160 AEE SOILS ENEICHED, IMPOVERISHED, pt. irr, 



favoiuite doctrines of the great Lyell himself, though 

 the doing so I feel to be as audacious a sacrilege as if 

 I were to atta'^k an astronomical opinion of Newton's. 



It is true that the direct action in waste and denu- 

 dation of torrents and rivers is on lines only : and 

 were it not for the atmospheric disintegration and the 

 lateral wash of rain, this their direct action would only 

 cut ravines and channels to the sea ; that is, where a 

 spring issues high up the rocky mountain-side it will 

 cut a deep ravine, and the deeper it cuts, the more 

 springs it will lay open. But what widens this ravine 

 into a broad valley with gently sloping sides ? The 

 lateral wash of rain into the longitudinal valley. 



And what forms the broad valley even where there 

 is no river at the bottom ? or within many miles ? 

 The longitudinal scooping power of the concentrated 

 rush of rain which in no respect differs from that of 

 the torrent, except in its being a hundredfold more 

 pOYv^erful than the torrent. It is indeed intermittent : 

 so is the real scooping force of the torrent ; for tor- 

 rents only really excavate when swollen by rain. A 

 torrent swollen by rain to perhaps twenty times the 

 volume of its usual spring water, and hurhng frag- 

 ments of rocks along of all sizes, is in point of exca- 

 vating and destructive power as much more formidable 

 than its usual self, as a shotted gun is more formidable 

 than an unshotted gun. We never see the clear tor- 

 rent set its rocky ammunition in movement, though 

 the shape of this ammunition tells us how often, and 



