230 FEAGMENTS OF SCIENCE. 



stones, associated with sand and gravel. Through this 

 mass of detritus, fortunately, a vertical cutting had 

 been made, which exhibited a section showing perfect 

 stratification. There was no agency in the place to roll 

 these stones, and to deposit these alternating layers of 

 sand and pebbles, but the river which now rushes some 

 hundreds of feet below them. At one period of the Via 

 Mala's history the river must have run at this high 

 level. Other evidences of water-action soon revealed 

 themselves. From the parapet of the first bridge I 

 could see the solid rock 200 feet above the bed of the 

 river scooped and eroded. 



It is stated in the guide-books that the river, which 

 usually rtins along the bottom of the gorge, has been 

 known almost to fill it during violent thunder-storms; and 

 it may be urged that the marks of erosion which the sides 

 of the chasm exhibit are due to those occasional floods. 

 In reply to this, it may be stated that even the exist- 

 ence of such floods is not well authenticated, and that 

 if the supposition we-re true, it would be an additional 

 argument in favour of the cutting power of the river. 

 For if floods operating at rare intervals could thus 

 erode the rock, the same agency, acting without ceasing 

 upon the river's bed, must certainly be competent to 

 excavate it. 



I proceeded upwards, and from a point near another 

 bridge (which of them I did not note) had a fine view 

 of a portion of the gorge. The river here runs at the 

 bottom of a cleft of profound depth, but so narrow that 

 it might be leaped across. That this cleft must be a 

 crack is the impression first produced ; but a brief in- 

 spection suffices to prove that it has been cut by the 

 river. From top to bottom we have the unmistakable 

 marks of erosion. This cleft was best seen on looking 

 downwards from a point near the bridge ; but looking 



