The Earth as Modified by Human Action | Page 7

Egypt--Sand Dunes and Sand Plains--Coast
Dunes--Sand Banks--Character of Dune Sand--Interior Structure of
Dunes--Geological Importance of Dunes--Dunes on American
Coasts--Dunes of Western Europe--Age, Character, and Permanence of
Dunes--Dunes as a Barrier against the Sea--Encroachments of the
Sea--Liimfjord--Coasts of Schleswig-Holstein, Netherlands, and
France--Movement of Dunes--Control of Dunes by Man--Inland
Dunes--Inland Sand Plains

CHAPTER VI.
GREAT PROJECTS OF PHYSICAL CHANGE ACCOMPLISHED
OR PROPOSED BY MAN.
Cutting of Isthmuses--Canal of Suez--Maritime Canals in
Greece--Canals to Dead Sea--Canals to Libyan Desert--Maritime
Canals in Europe--Cape Cod Canal--Changes in Caspian--Diversion of
the Nile--Diversion of the Rhine--Improvements in North American
Hydrography--Soil below Rock--Covering Rock with Earth--Desert
Valleys--Effects of Mining--Duponchel's Plans of
Improvement--Action of Man on the Weather--Resistance to Great
Natural Forces--Incidental Effects of Human Action--Nothing Small In
Nature

THE EARTH AS MODIFIED BY HUMAN ACTION.
CHAPTER 1.
INTRODUCTORY.
Natural Advantages of the Territory of the Roman Empire.--Physical
Decay of that Territory.--Causes of the Decay.--Reaction of Man on
Nature.-- Observation of Nature.--Uncertainty of Our Historical
Knowledge of Ancient Climates.--Uncertainty of Modern
Meteorology.--Stability of Nature.--Formation of Bogs--Natural
Conditions Favorable to Geographical Change.--Destructiveness of
Man--Human and Brute Action Compared.--Limits of Human
Power.--Importance of Physical Conservation and
Restoration--Uncertainty as to Effects of Human Action.
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 conditions. The provinces bordering on the principal and the

secondary basins of the Mediterranean enjoyed in healthfulness and
equability of climate, in fertility of soil, in variety of vegetable and
mineral products, and in natural facilities for the transportation and
distribution of exchangeable commodities, advantages which have not
been possessed in any 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 cornelian 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 the primitive
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. 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.
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.
Physical Decay of the Territory of the Roman Empire.
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 their
whole extent--not excluding 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 surrendored to hopeless desolation, or at
least greatly reduced in both productiveness and population. Vast
forests have disappeared from mountain spurs and