in the Production of Falicys, 1 99 



cumstances which have universally existed in the excavation 

 of vales. In the mountainous districts of the tropical re- 

 gions, gullies and ravines are frequently cut, to a vast 

 depth, through the hardest rock, merely by the temporary 

 torrents which descend during the rainy season; and similar 

 effects, but of far less magnitude, mnv be every where seen 

 in the hilly districts of our own country. And even the 

 bursting of a canal through its banks, or the overflowing 

 of a flooded river into a new tract, will often, in a few 

 hours, effect astonishing excavations, and carry away 

 amazing portions of matter. Extensive meadows in this 

 neighbourhood have been covered several feet in depth, 

 with sand and other alluvia brought down by the Mersey 

 in a single night. But ii is really painful to be compelled 

 to refer to such ordinary occurrences in support of so ob- 

 vious a fact, as that a stream of water, faUing over a decli- 

 vity, will there effect an excavation proportional to the 

 height of the fall, and the yielding nature of the strata. 



Now if we consider that the sources and spring-heads of 

 all streams, without perhaps an exception of one instance 

 in a thousand, and that admitting of an easy and natural 

 explanation, are situated above the level of the country out 

 of which the vallevs have been excavated, and previous to 

 the excavation must have flowed over it, and that the pre- 

 sent depths of the valleys satisfactorily prove that the streams 

 must have had falls equal to these depths, we shall surely 

 find, in the natural progress and descending forces of the 

 streams, all the means necessarv to have efl'ecied the exca- 

 vations ; and when in addition to all this we actually find so 

 many of the phaenomena of streams and valleys preciiely cor- 

 responding with such an action of the waters, we surely pos- 

 sess a quantum of harmonizing evidence, which will support 

 themost confident conclusion j and it would but ill comport 

 with the liberal spirit of philosophical research to turn away 

 from such a mass of evidence, and substitute for such ob- 

 vious and natural, agency, some baseless phantom of hypo- 

 thetical enigma. 



I cannot but lament that Mr. Farey should voluntarily 

 have made himself an habitual alien to that beautiful sim- 

 plicity which pervades and governs all the operative woiks 

 of Nature, and which constantly rises in dignified unity 

 with the magnitude of the occasion. 'I'hc tailing of an 

 apple from a tree is said to have suggested to Newton the 

 first iilea which led him to the developmentof his great 

 scheme of universal gravitation: nor do I eonsiclcr water 

 as less active and important in geology, than gravity is m 

 N 4 ^ " ' the 



