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



the theory of the Fluvialist, is bound in fairness to state his 

 own, that it may lie equally open to investigation. I shall en- 

 deavour to do so then, premising that while I frankly combat 

 that which appears to me improbable, I can only pretend to 

 suggest that which to me appears more probable; and that 

 should I fail in this, in the opinion of others, it by no means 

 follows that fhifialism is the correct explanation. As to my 

 own views, then, I offer them simply as those of one individual, 

 often, I am sensible, likely to require correction ; and when 

 that is not the case, yet susceptible of a far better development 

 than any I can give them. 



In the first place, then, as to the longitudinal valleys and the 

 basset escarpments of the strata bounding them. It seems very 

 possible that this configuration of surface is not exclusively 

 and entirely to be ascribed to excavation, although its features 

 may have been greatly modified and exaggerated by this ope- 

 ration. We may easily conceive forces in action during the 

 period of the original deposition of the strata, which may have 

 caused the strata to terminate with truncated edges, facing 

 towards the elevated ridges of the older rocks, against and upon 

 which they were precipitated, instead of having allowed their 

 planes uniformly to extend until they abutted against those 

 older ridges : for we must suppose the oceans which deposited 

 these strata to have possessed some lines of shore ; these we 

 may naturally conceive to be indicated by the most elevated 

 crests of the older ridges : against such lines of coast, currents 

 most probably have ranged. While therefore the depositions 

 were proceeding quietly in the deeper and more tranquil 

 waters, they would be interrupted in the range of these littoral 

 currents, may not the longitudinal valleys have originated in 

 this cause? The usual disposition of the actual submarine sand- 

 banks is, I believe, analogous ; they are cut off' from the coasts 

 by deep intervening channels, beyond which they rise with 

 escarpments often of considerable abruptness. 



To examine into the causes which may have modified and 

 increased these longitudinal valleys, and produced the trans- 

 verse defiles, we should, I apprehend, in the first place pro- 

 ceed regularly to investigate what would be the probable ac- 

 tion of the waters in their gradual retreat from the summits 

 of the strata originally formed beneath them to their present 

 level. We have reason, with regard to the more horizontal 

 strata, to which our attention is now confined, to conclude, 

 from the conformity of the stratification and absence of dislo- 

 cation, that the elevating forces must have in this instance pro- 

 ceeded with an uniform and gradual action, and consequently 

 that the retreat of the sea and relative depression of its level 



would 



