374 
THE ECONOMIC ASPECTS OF SOIL EROSION 
cient and beautiful relations of the earth and its living mantle. 
In this case the wasting of the soil would go on, hut at a rate no 
greater than it would he rej)laced hy the decay of the upper part 
of the hed-rocks. The continents would gradually he lowered 
hy the leaching out of the mineral matters in their superficial 
debris, and in some measure hy the direct wearing action of the 
streams, hut the life-giving covering would descend from stage 
to stage, affording at each step such fertility as the rocks on which 
it lay might determine. 
d'he primitive man disturbed the conditions of the soil no 
more than did the lower animals. He made avail of the natural 
products of forest, field, and stream, never stirring the earth ex- 
cept, it might he, to bury his dead ; hut in the first step upward 
he began his manly career as a devastator. He became a soil- 
tiller, and with the invention of this art began the greatest revo- 
lution in the economics of the earth that has ever been instituted 
by a living being. Each extension of civilization has widened 
the field of destruction, until nearly one-half of all the land is 
sul)ject to its ravages. It is now a question whether human 
culture, which rests upon the use of the soil, can devise and 
enforce wa}’S of dealing with the earth which will preserve this 
source of life so that it may siq)j)ort the men of the ages to come. 
If this cannot he done, we must look forward to the time — re- 
mote it may he, yet clearly discernible — when our kind, having 
wasted its great inheritance, will fade from the earth because of 
the ruin it has accomplished. It should he the province of 
science to point the way to the remedy for this ill. 
It seems to me to he the }>oint of first importance to make clear 
to the peoi)le the conditions under which the earth can he made 
to yield its fruits without destructive tax upon its resources. To 
attain this end they need, in the first place, to know that the 
rainfall which Hows over the surface is that which does the work 
of soil destruction ; so far as this surface water acts on the soil 
its inti Lienee is evil. The share of the rain which enters the 
earth does not, until it emerges in the temporary springs, do any 
erosion work whatever. In a variable measure it removes the 
soil materials in the state of complete solution, to appear as the 
mineral matter of the springs; hut this very limited destructive 
effect is on all naturally protected soils more than compensated 
for hy the action of the ground water in promoting the decay of 
the hed-rocks, a process by which the soil is deepened and en- 
riched. In the state of nature all the rainfall is indirectly led 
