OF THESEA AND LAND. 5 



channels of rivers consist of numerous branches, uniting 

 at many successive levels into a main trunk, so as to 

 form a perfect system of drainage. In the mountain, 

 the river is a torrent ; if a precipice occurs, it is a cata- 

 ract ; if a valley intervenes, more depressed near the 

 mountain than at its further extremity, its waters 

 spread into a lake ; while, finally, it wanders slowly 

 along the level plain till it reaches the sea. But no- 

 thing of all this is permanent. The cascade is deserted 

 or destroyed ; the torrent becomes the clear and rapid 

 stream of the elevated valley, the lake is either filled, 

 or is drained by the lowering of its exit, and is con- 

 verted into a plain, while the stream becomes conti- 

 nuous ; and the river of the plain for ever changes its 

 place as it protrudes fresh materials to retard its ter- 

 mination in the sea. 



Under the distance of time at which the original 

 actions of rivers commenced, it might be supposed that 

 we could no longer trace the first condition of things. 

 But the process is ever new, and ever recommencing 

 from the same point. If ended in one place it is be- 

 ginning in another ; and thus, in examining a river 

 from its sources onwards, we trace that which the 

 channel was when the river first began to flow, as we 

 follow the whole series, to the present hour and to all 

 future days. The sinuosity or the fissure of the moun- 

 tain rock is the picture of the original surface, which, 

 giving passage to the waters, at length becomes a ra- 

 vine : its sides gradually crumbling, and, by their fric- 

 tion on the bottom, aiding the water to deepen its bed. 

 Hence, among stratified rocks, that correspondence of 

 the strata on the opposite sides, which equally occurs 

 in wider vallies, since this is the further progress and 

 enlargement of the ravine. Hence have such ravines 

 been idly attributed to earthquakes, or, as is the vulgar 

 hrase, to " convulsions of Nature :" causes as unne- 



