156 ABSENCE OF WATERFALLS 



when the whole was under the sea level, the fluvial 

 action began as the sea-worn escarpments emerged. The 

 adjacent valleys may or may not have been filled with 

 gravel. If they were so filled, then these instances form 

 no exception to the general course of operation, the streams 

 having washed away the gravel and laid bare the cliffs 

 down which they then tumbled, and then began the slo^er 

 process of cutting into the rock. 



With the preceding observations thrown out, merely 

 suggestively and not dogmatically, I conclude. Although 

 inquiries of this kind, affecting the aspects of nature in 

 this our day, relate to the action of laws operating only 

 since the last elevation of the land above the sea, the 

 history of a waterfall is the history, as far as we can discern, 

 of a period of vast duration. The question of the reces- 

 sion of falls opens a wide field, but without travelling out 

 of our own island, I firmly believe that there are traces of 

 action by falling water for years the number of which are 

 inadequately represented by our modes of computation, 

 although extended to millions and billions and trillions. 

 If this be so, how are we to form any conception of the 

 distance separating us from geological epochs so far re- 

 moved, that compared with them a waterfall is but as a 

 creation of yesterday ? 



