310 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. 2/, 



difying the extreme views of the advocates for and against elevation- 

 craters. Although much indebted to M. Leopold von Buch for 

 suggesting the theory, to M. Elie de Beaumont for extending and 

 illustrating it, and to Sir C. Lyell for his eiforts to explain all these 

 appearances by reference to causes now visible, still I must express 

 my belief, that the truth which geologists are in quest of lies in 

 neither extreme. I think, indeed, that the day is not distant when 

 it will be admitted, that in some tracts, in which suhmarine volcanic 

 dejections have been very widely diffused and carried to great distances 

 from the orifices of eruption, the strata have smce been heaved up 

 eccentrically by the subsequent operation of heat and intumescence, 

 whether accompanied by an actual eruption of molten matter and 

 scoriae or not. Such then must be considered craters of elevation. 

 On the other hand, in reference to true volcanic coulees and detritus, 

 some districts will be shown to abound still in those grand volcanos, 

 which during countless ages have been augmenting their area by 

 materials, which, derived from their own bowels, have been continu- 

 ally added to their flanks. 



Postscript. 



On writing to Dr. Daubeny for an explanation of his views, I find 

 that on one essential point his opinion coincides with my own, viz. 

 that the external dejections around Eocca Monfina have been all 

 formed under ivater, perhaps of no great depth,^ — an opinion which 

 I am glad I have elicited, as the most careful perusal of his memoir, 

 in which he makes no allusion to subaqueous volcanic operations, had 

 led me to draw another inference. 



In the present state of geology, I hold it to be of the utmost im- 

 portance to distinguish in a marked manner between subaqueous and 

 subaerial volcanic action, and to note well, when it is possible, the 

 cases where both operations have been united. It was to bring this 

 point out in relief that the foregoing lines were penned. 



February 27, 1850. 

 The following communications were read : — 



1. An Account of the Strata and Organic Remains exposed in 

 the Cuttings of the Branch Railway, from the Great Western 

 Line near Chippenham, through Trowbridge, to Westbury in 

 Wiltshire. By Reginald Neville Mantell, Esq., C.E. 



[Commimicated by G. A. Mantell, Esq., LL.D., F.R.S., G.S.] 



This railway passes over the usual series of the ooHtic deposits of 

 that part of England, and in the distance of fifteen miles the cuttings 

 brought to light immense quantities of fossil shells, remains of nu- 

 merous species of Cephalopoda, trunks and branches of trees, and a 

 fe^v bones of reptiles. 



