INFLUENCE OF THE FOREST ON INUNDATIONS. 
225 
Inundations are produced by the insufficiency of the nat¬ 
ural channels of rivers to carry off the waters of their basins as 
fast as those waters flow into them. In accordance with the 
usual economy of nature, we should presume that she had 
everywhere provided the means of discharging, without dis¬ 
turbance of her general arrangements or abnormal destruction 
of her products, the precipitation which she sheds upon the 
face of the earth. Observation confirms this presumption, at 
least in the countries to which I confine my inquiries ; for, so 
far as we know the primitive conditions of the regions brought 
under human occupation within the historical period, it ap¬ 
pears that the overflow of river banks was much less frequent 
and destructive than at the present day, or, at least, that rivers 
rose and fell less suddenly before man had removed the natural 
checks to the too rapid drainage of the basins in which their 
tributaries originate. The banks of the rivers and smaller 
streams in the North American colonies were formerly little 
abraded by the currents. Even now the trees come down 
almost to the water’s edge along the rivers, in the larger for¬ 
ests of the United States, and the surface of the streams seems 
liable to no great change in level or in rapidity of current. A 
circumstance almost conclusive as to the regularity of flow in 
forest rivers, is that they do not form large sedimentary de¬ 
posits, at their points of discharge into lakes or larger streams, 
such accumulations beginning, or at least advancing far more 
rapidly, after the valleys are cleared. 
In the Northern United States, although inundations are 
sometimes produced in the height of summer by heavy rains, 
it will be found generally true that the most rapid rise of the 
fall on onr roofs and are collected in the gutters, form small streams at 
once. Now, the roofs are mountains—the gutters are valleys.” 
“To continue the comparison,” observes D’Hericourt, “roofs are 
smooth and impermeable, and the rain water pours rapidly off from their 
surfaces; but this rapidity of flow would be greatly diminished if the roofs 
were carpeted with mosses and grasses 5 more still, if they were covered 
with dry leaves, little shrubs, strewn branches, and other impediments—in 
short, if they were wooded.”— A.nnciles Fovestidres, Dec ., 18o7, p. 311. 
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