APPENDIX. 191 



the non-essential features of De Beaumont's grand scheme, but on the thcory-itself very little 

 light can be thrown by the examination of so limited an area. He only deals with mountain 

 systems and with the great elements of direction, and time of production as a whole. In fact 

 M. de Beaumont's speculations go so far beyond our actual knowledge of geology, both 

 descriptive and physical, that the full verification of them must be left to future generations. 



The character I have just expressed of De Beaumont's theory is borne out by the inattention 

 he shows to the minor facts of the case under examination, to the secondary effects of the 

 general phenomenon, the stratigraphical features of contortion and displacement that must 

 attend these great efforts of nature. At least in his special work on mountain systems there is 

 only an allusion to these features, and that allusion is to disclaim any decided views on the 

 subject ; he states (p. 1344) that his general theory is independent of any special mode of 

 action, such as crushing (ecrasement d'unfuseau), or sinking, (affuissement), or direct eleva- 

 tion, all of which he leaves open to discussion. It may be that, according to circumstances, 

 any one of these modes may dominate, but we must, I think, believe that a proper discussion 

 of the facts of structure will enable us to say what that mode was in any case ; yet it may 

 often also occur that the result is so complicated as to be impossible of explanation. It thus 

 remains evident that direction and the time of production are the only elements essentially 

 involved in M. de Beaumont's theory, and by which he has left it open to verification.* 



In the sober views propounded by Mr. Hopkins (Trans. Geol. Soc, 2nd Series,Vol. VII., 1841) 

 we find a salutary check upon the too ambitious theories of 

 eleTOtiOT? PkinS ' di8Cussion ° f M. de Beaumont. Mr. Hopkins limits his discussion to a single 

 area of elevation, his object being to elucidate the proximate 

 mechanical conditions by which such a feature may be produced ; he subsequently submits 

 his theoretical considerations to rigorous comparison with actual example. His views 

 originated, like those of M. de Beaumont, in the perception of symmetry in features of 

 disturbance, — in the long-recognized fact of the approximate parallelism of lines of dislo- 

 cation in the districts in which systems of such lines are found to exist. The hypotheses he 

 adopts, for the theoretical consideration of the question, respecting the constitution of the 

 mass acted upon, and the action of the elevatory force, are very simple. He assumes the 

 mass to be uniformly cohesive, at the same time indicating the effects of variations in this 

 respect within known limits. For the force, he assumes it to be vertical, to be simultaneous, 

 and to be approximately uniform over the area affected, such, in fact, as would be the result 

 of fluid pressure. With reference to the form of the area affected, Mr. Hopkins lays down 

 two theoretical limits. In a circular area a uniform force would tend to produce concentric 

 fissures ; or, if acting with greater intensity at the centre, it would produce fissures diverging 

 from the centre. In an area of limited breadth but of indefinite length longitudinal fissures 

 alone could be formed, corresponding to the concentric fissures of the circular area. Actual 

 cases will be compounded of these two. It is not necessary that the lines of longitudinal 

 fissure should be continuous, but they must observe a parallelism to the geometrical axis of the 

 area. The transverse fissures must be at each point perpendicular to the longitudinal ones. 



• Mr. Hopkins in his Presidential address to the Geological Society of London (Quar. Jour., Vol. IX., 1853) gavo 

 an elaborate analysis of M. de Beaumont's theory, showing many objections and difficulties in the way of its 

 acceptance, but it seems to me that he fails to give a perfectly correct interpretation of some of De Beaumont's 

 views, such as those regarding the limitation of the fuseau, and again those regarding the mode of production 

 the fuseau and Its fissures. 



