subsi-
dence of the alluvial ground, the weight of the dikes, and,f-the incessant
passage of men and cattle. However great may be the importance of
these combined causes, the phenomena of subsidence which have been
noted for the last ﬁfteen centuries are considerable enough to warrant us
in accepting M. Elie de Beaumont’s hypothesis as to the depression of the
ground of Holland. If, at least, we may judgeby the mean level both of
the pavement of the towns and of the ﬁelds under cultivation, the move-
ment of depression is most rapid at the mouths of the rivers—the Scheldt,
the Mouse, and the Rhine. At Calais the streets are more than a yard
above the high tide, while the cultivated ground descends to the limits of
the tide. At Dunkirk the height of the streets is not more than 23 inches,
and the ﬁelds are plowed at a level of a yard below ‘the sea. At Furnes
and Ostend the streets are still lower, and the level of the poltlers is ‘al-
ways sinking. Near the mouths of the Scheldt it is 11% feet below the
high tide. Farther to the north the ground gradually rises, but the streets
of ‘Rotterdam and Amsterdam are lower than the level of the equinoctial
tides.* . I ' ' ‘ ' ,i
All the adjacent coasts—those of the south of England, and ofCornwall
and Yorkshire, as well as those of Hanover and Schleswig—likewise afford
certain proofs of a considerable subsidence by their submarine peat-mosses,
their submerged forests, and their former coasts nowv become islands. On‘
the western coasts of Schleswig the subsidence has been, on the average,
* Bourlot, Variations dc Latitude et de Climat. ' s
Z’HE EARTH
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Fig. 224. Coast of Friesland.
13 feet during the present period. In this locality, at the bottom of ‘the
port of Husum, there was'discovered, in the midst of a submerged forest of
birches,ia tomb of the Age of Stone, necessarily dating fromaperiodante-
rior to the subsidence of the ground on which it stood. .On the eastern
coasts of Schleswig and Holstein many phenomena of the same nature
have been remarked, which can only be explained by a'gradual subsidence
of the shore. The remains of an old castle situated at ‘the mouth of the
Schlei are covered by the water. Farther on,-the stumpsof the trees of
an ancient deer-forest of the Middle Ages may be seen under the water
about half a mile from the shore. In the Straits of Fehmarn are found
the remains of an ancient Wall; and, lastly, near Travemunde, two blocks
of stone, which stood on the beach at the end of the last century, are now
surrounded by water.* These are facts which will not permit us to at-
tribute, solely and wholly, to the action of the waves the transformation
of several peninsulas into islands, and lakes by the sea-shore into arms of
the sea. According to John Paton, Denmark and Schleswig-Holstein have
lost, since the year 1240, an area of about 1225 square miles, or one eight-
eenth of the whole surface of the territory.
Farther to the east, all round the southern basin of the Baltic, the in-
roads of the water have led several geologists to admit that-the ground
of these countries is'slowly subsiding. Rugen is broken up into islets and
peninsulas; Bornholm is surrounded by submarine forests, one of which,
according to- Forchhammer, is' 26 .feet below» the line of the shore. Other
submerged forests fringe the coasts of Pomerania and Eastern Prussia.
* Von Maack, Das urgescliz'clzth'che Sclzleswz'g-Holstez'nisclze Land, 1860.
DEF-BESS] ON OF FRIESLAND AND DENMARK
The islands of Wollin and Usedom, situated in front of the mouths of the
Oder, have gradually been eaten away by the waves. The sandy bar
which impedes the entrance to the port of Swinemunde used to form a
peninsula of Usedom, indeed, during historical periods.* Lastly, accord-
ing to the evidence of Barth, the point of Samland has been overwhelmed
by the water, as may be easily recognized by the fact that the church of
St. Adalbert, which was built about the end of the ﬁfteenth century at a
point 4% miles from the sea, is now found in a state of ruin only 100 paces
from the beach. _
These are facts which can not be questioned. Nevertheless, we are not
yet warranted in considering them as positive proofs of the-‘subsidence’ of
the ground, for Voigt, and several other scientiﬁc observers, class them
among the simple phenomena of erosion and deposit. However this may
be, there are very strong reasons for considering the channel and the
southern waters of the North Sea and the Baltic as a trench of depression,
an elongated valley 1100 miles in extent, separating the area of upheaval
of Northern Europe from that which is bounded at its northern extremity
by the coasts of Poitou.
* Anton von Etzel, Die Ostsee.
‘550 _~ THE EARTH.
CHAPTER LXXXIV.
UPHEAVAL ‘on THE COASTS or crnrr AND rERu—PRoBABLE DEPRESSION
'oE'THE' COASTS or LA PLATA "AND BRAZIL.—-COASTS or NORTH AMERICA
AND GREENLAND. '
THE New ‘World—that double continent, the architecture of which is
distinguished by general features of - such simple grandeur—likewise ex-
hibitsiaremarkable regularity in the action of its gentleoscillations. The
latter are much more-easy'to study than the movements ‘of the more in-
dented and irregular peninsulas of Europe, and are also‘ better known:
since the epoch when the illustrious Darwin noted the fact that a great
part of South America was constantly rising, servants and observers have
only had to conﬁrm the result of his investigations.
It is principally on the coasts of Chili that the traces of the general up-
heaval of the country are quite self-evident. Round every headland, at


\
Fig. 225. Coasts of Puerto San Jorge.
' the outlets of many of the valleys which cut deep into the mountainous
masses on the coast, former sea-beaches may be distinguished, on which
shells of the present epoch, like those of the creatures which are now liv'‘
ing in the neighboring bays, are scattered about or even heaped up in
thick layers. These beaches, which are separated from one another by
cliffs or escarpments of various heights, resemble the steps of a gigantic
staircase. From these it may be readily seen that the coast was not
raised by any uniform movement, and that intervals of comparative re-
pose haveelapsed between each of the stages furnished by the growing
mass of rocks. On the hills of the Isle of Chiloe, Darwin found heaps of
modern shells at a height of 347 feet. On the north of Conception, several
lines of level out out by the waves during the present period are found at
an elevation of 600 to 1000 feet. Near Valparaiso these levels are no less
than 1295 feet above the level of the sea; but north of this town they be-
come lower. At Coquimbo they scarcely exceed 110 feet, and on the fron-
tier of Bolivia they are only 65 to 80 feet above the sea-level. Thus the
rising action of the rocks is especially developed in those regions of the
ELEVATION OF THE COASTS 0F CHILI AND PERU. 551
sea-coast which are in the same latitude as the loftiest summits of the
Chilian Andes—Aconcagua,Maypu, and Tupungato. We may infer from
this that these high peaks indicate the axis of the portion of the upheaved
crust, and that the mountains themselves tend to increase more rapidly
than the plateaux and shores situated below them. In fact, in Chili, as in
Norway, the terraces which overlook former bays or the mouths of val-
leys are not horizontal, as they appear to be; they rise gradually toward
the mountains, and increase in height as they recede from the present
coast. The upheaving force acts, therefore, with more energy under the
Chilian Andes than under the rocks of the adjacent coast. ‘The white
summits are gradually mounting up into the sky.
ft.
364 Y 301 ft. , I -
\ 68 f,
\ NW‘ 22 m

Fig. 226. Coasts of Ooquimbo.
Trigonometrical measurements carried on for a long series of years will
some day enable us to recognize this increase in the giants of Chili, and
their upward progress into the regions of eternal snow; but, up to the
present time, the only calculations which have been made on the subject
of the rapidity of the upheaval of the Andes are based merely on the study
of the sea-shores extended at their base. Comparing the present state of
things with the evidence derived from history, Darwin proves that, during
seventeen years, between 1817 and 1834, the ground at Valparaiso has
risen 10 feet 7 inches, or about 7%,- inches a year. This rather rapid move-
ment was preceded by a state of comparative inaction, for, from 1614 to
1817, more than two centuries, the elevation of the shore, as proved by an
examination of the localities, certainly could not have exceeded 5 feet 11
inches. At Coquimbo, Conception, and .the island of Chiloe, the emerge-
ment of the shore has taken place still more slowly. But, however im-
perceptible the phenomenon may be, it is none the less taking place during
the course of ages, and must ultimately'completely change the aspect of
the American coasts. Several ancient ports which were once. frequented
are now inaccessible; other harbors have been formed, thanks to the'fresh
‘protecting points which have emerged. Numerous islands, always desig-
nated by the Indian name‘lmapz', have become promontories.
The indications of a gradual upheaval are equally visible on the coasts
of Bolivia and Peru. In" the eastern zone of the Desert of Atacama the
ground is covered at considerable heights. with shells and saline eﬂlores-
cence, and seems as if it had 'beenabandoned by the ocean only the day
before. Above Cobija, Iquique, and several other'coast towns, stages are
marked outsimilar tothose at Coquimbo, and, like the latter, were once
washed by the water ofthe Paciﬁc. In front of Aricathesea has receded
165~ yards in the space of forty years,- and the merchants of the town have
been, in consequence, compelled to len'gthen'their landing-stage. But in
552 THE EARTH. -
an
front of Callao, on one of the cliffs of the island of San Lorenzo, a most in-
teresting proof has been found of the elevation of the shore during the pe-
riod it was inhabited by man. At a height of 85 feet above the sea, Dar-
win discovered, in a bed of modern shells deposited on a terrace, vroots of
l
1200 ft.
‘ 1197 ft.

ig. 227. Valley of Rio Santa Cruz.
////
sea-weed, bones of birds, ears of maize, plaited reeds, and some cotton
thread almost entirely decomposed. These relics of human industry ex-
actly resemble those which are found in the huacas or burial-places of the
ancient Peruvians. There can be no doubt that the island of San Lorenzo,
and probably the whole of the adjacent coast, have risen at least 80 feet
since the Red Man inhabited the country. It nevertheless appears that in
our days the ground on which Callao stands has again sunk, for the place
where the ancient town stood is now in great part under water. This de-
pression'is doubtless merely local, and only temporarily affects the gen-
eral ascending movement of the coast; for farther to the north, at Colon
and at Santa Marta, and several other points of the coast of New Granada,
the ground has visibly risen sinceEuropeans ﬁrst landed on the continent.
By admitting,-however, that Callao forms, in fa‘ct,~the northern-limit of the
area’ of upheaval, it results that the mass. raised presents from north- to
south a length of at least 2480 miles. It is almost equal to the distance
from London to Tobolsk..
. The movements of the eastern coast of South America which vare at pres-
ent going on have not been recognized so certainly as those~ of the west-
ern shore, doubtless on account of the extremely slow rate at which they
proceed. An investigation of geological facts proves that the ground rose
during the post-Pliocene period—that is, during the age of shell-ﬁsh still
existing, and of the great animals which were the contemporaries of our
ancestors, the megatherium, the mastodon, and the glyptodon. The Ar-
gentine .pampas have preserved the uniform appearance of the ocean which
once covered them. The parallel terraces of Patagonia, extending for
more than 500 miles, vary but a few yards in height along all the points
of their immense development, and the arms of the sea which wind in be-
tween the terminal promontory of America and the Tierra del Fuego re-
tainall their ancient outlines. At the present time-this portion of the
continent appears to be oscillating in a contrary direction, and to be sink-
ing by an imperceptible movement toward the level of the Atlantic. At
the foot of the high cliffs of Patagonia the‘ sea is incessantly-increasing at
the expense of the continent, and, although the breakers are not possessed
of force suﬂicient to demolish the rocky beds for more than 13 to 16 feet
below the surface, the depth of the sea nevertheless augments with an
OSCILLA TIONS 0F 180-UTE AMERICA. 5553
even slope, in proportion to the'distance from the shore, even over the site
of the-former cliffs. The bed-of the sea must therefore be sinking, and
with it the enormous mass of the plateaux which, during the recent period
of the great mammals, rose with such marvelous regularity.
On the coast of Brazil, especially at Bahia, various recent depressions
seem to indicate that there also the surface of the continent is regularly
sinking. The ascertained facts were not, however, sufficiently numerous
to justify any categorical assertion, until Professor Agassiz, in company
with some other geologists,'undertook his recent exploration ~'of-the River '
of ‘the Amazons. In the ﬁrst place, he veriﬁed the remarkable fact that,
in spite of the enormous quantity of sediment drifted down by its current,
this river does not form any deposits at its mouth. Instead of throwing
out’into the ocean a long peninsula of alluvium, like that of the Mississip-
pi, or at least forming, beyond the regular coast-line, a delta similar to
those of ‘the Rhone, the Nile, or the Po, the Amazon, on the contrary,
widens out in a large gulf toward the sea, and, in the great estuary, it is
difﬁcult to say exactly where the mouth, properly so called, commences.
The banks of the river, and the islands which lie in its outlet, are not com-
posed-‘of alluvium brought down'by' the current of fresh water, but are all
formed of rock‘with horizontal strata deposited by the water of the river
at some former epoch, and long since solidiﬁed. Thus, in the contest which
takes place in the estuary of the Amazon, as in'every other river-mouth,
between the currents of fresh and salt water, between the ﬂuviatile allu-
vium and the erosions of the sea, the latter always prevail. ‘Instead of en-
croaching on the ocean, the valley of the Amazons has been invaded by
the latter for at least 300 miles; for the geological study of the ground
on the two shores of the estuary proves that rocky layers, exactly'similar'
to those farther up stream, exist on the coast as far as the valleys of the
Itapicuru and the Parnahyba. These two rivers once fell into the Ama-
zon, but, in consequence of the erosion of their shores and those of the
great current which they joined, the sea has advanced, as it were, to meet
them, and they have thus, by degrees,- become entirely independent‘ of the
Amazon system. In a similar way, the stream of the Tocan-tins is now
only indirectly-connected with the great central'river, and‘soon'er or later
itmust ultimately become isolated,'as the Itapicuru and the Parnaliyba
already'are. The ‘action of erosion, caused doubtless by a c'onstant'sink-
ing of the ground, is still continuing. The shores‘ are noticed to recede all
round the estuary at Maranhao, at Piauhy, at‘Macapa, and on‘ the ~coasts
of Marajo. On the shores of the latter island, near Soure, a wide gulf, into
which ﬂows the Igarape Grande, has recently been form'e‘dacros‘s a forest
for a space of more than '18 miles from bank to bank.' The rocks in the
vicinity, which once rose above the sea-level, are gradually becoming cov-
ered. "At Braganca, the‘ bay, which used to advance scarcely a mile and a
half into the land, now penetrate'sfor nearly vﬁve miles. _ The light-house
of Vigia, which was built at some distance from the‘ sea, was wa very few
years afterward washed by the’waves. A signal-mast,which was set up,
554 THE EARTH.
in December out of reach of the water, was surrounded by the sea in the
June following. Facts of this kind render very probable‘the existence‘ of
a see-saw movement, which is upheaving all the western coast of America
from the island of Chiloe to Callao, and depressing the eastern side of the
Argentine Andes, of Patagonia, and Brazil. Thus a large portion of the
South American continent is constantly gaining on one side that which it
loses on the other, and is gradually making its way through the ocean in
a westward direction. Agassiz assigns to this phenomenon of _ displace-
' ment a very ancient origin, for in his view the Antilles, which once formed
the isthmus joining the two Americas, have been gradually submerged,
and the rivers of Guiana, once tributaries of the Orinoco, have become in-
dependent rivers. ,
In North America the vertical oscillations of the ground have not been
recognized over so considerable a length as in the southern continent, but
the few observations which have been already made on some points of the
coast, in California as well as round the Gulf of Mexico, render the hypoth-
esis very probable that" a general upheaval is taking place, to which one
of the parallel chains‘ of the Rocky Mountains, or of the Sierra Nevada,
serves as axis. The shore-belt of Tamaulipas and Texas increases so rap-
idly in width, not only because the south wind—which here blows almost
the whole year through—throws up a large quantity of sand, but also be-
cause the ground itself is rising. During eighteen years—from 1845 to
1863—the shores of the Bay of Matagorda have risen 11 to 22 inches- In
consequence of this gradual increase in the land, which is also proved by
the heaps of shells left far from the shore, it has been found’ necessary to
transfer the port of Indianola to Powderhorn,a place 4% miles nearer the
entry.* The peninsula of Florida is likewise being upheaved by some sub-
- terranean forces, as is proved by the coral-banks which are rising above
the level of the sea. Those mysterious elevations, the “ mud-lumps,” which
are scattered around the coast near the mouths of the Mississippi, the ori-
gin of which M. Thomassy has tried to explain by attributing them to the
pressure of subterranean water“t also appear to testify in favor of a gen-
eral upheaval of the region. _
The eastern side of North America is not rising uniformly, for, although
it is proved that the coasts of Labrador and Newfoundland are being
slowly elevated, it is also proved that other regions are sinking. Lyell
has ascertained that certain parts of the coasts of Georgia and South Car-
olina are subject to a movement of subsidence, and it is in consequence of
a gradual depression, no less than from a constant action of erosion, that
Sullivan and Morris Islands, at the entrance of Charleston Roads, are inces-
santly diminishing in area. In like manner, all that portion of the coast
which has as its centre the Bay of New York, and is bounded on the north
by Cape Cod, and on the south by Cape Hatteras, has gradually sunk un-
der the water of the Atlantic; and the subsidence has not yet ceased, at
least as regards the coasts of New York and New Jersey. An isle'which,
* Adolf Douai, Mittlzeilunyen von Petermann, April, 1864. i Vida above, p. 250. '
MOVEMENTS OF THE COASTS OF NORTH AMERICA. 5555
on a map of 1649, is marked down as possessing an area of 290 acres, is at
the present day not more than 100 square yards in extent at low tide, and
at high tide is entirely submerged. If we are to put faith in tradition,
the Straits of Hell Gate, which form the entry to the port of New York,
are of recent origin. Two centuries ago the natives related to the Dutch
colonists established in the island of Manhattan that, at the time of the
fathers of their grandfathers, it was possible to cross dry-shod from one
bank to the other, and that the sea only penetrated into the straits at the
' time of the great equinoctial ﬂoods. The land-surveyors employed on the
survey have calculated that the shores of the Bay of Delaware lose, on the
average, nearly eight feet every year. As far as it is possible to judge
from the observations made since the colonization of the country, the slow
subsidence of this portion of the American coast may be estimated at 231}
inches every century.*
In the vast island of Greenland,which lies in the axis of North America,
the progress of gradual subsidence, succeeding to a period of upheaval,
appears to be much more rapid. For a long time the Esquimaux have
been acquainted with this phenomenon, and the Danish colonists on the
western coast have also been enabled to verify the facts since the last
century by noticing, for a length of more than 620 miles, rocks, advanced
promontories, and, indeed, their own dwellings, gradually disappearing
under the inroads of the water. According to Wallich, this receding -
movement is still going on as regards the bed of the sea to the south of
Iceland, and the sunken land of Bass, marked out on all the old charts, has
really existed. On the north of Greenland, from latitude 76°, and in Gren-
nell’s Land, as well as in the other polar regions of the New World, the
directly contrary phenomenon is taking place. In his voyage undertaken
to discover the open sea, Hayes noticed on all the coasts the existence of
ancient sea-beaches, which had gradually risen to a height of 100 feet;
added to this, all the cliffs of the headlands had been polished up to this
height by the action of the ice.
* Cook, Geological Survey ,- Arnold Guyot, American Journal, March, 1861.
556 THE EARTH.
CHAPTER LXXXV.
REEFS OF THE SOUTH SEA.—DAR'WIN’S THEORY AS TO UPHEAVALS AND
DEPRESSIONS.
THE study of shores has not only enabled us to note the upheaval and
subsidence of great continental masses; it has also made known to savants
the oscillations of the tracts of ocean, for the numerous islands which lie
either alone or in groups in the Indian Ocean have served as evidence to
prove the movement of the ground on which they stand. Lines of erosion,
parallel terraces, banks of modern shells, and all the other marks of the
former presence of the water, point out, in each of the islands of the Pa-
ciﬁc, as well as on the coasts of Europe and the New World, the various
upheavals which have taken place. But, in addition, most of these islands
are surrounded with living girdlesof corals, which exactly measure all the
changes in level, either elevation or depression, to which the shores are
subject. The discovery of this fact, that the terrestrial oscillations are, so
to speak, rendered visible by the work of polypes, is doubtless one of the
most important achievements of modern geography; and it is to the pa-
tient investigations and sagacity of Darwin that science is indebted for it.
By comparing his own observations with those of the explorers who pre-
ceded him, the English geologist has been enabled to point out, just as if
he had witnessed them with his own eyes, the various movements which
raise or depress the bed of the ocean, over an area as great as that of the
two continents of Europe and Asia.
All the travelers who have crossed the South Seas have been struck
with astonishment at the sight of the reefs raised by the polypes in the
midst of the water. Some of these reefs circle round at a distance from
islands, or even archipelagoes ; they then form barriers of coral. Others,
situated far from any land, are distributed in the shape of rings, or of
more or less elongated crescents, round lagoons or bays remarkable for
their pale green water; these are the atolls. In those parts of the ring
where the constructions of the polypes and madrepores have not yet
reached the surface, the waves which ﬂow over the submarine bar rise in
foamy breakers; in other parts of the reef there are just visible above the
waves rocks of a dazzling white or a delicate pink hue. Next comes a
semicircular range of islets, like Druidical stones set up by giants in the
open sea. Lastly, upon the emerged group which occupies that portion
of the atoll which is most exposed to the violence of the waves and wind,
cocoa-nut trees and other tropical growths wave in the air, either in mere
groups or in regular groves. This is the most common form of the reefs
among all the thousands of atolls which are dotted over the South Seas.
ATOLLS, OR CORAL-BEETS. 5 57
12°5'


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When these coral-banks have not as yet reached the surface, their position
is only pointed out by a circle of breakers; those that have attained the
last stage of their development form a circular grove, which, seen from
above, would look like a coronal of leaves ﬂoating on the blue. water.
How have these wonderful reefs been raised? As was long ago proved
by Ohamisso, the French traveler, the polypes love to build in the midst '
of water which is breaking into foam; it may therefore be readily under-
stood that wherever a‘ submarine bank exists, the coral-reefs assume, like
the breakers themselves, a more or less annular form. But in spots where
the sounding-line reveals no shallows near the atolls, how have the polypes
been able to, raise from the bottom of the abyss their calcareous habita-
tions‘? In order to explain this phenomenon, scientiﬁc men once hit upon
a strange hypothesis; they looked upon every atoll as the circumference
of a crater, which the submarine forces of the globe had raised up to a dis-
tance of a few yards from‘ the surface, so as to form a base to the opera—
tions of the polypes. Although this explanation might be true enough
for a very limited number of atolls, it would be incomprehensible how
thousands and thousands of volcanoes should have been elevated to the
same height below the level of the sea. Nor could it be understood why
the craters of these supposed volcanoes should so often assume very elon-
gated forms. Lastly, it would be impossible to conceive why, taking into
account the multitudes of annular reefs, of which several archipelagoes
5 5 8 THE EAR TH.
are composed, and especially the double range of the Maldives, 465 miles
long by 50 miles broad, no atoll has ever distinguished itself by an erup-
tion of lava or ashes. -


t .1, ,
\,\\§-lfé_’;./2§ Sig-E72 -'
“’ 1' ,,, ¢\_../


. I ‘Fig. 229. Atollof Ebon.
.The form of these reefs, therefore, has no connection with volcanic phe-
nomena,properly so called, and, like so many other facts in the terrestrial
history, can only be explained by being attributed to slow movements of
the surface. The subsidence. of the bed of the sea will account for the
formation of atolls and-barriers of reefs; on the other hand, a gradual ele-
vation of the ground-explains the position of the corals which fringe the
shore at a certain height above the'waves. Thus, whether they rise or
sink, the reefs formed'by the polypes may serve as a measure of the ver-
tical oscillations to which continental coasts, islands, and even the abysses
of the sea are subject. . l '
. It is easy enough-to verify the movement‘ of land which is rising, as, in
this case, we see the banks of coral resting upon the beach, and sprinkling
with their '(lébrz's that portion ‘of the shore which is‘ above the level of the
OS CILLA T I ONS OF THE SEA-BOTTOM. _ 559
sea. - Often, too, the channels can be distinguished which once separated
them from the coast, and on the high ground of several islands calcareous
banks are found, which evidently owe their origin to polypiers. with re-
gard to the coral islands which are not included in the area of upheaval,
they are surrounded by annular reefs, constructed in the midst of the'
water at some distance from the shore... v\Vhen this distance is but small,
and the coral banks are not very thick, there is nothing to prove that the
level of the coast has changed; for the observations-of scwants prove that
polypes can live and build their rocky habitations at a depth of from 100
to 150 feet. Generally, however, the walls of coral and calcareous sand,
which form the outer sides of the reef, descend much lower. Most of them
lie on slopes composed of their own debris, and are immersed in the sea at
a slope of 45° to depths of several hundreds and even thousands of feet.

-
v[,l /
a, ,l
I,"

,l
I (v. ., (I,
,7.’_ x, . .
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Fig. 230. Isle of Vanikoro.
.
It is evident that in a case like this the bed of the ocean must have sub-
sided. The polypes commenced their work of construction a few yards
below the surface, and then, in proportion as the ground sank on which
their coral ediﬁce stood, they continued to build upward and upward, in
order to approach the light. The mountainous islands, which they sur-
round with their reefs, gradually diminish in height, leaving between them-
selves and the barrier of coral a channel of increasing width and depth.
The time is approaching when, ﬁrst having been reduced to the state of
islets, they will become divided into isolated peaks, which one after the
other will be submerged, and disappear in the sea. Then all that remains
560 THE EARTH.
will be an atoll, inclosing within its increasing walls a lagoon, in'which
calcareous debris is slowly gathered; narrow beaches and reefs, like the
pieces of wreck still ﬂoating above a founder-ing ship, surround the spot
where the island has been swallowed up. The natives of the atolls of
Ebon relate that they have heard their fathers say that an elevated island,
the hills of which were shaded by cocoa-nut trees and bread-fruit trees,
once occupied the greater part of the lagoon. The isles disappeared, but
the reefs are still maintained just above the level of the water.*
When the subsidence of a Whole archipelago of submarine peaks takes
place slowly and regularly, it may often happen that the sea, striking
forcibly against the outer walls of the reefs, breaks this barrier, and hol-
lows out for itself a free passage across the central lagoon. Then the
banks of coral rise in the midst of the breakers on both sides of the newly-
formed channel, and the original atoll is thus divided into two annular
isles. In proportion as the submarine mass sinks, other ruptures of the
same kind take place in each of the isolated fractions of the atoll, and the
archipelago of reefs is ultimately composed of a considerable number of
islets, which, in their turn, are also broken up. In this way are formed
these wonderful groups of annular banks arranged in immense ovals.


, ////1, . , ,1, I/I//////”///%Z////{///////;///////////;///[7//r¢- _
I
/
LEJW-yw‘ .
The Atoll Ari of the Maldives is an example of this astonishing forma-
tion of coral islands. If we could represent in a drawing the shapes that
the ensemble of the groups has successively assumed during the course of
centuries, we should obtain a series of curves similar to those which geog-
raphers avail themselves of to delineate the slopes of a mountainous
group. Sometimes, however, the movement of a depression is so rapid
that the sea does not conﬁne itself to opening channels here and there
across the atolls. The coral insects do not build fast enough to maintain
their dwellings on a level with the surface; they gradually perish, and


Fig. 231. Section of Isle Vanikoro.


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/
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r J
‘ I
AWL.‘ -vgisr
=-'


-'\.-. v. .:A ‘-
bsidin g.
Z'I-X-l'). . . b.
Fig. 232. Growth of Coral on a Mountain slowly su
* Doane, Nautical Magazine, Sept, 1863.
ATOLL ARI * PL.XXIV.


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OSCILLATIONS OF THE SEA—BOTTOM ~ 561
the atolls, which, layer by layer, have been raised by innumerable genera-
tionsof constructors, disappear, and form annular shoals. Of this kind is
the great bank of Chagos, south of the Maldives, which the sounding-line

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> 7 “ --.
- ~
\
‘,7


az/
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,,Q -
'rlzy


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Fig. 233. Great Bank of Chagos.
shows to have once been one of the largest atolls in the Indian Ocean. In
the group, indeed, of the Maldives, several islets, which were recently in-
habited and green with vegetation, are now slowly being swallowed up
beneath the surface of the water.*
* Darwin, Coral Reefs.
N _N
562 ' THE EARTH.
CHAPTER LXXXVI.
THE GREAT AREAS OF UPHEAVAL AND DEPRESSION.-—MOBILITY OF THE
SO-CALLED RIGID CRUST OF THE EARTH.
OwING to the evidence which is furnished by coral reefs, which evidence,
however, is supplemented at a large number of points by other indications,
it is now possible to ﬁx almost exactly the limits of the areas both of up-
heaval and subsidence, which divide between them the hemispheres in-
cluded within the coasts of South America and Africa. While the group
of the Sandwich Islands is rising, as if it were still subject to the forces
which are elevating the American continent, a gradual subsidence may be
noticed in the archipelagoes of the central basins of the South Seas, the
Bass and Society Islands, and also the Gilbert, Marshall, and Caroline Isl-
ands; in one word, all this “ milky way” of islands, islets, and reefs, which
extends diagonally across the Paciﬁc for a length of more than 9000 miles,
and with an average width of 1200 miles. These islands are the remnants
of a former continent, which has sunk down, with the people whp inhabited
it. Since the ﬁrst European navigators visited these seas, several islands
have disappeared, and others, such as Whit-Sunday Island, have consider-
ably diminished in size.
In a parallel line with this great area of depression, which is at least
twice as large as Europe, lies a wave of upheaval which coincides with
the semicircle of volcanoes running round the western side of the basin
of the South Sea. New Zealand, which is situated on the southern end
of this rising, and is based on a long furrow of ﬁre, is rising in certain
places so considerably, that English colonists, who have only arrived there
a few years, have been able to notice that the headlands increase in height,
and that banks of rocks are gradually obstructing the entrance of the
ports. At the commencement of the present geological epoch, the moun-
tains of Zealand were at least 1900 feet lower than they now are, and the
ice-ﬂees, from a continent situated to the east, ﬂoated with their load of‘
erratic- rocks on to the incipient islets, and were there stranded. But since
that time the New Zealand Alps have risen ten successive times, as is
proved by the ten terraces lying in stages on the sides of the mountains.*
Even at the present day the latter are still increasing. In ten years the
shores at Lyttlcton have risen three feet. The New Hebrides, the Salomon
Islands, the northern and western coasts of New Guinea, the numerous isl-
ands which compose the great Sunda Archipelago (which latter are proved
by their altogether Asiatic fauna, as studied by Wallace, to have once
* Julius Haast. F. von Hoehstetter also asserts that the eastern coast is being upheaved,
but he thinks that the western coast has sunk, and that the axis of a see-saw movement passes
through the two islands.
AREAS OF UI’HEA VAL ‘AND DEPRESSION. . 563
formed a portion of the neighboring continent), are all now rising, after
having quite recently subsided, and banks of coral emerging from the sea
are incessantly being added to the shores.
At the angle of the Asiatic continent the wave of elevation divides in
a fork, so as to run round the Chinese Sea, which is bordered by the
gradually-depressed coasts of Cochin-China and Tonquin. To the north
the upheaved region is continued toward America by the Philippine, For-
mosa,* Liou-Kieou Islandsfr and Japan; that is, all the islands from Borneo
to Kamtschatka, through which passes the ﬁssure of eruption of the vol-
canoes of the Western Paciﬁc. Quite recently Russian travelers have dis-
covered, on the coast of the great island Saghalien, heaps of modern shells,
lying not far from the shore, on beds of marine clay, and also former bays,
wlﬁch are now converted into lakes or salt marshes. In like manner, it
has been proved that the regions of the Amoor are gradually being up-
heaved; for, in order to maintain its level, the river has constantly to
hollow out its bed between the cliffs, and on the plateau by the river-side,
semicircular sheets of water may still be seen, which are evidently former
windings of the Amoor.
On the west of the Sunda Archipelago, Sumatra, fringed on its eastern
coasts by peninsulas which once were islands, and, indeed,"still bear the
name (poulo), seems to be the starting-point of another movement of up-
heaval, which embraces all the coasts situated round the Bay of Bengal.
The Nicobar and Andaman Archipelagoes are gradually rising. Ceylon
is likewise rising; at least part of it, as is proved by the banks of coral
lying in gradations one above another on the hills, and also by the tradi-
tions of the natives. But it is probable that the extremity of the isle is
undergoing a slight see—saw movement, for Adam’s Bridge, the chain of

77°
12. Straits 2f , Palk


9°
77° Lot‘ ram
Fig. 234. Bridge of Adam or Rama.

shoals which joins Ceylon to the Coromandel-coast, which, too, according
to the legend, formerly served as a road to the triumphal army of Hanou-
* Ferd. dc Richthofen, Zeitsclzrt'ft der Geologisclzen G'esellsclzaft, vol. xii.
'l' Swinhoe, North China Branch of Asiatic Society, No. 11,May,1859.
n
§
564 THE EARTH
man, the monkey, appears to have once been a perfect isthmus. Scarcely
three centuries have elapsed since the peninsula of Rameseram, whither
thousands of Hindoos went every year in pilgrimage, has become detached
from the main land, and formed an islet, like the ruins of a fallen pier.*
Farther to the north there has been an upheaval. If we may put faith in
the Brahmin legend, Veruna, the god of the sea, two thousand three hun-
dred years ago, ordered the waves to abandon the low plain of Malayala,
which extends along the Malabar coast between Mangalore and Cape Co—
morinql WVith regard to the basin of the Lower Ganges, it appears to
form a part of the area of upheaval of the Bay of Bengal, and, with all
its southern part, to be gradually rising; for the tributaries of the river
which traverse this region—the Coosy, the Mahanada, and the Scene—-
are constantly shifting their mouths farther up-stream. The last-named
water-course has retreated more than four miles during the last eighty
years. According to Mr. Ferguson, at the conﬂuence of the Gauges and
Gogra we ﬁnd the western limit of the wave of upheaval,which commences
at the islands of New Zealand, 8000 miles away toward the southeast.
Almost the whole of the space occupied by Australia and the Indian
Ocean, properly so called, is situated, like the central basin of the Paciﬁc,
in an area of gradual depression. While, from New Guinea to Sumatra
and the Philippines, a new continent is emerging from the water, the old
Australian continent, so remarkable for its fauna and its ﬂora, which seem
to belong to some former geological period, is gradually sinking down, to-
gether with the surrounding isles—the Louisiade Archipelago, New Cale-
donia, and the reefs of the Coral Sea. Up to the present time, one portion
alone of Australia is known to be experiencing a continuous movement of
elevation—the district of Hobson’s Bay, near Melbourne, which, according
to M. Becker, is rising at the rate of about four inches a year. Be this as
it may, the great mass of the continent is imperceptibly sinking, and the
polypes which surround the coast ‘are compelled to heighten their reefs
more and more]; The Indian Ocean, to the west of Australia, is almost
entirely devoid of islands; but all those that emerge from the depths of
the sea over a space of more than 3700 miles in width are atolls, which
would be slowly submerged if the polypes were not incessantly building
up the edges of the reefs. Among these islands are the celebrated Keel-
ing Atoll, which Mr. Darwin has studied so proﬁtably for science, and the
Maldive Archipelago, that double chain of submarine mountains, every
peak of which is crowned with a coral tiara raised above the water.
Thus the space which extends over two thirds of the circle of the globe,
from the eastern coast of America to the western shores of the Indian
Ocean, presents two areas of upheaval and two areas of subsidence suc-
ceeding one another from east to west. Next to the American continent,
which is slowly rising, we have the innumerable low-lying islands of
Oceania, the greater part of which would have long ago disappeared if
* Ritter, Erdlcunde. ‘I’ Duncan, Asiatic Researches, vol. v. ; Von Hoﬂ“, Verd'nderungen.
I Gregory, Philosophical Society of Brisbane.
ELE VA TION OF PARTS OF 0 CEANIA AND AFRICA. 5 6 5
it were not that the labor of the polypes has maintained them on a level
with the waves. N ext, there is developed, in a vast semicircle, pointed
out from afar by its volcanoes, a large zone of isles and sea-coasts which
are gradually rising, as if to replace in the future the old continent of
Australia. Lastly, the same causes which are depressing the bed of the
Central Paciﬁc are likewise lowering that of the Indian Ocean, with its
shallows and its reefs.
Beyond lies the enormous mass of Africa, the coasts of which have not
yet been explored by scientiﬁc men, except, perhaps, over some small ex-
tent. Nevertheless, suﬂicient observations have been made to warrant
us in considering Eastern Africa and the islands adjoining it as a third
wave of upheaval, corresponding with those of America and the Sunda
'Islands. The banks of coral which surround Mauritius Island, Reunion,
and Madagascar, and those which border the African coast from Mozam-
bique to Mombaze, bear witness to the elevation of the ground. In like
manner, the southern coasts of the Red Sea still exhibit at various eleva-
tions evident traces of the recent presence of sea-water. Most of the trav-
elers who have visited these places, Ferret and Gallinier, Riippel, Salt,
Valencia, and Niebuhr, have been struck by the sight of reefs emerged
from the sea, former sea-beaches white with salt, and bays which are now
left far inland, and are converted into marshes. Quite recently M. Lejean
has recognized the fact that, by the upheaval of the ground, the former
port of Djeddah is completely separated from the sea, and has become a
mere lake; this port, at the time of Niebuhr, was still accessible to ships
of small tonnage. The inhabitants of the coast assert that both the bed
and the shores of the Red Sea change every twenty years.
Not far from the Isthmus of Suez, on the north, the slow elevation of
the ground is replaced by a contrary movement; but on the western side
it is not yet known where the ﬁrst signs are to be found of any rising of
the ground. The observations of M. Eugene Robert on the coast of Sene-
gal would perhaps show that this portion of Africa is in an area of up-
heaval. It is, however, a fact, that beyond the African continent, Madeira,
St. Helena, and probably the Canary Islands, the remains of the ancient
Atlantis, are gradually sinking into the ocean. All these facts tell in favor
of the hypothesis according to which the equatorial position of .the circum-
ference of the globe presents three waves of upheaval, separated from one
another by three intervening depressions. The centre of each depression
lies in the middle of an ocean; the three upheaved regions are the great
Sunda Archipelago, a kind of continent in process of formation, and the
enormous masses of Africa and America. . ~ '
As will be understood, these regular oscillations must take place in obe-
dience to some general law still unknown, although none the less certain.
We can not consider them, with Berzelius, to ‘be nothing .but mere acci-
dents, produced by the subsidence or the rupture of the terrestrial crust.
Neither must these regular movements be confounded withvolcanic trem-
blings, for they are distinguished from the latter by their excessive slow-
566 THE EARTH.
ness, as well as by their character of generality. Moreover, all these facts,
whatever may be their origin, are determined by causes aﬁ'ecting the whole
mass of the planet. If earthquakes have their tides, as is said to be proved
by the greater frequency of these phenomena at the time of the full and
new moon, we can not doubt that the slow oscillations of the terrestrial
envelope also have their regular cycles. Only the reason of these secular
tides still remains unknown. Must we seek for it in some alteration of the
physical conditions of the globe, or in the revolutions of some astronom-
ical period? As far as regards these points, we are reduced to mere hy-
pothesis. Some day or other, when scientiﬁc men have observed all the
lines of level from the north to the south pole, and all the debris which
have been left by the sea, as it were so many precise measurements, on
sea-coasts and mountain-sides, we shall be able to exactly specify the di-
mensions of each wave of upheaval, and also what the impulsive force is
which actuates them. We shall then know whether the regions that are
elevated are always equal in extent to those that subside, and whether
the surface, like that of every vibrating body, presents certain “nodal
lines,” round which the'agitated portions arrange themselves in rhythmical
1 ﬁgures. We shall know, too, whether continents and seas, alternately ele-
vated and depressed as if by some secular tide, are slowly shifting their
positions round the planet, assuming therein various harmonic forms. Per-
haps even it will be proved that in the bowels of the earth an exchange
of solid particles is taking place similar to the circulation of the aerial and
liquid particles of the atmosphere and the ocean. The globe, a simple
mass as it is of condensed gas, is not entirely congealed; it has retained,
like every other body, some remains of its former ﬂuidity, and, just as in
a lump of metal coming out of a furnace, tire particles which compose it
never cease to turn slowly round and round one another.
Be this as it may, it remains an ‘unquestionable fact that an incessant
movement is causing an undulation in the so-called rigid crust of our
globe. The continental masses are still elevated through a long course
of ages; next, they sink only to rise again with slow and majestic oscilla-
tions. Scandinavia, which is at present rising, sank during the Glacial pe-
riod, and the population which at that time made it their abode were
forced to abandon their valleys step by step as they became converted
into fjords. In like manner, the Chilian Andes and the mountains of New
Zealand, which are at the present time increasing in height, previously
sank by degrees, the former 8000 and the latter 5000 feet, before they rose
as they are now doing. It is likewise proved that at a great number of
other points—in Peru, in Egypt, in North America, and in Greenland——
changes of the same nature have taken place during the present era of
geological history, without any violent revolution having thrown the earth
into confusion. Continents rise and sink as if through some gentle action
of respiration; they move in long undulations, which may be compared to
the waves of the sea; the far-reaching glance of science can already trace
out these undulations through the long lapse of centuries. “The time
OSOILLATIONS OF THE C’RUST OF THE EARTH. 567
will come,” says Darwin, “ when geologists will consider the quiescence of
the terrestrial crust through a long period of its history to be as improba-
ble as an absolute calm in the atmosphere during a whole season of the
year.”
In the universe every thing is changing and every thing is in motion,
for motion itself is the ﬁrst condition of vitality. In by-gone days, men
who, through isolation, hatred, and fear, were left in their native ignorance,
and ﬁlled with a feeling of their own weakness, could recognize in all that
surrounded them nothing but the Immovable and the Eternal. In their
ideas the heavens were a solid vault, a ﬁrmament on which the stars were
fastened; the earth was the ﬁrm, unshaken foundation of the heavens, and
nothing but a miracle could disturb its surface. But since civilization has
connected all the nations of the earth in one common humanity—since
history has linked century to century—since astronomy and geology have
enabled science to cast her retrospective glance on epochs thousands and
thousands of years back, man has ceased to be an isolated being, and, if we
may so speak, is no longer merely mortal: he is become the onsciousness
of the imperishable universe. No longer connecting the vitgty either of
the stars or the earth merely with his own brief and ﬂeeting existence, but
comparing it with the duration of the existence of his own race and of all
the beings who have lived before him, he has seen the celestial vault re-
solve itself into inﬁnite space, and has recognized the earth as nothing but
a little globe rotating in the midst of the “ milky way.” The ﬁrm ground
which he treads under his feet, and long thought to be immovable, is re-
plete with vitality, and is actuated by incessant motion; tlie very moun-
tains rise or sink; not only do the winds and ocean-currents circulate
round the planet, but the continents themselves, with their summits and
their valleys, are changing their places, and are slowly traveling round the
circle of the globe. In order to explain all these geologiealsphenomena, it
is no longer necessary to imagine alterations in the earth’s axis, ruptures
of the solid crust, or gigantic subterranean downfalls. This is not the
mode in which Nature generally proceeds; she is more calm and more
regular in her operations, and, chary of her might, brings about changes
of the grandest character without even the knowledge of the beings that
she nourishes. She upheaves mountains and dries up seas without dis-
turbing the ﬂight of the gnat. Some revolution, which appears to us to
have been produced by a mighty cataclysm, has perhaps taken thousands
of years to accomplish. Time is the earth’s attribute. Year after year
she leisurely renews her charming drapery of foliage and ﬂowers, just as,
during the long lapse of ages, she reconstitutes her seas and her continents,
and moves them slowly over her surface.
INDEX.
The references are throughout to the pages of the volume. An asterisk (*) indicates that the
, topic is pictoriallg illustrated. ‘ .

. America : North America,* 52.
Aar, ancient glaciers of,‘ 217.
Ablation of glaciers, 197.
Adam, bridge of,* 563.
Adelsberg, grotto of,* 257.
Adige, river and valley,* 211. Talus formed by tor-
rents)‘ 293.
Adour, river,* 345. Bars at its month, 366, 368.
Africa: Continent of, 60. Orographical map of,‘
67. Section across,* 115. '1‘ e Ethiopian pla-
teau, 116. _ River systems, 277.
vAiguilles, mountain peaks, 124.
Ain Musa, Wells of Moses, 231.
Aletsch, lacier of,* 208.
Alios an Brandes, 81. .
Alps, the: Alpine clubs, 119. Ratio , between
presses and summits, 135. Apparent chaos, 148.
iew of the system,* 149. An ethnolo ical bar-
rier, 149. Reads across, 150. Downfal s in, 160.
Snow-line of, 163. Glaciers of,‘ 207. Erosions
igﬁsggd Devastations by torrents, 292. Lakes
0 , .
Altitudes, diminish from equator to poles, 139.
Altenfjord, bank of,* 535.
Aluta, lake and deﬁles,’ 294.
Amazon River: Basin of,* 277. Course of, 280.
Compensation of ﬂoods,* 318. Its risings, 320.
- Amount of discharge, 378. - -
South America) 58.
Continents of, 59. River systems of, 275.
Amen-Daria, river,* 362. -
Anahuac, table-land of Mexico, 113.
Andes, the: General characteristics of, 153. (See
also Volcanoes.) _
Antarctic Continent, its place in continental har-
mony, 77.
Arctic Ocean, general characteristics, 77.
Arno, river, 332.
Artes'lan Wells : In the Sahara,* 95, 233. Theory of,
232. Some notable ones, 233. Temperature of,
233. Depths estimated by increase of tempera-
ture, 234.
Arveiron, river, sources of,* 199.
Ashes from volcanoes,‘ 469.
Am : Continental aspect, 64. orographical map
of,*71. Great plateaux of, 111. Mountain chains
of, 151. River systems of, 272.
Asphaltites, lake, 408.
Atacama, desert of, 105. '
Atlantic Ocean: General characteristics of, 76. Its
double basin, 76. Submarine volcanoes in,‘ 489.
Atolls, coral islands,’ 557, 560.
Auckland, volcanoes in,* 446. '
Australia : Its continental aspect, 64. orographic—
a1 map of,“ 73. Its river system, 278. A depress-
ed basin, 564. w ' a
' Avalanches, 169. Defensive works against, 171.
Avoca, valleypf,’ 195.
Axes, geolo cal, of the earth, 63. Their trans-
verse position 1n the two hemispheres, 75.
Bars of rivers,‘ 363. How removed, 366.
Bauerngraben, lake, 260. -
Basalt, 454. Basaltic columns, 456.
Bayous, 347, 349. ~
Black earth of Russia,‘ 85.

Blane, Mont, 148.
Bogs. (See Marshes.)
Bosphorus, channel of,*131.
Bot nia, gulf of,* 534.
Boulders, dispersion of,* 217.
Bear, ogne, valleys of erosion in,* 291.
Bran es and Alios, 81.
Brienz, lake,* 294. '
Bugors of the Caspian,* 404.
O
Cactus, 103. ‘
Callao, earthquake at, 510.
Campine of Belgium, 83. 3;’,
Carbonic acid gas from volcan'oesfASS.
Car athian mountains, destitute of glaciers, 211.
Gas mere, valley of,* 152.
Caspian Sea,* 404.
Caussade, lateau of,‘ 113. -
Caverns : nhabitants of, 253. TheMammoth Gave,
‘254. Chasms of Carniola,* 254. ‘Grotto of Lueg,*
255. Of Adelsberg,* 257. Of Planina,* 259.
Chao'os, great bank of,* 561.
Chilian, Nevado de,* 466.
Circle of Fire, the, 55. 4
Circle of inland lakes,* 55.
Circnmpolar Circle,* 54.
Climates : Changes in, 43.
continents, 75. '
Cluses, cuts in mountains, 132.
Cobi, desert of, 96.
Contrasts of in different
.Cogne, valley of,* 289. ~
‘Colorado, desert of, 103. Great canon of,* 153.
Cols, necks in mountain ranges, 135.
Columbia River, the, 275. . ‘
Continents: Formation of, 39. A lost continent, 42.
Harmonious arrangement, 46. Three double con-
tinents, 59. Term quadriﬁda,* 61. Continental
_ analogies, 64. General pyramidal form, 64.' Their
water-basins, 65. Circle of junction of continent-
all points,* 66. Contrasts between the conti-
nents, 69, 74.‘ Continental areas, 70. General
elevation of, 72. Counterpoises in, 74.
Contrasts and Harmony in Nature, 77.
Coral reefs,* 556.
Cordilleras, the, 155.
Coseguina, volcano,‘ 471.
Cosmogon : Laplace?s hypothesis, 24. Objections to
it, 27. indoo'le ends, 47. Greek legends, 48.
The world, accor ing to Homer,* 49. Muudus
tripartitusf" 62. - -
Craters of volcanoes,’ 448.
Crevasses in glaciers,* 182. -
Cutch, earthquake at,* 521.
Danube, river,’ 370.
Débouchements, law of, 136.
Dead Sea, the,* 407. -
Débris of torrents,’ 293, 321.
Deltas: In general, 346, 349. Of the Ganges,* 352.
Of the Nile,‘ 354. ' Of the P0,* 356. Of the Rhone,‘
357. Advance of deltas,* 359. a . .
Deluges, hypothesis of periodical, 67.
Demavend, crater of,’ 480. .
Deserts : Semicircle of,* 56. Characteristics of, 90.
The Sahara, 90. Of Egypt and Arabia, 95. Ol‘
5'70
INDEX.
Persia and India, 96. Of Cobi, 96._ Of Utah, 102.
01’ Colorado, 103. Of South America, 104.
Devil's Canon, the, 481. _ _
Dikes : Upon the Rhone,* 333. Upon the MISSIS-
sippi, 334. Upon the P0, 336. Natural dikes, 345.
Dombes, lake region of France,“ 386.
Downfalls of Mountains (see also Upheavals): Gen-
eral character, 159. Subterranean downfalls, 505.
Durance, river, 331. ' '
Earth, the: Its rank in the stellar system, 13. Form
and dimensions, 14... Metrical notation,.15.. Ro-
tation upon its axis, 16. Revolution around the
sun, 17. Distance from_ the sun, 17. Solar and
Sidereal year, 17. ‘Its orbit around the sun,* 20.
Great cosmical year, 22. Nutation, 22. Great cos-
mica] movement through space, 23. Probable
end, 23. Laplace's hypothesis "of its vformation,
24. Estimated thickness of crust, 28, 31. Theory
of a central ﬁre, 30. Geological history of the
earth, 32. Ideal pyramid mountain,* 33. Or-
ganic remains, 34. ' Fossils, 35. Oscillations
of its surface, 52.7. Mobility of its crust, 566.
Earthquakes (see also Volcanoes): General charac-
teristics, 500. Theories respecting earthquakes,
501. 'Relations to volcanoes, 503. - Subterranean
downfalls, .504. Artiﬁcial . earthquakes,* 505.
Earthquake at Lisbon, 507. In South America,
Sept., 1866,* 509. At Callao, 510. Atsea, 510.
Movements of terrestrial waves,* 511. Variations
caused by rocks, ctc., 513. ‘ Earthquake at Viége,*
514. ,Areas of disturbance,* 515. Characteristics
of shocks,- 516. Eﬁ'ectsnpon animals, 517. Sec-
ondary effects of shocks, 519. Springs, ﬁssures,
ctc., caused by earthquakes, 519. The Ruun of
Cutch,* 521. Periodicity of earthquakes,* 523.
Connection with meteoric inﬂuences, 524. Two
great classes of earthquakes, 526. Upheavals and
depressions caused by earthquakes, 526.
Eaux-Bonnes, peaks,* 126. ‘
Ebon, atoll of, 55S. .
Egypt (see also Nile): General notice of, 95. Up-
heavals and depressions, 544.
Elevation, inﬂuence upon temperature, 156.
Embarras of the Mississippi, 321. '
England, geological map of,* 37.
Equinoxes, the,* 20. , -
Eruptions (see also Volcanoes and Earthquakes): 0f
Etna, in 1865,* 420. Material thrown out, 433.
Their periodicity, 497.
Estavelles, supplementary springs,* 228.
Estom, lakes of,* 393.
Estuaries, 340.
Etna: Eruption of, in 1865,* 420. Former erup-
tions,* 425. Line between Etna and Vesuvius,*
437. Section ofEtna,*449. Cone ofEtna,*469.
Europe: Continent of, 60. ' Orographical map of,*
63. Its advantageous position, 70. Plateaux of,
72, 112. Central mountains of, 144. River sys-
tems of, 273.
Explosions in mines, ctc.,* 506.
Fayoum, E t,* 331.
Felon, cataigziliiﬁ 302.
Finland, lakes of,* 385.
Fire, central of the earth, 30, 31.
Floods. (See Inundations and Rivers.)
Fogs, dry, 84.
Fehn, dry south wind, 168. _
Forces, modifying the form of the universe, 44.
Forks of rivers,* 264, 266. '
Forests: A protection against avalanches, 171. Re-
lations toirrigation, 223. .
Fossils : Modes of preservation, 34. Order of their
creation, 36. " ~ -
Frumento, Monte,* 421.
Fumerolles of volcanoes, 434, 486.
Furos, net-works of rivers, 348..
Ganges, delta of,‘ 353.
Garda, lake,*'388. '
Gzgronne, river, sources of,” 274. Inundations of,
Gavarnie, mountains,* 126;

Gaves of the Pyreneesf‘ 376.
George's Island, 493
Geysers, the, 482.
Gietroz, glacier .of,* 190.
Gironde, the, 341.
Glacial period, the, 211, 219.
Glaciers: First and second orders of, 176. Move-
ments. of, 177. Windings of,*180. Cascades of,*
180. Slopes of, 181. Marginal crevasses,* 182. In-
tersecting crevasses, 183. Transverse crevasses,*
184. Longitudinal erevasses,f‘185. Terminal cre-
vasses,* 186. . Superﬁcial torrents,* 187. Ohasms
ﬁlled with snow,* 188. Ponds in, 188. Glacier of
Giétroz,* 190. ‘ Debris on laciers, 192. Glacier
tables,* 193. Moraines of g aciers,*194. Glaciers
of Geisberg and R0thmoos,* 194. Mud-ribbons
in the Mer-de-'Glace,* 196. Measurements of
movement, 197. Ablation of, 197. Sub-glacial
streams, 198. Terminal arches of glaciers, 199.
Contrast between ice and vegetation, 200. Gla-
ciers of Langthal and Gur_ l,* 201. Advance and
retirement of glaciers, 20 . Appearance of the
glacier-bed, 204. Glacier of Vernagt,* 204. DIS-
tribution of glaciers, 206. Glaciers of the Alps,*
207. Glacier d’Aletsch,*208. Glaciers of Central
Europe, 210. Of the Himalayas, 211. Of Scandi-
navia, 212. Of the Arctic regions, 213. Paucity
of glaciers in tropical America, 215. Antarctic
glaciers, 215. Diminntion in size of European
laciers, 216. Ancientw tropical glaciers, 220. In-
2p2ence of glaciers on the circulation of water,
Goldau, overthrow of,* 161.
Golenas. (See Dikcs.)
Gothard, Mont St., 146, 148.
Graham’s Island,* 495.
Greenland, glaciers of, 213.
Gross—Glockner, the,* 126.
Grottoes. (See Caverns.)
Guano, 105.
Guiding-banks for rivers,* 315.
Gurgl, glacier of,* 201. , -
Guscha, Piz-a-Lun de,* 127.
Gypsum, amount thrown up, 244.
Hawaii: Section of,* 438. Volcanic craters in,*445.
Heaths: Of Holland and Germany, 83. Conﬂawra-
tions in, 84. Extent of heath-smoke in 1857, 84.
Himalaya Mountains: The apex of the earth, 63.
Their geographical position, 151. Peaks of, 152.
Snow-line of, 165. Glaciers of, 211.
Hoang-Ho, river, 338. .
Huiduck, lakes of,* 412.
Humidity of the American continent, 97.
Hydrographical systems, general view of, 271.
Ice: Transformation of snow into, 173. Melting
oint of, 175. Banded structure of,* 175. Break-
ing up in rivers, 322. Formation in lakes, 396.
Ice-period, ancient, 219. .
Igharghar river, the,* 288.
Indian Ocean, general characteristics of, 7 7.
Inundations: Alpine, 189. Of the Rhone,* 322.
General features ‘of, 324. Means of preventing,
325, 328. Growth of land byﬁ 326. .
Isalco, volcano, 458. I '
Isére, river,* 335. , .
Islands: How formed in rivers,* 306. Curve of vol-
canic islands,* 428. Atolls, or coral islands,* 557.
Java, volcanoes of,* 451.
Jordan, theﬁ 408. ‘
J orullo, volcanic hill,* 443. , ‘
Jum Mountains: Their general aspect,* 145. Com-
pared with the Alps, 146. Valleys and combos
of,* 147, 390. .
Kaimeni, volcanic island,* 492.
Karaboghaz sea, 403. .
Karakorum mountains, 151.
Kilauea, volcano)? 461.
Kinchiujiuga, peak, 153.
Kouen-Lun, mountains, 151.
Kurile islands, volcanoes of, 427.
INDEX.
Lakes: Filled up by torrents,‘ 289, 295. Lakes of
Aluta Thun, and Brienz,* 294. Lacustrine lakes,*
296. Lake of Geneva,* 297. Drying up of lakes,
380. General formation oflakes, 383. Lakes of
Finland,* 385. Lakes of the Dombes,* 386. Alti-
tudes and depths of Italian lakes,‘ 387. Of Swiss
lakes,* 388. Lake Garda,‘ 388. Lake of Neucha-
tel,* 389. Lake of 00,’ 391. Lakes of Nors Elf,*
392. Lakes of Estom,‘ 393. Various phenomena
of lakes, 394. Storms u on lakes, 395. Currents
in lakes, 396. Formation of ice in lakes, 396.
Lakes as regulators of rivers, 399. Fresh and
salt lakes, 400. The Caspian sea or salt lake,*
401. The Karabo haz, 403. The Dead Sea,*407.
Lake Van, 410. he Great Salt Lake of Utah,
410. Lakes of Huiduck,* 412.
Land: Relative proportion to water on the earth,*
50. The oceanic hemisphere} 51. The conti-
nental hemis here,* 52. Lbs circumpolar circle,*
54. The circ e of inland seas and lakes,*55. The
semicircle of deserts)‘ 56.
Landes: Of Gascony,* 81. Stilt-walking on, 83.
Landes of northern Europe, 85. The French
landes, 344.
Lan vthal, glacier of,* 201.
Lsélface, hypothesis of the formation of the earth,
Lava: Composition of, 435, 453. Cones of lava,*
447. Sources of lava, 458. Flow of lava, 462, 466.
Levees upon river banks, 334. .
Lisbon, earthquake at, 507.
Llanos, of South America, 99.
Loire, river, 286. Floods of, 334.
Luchon and Val d’Aran,* 142.
Lys, river,* 286.
Mammoth Cave, the, 254.
Maps (colored, eological and orographical): En-
land,* 37. orth America,* 52. South Amer-
ica,* 58. Europe)‘ 62. Africa,* 66. Australia,
ctc.,* 73. The Alps,* 149. Mer-de-Glace, etc.,*
178. Glaciers of Geisberg and Rothmoos,* 194.
Glaciers of Langthal and Gurgl,* 201. Glacier of
Vernagt,* 204. Glacier d’Aletsch,* 208. Former
glaciers of the valley of the Adi e,* 211. Middle
course of the Mississippi,* 31 . Delta of the
Ganges,* 353. Lake Garda,* 388. Eruptions of
Etna,* 425. General chart of volcanoes,* 432.
Steam in eruptions,* 433. The crater of Manna-
Loa,* 460. General map of upheavals and de-
pressions,*526. Atoll Ari,* 560. -
Marcadau, Sierra de,* 143.
Marshes: General characteristics of, 413. Marshes
of Paraguay,* 414. Marshes of Corrientes,* 415.
Marshes of Florida, Carolina, and Virginia, 415.
The Great Dismal Swamp, 416. Marshes of New-
foundland, 416.
Marubia, or lake-risings, 395.
Masaya, volcano, 458.
Manna-Lea, volcano,* 460.
Maypures, rapids of,* 300.
Mediterranean Sea: Its western shores,* 57. Up-
heavals of its shores, 538.
b
571
Melr'ir Chott, marshes, 412.
Mentz, gunpowder ex lesion at,* 506.
Mer-de-Glace: Genera view of,* 168. Slope of the
Mer-de-Glace,* 181. Ribbons of mud in,* 196.
Meteoric action, slow course of, 161.
House River: Its msanderings,‘ 308.
and depressions of its shores, 530, 544. _
llh'sstssippi River: Mud islands in,’ 249. River sys-
tem of, 269. Middle course of,* 311. Old chan-.
nels of,* 311. Channel atVicksburg,*314. Floods
of the Mississi pi, 319. The embarras, 321. La-
goons of, 327. vées along, 334. Gap at New Or-
leans,‘ 338. Bayous and channels,‘ 350. Months
of the‘ Mississi pi,‘ 350. Depths of current in the
Gulf,‘ 352. A vance of its delta,’ 359. Bars at
its month,‘ 364, 368. General course of the Mis-
sissi pi, 376.
Mistra , an aerial current, 377.
Mmris, lake, 329.
Moraines, in glaciers,‘ 194, 218.
Moulins in glaciers, 187.
Upheavals
Mountains: Great bounding ranges, 52. General
characteristics of, 117. Sacred mountains, 119.
The leasnre in climbing mountains, 120. Vari-
ous orms of mountains, 122. Poverty of terms
to describe mountains, 122. Special terms in va-
rious languages, 123. Elements in the grandeur
of mountains, 129. Geolo ical considerations re-
specting mountains, 130. epressions_in mount-
ain ranges, 130. Origin of valleys and gorges,
130. Actual and apparent slopes of mountains,
137. Mass of mountains as compared with that
of the earth, 138. Hypotheses as to the general
law of mountain chains, 139. Theory of parallel
upheavals, 139. ‘Cooling power of mountains,
156. Highest 1points reached by man, 157. The
soroche, 158. ownfall ofmountains, 159. Snow-
fall upon mountains, 162, 168. Avalanches, 169.
Mourzouk, oases of, 93. The Oueld-R’ir,* 94.
Movements of the Earth: Rotation upon its axis, 16.
Revolution around the sun, 19. Procession 0f the
equinoxes, 21. Nutation, 22. The great cosmic-
al movement, 23. The rotation of the earth as
modifying the course of rivers, 372.
Mud islands of the Mississippi,* 249.
Mud volcanoes,‘ 475.
Mundus tripartitus,* 62.
Nantua, plateau of,* 114.
Nefouds, Arabian deserts, 95.
Névé, or snow-ice, 173. In the arctic
New Zealand, volcanic region of,*
Niagara, cataract of,* 297. Proﬁle of, 303.
Nile River, the : Slope of,* 282. Periodical rising
of, 317. Its ﬂood,* 330. Its delta,* 354.
Nors Elf, lakes of,“ 392.
regions, 213.
Oases : General characteristics of, 92. Cases of
Mourzouk, 93. Of the Oued-R’ir,* 94, 233.
Obsidian, 453.
Oceans : Harmony in their shapes, '76. General
characteristics of, '76. Similarities and contrasts
77. The Atlantic, 76. Submarine volcanoes of
the Atlantic,* 489. The Paciﬁc,* 53. Double
basin of the Paciﬁc, '76. Tributary rivers of the
Paciﬁc and Atlantic, 271. The Indian Ocean, 77.
00, valley and lakes of,* 391.
Orinoco, river, bifurcations of,* 265.
Orizaba, volcano,* 449.
Oro raphical maps and charts. (See Maps.)
Oscillation of the earth’s surface, 527.
Ossau, Pic du Midi,* 124.
Oued-R’ir, cases of,* 94. Artesian system of,’ 233.
Oules, of the Pyrenees, 134.
Ourdinse, valley of,* 134.
Paciﬁc gcean: Its basin,* 53, 76. Its tributary riv-
ers, 2 1.
Pakereman, or Valley of Death, 488.
Palestine, section of,* 409.
Panbouk-Kelessi, natural bridge)’ 240.
Papandayang, volcano, 476.
Paradoxides Harlani,* 37 .
Passes, Alpine, 136.
Peat-mosses, 417.
Peninsula, 67.
Pinsk, marshes of,‘ 269.
Pitahayas, or cactus, 103.
Pitch-stone, 454. _ _
Plains: General characteristics, '78. Often synony-
mous with deserts, '79. Variations in the features
of lains, 79. Plains of the New World, 97.
Planina, grotto of,‘ 259. 3 \H
Plata, river and estuary, 34!. ""‘ _ ' I
Plateaux: Comparative view of, 72. Distinction
between plateaux and plains, 107.. Importance
of plateaux, 108. Their comparative altitudes,
109. Their distribution, 110. Great (plateaux of
Central Asia, 111. Of Europe, 112. 1‘ America,
113. . Of Africa,‘ 115. _
Po River : Its slopeif 2S2. Utilization of its waters,
331. Dikes upon its banks,’ 336. Delta of,* 356.
Poik, subterranean river,‘ 258.
Polders of Holland, 84.
Ponto-Caspian Isthmus,’ 270.
572
INDEX.
Poudreuses, avalanches, 170.
Promontories, great continental, 65.
Pumice-stone, 453.
Puy dc Pariou, Coulee of,* 499.
Pusztas of Hungary, 85.
Pyramus, river, 362.
Pyrenees, the: Their general form,‘ 141. Compared
with the Alps, 143. An ethnological barrier, 143.
General aspects of, 210. Gaves of,* 376.
Ran vitoto, volcano,* 447.
Reels, coral,* 557.
Regclation of ice, 175.
Reservoirs, natural and artiﬁcial, 32S.
Rhine River: Bifurcation of,* 267. Course of, 283.
Old mcauderings of,* 312. Middle course of,* 316.
Bikes of,* 333.
Rhone River: General characteristics,* 297. Floods
of, 319. Inundation of,* 323. Delta of,* 337. Bars
Of, 367, a
Rinihne, cut off‘ 264.
Rivers: Various designations of, 261. Determina-
tion ot'maiu branch, 262. Basins and watersheds,
263. Forks and bifurcationsf.‘ 264. River systems
. of North America, 269. Of France, 270. General
view of river systems, 271. Functions of rivers,
280. Slope of rivers,* 282. Mountain torrents,
284. Inequalities of discharge, 285. The Lys,Var,
and Loire, 286. Wadys, or temporary streams,
287. . The Igharghar,“ 288. Erosion by torrents,*
289. Talus of debris,* 293. How rivers regulate
their slopes, 304. Windings and cuttings,* 307.
Reciproclty of curves,*307. Shifting of courses,*
309. Guiding banks for rivers,* 315. Periodical
risine's, 317. Regulating the ﬂow of rivers,* 332.
Mont s of rivers, 339. Their course modiﬁed by
the earth’s rotation, 372. Their right and left
banks,* 375. Amount of water, brought down,
377. Comparative discharge,* 378. Amount of
sediment, 379. Relations of rivers to civiliza-
tion, 381. Relations of rivers to lakes, 399.
Rivers, subterranean : General features of, The
Sorgues of Vaucluse,* 245. The Touvre,* 246.
Sn marine streams, 247. In the Gulf of Florida,
248. In Yucatan, 248. Mud lumps of the Missis-
sippi,‘ 249. System of subterranean rivers, 251.
How they are produced, 252. The Timavo, 256.
Rocks, their capacity for absorbing moisture, 224.
Rosa, Monte, proﬁle of,* 149.
Rossberg, downfall of, 160.
Sahara, desert of, 90.
Sahel, desert of, 91.
St. Lawrence, river, 269, 341.
St. Paul, volcanic island,* 490.
. Salt, whence it comes, 104. Saltuess of seas, 400.
Salt Lake, the great, 410.
Saltpetre, its origin, 105.
San Francisco, cataract, 298.
San Miguel, submarine volcano, 495.
Sautorin, volcanic island,* 492.
Savannas, of America, 98.
Scheldt, river, islands in,* 307. .
Sea-coasts, extent of, 71.
Seasons, order of in the two hemispheres,* 19.
Sediment of rivers, 379.
Seiches, lake risings, 394.
Seine River: Meanderings of,* 309, 310. Ancient
and present level, 323.
Selvas of the Amazon, 97.
Senegal, river,* 342.
Séracs in laciers, 186.
Sete Cida es, volcano,* 476.
Slopes of mountains, 137.
Snow: General characteristics of, 162. Effects of
the sun, rain, and atmosphere upon, 168. How
transformed into ice, 173. Snow cornice,* 173.
The snow-line, 163, 166. Snow-line of the Alps,
In South America,* 165. In the Himalayas,
Soroche, snow-blindness, 158.
Solfataras, sulphur mines,‘ 4S7.
Sorgues of Vaucluse,* 245.
Soulina, mouth of the Danube}? 370.

Sphagnum palustre, peat-moss, 416.
Splugen, Einshorn de,* 125.
Springs: How they originate, 223, 228. Springs
~ near mountain tops, 224. Chains of springs and
' fountains, 225. Variations in their discharge, 227.
Esthvellesﬁ 228. Intermittent springs,‘ 229. As-
cending springs, 231. The Wells 0 Moses, 231.
Cold springs, 234. . Hot springs, 235. Constitu-
ents of their water, 236. Amount of heat, 237.
Mineral springs, 238, 242. Iucrusting sprin s,
239. Metallic veins, 240. Salt springs, 241. a-
line springs at Touzla,* 243. Springs aﬁ‘ected by
earthquakes, 519. .
Stalactites, 252.
Steppes of Russia, 85, 87.
Streams. (See Rivers.)
Stromboli, volcano, 45S.
Submarine volcanoes, 489.
Swamps. (See Marshes.)
Taal, volcanic island,* 491.
Talus, formed by torrents,‘ 293.
Tamarugal, pampa of, 104.
Tauretunum, overthrow of, 160.
Tehornosjorn, the black earth of Russia,* 85,86.
Temperature: How aﬁ‘ected by elevation, 156. In-
crease in descending, 234, 436. Inﬂuence upon
volcanic phenomena, 498. '
: Terra quadriﬁda,* 61.
Tetarata, volcanic basin,* 4S5.
Thermal springs, 480.
Thun, lake,* 294.
Tides, 339. .
Timavo, subterranean river, 256.
Timboro, volcano,* 472.
Torrents. (See Rivers.)
Touvre, subterranean river,* 246.
Touzla, saline springs of,* 243.
Trachyte, 453.
Tunguragua, volcano, 477.
Tuﬁ‘, volcanic scorizef‘ 447.
Tundras of Russia, 88.
Ullah Bund, earthquake at,* 521.
Upheavals and Dcpress'lons : General features)‘ 526.
Of Northern Europe,* 531. Of the shores of the
Mediterranean, 530. Of the coasts of Asia Mi-
nor, 542. In Eeypt,544. Subsidence ofHolland,*
546. ‘Of the English coast, 547. Upheaval of
Chili and Peru,* 550. Depression of La Plata
and Brazil,* 550. U heaval of Northern Ameri-
ca, 554. Rise of cora reefs,*‘556. Darwin’sthco-
ry of‘upheavals and depressions, 556. Great area
of upheavals and depressions, 562.
Utah, basin of, 102.
Valleys: Their origin, 130. Various formations, 132.
Growth of valleys, 134. Valleys of erosion,* 291.
Van, lake, 410.
Vanikoro, coral island,* 559.
Var, river, 286.
Vellej'a, overthrow of, 159.
Vernagt, glacier,* 189, 204.
Vesuvius: General features of, 437. Line of frac-
ture between it and Etna,* 437. The crater of
Vesuvius,* 448.
Viége, earthquake at,* 514.
Visa: Crest of the mountain,* 123. Its position,
147. Ice-ﬁelds near, 210.
Volcanoes: General theories respecting, .419. Sea-
coastline of, 426. The Paciﬁc-circle of ﬁre,* 426.
Curve of volcanic islands,* 428. American vol-
canoes,* 429. Volcanoes of the Indian Ocean,
430. Of the Atlantic, 431. Of the Mediterranean
431. Of the Caspian, 431. Of Central Asia,431.
Probable number of volcanoes, 432. General
map of volcanoes,* 432. Independence of vol-
canic outlets, 438. Growth of volcanoes, 440.
Theories of Humboldt and Von Each, 440-. . The
Isle of Palma,‘ 441. Arrangements of outlets of
volcanoes,* 445. Volcanoes in New Zealand,*
446. Etna, Vesuvius, and Orizaba,* 448. Vol-
canoes of Java,* 451. Superstitions connected
with volcanoes, 452. Stromboli, Masaya, Isalco,
INDEX. 5 73
Sandwich Islands,‘ 453. Projectiles from volca- to glaciers, 222. Power of penetrating the soil,
noes,* 468, 473. Eruption of Vesuvius, 79 AJL, 223. Amount conveyed by rivers, 377.
470. Of Coseguina,* 471. Of Timboro,’ 472. Weald of Kent, the,* 41.
Mud volcanoes, 475. Volcano of Demavend,‘ Wells. (See Springs and Artesz'an Wells.)
480. Solfatara of volcauoes,* 487. Submarine Wolfenschiessen,peak,* 127.
volcanoes, 489. Periodicity of eruptions, 497.
Extinct volcanoes, 499. Yangma, lacier,‘ 220.
Volga, river,‘ 374. Year: So ar and: sidereal,* 17. The astronomical
year, 19. The great cosmical year, 22. ,
Wadys, temporary torrents, 287.
Water: Relative proportion to land,50. Relations Zambesi,cataract,‘ 299.

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