ALPINE SCULPTURE. 237 



which is not less significant than the great one. The 

 river flows here through a profound limestone gorge, 

 and to the very edges of the gorge we have the evidences 

 of erosion. But the most striking illustration of water- 

 action upon limestone rock that I have ever seen is 

 the gorge at Pfatf'ers. Here the traveller passes 

 along the side of the chasm midway between top and 

 bottom. Whichever way he looks, backwards or for- 

 wards, upwards or downwards, towards the sky or to- 

 wards the river, he meets everywhere the irresistible 

 and impressive evidence that this wonderful fissure has 

 been sawn through the mountain by the waters of the 

 Tamina. 



I have thus far confined myself to the consideration 

 of the gorges formed by the cutting through of the rock- 

 barriers which frequently cross the valleys of the Alps ; 

 as far as they have been examined by me they are the 

 work of erosion. But the larger question still remains, To 

 what action are we to ascribe the formation of the valleys 

 themselves ? This question includes that of the forma- 

 tion of the mountain-ridges, for were the valleys wholly 

 filled, the ridges would disappear. Possibly no answer 

 can be given to this question which is not beset with more 

 or less of difficulty. Special localities might be found 

 which would seem to contradict every solution which 

 refers the conformation of the Alps to the operation of 

 a single cause. 



Still the Alps present features of a character suffi- 

 ciently definite to bring the question of their origin with- 

 in the sphere of close reasoning. That they were in whole 

 or in part once beneath the sea will not be disputed ; for 

 they are in great part composed of sedimentary rocks 

 which required a sea to form them. Their present elevation 

 above the sea is due to one of those local changes in the 

 shape of the earth which have been of frequent occurrence 



