ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixxxiil 



great fault bounding the district ou the west (to which our author 

 alludes) has been traced southwards into the Lias which it dislocates. 

 This system is also supposed to show itself in Coalbrook Dale ; but 

 there the general direction is nearly the general north-eastern direction 

 which characterizes the surrounding region. Again, the N.N.E. 

 strike of the south-eastern part of Ireland is supposed to indicate its 

 influence ; but Sir H. De la Beche asserts that strike to be due to a 

 movement anterior to the Old Red Sandstone*. Other applications 

 of the system to this country appear to me too vague to be of much 

 value, unless they were sanctioned by more determinate cases in the 

 same region than any which the author has cited. 



The eleventh system is that of Thilringerwald, between Bavaria 

 and Bohemia, where it appears to be most distinctly developed. Its 

 orientation there is about W. 39° N. Its epoch seems to be well 

 defined between the Marnes iri'isees (the latest formation of the Trias) 

 and the earliest beds of the Lias. Indications of this system exist 

 to a considerable extent in France, but scarcely any applications are 

 made of it in this country. It is suggested, however, that faults 

 may belong to this system pe)'pendieular to its characteristic direction. 

 In support of this supposition, reasoning of my own is quoted, in 

 which I have shown that systems of fissures perpendicular to each 

 other might be formed simultaneously. But I must repeat what I 

 have already stated (p. Ixxxi), that that conclusion is only true when 

 the action is that of forces of extension, and not at all necessarily so 

 when the forces compress the mass on which they act. Such per- 

 pendicular or transverse faults would nearly coincide, it is said, in 

 direction with the great fault on the western side of the Dudley 

 coal-field, which, therefore, might be connected with this system. 

 The author had previously referred it to the system of the Rhine, as 

 above stated. 



The period which intervened between the deposition of the Coal- 

 measures and the commencement of the Lias, during which the 

 Permian and Triassic groups were formed, was one of great disturb- 

 ance. The last four systems, it will be observed, are referred to this 

 period. The first of these, that of the North of England, seems very 

 well to represent the movement antecedent to the lowest Permian 

 beds. The epoch of the second, that of the Netherlands and S. 

 Wales, is subject to great uncertainty, as depending on that of the 

 Dolomitic Conglomerate. Its separation, also, from the succeeding 

 system, that of the Rhine, merely by the supposed intervention of the 

 same uncertain formation, is unsatisfactory. The last of these four 

 systems, that of Thiiringerioald, is the only one after the commence- 

 ment of the Trias, but is altogether insufficient to represent with that 

 accuracy to which the theory aspires, all those lines of elevation which 

 resulted from movements subsequent to that epoch in our own country. 



The next system is that of Mont Pilas and the Cote d' Or. The 



former mountain is situated in Forez, in the department of the Loire. 



The epoch of the system is between the Oolites and Lower Green 



Sand. It is recognized in the eastern and some other parts of France, 



"^ Memoirs of the Survey, vol. i. p. 222. 



/2 



