TRANSPORTING POWER OF WATER. 275 
confined to erosion of earth and comminution of rock; for 
they and the rivers to which they contribute transport the dé- 
bris of the mountains to lower levels and spread them out over 
the dry land and the bed of the sea, thus forming alluvial de- 
posits, sometimes of a beneficial, sometimes of an injurious, 
character, and of vast extent.* 
A mountain rivulet swollen by rain or melted snow, when it 
escapes from its usual channel and floods the adjacent fields, 
naturally deposits pebbles and gravel upon them; but even at 
low water, if its course is long enough for its grinding action 
to have full scope, it transports the solid material with which it 
is charged to some larger stream, and there lets it fall in a state 
of minute division, and at last the spoil of the mountain is used 
to raise the level of the plains or carried down to the sea. 
An instance that fell under my own observation, in 1857, will 
serve to show something of the eroding and transporting power 
of streams which, in these respects, fall incalculably below the 
torrents of the Alps. In a flood of the Ottaquechee, a small 
river which flows through Woodstock, Vermont, a mill-dam on 
that stream burst, and the sediment with which the pond was 
filled, estimated after careful measurement at 13,000 cubic 
yards, was carried down by the current. Between this dam 
and the slackwater of another, four miles below, the bed of the 
stream, which is composed of pebbles interspersed in a few 
places with larger stones, is about sixty-five feet wide, though, 
at low water, the breadth of the current is considerably less. 
The sand and fine gravel were smoothly and evenly distributed 
over the bed to a width of fifty-five or sixty feet, and, for a dis- 
tance of about two miles, except at two or three intervening 
rapids, filled up all the interstices between the stones, covering 
them to the depth of nine or ten inches, so as to present a regu- 
* Lorentz, in an official report quoted by Marchand, says: ‘‘ The felling of 
the woods produces torrents which cover the cultivated soil with pebbles and 
fragments of rock, and they do not confine their ravages to the vicinity of the 
mountains, but extend them into the fertile fields of Provence and other de- 
partments, to the distance of forty or fifty leagues,”—Hntwaldung der Gebirge, 
p17. 
