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MAN AND NATURE;
OR,
PHYSICAL GEOGRAPHY
AS MODIFIED BY HUMAN ACTION.
BY
GEORGE P. MARSH.
"Not all the winds, and storms, and earthquakes, and seas, and seasons
of the world, have done so much to revolutionize the earth as MAN, the
power of an endless life, has done since the day he came forth upon it,
and received dominion over it."--H. BUSHNELL, _Sermon on the Power of an
Endless Life_.
NEW YORK:
CHARLES SCRIBNER & CO., No. 654 BROADWAY.
1867.
ENTERED, according to Act of Congress, in the year 1864, by
CHARLES SCRIBNER,
In the Clerk's Office of the District Court of the United States for the
Southern District of New York.
JOHN F. TROW & CO.
PRINTER, STEREOTYPER, AND ELECTROTYPER,
46, 48, & 50 Greene St., New York.
PREFACE.
The object of the present volume is: to indicate the character and,
approximately, the extent of the changes produced by human action in the
physical conditions of the globe we inhabit; to point out the dangers of
imprudence and the necessity of caution in all operations which, on a
large scale, interfere with the spontaneous arrangements of the organic
or the inorganic world; to suggest the possibility and the importance of
the restoration of disturbed harmonies and the material improvement of
waste and exhausted regions; and, incidentally, to illustrate the
doctrine, that man is, in both kind and degree, a power of a higher
order than any of the other forms of animated life, which, like him, are
nourished at the table of bounteous nature.
In the rudest stages of life, man depends upon spontaneous animal and
vegetable growth for food and clothing, and his consumption of such
products consequently diminishes the numerical abundance of the species
which serve his uses. At more advanced periods, he protects and
propagates certain esculent vegetables and certain fowls and
quadrupeds, and, at the same time, wars upon rival organisms which prey
upon these objects of his care or obstruct the increase of their
numbers. Hence the action of man upon the organic world tends to subvert
the original balance of its species, and while it reduces the numbers of
some of them, or even extirpates them altogether, it multiplies other
forms of animal and vegetable life.
The extension of agricultural and pastoral industry involves an
enlargement of the sphere of man's domain, by encroachment upon the
forests which once covered the greater part of the earth's surface
otherwise adapted to his occupation. The felling of the woods has been
attended with momentous consequences to the drainage of the soil, to the
external configuration of its surface, and probably, also, to local
climate; and the importance of human life as a transforming power is,
perhaps, more clearly demonstrable in the influence man has thus exerted
upon superficial geography than in any other result of his material
effort.
Lands won from the woods must be both drained and irrigated; river banks
and maritime coasts must be secured by means of artificial bulwarks
against inundation by inland and by ocean floods; and the needs of
commerce require the improvement of natural, and the construction of
artificial channels of navigation. Thus man is compelled to extend over
the unstable waters the empire he had already founded upon the solid
land.
The upheaval of the bed of seas and the movements of water and of wind
expose vast deposits of sand, which occupy space required for the
convenience of man, and often, by the drifting of their particles,
overwhelm the fields of human industry with invasions as disastrous as
the incursions of the ocean. On the other hand, on many coasts, sand
hills both protect the shores from erosion by the waves and currents,
and shelter valuable grounds from blasting sea winds. Man, therefore,
must sometimes resist, sometimes promote, the formation and growth of
dunes, and subject the barren and flying sands to the same obedience to
his will to which he has reduced other forms of terrestrial surface.
Besides these old and comparatively familiar methods of material
improvement, modern ambition aspires to yet grander achievements in the
conquest of physical nature, and projects are meditated which quite
eclipse the boldest enterprises hitherto undertaken for the modification
of geographical surface.
The natural character of the various fields where human industry has
effected revolutions so important, and where the multiplying population
and the impoverished resources of the globe demand new triumphs of mind
over matter, suggests a corresponding division of the general subject,
and I have conformed the distribution of the several topics to the
chronological succession in which man must be supposed to have extended
his sway over the different provinces of his material kingdom. I have,
then, in the Introductory chapter, stated, in a comprehensive way, the
general effects and the prospective consequences of human action upon
the earth's surface and the life which peoples it. This chapter is
followed by four others in which I have traced the history of man's
industry as exerted upon Animal and Vegetable Life, upon the Woods,
upon the Waters, and upon the Sands; and to these I have added a
concluding chapter upon Probable and Possible Geographical Revolutions
yet to be effected by the art of man.
I have only to add what, indeed, sufficiently appears upon every page of
the volume, that I address myself not to professed physicists, but to
the general intelligence of educated, observing, and thinking men; and
that my purpose is rather to make practical suggestions than to indulge
in theoretical speculations properly suited to a different class from
that to which those for whom I write belong.
GEORGE P. MARSH.
_December 1, 1863._
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TABLE OF CONTENTS.
CHAPTER I.
INTRODUCTORY.
Natural Advantages of the Territory of the Roman Empire--Physical
Decay of that Territory and of other parts of the Old World--
Causes of the Decay--New School of Geographers--Reaction of
Man upon Nature--Observation of Nature--Cosmical and Geological
Influences--Geographical Influence of Man--Uncertainty of our
Meteorological Knowledge--Mechanical Effects produced by Man on
the surface of the Earth--Importance and Possibility of Physical
Restoration--Stability of Nature--Restoration of Disturbed
Harmonies--Destructiveness of Man--Physical Improvement--Human
and Brute Action Compared--Forms and Formations most liable to
Physical Degradation--Physical Decay of New Countries--Corrupt
Influence of Private Corporations, _Note_, 1
CHAPTER II.
TRANSFER, MODIFICATION, AND EXTIRPATION OF VEGETABLE AND OF ANIMAL
SPECIES.
Modern Geography embraces Organic Life--Transfer of Vegetable
Life--Foreign Plants grown in the United States--American
Plants grown in Europe--Modes of Introduction of Foreign
Plants--Vegetables, how affected by transfer to Foreign
Soils--Extirpation of Vegetables--Origin of Domestic Plants--
Organic Life as a Geological and Geographical Agency--Origin
and Transfer of Domestic Animals--Extirpation of Animals--
Numbers of Birds in the United States--Birds as Sowers and
Consumers of Seeds, and as Destroyers of Insects--Diminution
and Extirpation of Birds--Introduction of Birds--Utility of
Insects and Worms--Introduction of Insects--Destruction of
Insects--Reptiles--Destruction of Fish--Introduction and
Breeding of Fish--Extirpation of Aquatic Animals--Minute
Organisms, 57
CHAPTER III.
THE WOODS.
The Habitable Earth originally Wooded--The Forest does not
furnish Food for Man--First Removal of the Woods--Effects
of Fire on Forest Soil--Effects of the Destruction of the
Forest--Electrical Influence of Trees--Chemical Influence
of the Forest.
Influence of the Forest, considered as Inorganic Matter, on
Temperature: _a_, Absorbing and Emitting Surface; _b_, Trees
as Conductors of Heat; _c_, Trees in Summer and in Winter;
_d_, Dead Products of Tree; _e_, Trees as a Shelter to Grounds
to the leeward of them; _f_, Trees as a Protection against
Malaria--The Forest, as Inorganic Matter, tends to mitigate
extremes.
Trees as Organisms: Specific Temperature--Total Influence of
the Forest on Temperature.
Influence of Forests on the Humidity of the Air and the Earth:
_a_, as Inorganic Matter; _b_, as Organic--Wood Mosses and
Fungi--Flow of Sap--Absorption and Exhalation of Moisture by
Trees--Balance of Conflicting Influences--Influence of the
Forest on Temperature and Precipitation--Influence of the
Forest on the Humidity of the Soil--Its Influence on the Flow
of Springs--General Consequences of the Destruction of the
Woods--Literature and Condition of the Forest in different
Countries--The Influence of the Forest on Inundations--
Destructive Action of Torrents--The Po and its Deposits--
Mountain Slides--Protection against the Fall of Rocks and
Avalanches by Trees--Principal Causes of the Destruction of
the Forest--American Forest Trees--Special Causes of the
Destruction of European Woods--Royal Forests and Game Laws--
Small Forest Plants, Vitality of Seeds--Utility of the
Forest--The Forests of Europe--Forests of the United States
and Canada--The Economy of the Forest--European and American
Trees Compared--Sylviculture--Instability of American Life, 128
CHAPTER IV.
THE WATERS.
Land artificially won from the Waters: _a_, Exclusion of the Sea
by Diking; _b_, Draining of Lakes and Marshes; _c_, Geographical
Influence of such Operations--Lowering of Lakes--Mountain Lakes--
Climatic Effects of Draining Lakes and Marshes.
Geographical and Climatic Effects of Aqueducts, Reservoirs,
and Canals--Surface and Underdraining, and their Climatic and
Geographical Effects--Irrigation and its Climatic and Geographical
Effects.
Inundations and Torrents: _a_, River Embankments; _b_, Floods of
the Ardeche; _c_, Crushing Force of Torrents; _d_, Inundations of
1856 in France; _e_, Remedies against Inundations--Consequences
if the Nile had been confined by Lateral Dikes.
Improvements in the Val di Chiana--Improvements in the Tuscan
Maremme--Obstruction of River Mouths--Subterranean Waters--
Artesian Wells--Artificial Springs--Economizing Precipitation, 330
CHAPTER V.
THE SANDS.
Origin of Sand--Sand now carried down to the Sea--The Sands of
Egypt and the adjacent Desert--The Suez Canal--The Sands of
Egypt--Coast Dunes and Sand Plains--Sand Banks--Dunes on Coast of
America--Dunes of Western Europe--Formation of Dunes--Character of
Dune Sand--Interior Structure of Dunes--Form of Dunes--Geological
Importance of Dunes--Inland Dunes--Age, Character, and Permanence
of Dunes--Use of Dunes as Barrier against the Sea--Encroachments
of the Sea--The Luemfjord--Encroachments of the Sea--Drifting
of Dune Sands--Dunes of Gascony--Dunes of Denmark--Dunes of
Prussia--Artificial Formation of Dunes--Trees suitable for Dune
Plantations--Extent of Dunes in Europe--Dune Vineyards of Cape
Breton--Removal of Dunes--Inland Sand Plains--The Landes of
Gascony--The Belgian Campine--Sands and Steppes of Eastern
Europe--Advantages of Reclaiming Dunes--Government Works of
Improvement, 451
CHAPTER VI.
PROJECTED OR POSSIBLE GEOGRAPHICAL CHANGES BY MAN.
Cutting of Marine Isthmuses--The Suez Canal--Canal across Isthmus
of Darien--Canals to the Dead Sea--Maritime Canals in Greece--
Canal of Saros--Cape Cod Canal--Diversion of the Nile--Changes
in the Caspian--Improvements in North American Hydrography--
Diversion of the Rhine--Draining of the Zuiderzee--Waters of
the Karst--Subterranean Waters of Greece--Soil below Rock--
Covering Rocks with Earth--Wadies of Arabia Petraea--Incidental
Effects of Human Action--Resistance to great Natural Forces--
Effects of Mining--Espy's Theories--River Sediment--Nothing
small in Nature, 517
CHAPTER I.
INTRODUCTORY.
NATURAL ADVANTAGES OF THE TERRITORY OF THE ROMAN EMPIRE--PHYSICAL
DECAY OF THAT TERRITORY AND OF OTHER PARTS OF THE OLD WORLD--CAUSES
OF THE DECAY--NEW SCHOOL OF GEOGRAPHERS--REACTION OF MAN UPON NATURE--
OBSERVATION OF NATURE--COSMICAL AND GEOLOGICAL INFLUENCES--GEOGRAPHICAL
INFLUENCE OF MAN--UNCERTAINTY OF OUR METEOROLOGICAL KNOWLEDGE--
MECHANICAL EFFECTS PRODUCED BY MAN ON THE SURFACE OF THE EARTH--
IMPORTANCE AND POSSIBILITY OF PHYSICAL RESTORATION--STABILITY OF
NATURE--RESTORATION OF DISTURBED HARMONIES--DESTRUCTIVENESS OF MAN--
PHYSICAL IMPROVEMENT--HUMAN AND BRUTE ACTION COMPARED--FORMS AND
FORMATIONS MOST LIABLE TO PHYSICAL DEGRADATION--PHYSICAL DECAY OF NEW
COUNTRIES--CORRUPT INFLUENCE OF PRIVATE CORPORATIONS, _note_.
_Natural Advantages of the Territory of the Roman Empire._
The Roman Empire, at the period of its greatest expansion, comprised the
regions of the earth most distinguished by a happy combination of
physical advantages. The provinces bordering on the principal and the
secondary basins of the Mediterranean enjoyed a healthfulness and an
equability of climate, a fertility of soil, a variety of vegetable and
mineral products, and natural facilities for the transportation and
distribution of exchangeable commodities, which have not been possessed
in an equal degree by any territory of like extent in the Old World or
the New. The abundance of the land and of the waters adequately supplied
every material want, ministered liberally to every sensuous enjoyment.
Gold and silver, indeed, were not found in the profusion which has
proved so baneful to the industry of lands richer in veins of the
precious metals; but mines and river beds yielded them in the spare
measure most favorable to stability of value in the medium of exchange,
and, consequently, to the regularity of commercial transactions. The
ornaments of the barbaric pride of the East, the pearl, the ruby, the
sapphire, and the diamond--though not unknown to the luxury of a people
whose conquests and whose wealth commanded whatever the habitable world
could contribute to augment the material splendor of their social
life--were scarcely native to the territory of the empire; but the
comparative rarity of these gems in Europe, at somewhat earlier periods,
was, perhaps, the very circumstance that led the cunning artists of
classic antiquity to enrich softer stones with engravings, which invest
the common onyx and carnelian with a worth surpassing, in cultivated
eyes, the lustre of the most brilliant oriental jewels.
Of these manifold blessings the temperature of the air, the distribution
of the rains, the relative disposition of land and water, the plenty of
the sea, the composition of the soil, and the raw material of some of
the arts, were wholly gratuitous gifts. Yet the spontaneous nature of
Europe, of Western Asia, of Libya, neither fed nor clothed the civilized
inhabitants of those provinces. Every loaf was eaten in the sweat of the
brow. All must be earned by toil. But toil was nowhere else rewarded by
so generous wages; for nowhere would a given amount of intelligent labor
produce so abundant, and, at the same time, so varied returns of the
good things of material existence. The luxuriant harvests of cereals
that waved on every field from the shores of the Rhine to the banks of
the Nile, the vines that festooned the hillsides of Syria, of Italy, and
of Greece, the olives of Spain, the fruits of the gardens of the
Hesperides, the domestic quadrupeds and fowls known in ancient rural
husbandry--all these were original products of foreign climes,
naturalized in new homes, and gradually ennobled by the art of man,
while centuries of persevering labor were expelling the wild vegetation,
and fitting the earth for the production of more generous growths.
Only for the sense of landscape beauty did unaided nature make
provision. Indeed, the very commonness of this source of refined
enjoyment seems to have deprived it of half its value; and it was only
in the infancy of lands where all the earth was fair, that Greek and
Roman humanity had sympathy enough with the inanimate world to be alive
to the charms of rural and of mountain scenery. In later generations,
when the glories of the landscape had been heightened by plantation, and
decorative architecture, and other forms of picturesque improvement, the
poets of Greece and Rome were blinded by excess of light, and became, at
last, almost insensible to beauties that now, even in their degraded
state, enchant every eye, except, too often, those which a lifelong
familiarity has dulled to their attractions.
_Physical Decay of the Territory of the Roman Empire, and of other parts
of the Old World._
If we compare the present physical condition of the countries of which I
am speaking, with the descriptions that ancient historians and
geographers have given of their fertility and general capability of
ministering to human uses, we shall find that more than one half of
their whole extent--including the provinces most celebrated for the
profusion and variety of their spontaneous and their cultivated
products, and for the wealth and social advancement of their
inhabitants--is either deserted by civilized man and surrendered to
hopeless desolation, or at least greatly reduced in both productiveness
and population. Vast forests have disappeared from mountain spurs and
ridges; the vegetable earth accumulated beneath the trees by the decay
of leaves and fallen trunks, the soil of the alpine pastures which
skirted and indented the woods, and the mould of the upland fields, are
washed away; meadows, once fertilized by irrigation, are waste and
unproductive, because the cisterns and reservoirs that supplied the
ancient canals are broken, or the springs that fed them dried up; rivers
famous in history and song have shrunk to humble brooklets; the willows
that ornamented and protected the banks of the lesser watercourses are
gone, and the rivulets have ceased to exist as perennial currents,
because the little water that finds its way into their old channels is
evaporated by the droughts of summer, or absorbed by the parched earth,
before it reaches the lowlands; the beds of the brooks have widened into
broad expanses of pebbles and gravel, over which, though in the hot
season passed dryshod, in winter sealike torrents thunder; the entrances
of navigable streams are obstructed by sandbars, and harbors, once marts
of an extensive commerce, are shoaled by the deposits of the rivers at
whose mouths they lie; the elevation of the beds of estuaries, and the
consequently diminished velocity of the streams which flow into them,
have converted thousands of leagues of shallow sea and fertile lowland
into unproductive and miasmatic morasses.
Besides the direct testimony of history to the ancient fertility of the
regions to which I refer--Northern Africa, the greater Arabian
peninsula, Syria, Mesopotamia, Armenia and many other provinces of Asia
Minor, Greece, Sicily, and parts of even Italy and Spain--the multitude
and extent of yet remaining architectural ruins, and of decayed works of
internal improvement, show that at former epochs a dense population
inhabited those now lonely districts. Such a population could have been
sustained only by a productiveness of soil of which we at present
discover but slender traces; and the abundance derived from that
fertility serves to explain how large armies, like those of the ancient
Persians, and of the Crusaders and the Tartars in later ages, could,
without an organized commissariat, secure adequate supplies in long
marches through territories which, in our times, would scarcely afford
forage for a single regiment.
It appears, then, that the fairest and fruitfulest provinces of the
Roman Empire, precisely that portion of terrestrial surface, in short,
which, about the commencement of the Christian era, was endowed with the
greatest superiority of soil, climate, and position, which had been
carried to the highest pitch of physical improvement, and which thus
combined the natural and artificial conditions best fitting it for the
habitation and enjoyment of a dense and highly refined and cultivated
population, is now completely exhausted of its fertility, or so
diminished in productiveness, as, with the exception of a few favored
oases that have escaped the general ruin, to be no longer capable of
affording sustenance to civilized man. If to this realm of desolation we
add the now wasted and solitary soils of Persia and the remoter East,
that once fed their millions with milk and honey, we shall see that a
territory larger than all Europe, the abundance of which sustained in
bygone centuries a population scarcely inferior to that of the whole
Christian world at the present day, has been entirely withdrawn from
human use, or, at best, is thinly inhabited by tribes too few in
numbers, too poor in superfluous products, and too little advanced in
culture and the social arts, to contribute anything to the general moral
or material interests of the great commonwealth of man.
_Causes of this Decay._
The decay of these once flourishing countries is partly due, no doubt,
to that class of geological causes, whose action we can neither resist
nor guide, and partly also to the direct violence of hostile human
force; but it is, in a far greater proportion, either the result of
man's ignorant disregard of the laws of nature, or an incidental
consequence of war, and of civil and ecclesiastical tyranny and misrule.
Next to ignorance of these laws, the primitive source, the _causa
causarum_, of the acts and neglects which have blasted with sterility
and physical decrepitude the noblest half of the empire of the Caesars,
is, first, the brutal and exhausting despotism which Rome herself
exercised over her conquered kingdoms, and even over her Italian
territory; then, the host of temporal and spiritual tyrannies which she
left as her dying curse to all her wide dominion, and which, in some
form of violence or of fraud, still brood over almost every soil subdued
by the Roman legions.[1] Man cannot struggle at once against crushing
oppression and the destructive forces of inorganic nature. When both are
combined against him, he succumbs after a shorter or a longer struggle,
and the fields he has won from the primeval wood relapse into their
original state of wild and luxuriant, but unprofitable forest growth,
or fall into that of a dry and barren wilderness.
Rome imposed on the products of agricultural labor in the rural
districts taxes which the sale of the entire harvest would scarcely
discharge; she drained them of their population by military
conscription; she impoverished the peasantry by forced and unpaid labor
on public works; she hampered industry and internal commerce by absurd
restrictions and unwise regulations. Hence, large tracts of land were
left uncultivated, or altogether deserted, and exposed to all the
destructive forces which act with such energy on the surface of the
earth when it is deprived of those protections by which nature
originally guarded it, and for which, in well-ordered husbandry, human
ingenuity has contrived more or less efficient substitutes.[2] Similar
abuses have tended to perpetuate and extend these evils in later ages,
and it is but recently that, even in the most populous parts of Europe,
public attention has been half awakened to the necessity of restoring
the disturbed harmonies of nature, whose well-balanced influences are so
propitious to all her organic offspring, of repaying to our great mother
the debt which the prodigality and the thriftlessness of former
generations have imposed upon their successors--thus fulfilling the
command of religion and of practical wisdom, to use this world as not
abusing it.
_New School of Geographers._
The labors of Humboldt, of Ritter, of Guyot and their followers, have
given to the science of geography a more philosophical, and, at the same
time, a more imaginative character than it had received from the hands
of their predecessors. Perhaps the most interesting field of
speculation, thrown open by the new school to the cultivators of this
attractive study, is the inquiry: how far external physical conditions,
and especially the configuration of the earth's surface, and the
distribution, outline, and relative position of land and water, have
influenced the social life and social progress of man.
_Reaction of Man on Nature._
But, as we have seen, man has reacted upon organized and inorganic
nature, and thereby modified, if not determined, the material structure
of his earthly home. The measure of that reaction manifestly constitutes
a very important element in the appreciation of the relations between
mind and matter, as well as in the discussion of many purely physical
problems. But though the subject has been incidentally touched upon by
many geographers, and treated with much fulness of detail in regard to
certain limited fields of human effort, and to certain specific effects
of human action, it has not, as a whole, so far as I know, been made
matter of special observation, or of historical research by any
scientific inquirer.[3] Indeed, until the influence of physical
geography upon human life was recognized as a distinct branch of
philosophical investigation, there was no motive for the pursuit of such
speculations; and it was desirable to inquire whether we have or can
become the architects of our own abiding place, only when it was known
how the mode of our physical, moral, and intellectual being is affected
by the character of the home which Providence has appointed, and we have
fashioned, for our material habitation.[4]
It is still too early to attempt scientific method in discussing this
problem, nor is our present store of the necessary facts by any means
complete enough to warrant me in promising any approach to fulness of
statement respecting them. Systematic observation in relation to this
subject has hardly yet begun,[5] and the scattered data which have
chanced to be recorded have never been collected. It has now no place in
the general scheme of physical science, and is matter of suggestion and
speculation only, not of established and positive conclusion. At
present, then, all that I can hope is to excite an interest in a topic
of much economical importance, by pointing out the directions and
illustrating the modes in which human action has been or may be most
injurious or most beneficial in its influence upon the physical
conditions of the earth we inhabit.
_Observation of Nature._
In these pages, as in all I have ever written or propose to write, it is
my aim to stimulate, not to satisfy, curiosity, and it is no part of my
object to save my readers the labor of observation or of thought. For
labor is life, and
Death lives where power lives unused.[6]
Self is the schoolmaster whose lessons are best worth his wages; and
since the subject I am considering has not yet become a branch of formal
instruction, those whom it may interest can, fortunately, have no
pedagogue but themselves. To the natural philosopher, the descriptive
poet, the painter, and the sculptor, as well as to the common observer,
the power most important to cultivate, and, at the same time, hardest to
acquire, is that of seeing what is before him. Sight is a faculty;
seeing, an art. The eye is a physical, but not a self-acting apparatus,
and in general it sees only what it seeks. Like a mirror, it reflects
objects presented to it; but it may be as insensible as a mirror, and it
does not necessarily perceive what it reflects.[7] It is disputed
whether the purely material sensibility of the eye is capable of
improvement and cultivation. It has been maintained by high authority,
that the natural acuteness of none of our sensuous faculties can be
heightened by use, and hence that the minutest details of the image
formed on the retina are as perfect in the most untrained, as in the
most thoroughly disciplined organ. This may well be doubted, and it is
agreed on all hands that the power of multifarious perception and rapid
discrimination may be immensely increased by well-directed practice.[8]
This exercise of the eye I desire to promote, and, next to moral and
religious doctrine, I know no more important practical lessons in this
earthly life of ours--which, to the wise man, is a school from the
cradle to the grave--than those relating to the employment of the sense
of vision in the study of nature.
The pursuit of physical geography, embracing actual observation of
terrestrial surface, affords to the eye the best general training that
is accessible to all. The majority of even cultivated men have not the
time and means of acquiring anything beyond a very superficial
acquaintance with any branch of physical knowledge. Natural science has
become so vastly extended, its recorded facts and its unanswered
questions so immensely multiplied, that every strictly scientific man
must be a specialist, and confine the researches of a whole life within
a comparatively narrow circle. The study I am recommending, in the view
I propose to take of it, is yet in that imperfectly developed state
which allows its votaries to occupy themselves with such broad and
general views as are attainable by every person of culture, and it does
not now require a knowledge of special details which only years of
application can master. It may be profitably pursued by all; and every
traveller, every lover of rural scenery, every agriculturist, who will
wisely use the gift of sight, may add valuable contributions to the
common stock of knowledge on a subject which, as I hope to convince my
readers, though long neglected, and now inartificially presented, is not
only a very important, but a very interesting field of inquiry.
_Cosmical and Geological Influences._
The revolutions of the seasons, with their alternations of temperature
and of length of day and night, the climates of different zones, and the
general condition and movements of the atmosphere and the seas, depend
upon causes for the most part cosmical, and, of course, wholly beyond
our control. The elevation, configuration, and composition of the great
masses of terrestrial surface, and the relative extent and distribution
of land and water, are determined by geological influences equally
remote from our jurisdiction. It would hence seem that the physical
adaptation of different portions of the earth to the use and enjoyment
of man is a matter so strictly belonging to mightier than human powers,
that we can only accept geographical nature as we find her, and be
content with such soils and such skies as she spontaneously offers.
_Geographical Influence of Man._
But it is certain that man has done much to mould the form of the
earth's surface, though we cannot always distinguish between the results
of his action and the effects of purely geological causes; that the
destruction of the forests, the drainage of lakes and marshes, and the
operations of rural husbandry and industrial art have tended to produce
great changes in the hygrometric, thermometric, electric, and chemical
condition of the atmosphere, though we are not yet able to measure the
force of the different elements of disturbance, or to say how far they
have been compensated by each other, or by still obscurer influences;
and, finally, that the myriad forms of animal and vegetable life, which
covered the earth when man first entered upon the theatre of a nature
whose harmonies he was destined to derange, have been, through his
action, greatly changed in numerical proportion, sometimes much modified
in form and product, and sometimes entirely extirpated.
The physical revolutions thus wrought by man have not all been
destructive to human interests. Soils to which no nutritious vegetable
was indigenous, countries which once brought forth but the fewest
products suited for the sustenance and comfort of man--while the
severity of their climates created and stimulated the greatest number
and the most imperious urgency of physical wants--surfaces the most
rugged and intractable, and least blessed with natural facilities of
communication, have been made in modern times to yield and distribute
all that supplies the material necessities, all that contributes to the
sensuous enjoyments and conveniences of civilized life. The Scythia, the
Thule, the Britain, the Germany, and the Gaul which the Roman writers
describe in such forbidding terms, have been brought almost to rival the
native luxuriance and easily won plenty of Southern Italy; and, while
the fountains of oil and wine that refreshed old Greece and Syria and
Northern Africa have almost ceased to flow, and the soils of those fair
lands are turned to thirsty and inhospitable deserts, the hyperborean
regions of Europe have conquered, or rather compensated, the rigors of
climate, and attained to a material wealth and variety of product that,
with all their natural advantages, the granaries of the ancient world
can hardly be said to have enjoyed.
These changes for evil and for good have not been caused by great
natural revolutions of the globe, nor are they by any means attributable
wholly to the moral and physical action or inaction of the peoples, or,
in all cases, even of the races that now inhabit these respective
regions. They are products of a complication of conflicting or
coincident forces, acting through a long series of generations; here,
improvidence, wastefulness, and wanton violence; there, foresight and
wisely guided persevering industry. So far as they are purely the
calculated and desired results of those simple and familiar operations
of agriculture and of social life which are as universal as
civilization--the removal of the forests which covered the soil required
for the cultivation of edible fruits, the drying of here and there a few
acres too moist for profitable husbandry, by draining off the surface
waters, the substitution of domesticated and nutritious for wild and
unprofitable vegetable growths, the construction of roads and canals and
artificial harbors--they belong to the sphere of rural, commercial, and
political economy more properly than to geography, and hence are but
incidentally embraced within the range of our present inquiries, which
concern physical, not financial balances. I propose to examine only the
greater, more permanent, and more comprehensive mutations which man has
produced, and is producing, in earth, sea, and sky, sometimes, indeed,
with conscious purpose, but for the most part, as unforeseen though
natural consequences of acts performed for narrower and more immediate
ends.
The exact measurement of the geographical changes hitherto thus effected
is, as I have hinted, impracticable, and we possess, in relation to
them, the means of only qualitative, not quantitative analysis. The fact
of such revolutions is established partly by historical evidence, partly
by analogical deduction from effects produced in our own time by
operations similar in character to those which must have taken place in
more or less remote ages of human action. Both sources of information
are alike defective in precision; the latter, for general reasons too
obvious to require specification; the former, because the facts to which
it bears testimony occurred before the habit or the means of rigorously
scientific observation upon any branch of physical research, and
especially upon climatic changes, existed.
_Uncertainty of our Meteorological Knowledge._
The invention of measures of heat, and of atmospheric moisture,
pressure, and precipitation, is extremely recent. Hence, ancient
physicists have left us no thermometric or barometric records, no tables
of the fall, evaporation, and flow of waters, and even no accurate maps
of coast lines and the course of rivers. Their notices of these
phenomena are almost wholly confined to excessive and exceptional
instances of high or of low temperatures, extraordinary falls of rain
and snow, and unusual floods or droughts. Our knowledge of the
meteorological condition of the earth, at any period more than two
centuries before our own time, is derived from these imperfect details,
from the vague statements of ancient historians and geographers in
regard to the volume of rivers and the relative extent of forest and
cultivated land, from the indications furnished by the history of the
agriculture and rural economy of past generations, and from other almost
purely casual sources of information.
Among these latter we must rank certain newly laid open fields of
investigation, from which facts bearing on the point now under
consideration have been gathered. I allude to the discovery of
artificial objects in geological formations older than any hitherto
recognized as exhibiting traces of the existence of man; to the ancient
lacustrine habitations of Switzerland, containing the implements of the
occupants, remains of their food, and other relics of human life; to the
curious revelations of the Kjoekkenmoeddinger, or heaps of kitchen refuse,
in Denmark, and of the peat mosses in the same and other northern
countries; to the dwellings and other evidences of the industry of man
in remote ages sometimes laid bare by the movement of sand dunes on the
coasts of France and of the North Sea; and to the facts disclosed on the
shores of the latter, by excavations in inhabited mounds which were,
perhaps, raised before the period of the Roman Empire. These remains are
memorials of races which have left no written records, because they
perished before the historical period of the countries they occupied
began. The plants and animals that furnished the relics found in the
deposits were certainly contemporaneous with man; for they are
associated with his works, and have evidently served his uses. In some
cases, the animals belonged to species well ascertained to be now
altogether extinct; in some others, both the animals and the vegetables,
though extant elsewhere, have ceased to inhabit the regions where their
remains are discovered. From the character of the artificial objects, as
compared with others belonging to known dates, or at least to known
periods of civilization, ingenious inferences have been drawn as to
their age; and from the vegetation, remains of which accompany them, as
to the climates of Central and Northern Europe at the time of their
production.
There are, however, sources of error which have not always been
sufficiently guarded against in making these estimates. When a boat,
composed of several pieces of wood fastened together by pins of the same
material, is dug out of a bog, it is inferred that the vessel, and the
skeletons and implements found with it, belong to an age when the use of
iron was not known to the builders. But this conclusion is not warranted
by the simple fact that metals were not employed in its construction;
for the Nubians at this day build boats large enough to carry half a
dozen persons across the Nile, out of small pieces of acacia wood pinned
together entirely with wooden bolts. Nor is the occurrence of flint
arrow heads and knives, in conjunction with other evidences of human
life, conclusive proof as to the antiquity of the latter. Lyell informs
us that some Oriental tribes still continue to use the same stone
implements as their ancestors, "after that mighty empires, where the use
of metals in the arts was well known, had flourished for three thousand
years in their neighborhood;"[9] and the North American Indians now
manufacture and use weapons of stone, and even of glass, chipping them
in the latter case out of the bottoms of thick bottles, with great
facility.[10]
We may also be misled by our ignorance of the commercial relations
existing between savage tribes. Extremely rude nations, in spite of
their jealousies and their perpetual wars, sometimes contrive to
exchange the products of provinces very widely separated from each
other. The mounds of Ohio contain pearls, thought to be marine, which
must have come from the Gulf of Mexico, or perhaps even from California,
and the knives and pipes found in the same graves are often formed of
far-fetched material, that was naturally paid for by some home product
exported to the locality whence the material was derived. The art of
preserving fish, flesh, and fowl by drying and smoking is widely
diffused, and of great antiquity. The Indians of Long Island Sound are
said to have carried on a trade in dried shell fish with tribes residing
very far inland. From the earliest ages, the inhabitants of the Faroe
and Orkney Islands, and of the opposite mainland coasts, have smoked
wild fowl and other flesh. Hence it is possible that the animal and the
vegetable food, the remains of which are found in the ancient deposits I
am speaking of, may sometimes have been brought from climates remote
from that where it was consumed.
The most important, as well as the most trustworthy conclusions with
respect to the climate of ancient Europe and Asia, are those drawn from
the accounts given by the classical writers of the growth of cultivated
plants; but these are by no means free from uncertainty, because we can
seldom be sure of an identity of species, almost never of an identity of
race or variety, between vegetables known to the agriculturists of
Greece and Rome and those of modern times which are thought most nearly
to resemble them. Besides this, there is always room for doubt whether
the habits of plants long grown in different countries may not have been
so changed by domestication that the conditions of temperature and
humidity which they required twenty centuries ago were different from
those at present demanded for their advantageous cultivation.[11]
Even if we suppose an identity of species, of race, and of habit to be
established between a given ancient and modern plant, the negative fact
that the latter will not grow now where it flourished two thousand years
ago does not in all cases prove a change of climate. The same result
might follow from the exhaustion of the soil,[12] or from a change in
the quantity of moisture it habitually contains. After a district of
country has been completely or even partially cleared of its forest
growth, and brought under cultivation, the drying of the soil, under
favorable circumstances, goes on for generations, perhaps for ages.[13]
In other cases, from injudicious husbandry, or the diversion or choking
up of natural watercourses, it may become more highly charged with
humidity. An increase or diminution of the moisture of a soil almost
necessarily supposes an elevation or a depression of its winter or its
summer heat, and of its extreme, if not of its mean annual temperature,
though such elevation or depression may be so slight as not sensibly to
raise or lower the mercury in a thermometer exposed to the open air. Any
of these causes, more or less humidity, or more or less warmth of soil,
would affect the growth both of wild and of cultivated vegetation, and
consequently, without any appreciable change in atmospheric temperature,
precipitation, or evaporation, plants of a particular species might
cease to be advantageously cultivated where they had once been easily
reared.[14] We are very imperfectly acquainted with the present mean
and extreme temperature, or the precipitation and the evaporation of any
extensive region, even in countries most densely peopled and best
supplied with instruments and observers. The progress of science is
constantly detecting errors of method in older observations, and many
laboriously constructed tables of meteorological phenomena are now
thrown aside as fallacious, and therefore worse than useless, because
some condition necessary to secure accuracy of result was neglected, in
obtaining the data on which they were founded.
To take a familiar instance: it is but recently that attention has been
drawn to the great influence of slight changes of station upon the
results of observations of temperature and precipitation. A thermometer
removed but a few hundred yards from its first position differs not
unfrequently five, sometimes even ten degrees in its readings; and when
we are told that the annual fall of rain on the roof of the observatory
at Paris is two inches less than on the ground by the side of it, we may
see that the level of the rain-gauge is a point of much consequence in
making estimates from its measurements. The data from which results have
been deduced with respect to the hygrometrical and thermometrical
conditions, the climate in short, of different countries, have very
often been derived from observations at single points in cities or
districts separated by considerable distances. The tendency of errors
and accidents to balance each other authorizes us, indeed, to entertain
greater confidence than we could otherwise feel in the conclusions drawn
from such tables; but it is in the highest degree probable that they
would be much modified by more numerous series of observations, at
different stations within narrow limits.[15]
There is one branch of research which is of the utmost importance in
reference to these questions, but which, from the great difficulty of
direct observation upon it, has been less successfully studied than
almost any other problem of physical science. I refer to the proportions
between precipitation, superficial drainage, absorption, and
evaporation. Precise actual measurement of these quantities upon even a
single acre of ground is impossible; and in all cabinet experiments on
the subject, the conditions of the surface observed are so different
from those which occur in nature, that we cannot safely reason from one
case to the other. In nature, the inclination of the ground, the degree
of freedom or obstruction of the surface, the composition and density of
the soil, upon which its permeability by water and its power of
absorbing and retaining or transmitting moisture depend, its
temperature, the dryness or saturation of the subsoil, vary at
comparatively short distances; and though the precipitation upon and the
superficial flow from very small geographical basins may be estimated
with an approach to precision, yet even here we have no present means
of knowing how much of the water absorbed by the earth is restored to
the atmosphere by evaporation, and how much carried off by infiltration
or other modes of underground discharge. When, therefore, we attempt to
use the phenomena observed on a few square or cubic yards of earth, as a
basis of reasoning upon the meteorology of a province, it is evident
that our data must be insufficient to warrant positive general
conclusions. In discussing the climatology of whole countries, or even
of comparatively small local divisions, we may safely say that none can
tell what percentage of the water they receive from the atmosphere is
evaporated; what absorbed by the ground and conveyed off by subterranean
conduits; what carried down to the sea by superficial channels; what
drawn from the earth or the air by a given extent of forest, of short
pasture vegetation, or of tall meadow-grass; what given out again by
surfaces so covered, or by bare ground of various textures and
composition, under different conditions of atmospheric temperature,
pressure, and humidity; or what is the amount of evaporation from water,
ice, or snow, under the varying exposures to which, in actual nature,
they are constantly subjected. If, then, we are so ignorant of all these
climatic phenomena in the best-known regions inhabited by man, it is
evident that we can rely little upon theoretical deductions applied to
the former more natural state of the same regions--less still to such as
are adopted with respect to distant, strange, and primitive countries.
_Mechanical Effects produced by Man on the Surface of the Earth more
easily ascertainable._
In investigating the mechanical effects of human action on superficial
geography, we are treading on safer ground, and dealing with much less
subtile phenomena, less intractable elements. Great physical changes
can, in some cases, be positively shown, in some almost certainly
inferred, to have been produced by the operations of rural industry, and
by the labors of man in other spheres of material effort; and hence, in
this most important part of our subject, we can arrive at many positive
generalizations, and obtain practical results of no small economical
value.
_Importance and Possibility of Physical Restoration._
Many circumstances conspire to invest with great present interest the
questions: how far man can permanently modify and ameliorate those
physical conditions of terrestrial surface and climate on which his
material welfare depends; how far he can compensate, arrest, or retard
the deterioration which many of his agricultural and industrial
processes tend to produce; and how far he can restore fertility and
salubrity to soils which his follies or his crimes have made barren or
pestilential. Among these circumstances, the most prominent, perhaps, is
the necessity of providing new homes for a European population which is
increasing more rapidly than its means of subsistence, new physical
comforts for classes of the people that have now become too much
enlightened and have imbibed too much culture to submit to a longer
deprivation of a share in the material enjoyments which the privileged
ranks have hitherto monopolized.
To supply new hives for the emigrant swarms, there are, first, the vast
unoccupied prairies and forests of America, of Australia, and of many
other great oceanic islands, the sparsely inhabited and still
unexhausted soils of Southern and even Central Africa, and, finally, the
impoverished and half-depopulated shores of the Mediterranean, and the
interior of Asia Minor and the farther East. To furnish to those who
shall remain after emigration shall have conveniently reduced the too
dense population of many European states, those means of sensuous and of
intellectual well-being which are styled "artificial wants" when
demanded by the humble and the poor, but are admitted to be
"necessaries" when claimed by the noble and the rich, the soil must be
stimulated to its highest powers of production, and man's utmost
ingenuity and energy must be tasked to renovate a nature drained, by
his improvidence, of fountains which a wise economy would have made
plenteous and perennial sources of beauty, health, and wealth.
In those yet virgin lands which the progress of modern discovery in both
hemispheres has brought and is still bringing to the knowledge and
control of civilized man, not much improvement of great physical
conditions is to be looked for. The proportion of forest is indeed to be
considerably reduced, superfluous waters to be drawn off, and routes of
internal communication to be constructed; but the primitive geographical
and climatic features of these countries ought to be, as far as
possible, retained.
_Stability of Nature._
Nature, left undisturbed, so fashions her territory as to give it almost
unchanging permanence of form, outline, and proportion, except when
shattered by geologic convulsions; and in these comparatively rare cases
of derangement, she sets herself at once to repair the superficial
damage, and to restore, as nearly as practicable, the former aspect of
her dominion. In new countries, the natural inclination of the ground,
the self-formed slopes and levels, are generally such as best secure the
stability of the soil. They have been graded and lowered or elevated by
frost and chemical forces and gravitation and the flow of water and
vegetable deposit and the action of the winds, until, by a general
compensation of conflicting forces, a condition of equilibrium has been
reached which, without the action of man, would remain, with little
fluctuation, for countless ages.
We need not go far back to reach a period when, in all that portion of
the North American continent which has been occupied by British
colonization, the geographical elements very nearly balanced and
compensated each other. At the commencement of the seventeenth century,
the soil, with insignificant exceptions, was covered with forests;[16]
and whenever the Indian, in consequence of war or the exhaustion of the
beasts of the chase, abandoned the narrow fields he had planted and the
woods he had burned over, they speedily returned, by a succession of
herbaceous, arborescent, and arboreal growths, to their original state.
Even a single generation sufficed to restore them almost to their
primitive luxuriance of forest vegetation.[17] The unbroken forests had
attained to their maximum density and strength of growth, and, as the
older trees decayed and fell, they were succeeded by new shoots or
seedlings, so that from century to century no perceptible change seems
to have occurred in the wood, except the slow, spontaneous succession of
crops. This succession involved no interruption of growth, and but
little break in the "boundless contiguity of shade;" for, in the
husbandry of nature, there are no fallows. Trees fall singly, not by
square roods, and the tall pine is hardly prostrate, before the light
and heat, admitted to the ground by the removal of the dense crown of
foliage which had shut them out, stimulate the germination of the seeds
of broad-leaved trees that had lain, waiting this kindly influence,
perhaps for centuries. Two natural causes, destructive in character,
were, indeed, in operation in the primitive American forests, though, in
the Northern colonies, at least, there were sufficient compensations;
for we do not discover that any considerable permanent change was
produced by them. I refer to the action of beavers and of fallen trees
in producing bogs,[18] and of smaller animals, insects, and birds, in
destroying the woods. Bogs are less numerous and extensive in the
Northern States of the American union, because the natural inclination
of the surface favors drainage; but they are more frequent, and cover
more ground, in the Southern States, for the opposite reason.[19] They
generally originate in the checking of watercourses by the falling of
timber, or of earth and rocks, across their channels. If the impediment
thus created is sufficient to retain a permanent accumulation of water
behind it, the trees whose roots are overflowed soon perish, and then by
their fall increase the obstruction, and, of course, occasion a still
wider spread of the stagnating stream. This process goes on until the
water finds a new outlet, at a higher level, not liable to similar
interruption. The fallen trees not completely covered by water are soon
overgrown with mosses; aquatic and semi-aquatic plants propagate
themselves, and spread until they more or less completely fill up the
space occupied by the water, and the surface is gradually converted from
a pond to a quaking morass.[20] The morass is slowly solidified by
vegetable production and deposit, then very often restored to the
forest condition by the growth of black ashes, cedars, or, in southern
latitudes, cypresses, and other trees suited to such a soil, and thus
the interrupted harmony of nature is at last reestablished.
I am disposed to think that more bogs in the Northern States owe their
origin to beavers than to accidental obstructions of rivulets by
wind-fallen or naturally decayed trees; for there are few swamps in
those States, at the outlets of which we may not, by careful search,
find the remains of a beaver dam. The beaver sometimes inhabits natural
lakelets, but he prefers to owe his pond to his own ingenuity and toil.
The reservoir once constructed, its inhabitants rapidly multiply, and as
its harvests of pond lilies, and other aquatic plants on which this
quadruped feeds in winter, become too small for the growing population,
the beaver metropolis sends out expeditions of discovery and
colonization. The pond gradually fills up, by the operation of the same
causes as when it owes its existence to an accidental obstruction, and
when, at last, the original settlement is converted into a bog by the
usual processes of vegetable life, the remaining inhabitants abandon it
and build on some virgin brooklet a new city of the waters.
In countries somewhat further advanced in civilization than those
occupied by the North American Indians, as in mediaeval Ireland, the
formation of bogs may be commenced by the neglect of man to remove, from
the natural channels of superficial drainage, the tops and branches of
trees felled for the various purposes to which wood is applicable in
his rude industry; and, when the flow of the water is thus checked,
nature goes on with the processes I have already described. In such
half-civilized regions, too, windfalls are more frequent than in those
where the forest is unbroken, because, when openings have been made in
it, for agricultural or other purposes, the entrance thus afforded to
the wind occasions the sudden overthrow of hundreds of trees which might
otherwise have stood for generations, and thus have fallen to the
ground, only one by one, as natural decay brought them down.[21] Besides
this, the flocks bred by man in the pastoral state, keep down the
incipient growth of trees on the half-dried bogs, and prevent them from
recovering their primitive condition.
Young trees in the native forest are sometimes girdled and killed by the
smaller rodent quadrupeds, and their growth is checked by birds which
feed on the terminal bud; but these animals, as we shall see, are
generally found on the skirts of the wood only, not in its deeper
recesses, and hence the mischief they do is not extensive. The insects
which damage primitive forests by feeding upon products of trees
essential to their growth, are not numerous, nor is their appearance, in
destructive numbers, frequent; and those which perforate the stems and
branches, to deposit and hatch their eggs, more commonly select dead
trees for that purpose, though, unhappily, there are important
exceptions to this latter remark.[22] I do not know that we have any
evidence of the destruction or serious injury of American forests by
insects, before or even soon after the period of colonization; but since
the white man has laid bare a vast proportion of the earth's surface,
and thereby produced changes favorable, perhaps, to the multiplication
of these pests, they have greatly increased in numbers, and, apparently,
in voracity also. Not many years ago, the pines on thousands of acres of
land in North Carolina, were destroyed by insects not known to have ever
done serious injury to that tree before. In such cases as this and
others of the like sort, there is good reason to believe that man is the
indirect cause of an evil for which he pays so heavy a penalty. Insects
increase whenever the birds which feed upon them disappear. Hence, in
the wanton destruction of the robin and other insectivorous birds, the
_bipes implumis_, the featherless biped, man, is not only exchanging the
vocal orchestra which greets the rising sun for the drowsy beetle's
evening drone, and depriving his groves and his fields of their fairest
ornament, but he is waging a treacherous warfare on his natural
allies.[23]
In fine, in countries untrodden by man, the proportions and relative
positions of land and water, the atmospheric precipitation and
evaporation, the thermometric mean, and the distribution of vegetable
and animal life, are subject to change only from geological influences
so slow in their operation that the geographical conditions may be
regarded as constant and immutable. These arrangements of nature it is,
in most cases, highly desirable substantially to maintain, when such
regions become the seat of organized commonwealths. It is, therefore, a
matter of the first importance, that, in commencing the process of
fitting them for permanent civilized occupation, the transforming
operations should be so conducted as not unnecessarily to derange and
destroy what, in too many cases, it is beyond the power of man to
rectify or restore.
_Restoration of Disturbed Harmonies._
In reclaiming and reoccupying lands laid waste by human improvidence or
malice, and abandoned by man, or occupied only by a nomade or thinly
scattered population, the task of the pioneer settler is of a very
different character. He is to become a co-worker with nature in the
reconstruction of the damaged fabric which the negligence or the
wantonness of former lodgers has rendered untenantable. He must aid her
in reclothing the mountain slopes with forests and vegetable mould,
thereby restoring the fountains which she provided to water them; in
checking the devastating fury of torrents, and bringing back the surface
drainage to its primitive narrow channels; and in drying deadly morasses
by opening the natural sluices which have been choked up, and cutting
new canals for drawing off their stagnant waters. He must thus, on the
one hand, create new reservoirs, and, on the other, remove mischievous
accumulations of moisture, thereby equalizing and regulating the sources
of atmospheric humidity and of flowing water, both which are so
essential to all vegetable growth, and, of course, to human and lower
animal life.
_Destructiveness of Man._
Man has too long forgotten that the earth was given to him for usufruct
alone, not for consumption, still less for profligate waste. Nature has
provided against the absolute destruction of any of her elementary
matter, the raw material of her works; the thunderbolt and the tornado,
the most convulsive throes of even the volcano and the earthquake, being
only phenomena of decomposition and recomposition. But she has left it
within the power of man irreparably to derange the combinations of
inorganic matter and of organic life, which through the night of aeons
she had been proportioning and balancing, to prepare the earth for his
habitation, when, in the fulness of time, his Creator should call him
forth to enter into its possession.
Apart from the hostile influence of man, the organic and the inorganic
world are, as I have remarked, bound together by such mutual relations
and adaptations as secure, if not the absolute permanence and
equilibrium of both, a long continuance of the established conditions of
each at any given time and place, or at least, a very slow and gradual
succession of changes in those conditions. But man is everywhere a
disturbing agent. Wherever he plants his foot, the harmonies of nature
are turned to discords. The proportions and accommodations which insured
the stability of existing arrangements are overthrown. Indigenous
vegetable and animal species are extirpated, and supplanted by others of
foreign origin, spontaneous production is forbidden or restricted, and
the face of the earth is either laid bare or covered with a new and
reluctant growth of vegetable forms, and with alien tribes of animal
life. These intentional changes and substitutions constitute, indeed,
great revolutions; but vast as is their magnitude and importance, they
are, as we shall see, insignificant in comparison with the contingent
and unsought results which have flowed from them.
The fact that, of all organic beings, man alone is to be regarded as
essentially a destructive power, and that he wields energies to resist
which, nature--that Nature whom all material life and all inorganic
substance obey--is wholly impotent, tends to prove that, though living
in physical nature, he is not of her, that he is of more exalted
parentage, and belongs to a higher order of existences than those born
of her womb and submissive to her dictates.
There are, indeed, brute destroyers, beasts and birds and insects of
prey--all animal life feeds upon, and, of course, destroys other
life,--but this destruction is balanced by compensations. It is, in
fact, the very means by which the existence of one tribe of animals or
of vegetables is secured against being smothered by the encroachments of
another; and the reproductive powers of species, which serve as the food
of others, are always proportioned to the demand they are destined to
supply. Man pursues his victims with reckless destructiveness; and,
while the sacrifice of life by the lower animals is limited by the
cravings of appetite, he unsparingly persecutes, even to extirpation,
thousands of organic forms which he cannot consume.[24]
The earth was not, in its natural condition, completely adapted to the
use of man, but only to the sustenance of wild animals and wild
vegetation. These live, multiply their kind in just proportion, and
attain their perfect measure of strength and beauty, without producing
or requiring any change in the natural arrangements of surface, or in
each other's spontaneous tendencies, except such mutual repression of
excessive increase as may prevent the extirpation of one species by the
encroachments of another. In short, without man, lower animal and
spontaneous vegetable life would have been constant in type,
distribution, and proportion, and the physical geography of the earth
would have remained undisturbed for indefinite periods, and been subject
to revolution only from possible, unknown cosmical causes, or from
geological action.
But man, the domestic animals that serve him, the field and garden
plants the products of which supply him with food and clothing, cannot
subsist and rise to the full development of their higher properties,
unless brute and unconscious nature be effectually combated, and, in a
great degree, vanquished by human art. Hence, a certain measure of
transformation of terrestrial surface, of suppression of natural, and
stimulation of artificially modified productivity becomes necessary.
This measure man has unfortunately exceeded. He has felled the forests
whose network of fibrous roots bound the mould to the rocky skeleton of
the earth; but had he allowed here and there a belt of woodland to
reproduce itself by spontaneous propagation, most of the mischiefs which
his reckless destruction of the natural protection of the soil has
occasioned would have been averted. He has broken up the mountain
reservoirs, the percolation of whose waters through unseen channels
supplied the fountains that refreshed his cattle and fertilized his
fields; but he has neglected to maintain the cisterns and the canals of
irrigation which a wise antiquity had constructed to neutralize the
consequences of its own imprudence. While he has torn the thin glebe
which confined the light earth of extensive plains, and has destroyed
the fringe of semi-aquatic plants which skirted the coast and checked
the drifting of the sea sand, he has failed to prevent the spreading of
the dunes by clothing them with artificially propagated vegetation. He
has ruthlessly warred on all the tribes of animated nature whose spoil
he could convert to his own uses, and he has not protected the birds
which prey on the insects most destructive to his own harvests.
Purely untutored humanity, it is true, interferes comparatively little
with the arrangements of nature,[25] and the destructive agency of man
becomes more and more energetic and unsparing as he advances in
civilization, until the impoverishment, with which his exhaustion of the
natural resources of the soil is threatening him, at last awakens him to
the necessity of preserving what is left, if not of restoring what has
been wantonly wasted. The wandering savage grows no cultivated
vegetable, fells no forest, and extirpates no useful plant, no noxious
weed. If his skill in the chase enables him to entrap numbers of the
animals on which he feeds, he compensates this loss by destroying also
the lion, the tiger, the wolf, the otter, the seal, and the eagle, thus
indirectly protecting the feebler quadrupeds and fish and fowls, which
would otherwise become the booty of beasts and birds of prey. But with
stationary life, or rather with the pastoral state, man at once
commences an almost indiscriminate warfare upon all the forms of animal
and vegetable existence around him, and as he advances in civilization,
he gradually eradicates or transforms every spontaneous product of the
soil he occupies.[26]
_Human and Brute Action Compared._
It has been maintained by authorities as high as any known to modern
science, that the action of man upon nature, though greater in _degree_,
does not differ in _kind_, from that of wild animals. It appears to me
to differ in essential character, because, though it is often followed
by unforeseen and undesired results, yet it is nevertheless guided by a
self-conscious and intelligent will aiming as often at secondary and
remote as at immediate objects. The wild animal, on the other hand, acts
instinctively, and, so far as we are able to perceive, always with a
view to single and direct purposes. The backwoodsman and the beaver
alike fell trees; the man that he may convert the forest into an olive
grove that will mature its fruit only for a succeeding generation, the
beaver that he may feed upon their bark or use them in the construction
of his habitation. Human differs from brute action, too, in its
influence upon the material world, because it is not controlled by
natural compensations and balances. Natural arrangements, once disturbed
by man, are not restored until he retires from the field, and leaves
free scope to spontaneous recuperative energies; the wounds he inflicts
upon the material creation are not healed until he withdraws the arm
that gave the blow. On the other hand, I am not aware of any evidence
that wild animals have ever destroyed the smallest forest, extirpated
any organic species or modified its natural character, occasioned any
permanent change of terrestrial surface, or produced any disturbance of
physical conditions which nature has not, of herself, repaired without
the expulsion of the animal that had caused it.[27]
The form of geographical surface, and very probably the climate of a
given country, depend much on the character of the vegetable life
belonging to it. Man has, by domestication, greatly changed the habits
and properties of the plants he rears; he has, by voluntary selection,
immensely modified the forms and qualities of the animated creatures
that serve him; and he has, at the same time, completely rooted out many
forms of animal if not of vegetable being.[28] What is there, in the
influence of brute life, that corresponds to this? We have no reason to
believe that in that portion of the American continent which, though
peopled by many tribes of quadruped and fowl, remained uninhabited by
man, or only thinly occupied by purely savage tribes, any sensible
geographical change had occurred within twenty centuries before the
epoch of discovery and colonization, while, during the same period, man
had changed millions of square miles, in the fairest and most fertile
regions of the Old World, into the barrenest deserts.
The ravages committed by man subvert the relations and destroy the
balance which nature had established between her organized and her
inorganic creations; and she avenges herself upon the intruder, by
letting loose upon her defaced provinces destructive energies hitherto
kept in check by organic forces destined to be his best auxiliaries, but
which he has unwisely dispersed and driven from the field of action.
When the forest is gone, the great reservoir of moisture stored up in
its vegetable mould is evaporated, and returns only in deluges of rain
to wash away the parched dust into which that mould has been converted.
The well-wooded and humid hills are turned to ridges of dry rock, which
encumbers the low grounds and chokes the watercourses with its debris,
and--except in countries favored with an equable distribution of rain
through the seasons, and a moderate and regular inclination of
surface--the whole earth, unless rescued by human art from the physical
degradation to which it tends, becomes an assemblage of bald mountains,
of barren, turfless hills, and of swampy and malarious plains. There are
parts of Asia Minor, of Northern Africa, of Greece, and even of Alpine
Europe, where the operation of causes set in action by man has brought
the face of the earth to a desolation almost as complete as that of the
moon; and though, within that brief space of time which we call "the
historical period," they are known to have been covered with luxuriant
woods, verdant pastures, and fertile meadows, they are now too far
deteriorated to be reclaimable by man, nor can they become again fitted
for human use, except through great geological changes, or other
mysterious influences or agencies of which we have no present knowledge,
and over which we have no prospective control. The earth is fast
becoming an unfit home for its noblest inhabitant, and another era of
equal human crime and human improvidence, and of like duration with that
through which traces of that crime and that improvidence extend, would
reduce it to such a condition of impoverished productiveness, of
shattered surface, of climatic excess, as to threaten the depravation,
barbarism, and perhaps even extinction of the species.[29]
_Physical Improvement._
True, there is a partial reverse to this picture. On narrow theatres,
new forests have been planted; inundations of flowing streams restrained
by heavy walls of masonry and other constructions; torrents compelled to
aid, by depositing the slime with which they are charged, in filling up
lowlands, and raising the level of morasses which their own overflows
had created; ground submerged by the encroachments of the ocean, or
exposed to be covered by its tides, has been rescued from its dominion
by diking;[30] swamps and even lakes have been drained, and their beds
brought within the domain of agricultural industry; drifting coast dunes
have been checked and made productive by plantation; seas and inland
waters have been repeopled with fish, and even the sands of the Sahara
have been fertilized by artesian fountains. These achievements are more
glorious than the proudest triumphs of war, but, thus far, they give but
faint hope that we shall yet make full atonement for our spendthrift
waste of the bounties of nature.
It is, on the one hand, rash and unphilosophical to attempt to set
limits to the ultimate power of man over inorganic nature, and it is
unprofitable, on the other, to speculate on what may be accomplished by
the discovery of now unknown and unimagined natural forces, or even by
the invention of new arts and new processes. But since we have seen
aerostation, the motive power of elastic vapors, the wonders of modern
telegraphy, the destructive explosiveness of gunpowder, and even of a
substance so harmless, unresisting, and inert as cotton, nothing in the
way of mechanical achievement seems impossible, and it is hard to
restrain the imagination from wandering forward a couple of generations
to an epoch when our descendants shall have advanced as far beyond us in
physical conquest, as we have marched beyond the trophies erected by our
grandfathers.
I must therefore be understood to mean only, that no agencies now known
to man and directed by him seem adequate to the reducing of great Alpine
precipices to such slopes as would enable them to support a vegetable
clothing, or to the covering of large extents of denuded rock with
earth, and planting upon them a forest growth. But among the mysteries
which science is yet to reveal, there may be still undiscovered methods
of accomplishing even grander wonders than these. Mechanical
philosophers have suggested the possibility of accumulating and
treasuring up for human use some of the greater natural forces, which
the action of the elements puts forth with such astonishing energy.
Could we gather, and bind, and make subservient to our control, the
power which a West Indian hurricane exerts through a small area in one
continuous blast, or the momentum expended by the waves, in a
tempestuous winter, upon the breakwater at Cherbourg,[31] or the lifting
power of the tide, for a month, at the head of the Bay of Fundy, or the
pressure of a square mile of sea water at the depth of five thousand
fathoms, or a moment of the might of an earthquake or a volcano, our
age--which moves no mountains and casts them into the sea by faith
alone--might hope to scarp the rugged walls of the Alps and Pyrenees and
Mount Taurus, robe them once more in a vegetation as rich as that of
their pristine woods, and turn their wasting torrents into refreshing
streams.[32]
Could this old world, which man has overthrown, be rebuilded, could
human cunning rescue its wasted hillsides and its deserted plains from
solitude or mere nomade occupation, from barrenness, from nakedness, and
from insalubrity, and restore the ancient fertility and healthfulness of
the Etruscan sea coast, the Campagna and the Pontine marshes, of
Calabria, of Sicily, of the Peloponnesus and insular and continental
Greece, of Asia Minor, of the slopes of Lebanon and Hermon, of
Palestine, of the Syrian desert, of Mesopotamia and the delta of the
Euphrates, of the Cyrenaica, of Africa proper, Numidia, and Mauritania,
the thronging millions of Europe might still find room on the Eastern
continent, and the main current of emigration be turned toward the
rising instead of the setting sun.
But changes like these must await great political and moral revolutions
in the governments and peoples by whom those regions are now possessed,
a command of pecuniary and of mechanical means not at present enjoyed by
those nations, and a more advanced and generally diffused knowledge of
the processes by which the amelioration of soil and climate is possible,
than now anywhere exists. Until such circumstances shall conspire to
favor the work of geographical regeneration, the countries I have
mentioned, with here and there a local exception, will continue to sink
into yet deeper desolation, and in the mean time, the American
continent, Southern Africa, Australia, and the smaller oceanic islands,
will be almost the only theatres where man is engaged, on a great scale,
in transforming the face of nature.
_Arrest of Physical Decay of New Countries._
Comparatively short as is the period through which the colonization of
foreign lands by European emigrants extends, great, and, it is to be
feared, sometimes irreparable, injury has been already done in the
various processes by which man seeks to subjugate the virgin earth; and
many provinces, first trodden by the _homo sapiens Europae_ within the
last two centuries, begin to show signs of that melancholy dilapidation
which is now driving so many of the peasantry of Europe from their
native hearths. It is evidently a matter of great moment, not only to
the population of the states where these symptoms are manifesting
themselves, but to the general interests of humanity, that this decay
should be arrested, and that the future operations of rural husbandry
and of forest industry, in districts yet remaining substantially in
their native condition, should be so conducted as to prevent the
widespread mischiefs which have been elsewhere produced by thoughtless
or wanton destruction of the natural safeguards of the soil. This can be
done only by the diffusion of knowledge on this subject among the
classes that, in earlier days, subdued and tilled ground in which they
had no vested rights, but who, in our time, own their woods, their
pastures, and their ploughlands as a perpetual possession for them and
theirs, and have, therefore, a strong interest in the protection of
their domain against deterioration.
_Forms and Formations most liable to Physical Degradation._
The character and extent of the evils under consideration depend very
much on climate and the natural forms and constitution of surface. If
the precipitation, whether great or small in amount, be equally
distributed through the seasons, so that there are neither torrential
rains nor parching droughts, and if, further, the general inclination of
ground be moderate, so that the superficial waters are carried off
without destructive rapidity of flow, and without sudden accumulation in
the channels of natural drainage, there is little danger of the
degradation of the soil in consequence of the removal of forest or other
vegetable covering, and the natural face of the earth may be considered
as substantially permanent. These conditions are well exemplified in
Ireland, in a great part of England, in extensive districts in Germany
and France, and, fortunately, in an immense proportion of the valley of
the Mississippi and the basin of the great American lakes, as well as in
many parts of the continents of South America and of Africa.
Destructive changes are most frequent in countries of irregular and
mountainous surface, and in climates where the precipitation is confined
chiefly to a single season, and where the year is divided into a wet and
a dry period, as is the case throughout a great part of the Ottoman
empire, and, more or less strictly, the whole Mediterranean basin. It is
partly, though by no means entirely, owing to topographical and climatic
causes that the blight, which has smitten the fairest and most fertile
provinces of Imperial Rome, has spared Britannia, Germania, Pannonia,
and M[oe]sia, the comparatively inhospitable homes of barbarous races,
who, in the days of the Caesars, were too little advanced in civilized
life to possess either the power or the will to wage that war against
the order of nature which seems, hitherto, an almost inseparable
condition precedent of high social culture, and of great progress in
fine and mechanical art.[33]
In mountainous countries, on the other hand, various causes combine to
expose the soil to constant dangers. The rain and snow usually fall in
greater quantity, and with much inequality of distribution; the snow on
the summits accumulates for many months in succession, and then is not
unfrequently almost wholly dissolved in a single thaw, so that the
entire precipitation of months is in a few hours hurried down the flanks
of the mountains, and through the ravines that furrow them; the natural
inclination of the surface promotes the swiftness of the gathering
currents of diluvial rain and of melting snow, which soon acquire an
almost irresistible force, and power of removal and transportation; the
soil itself is less compact and tenacious than that of the plains, and
if the sheltering forest has been destroyed, it is confined by few of
the threads and ligaments by which nature had bound it together, and
attached it to the rocky groundwork. Hence every considerable shower
lays bare its roods of rock, and the torrents sent down by the thaws of
spring, and by occasional heavy discharges of the summer and autumnal
rains, are seas of mud and rolling stones that sometimes lay waste, and
bury beneath them acres, and even miles, of pasture and field and
vineyard.[34]
_Physical Decay of New Countries._
I have remarked that the effects of human action on the forms of the
earth's surface could not always be distinguished from those resulting
from geological causes, and there is also much uncertainty in respect to
the precise influence of the clearing and cultivating of the ground,
and of other rural operations, upon climate. It is disputed whether
either the mean or the extremes of temperature, the periods of the
seasons, or the amount or distribution of precipitation and of
evaporation, in any country whose annals are known, have undergone any
change during the historical period. It is, indeed, impossible to doubt
that many of the operations of the pioneer settler tend to produce great
modifications in atmospheric humidity, temperature, and electricity; but
we are at present unable to determine how far one set of effects is
neutralized by another, or compensated by unknown agencies. This
question scientific research is inadequate to solve, for want of the
necessary data; but well conducted observation, in regions now first
brought under the occupation of man, combined with such historical
evidence as still exists, may be expected at no distant period to throw
much light on this subject.
Australia is, perhaps, the country from which we have a right to expect
the fullest elucidation of these difficult and disputable problems. Its
colonization did not commence until the physical sciences had become
matter of almost universal attention, and is, indeed, so recent that the
memory of living men embraces the principal epochs of its history; the
peculiarities of its fauna, its flora, and its geology are such as to
have excited for it the liveliest interest of the votaries of natural
science; its mines have given its people the necessary wealth for
procuring the means of instrumental observation, and the leisure
required for the pursuit of scientific research; and large tracts of
virgin forest and natural meadow are rapidly passing under the control
of civilized man. Here, then, exist greater facilities and stronger
motives for the careful study of the topics in question than have ever
been found combined in any other theatre of European colonization.
In North America, the change from the natural to the artificial
condition of terrestrial surface began about the period when the most
important instruments of meteorological observation were invented. The
first settlers in the territory now constituting the United States and
the British American provinces had other things to do than to tabulate
barometrical and thermometrical readings, but there remain some
interesting physical records from the early days of the colonies,[35]
and there is still an immense extent of North American soil where the
industry and the folly of man have as yet produced little appreciable
change. Here, too, with the present increased facilities for scientific
observation, the future effects, direct and contingent, of man's labors,
can be measured, and such precautions taken in those rural processes
which we call improvements, as to mitigate evils, perhaps, in some
degree, inseparable from every attempt to control the action of natural
laws.
In order to arrive at safe conclusions, we must first obtain a more
exact knowledge of the topography, and of the present superficial and
climatic condition of countries where the natural surface is as yet more
or less unbroken. This can only be accomplished by accurate surveys, and
by a great multiplication of the points of meteorological registry,[36]
already so numerous; and as, moreover, considerable changes in the
proportion of forest and of cultivated land, or of dry and wholly or
partially submerged surface, will often take place within brief periods,
it is highly desirable that the attention of observers, in whose
neighborhood the clearing of the soil, or the drainage of lakes and
swamps, or other great works of rural improvement, are going on or
meditated, should be especially drawn not only to revolutions in
atmospheric temperature and precipitation, but to the more easily
ascertained and perhaps more important local changes produced by these
operations in the temperature and the hygrometric state of the
superficial strata of the earth, and in its spontaneous vegetable and
animal products.
The rapid extension of railroads, which now everywhere keeps pace with,
and sometimes even precedes, the occupation of new soil for agricultural
purposes, furnishes great facilities for enlarging our knowledge of the
topography of the territory they traverse, because their cuttings reveal
the composition and general structure of surface, and the inclination
and elevation of their lines constitute known hypsometrical sections,
which give numerous points of departure for the measurement of higher
and lower stations, and of course for determining the relief and
depression of surface, the slope of the beds of watercourses, and many
other not less important questions.[37]
The geological, hydrographical, and topographical surveys, which almost
every general and even local government of the civilized world is
carrying on, are making yet more important contributions to our stock of
geographical and general physical knowledge, and, within a comparatively
short space, there will be an accumulation of well established constant
and historical facts, from which we can safely reason upon all the
relations of action and reaction between man and external nature.
But we are, even now, breaking up the floor and wainscoting and doors
and window frames of our dwelling, for fuel to warm our bodies and
seethe our pottage, and the world cannot afford to wait till the slow
and sure progress of exact science has taught it a better economy. Many
practical lessons have been learned by the common observation of
unschooled men; and the teachings of simple experience, on topics where
natural philosophy has scarcely yet spoken, are not to be despised.
In these humble pages, which do not in the least aspire to rank among
scientific expositions of the laws of nature, I shall attempt to give
the most important practical conclusions suggested by the history of
man's efforts to replenish the earth and subdue it; and I shall aim to
support those conclusions by such facts and illustrations only as
address themselves to the understanding of every intelligent reader, and
as are to be found recorded in works capable of profitable perusal, or
at least consultation, by persons who have not enjoyed a special
scientific training.