248 FRAGMENTS OF SCIENCE 



became a powerful eroding agent, and finally cut the 

 channel to its present depth. 



Geological writers of reputation assume at this place 

 the existence of a fissure, the " washing out" of which 

 resulted in the formation of the gorge. Now, no exami- 

 nation of the bed of the river ever proved the existence 

 of this fissure; and it is certain that water, particularly 

 when charged with solid matter in suspension, can cut a 

 channel through unfissured rock. Cases of deep cutting 

 can be pointed out where the clean bed of the stream is 

 exposed, the rock which forms the floor of the river not 

 exhibiting a trace of fissure. An example of this kind on 

 a small scale occurs near the Bernina Grasthaus, about two 

 hours from Pontresina. A little way below the junction 

 of the two streams from the Bernina Pass and the He u thai 

 the river flows through a channel cut by itself, and 20 or 

 30 feet in depth. At some places the river-bed is covered 

 with rolled stones; at other places it is bare, but shows no 

 trace of fissure. The abstract power of water, if I may 

 use the term, to cut through rock is demonstrated by such 

 instances. But if water be competent to form a gorge 

 without the aid of a fissure, why assume the existence of 

 such fissures in cases like that at Pontresina? It seems 

 far more philosophical to accept the simple and impressive 

 history written on the walls ot those gorges by the agent 

 which produced them. 



Numerous cases might be pointed out, varying in mag- 

 nitude, but all identical in kind, of barriers which crossed 

 valleys and formed lakes having been cut through by 

 rivers, narrow gorges being the consequence. One of the 

 most famous examples of this kind is the Finsteraarschlucht 

 in the valley of Hasli. Here the ridge called the Kirchet 



