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and cheerless equality. The air decomposes mat- 

 ter subjected to its influence, the storm scatters 

 it, the rain washes it away, the frost rends it asun- 

 der, rivers and overflowing torrents carry it to 

 the valleys and the ocean ; the formation of downs, 

 the fall of forests, and the decay of vegetation, 

 are continually altering the relative depth of 

 the low grounds by their accumulations. Ages 

 on ages might indeed pass away before these 

 agents could produce their extreme effects yet 

 that their action is neither inconsiderable nor 

 very slow, innumerable observations have ren- 

 dered incontestable. Now, these are changes, 

 the average extent of which can, in some degree, 

 be estimated. It is quite possible, for example, 

 to ascertain to what amount the deposits in the 

 bottom of lakes, or at the mouth of rivers, ac- 

 tually accumulate in the course of a year, or 

 series of years, and from the rate of accumula- 

 tion thus acquired, to calculate back to the pe- 

 riod when this accumulation first commenced 

 that is, to the period when the rivers began to 

 flow, and the agents of change first exercised 

 their influence. If many observations of this 

 kind in various quarters of the earth be found 

 nearly to coincide in their results, we are obvi- 

 ously carried back to an epoch at which the pre- 

 sent state of the surface of the earth had its ori- 

 gin ; and if various dissimilar modes of calcu- 

 lation are found to coincide, the proof rises to 

 demonstration. Now, this is in fact the remark- 

 able conclusion to which Baron Cuvier, and 



