INUNDATIOTfS IN WINTER. 235 



freezing, and does not materially contribute to swell the current 

 of the rivers. If tlie mild weather, in which great snow-storms 

 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 over the cleared ground 

 leaves the ridges of the surface-soil comparatively bare, while the 

 depressions ai-e often filled with di-if ts to the height of many feet. 

 The knolls become frozen to a great dejDth ; 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 sohd 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 smoothness 

 of the ground, it offers httle mechanical resistance to superficial 

 currents. If, under these circumstances, warm weather accom- 

 panied by rain occurs, the rain and melted snow are swiftly hur- 

 ried to the bottom of the valleys and gathered to raging torrents. 

 It ought fm'ther to be considered that, though the lighter 

 ploughed soils readily imbibe a great deal of water, yet grass-lands, 

 and all the heavy and tenacious earths, absorb it in much smaller 

 •quantities, and less rapidly, than does the vegetable mould of the 

 forest. Pasture, meadow, and clayey soils, taken together, greatly 

 predominate over sandy ploughed fields, in aU large agricultural 

 districts, and hence, even if, in the case we are supposing, the open 

 ground chance to have been thawed before the melting of the 

 snow which covers it, it is already saturated with moisture, or 

 very soon becomes so, and, of course, can not reheve the pressure 

 by absorbing more water. The consequence is, that the face of 

 the country is suddenly flooded with a quantity of melted snow 

 and rain equivalent to a fall of six or eight inches of the latter, or 

 even more. This runs unobstructed to rivers often still-bound 

 with thick ice, and thus inundations of a fearfully devastating 

 character are produced. The ice bursts, from the hydrostatic 

 pressure from below, or is violently torn up by the current, and 

 is swept by the impetuous stream, in large masses and with resist- 

 less fury, against banks, bridges, dams, and miUs erected near 

 them. The bark of the trees along the rivers is often abraded, at 

 a height of many feet above the ordinary water-level, by cakes of 

 floating ice, which are at last stranded by the receding flood on 



