524 Progress of Geological Science. [Nor. 



which I have pointed he true, (and as far as I comprehend them, they seem to be 

 based on an immovable mass of evidence,) we must then conclude that there have 

 been in the history of the earth long periods of comparative repose, during- which 

 the sedimentary deposits went on in regular continuity, and comparatively short 

 periods of violence and revolution, during which that continuity was broken. 

 And if we admit, that the higher regions of the globe have been raised from the sea 

 by any modification of volcanic force, we must then also admit that there have been 

 several successive periods of extraordinary volcanic energy. 



" How we are to escape from this conclusion I am unable to comprehend, unless 

 we shut out the evidence of our senses. Of volcanic powers we know nothing, 

 except during the irregular periods of their activity — and returning periods of 

 intense activity, after long ages of comparative repose, may be among the endur- 

 ing principles in the mechanism of nature. I do not throw this out as even a 

 probable hypothesis : but it is, at least, as probable as any other hypothesis un- 

 founded on the evidence of geological phenomena. 



" That the sj'stem of M. Elie de Beaumont is directly opposed to a fundament- 

 al principle, vindicated by Mr. Lyell, cannot admit of doubt. And I have decided 

 to the best of my judgement, in favour of the former author, because his conclu- 

 sions are not based upon any a priori reasoning, but on the evidence of facts ; 

 and also, because, in part, they are in accordance with my own observations*." 



Mr. Boue and other able writers have opposed the views of this eminent geolo- 

 gist ; they deny him the merit of being the first to point out, that different forma- 

 tions and masses of land have been elevated at distant and separate periods, and re- 

 ject that part of his system which asserts the synchronous elevation of distant 

 mountain chains parallel to each other. Before we are warranted in arriving at 

 general conclusions on this latter point, numerous facts must be collected, and we 

 can but urge all our working brethren to try the adequacy of M. de Beaumont's 

 ingenious theory, by an appeal to naturef ; M. de Humboldt believes, that the 

 four great chains of Asiatic mountains are parallel to one another, and that cir- 

 cumstance tends powerfully to confirm the theory. As however, the personal ob- 

 servations of this traveller have not extended beyond the Altai, we must still look 

 for evidence whereon the synchronism of the elevations of these mountains may 

 rest to our Indian geologists, whose exertions will naturally be stimulated to attempt 

 the solution of the problem. Russia has been before hand with us in exploring their 

 newly acquired portion of Asia ; their government, with its characteristic enterprize, 

 being desirous of acquiring accurate information respecting the structure, natural 

 history, and heights of the Caucasus, sent hither in the summer of 1829, under a 

 strong escort, commanded by General Emanuel, a party of men of science, the chief 

 of whom, M. Kupfer, has given in his report to the Academy of Sciences of St. 

 Petersburg. 



* " For example, the vertical position of the green-sand and chalk on the eastern 

 flank of the Hartz mountains, and the horizontal position of the same formations on the 

 flanks of the Erzgebirge, were remarked by Mr. Murchison and myself, in the summer 

 of 1829. During the same tour, we had repeated proofs of the recent elevation of the 

 chain of the Eastern Alps ; of the high elevation of the green-sand series in the calcare- 

 ous chain to the north-east of Trieste ; and of the horizontality of the tertiary deposits 

 of Styria. All these facts (of which we did not at the time comprehend the whole import- 

 ance), harmonize with the system of M. de Beaumont." 



f Address, 383. 



