312 Geological Society. 



Let me not, however, be misunderstood. I have been offering no 

 general criticism of Mr. Lyell's work : I have merely been arguing 

 against the extension of one hypothetical principle (an important 

 one indeed in the interpretation of geological phenomena) on which 

 we differ in opinion. Nineteen twentieths of his work remain un- 

 touched by these remarks. His excellent and original historic narra- 

 tive his dignified philosophic views and clear descriptions his ad- 

 mirable account of the effects brought about by the great causes, 

 whether aqueous or igneous, now acting on the crust of the globe, 

 contribute to make his volume, in the highest degree, both popular 

 and instructive ; and I cannot but express a wish, that, in the future 

 editions of his work, the system of " geological dynamics" may be 

 stripped of even the semblance of hypothetical assumption ; and that 

 having first ascertained by a mere appeal to facts, what the powers 

 of nature now are (and 1 know no one more competent to the 

 task), he will then proceed to apply them to the solution of the 

 dark problems of geology. This arrangement would not only be the 

 most fair and logical, but would take away that controversial cha- 

 racter, by which, in my opinion, some pages of his present volume are 

 disfigured j and would, in the end, give him incomparably the best 

 chance, either of limiting or extending his own principles, as might 

 seem good during the advances of our science. What he has written 

 with so much power, must inevitably produce a great impression on 

 the English school of geology. It is on this account, and not with any 

 spirit of unfriendly criticism, that I have discussed, at greater length 

 than I first intended, the points on which we differ j and 1 am only 

 anxious, that a work abounding in so many admirable details, should 

 hereafter appear, as tar as any human production can do, without a 

 blemish in the enunciation of a single principle. 



Greatly as I admire the generalizations of M. de Beaumont, they 

 have, I think, been already pushed too far. We may follow them as 

 our guides, but they must never take the place of direct observations. 

 It is only through limited regions of the earth that we shall perhaps be 

 ever able to make out the true parallels of contemporaneous elevation. 

 Distant continents may have independent parallel systems of eleva- 

 tion. In several mountain chains (for example, in the Eastern Alps) we 

 have direct proof, that the forces of elevation have acted on the same 

 line at successive epochs -, and in our island, there have been move- 

 ments of elevation at different epochs, yet on lines which are parallel. 

 Lastly, lines of elevation (like the existing lines of modern volcanic 

 vent) may, in their prolongation, have deflected far from their first 

 direction. But I must forbear, for the discussion of these questions 

 would lead me into endless details*. 



* That part of the generalizations of M. Elie cle Beaumont, in which he seems 

 to assume, that each great period of elevation was followed by a great change in 

 organic forms, is, perhaps, the least secure. In England, there is a great break be- 

 tween the greywacke and carboniferous systems ; yet the fossils, in the calcareous 

 groups, alternating with the greywacke, very nearly approach to those of the car- 

 boniferous limestone. There is also a great break between the carboniferous and 

 magnesian limestone series of this country ; but their suites of fossils very nearly 

 resemble each other, and several species are common to both. Again, on the 

 outskirts of the calcareous zone of the Alps, there are large groups of strata, with 



fossils 



