506 PEOCEEDIIS^GS OF THE GEOLOaiCAL SOCIETY. [Feb. 2, 



lava- currents conduct themselves when expelled under varying cir- 

 cumstances upon the earth's surface — what volcanic mountains, or 

 what portions of any such, are the product of eruption and accumu- 

 lation, and what of the mere mechanical upheaval in mass of pre- 

 existing beds. The whole subject is rendered indistinct, and I will 

 venture to say unintelligible, by the author's adhesion to the theory 

 of " Cones and Craters of Upheaval," first dogmatically enounced 

 by M. Leopold von Buch, and subsequently supported, with most 

 elaborate — ^but, as it appears to me, very inconclusive — arguments, 

 by MM. De Beaumont and Dufrenoy. IS'ow, although the study 

 of the laws of volcanic action is a branch of geology which has not 

 attracted much attention in this country, yet every one wiU, on 

 consideration, admit that, among all the forces of nature which may 

 be seen in activity on the surface of the earth, the volcano is by far 

 the most striking in its phenomena, and the most directly demon- 

 strative of the character and mode of oj)eration of those (as yet little 

 understood) subterranean agencies by which the crust of our globe 

 has been unquestionably from time to time modified, and was in aU 

 probability in a large degree elaborated. 



It cannot, therefore, but be of paramount importance to the pro- 

 gress of the science, that just and correct views should prevail upon 

 this subject, and that, if erroneous opinions have been promulgated, 

 they should be thoroughly exposed and refuted. 



It is true that the able, though succinct, argument against the 

 Upheaval doctrine, contained in the last editions of the ' Principles' 

 and ' Manual' of Sir Charles Lyell, together with the paper recently 

 read by him before the Royal Society, and printed in the ' Philoso- 

 phical Transactions,' in which he corrects the representations of 

 M.Elie de Beaumont on this point, with respect to the lava-currents 

 of Etna, may be thought to have rendered any other effort of the 

 kind superfluous. I may, however, remark that this, like many 

 other unsound doctrines, when once promulgated by high authority, 

 requires more than one blow to destroy it. In more than one recent 

 elementary work on Geology * the Upheaval theory is still put for- 

 ward as the true explanation of volcanic action. Our distinguished 

 associate. Dr. Daubeny, to a great extent, advocates it in the last 

 edition of his work on that subject, and has not hitherto changed 

 his opinion, so far as I am aware. Professor James Forbes yet lends 

 it his countenance. The majority of geological schools on the Con- 

 tinent still teach it as a matter not open to controversy. It is, 

 indeed, disheartening to reflect how successfully an erroneous theory 

 of this character may be set up, and how widely and enduringly it 

 may be thenceforward propagated, under the influence of one or two 

 great names — finding its way, as a matter of course, into all popular 

 compilations,— and with what difficulty its refutation can be esta- 

 blished. 



In the present instance I have myself to repeat arg-uments which 



* E. ff. in Keith Johnston's 'Physical Geography*; Lardner's 'Geology'; 

 Professor Ansted's ' Elementary Geology' ; the article Geology in the ' Encyclo- 

 paedia MetropoUtana,' &c. 



