ALPINE SCULPTURE 245 



the bridge ; but looking upward from the bridge itself, the 

 evidence of aqueous erosion was equally convincing. 



The character of the erosion depends upon the rock as 

 well as upon the river. The action of water upon some 

 rocks is almost purely mechanical ; they are simply ground 

 away or detached in sensible masses. Water, however, in 

 passing over limestone, charges itself with carbonate of 

 lime without damage to its transparency; the rock is dis- 

 solved in the water; and the gorges cut by water in such 

 rocks often resemble those cut in the ice of glaciers by 

 glacier streams. To the solubility of limestone is probably 

 to be ascribed the fantastic forms which peaks of this rock 

 usually assume, and also the grottos and caverns which 

 interpenetrate limestone formations. A rock capable of 

 being thus dissolved will expose a smooth surface after 

 the water has quitted it; and in the case of the Via Mala 

 it is the polish of the surfaces and the curved hollowa 

 scooped in the sides of the gorge which assure us that 

 the chasm has been the work of the river. 



About four miles from Tusis, and not far from the 

 little village of Zillis, the Via Mala opens into a plain 

 bounded by high terraces. It occurred to me the moment 

 I saw it that the plain had been the bed of an ancient 

 lake; and a farmer, who was my temporary companion, 

 immediately informed me that such was the tradition of 

 the neighborhood. This man conversed with intelligence, 

 and as I drew his attention to the rolled stones, which 

 rest not only above the river, but above the road, and 

 inferred that the river must once have been there to have 

 rolled those stones, he saw the force of the evidence per- 

 fectly. In fact, in former times, and subsequent to the 

 retreat of the great glaciers, a rocky barrier crossed the 



