ALP IN /a SCVLPT&n& 181 



which the rivers have, in most cases, left behind them, and 

 which refer, geologically considered, to actions of yesterday, 

 give us ground and courage to conceive what may be ef- 

 fected in geologic periods. Thus the modern portion of the 

 Via Mala throws light upon the whole. Near Bergun, in 

 the valley of the Albula, there is also a little Via Mala, 

 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 Pfaffers. 

 Here the traveler passes along the side of the chasm mid- 

 way between top and bottom. Whichever way he looks, 

 backward or forward, upward or downward, toward the 

 sky or toward the river, he meets everywhere the irresist- 

 ible and impressive evidence that this wonderful fissure has 

 been sawn through the mountain by the waters of the 

 Tarnina, 



I have thus far confined myself to the consideration of 

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

 riers 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 them- 

 selves? This question includes that of the formation 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 con- 

 formation of the Alps to the operation of a single cause. 



Still the Alps present features of a character sufficiently 

 definite to bring the question of their origin within 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 re- 

 quired 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 through- 

 out geologic time, in some cases depressing the land, and in 

 others causing the sea-bottom to protrude beyond its sur- 

 face. Considering the inelastic character of its materials, 

 the protuberance of the Alps could hardly have been pushed- 



