of the London and Hampshire Basi?is, ^c. 117 



the South Downs, and its denudation there, inclines me to 

 believe it to be of great thickness. 



At a moderate computation, therefore*, supposing that no 

 denuding flood had existed to carry away the materials, we 

 should have had in the place of what is now the Weald Val- 

 ley, a mountain far exceeding the highest of our English hills, 

 and rising to half the height at which Dr. Buckland says relics 

 of tertiary strata are still to be found in Alpine districts. If 

 to this 4000 feet of elevation above our present sea level, we 

 add the range of these strata below the German Ocean, we 

 have much reason to suppose a still greater removal from the 

 horizontal line. The average depth of the North Sea is less 

 than 200 feet: how much of it is filled up with diluvium, and 

 how much by strata which have escaped destruction by sub- 

 sidence, or a minor elevation, is uncertain ; but it is by no 

 means impossible that a submergence may exist equal to the 

 elevation which we see demonstrated upon the surface. At 

 all events here is a valley where a mountain of no mean eleva- 

 tion once stood, or might have existed still, but for the act of 

 another agency ; and whether the operation of elevation, frac- 

 ture and removal, took place under water at a higher or 

 lower elevation of this part of the globe than the present, or 

 not, is not now material. Contemplating the removal of 

 masses of comparatively recent structure like these, of which 

 it is hoped we have proof, it becomes no extravagance to 

 suppose that the chalk of England and Ireland have been 

 united, and that the lias of both these countries and of the 

 west of Scotlandf form parts of the same expansion. 



The modification of the earth's present sui-face may by 

 some be considered us a matter of secondary importance, the 

 mode of formation, next to structural arrangement, being 

 with them the greatest point of attraction. There are others 

 who consider it a matter of such inexplicable confusion, as to 

 be out of the reach of a rational theory. To the first it may 

 be answered, that all the parts of a science so hinge upon each 

 other, that the establishment of a truth upon one point can- 

 not l)ut benefit the whole. And to the latter class of objectors 

 we may reply, that the most discordant things in nature, or 

 that are apparently so, have a plan ; and that to reason from 

 particulars to generals is, and has been, the means of achiev- 

 ing the greatest victories of the human mind;}:. tt 



• It is probable that a very strict examination into this part of the sub- 

 ject would adfl more than 1000 feet to this computation. 



f (ico\. Trans, vol. ii. p. IW.i. New Series. 



J These may be deemed threadbare truisms; and yet they will be recog- 

 nised by many who lament that the labours of the last twenty years yet re- 



main 



