138 Dr Boue on the Elevation of Mountain Chains ^ 



seas or great gulfs, (Mem. Geolog, vi. p. 48.) These deposits have 

 been formed in a horizontal or gently inclined position, and 

 while some of them have been subsequently upheaved, the rest 

 remained in their original position either in the form of a flat 

 tract of country, a low table land, or pretty high truncated hills 

 as in Bavaria. 



M. de Beaumont assigns to this system a direction W. 40** 

 N. to E. 40° S. ; and the formations which were disturbed by 

 its elevation are the beds of the variegated sandstone, of the 

 muschelkalk, and of the keuper as well as the older rocks, and 

 these formations must have formed the steep walls (falaises) at 

 the base of which the Jurassic beds were horizontally extended.' 

 The movement took place between the period of the keuper 

 and that of the inferior lias sandstone. As examples, M. de 

 Beaumont mentions the north-eastern part of Germany, the 

 Thiiringerwald, the Western Bohmerwaldgebirge, the neigh- 

 bourhood of Autun and Avallon, and in Greece the Olympic 

 system of MM. Boblaye and Virlet. In north-east Germany 

 the floetz formations, from the variegated sandstone to the Jura 

 limestone, form curved beds or inclined masses ; and it might be 

 a subject of discussion whether these accidens are original, or if 

 all these deposits were at first horizontal. But entering into M. 

 de Beaumont's views, it would be at least necessary to date the 

 upheaving from the epoch of the middle part of the Jurassic 

 formation. 



With regard to the Thiiringerwald, the Jurassic deposits and 

 even the lias beds do not touch its base at the west end, and they 

 do not exist between its eastern extremity and the Hartz ; and 

 the keuper only approaches its neighbourhood. If the zechstein 

 covers in nearly horizontal beds the secondary sandstone of Eise- 

 nach, we can observe near Ilmenau and elsewhere disturbances, 

 and especially singular faults (failles), which extend from the 

 older coal measures to the variegated sandstone. Voigt, Von 

 Hoff, &c. have described these minutely, and the last mentioned 

 distinguished observer, in a recent work on Thuringia, has ex- 

 pressed a suspicion that the muschelkalk has been dislocated 

 and contorted after its formation, and before the formation of the 

 succeeding deposits which occur in its valleys (Hohenmessungen 

 von Thuringen, 1833, in 4to.) In the Coburg country, the 



