DISCUSSION : FORESTS, RESERVOIRS, AND STREAM FLOW 539 
APPENDIX. 
The following extracts from writings upon the subject of forests and mr. cnitten- 
stream flow are reproduced here because of their historic value in the 42. 
Hterature of the subject. In every case they present early, if not 
original, enunciations of the principles which are now being brought 
into prominence through the medium of this discussion. 
I 
The first extract is from “The Earth as Modified by Human Ac- 
tion,” by Mr. G. P. Marsh, first published in 1864, and is reproduced 
because of its early date and because it is a perfect example of the 
mixture of wheat and chaff so conspicuous in the present forestry 
propaganda. 
“General Consequences of the Destruction of the Forests. 
“With the extirpation of the forest, all is changed. At one season 
the earth parts with its warmth by radiation to an open sky; receives, 
at another, an immoderate heat from the unobstructed rays of the 
sun. Hence the climate becomes excessive, and the soil is alternately 
parched by the fervors of summer, and seared by the rigors of win- 
ter. Bleak winds sweep unresisted over its surface, drift away the 
snow that sheltered it from the frost, and dry up its scanty moisture. 
The precipitation becomes as irregular as the temperature; the melting 
snows and vernal rains, no longer absorbed by a loose and bibulous 
vegetable mould, rush over the frozen surface, and pour down the 
valley seawards, instead of filling a retentive bed of absorbent earth, 
and storing up a supply of moisture to feed perennial springs. The 
soil is bared of its covering of leaves, broken and loosened by the 
plough, deprived of the fibrous rootlets which held it together, dried 
and pulverized by sun and wind, and at last taken up by new com- 
binations. The face of the earth is no longer a sponge, but a dust 
heap, and the floods which the water of the sky pour over it hurry 
swiftly along its slopes, carrying in suspension vast quantities of earthy 
particles which increase the abrading power and mechanical force of 
the current, and, augmented by the sand and gravel of falling banks, 
fill the beds of the streams, divert them into new channels, and ob- 
struct their outlets. The rivulets, wanting their former regularity of 
supply and deprived of the protecting shade of the woods, are heated, 
evaporated, and thus reduced in their summer currents, but swollen to 
raging torrents in autumn and in spring. From these causes there is 
a constant degradation of the uplands, and a consequent elevation of 
the beds of water courses and of lakes, by the deposition of the min- 
erals and vegetable matter carried down by the waters. The channels 
of great rivers become unnavigable, their estuaries are choked up, and 
harbors which once sheltered large navies are shoaled by dangerous 
sand-bars. The earth, stripped of its vegetable glebe, grows less and 
less productive, and, consequently, less able to protect itself by weav- 
ing a new network of roots to bind its particles together, a mew car- 
peting of turf to shield it from wind and sun and scouring rain. 
Gradually it becomes altogether barren. The washing of the soil from 
