360 Rev. W. D. Conybeare on the Phenomena of Geology. 



causes still in operation and acting with their present power; 

 and thus taking our departure from circumstances with which 

 we are familiarly acquainted, we may proceed to the consider- 

 ation of the geological changes produced at former periods, 

 hoping to illustrate them by the light elicited in the course of 

 this progress from the known to the unknown. This is the 

 method which it is apparently the intention of Mr. Lyell to 

 adopt ; as the portion of his work as yet published is confined 

 to the present order of things, or, as Brongniart in his late 

 Treatise somewhat affectedly calls it, the Jovian, as distin- 

 guished from the Saturnian period. I hope I have fairly stated 

 the advantages which this method appears to offer. The other 

 method is, Secondly, to survey the geological phenomena, in 

 what may be called a chronological order 5 beginning with those 

 which appear to have taken place at the earliest periods, class- 

 ing, as completely as we can, the effects which have been pro- 

 duced in the successive geological epochs in a regular order, 

 of which the effects still in progress at the present time will 

 of course form the last term ; and finally, comparing the whole 

 together, with the view of observing whether they all indicate 

 a uniform and constant operation of the same causes, acting 

 •with the same intensity, and under the same circumstances ; or 

 rather evince that there has been a gradual change in these 

 respects, and that the successive periods have often given rise 

 to such new circumstances, as must have in a very great de- 

 gree modified the original forces. 



This second method, appearing to me more strictly philoso- 

 phical, I shall at present adopt; but I would here for once 

 observe, that the geologists whose cause I advocate, seem from 

 the frequent employment of the phrases " existing causes" and 

 "the uniformity of Nature" to lie under a misconception in Mr. 

 L.'smind; as though they speculated on causes of a different 

 order from any with which we are acquainted, and almost 

 reasoned on the supposition of different laws of nature : 

 Whereas I conceive both parties equally ascribe geological 

 effects to known causes, viz. to the action of water, and of vol- 

 canic power : only those with whom I class myself maintain, 

 that much which has resulted from aqueous action, e. g. the 

 excavation of many valleys, indicates rather the violent action 

 of mighty diluvial currents, than effects which do or can result 

 from the present drainage, by the actual rivers, of the waters 

 descencing from the atmosphere in rain, &c. to which Mr. 

 Lyell looks exclusively. As I shall hope to show, that on every 

 possible geological hypothesis, which either Mr. L. or any one 

 else can embrace, it must be allowed that such violent currents 

 must have swept over our continents, as it is probable, at several 



periods ; 



