226 
FLOODS IN THE UNITED STATES. 
waters, and, of course, the most destructive “ freshets,” as they 
are called in America, are produced by the sudden dissolution 
of the snow before the open ground is thawed in the spring. 
It frequently happens that a powerful thaw sets in after a long 
period of frost, and the snow which had been months in accu¬ 
mulating is dissolved and carried off in a few hours. When 
the snow is deep, it, to use a popular expression, “ takes the 
frost out of the ground ” in the woods, and, if it lies long 
enough, in the fields also. But the heaviest snows usually fall 
after midwinter, and are succeeded by warm rains or sunshine, 
which dissolve the snow on the cleared land before it has had 
time to act upon the frost-bound soil beneath it. In this case, 
the snow in the woods is absorbed as fast as it melts, by the 
soil it has protected from freezing, and does not materially con¬ 
tribute to swell the current of the rivers. If the mild weather, 
in which great snowstorms usually occur, does not continue 
and become a regular thaw, it is almost sure to be followed by 
drifting winds, and the inequality with which they distribute 
the snow leaves the ridges comparatively bare, while the de¬ 
pressions are often filled with drifts to the height of many feet. 
The knolls become frozen to a great depth ; succeeding partial 
thaws melt the surface snow, and the water runs down into the 
furrows of ploughed fields, and other artificial and natural hol¬ 
lows, and then often freezes to solid ice. In this state of things, 
almost the entire surface of the cleared land is impervious to 
water, and from the absence of trees and the general smooth¬ 
ness of the ground, it offers little mechanical resistance to 
superficial currents. If, under these circumstances, warm 
weather accompanied by rain occurs, the rain and melted 
snow are swiftly hurried to the bottom of the valleys and 
gathered to raging torrents. 
It ought further to be considered that, though the lighter 
ploughed soils readily imbibe a great deal of water, yet the 
grass lands, and all the heavy and tenacious earths, absorb it 
in much smaller quantities, and less rapidly than the vegetable 
mould of the forest. Pasture, meadow, and clayey soils, taken 
together, greatly predominate over the sandy ploughed fields, 
