the Eevolutiotis 'which have taken place on the Globe. 24/5 



of beds having been thrown up at the same time by a single 

 eiFort of nature: whence it would follow that the number of 

 the epochs of elevation would not be unlimited, but that it 

 would at least be equal to that of the directions of those chains 

 which are clearly distinct,— a number not incompatible with 

 that of the solutions of continuity observable in the sedimen- 

 tary deposits. , . I J 

 It became necessary, in order to carry the subject beyond 

 these vao-ue and general views, that a comparison should be 

 instituted between the number of those lines of demarcation 

 observable in the sedimentary deposits, and the same number 

 of mountain systems. It has been attempted to accomplish 

 this by combining the two great principles above noticed; 

 namely, that the highly inclined sedimentary beds are up- 

 heaved strata, and that in each mountainous district all the 

 beds upheaved at the same moment have been so raised in the 

 same general direction. 



The examination of the surface of Europe has in this man- 

 ner already led to the determination, both with respect to age 

 and direction, of the twelve systems of mountains to be suc- 

 cessively noticed in the sequel, as also their relation to twelve 

 solutions of continuity observed in the series of sedimentary 

 deposits. 



I. Srjstem of Westmoreland and of the Hundsruck. — The cor- 

 respondence of this nature which may be referred to the most 

 ancient geological epoch has been made known by the re- 

 searches of Professor Sedgwick, recently communicated to the 

 Geolo'ncal Society of London. The mean line of bearing of 

 the different systems of slate rocks in the lake mountains of 

 Westmoreland, is shown by this author to be nearly N.E. by 

 E., and S.W. by W. This causes them to abut successively 

 against the carboniferous zone ; from which it follows that 

 they must also be unconformable to it. Professor Sedgwick 

 strengthens this inference by reference to detailed sections : 

 and from the whole of the evidence he concludes, that the 

 central lake mountains were placed in their present position, 

 not by a long continued, but by a sudden movement of eleva- 

 tion, before or during the period of the old red sandstone*. 



Professor Sedgwick has also shown that if lines be drawn 

 in the principal bearing of the following chains, — viz. the 

 southern chain of Scodand, from St. Abbs Head to the Mull 

 of Galloway; the grauwackc chain of the Isle of Man; the 

 slate ranges of the Isle of Anglesea ; the principal grauwacke 



• From other circumstances to be noticed in the sequel, it appears very 

 probable that this inovcniont of elevation was anterior to the deposition 

 of the most recent strata of the transition series. 



chains 



