The Earth as Modified by Human Action

Earth as Modified by Human
Action, The

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Title: The Earth as Modified by Human Action
Author: George P. Marsh
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THE EARTH AS MODIFIED BY HUMAN ACTION.
A NEW EDITION OF MAN AND NATURE.
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.
1874.

PREFACE TO THE FIRST EDITION.
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
derange its original balances, and while it reduces the numbers of some
species, 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