382 



REPORT — 1856. 



whole grow greater and greater toward the southern end ; so that beginning 

 in the northern part at 60° and 66°, they augment in the synclinal roll to 72°, 

 south of it to 80°, and at length appear vertical, near the line of the North 

 Craven Fault, which ranges E.S.E., nearly parallel to the strike of the beds 

 and the cleavage. In Diagrams 16 and 17 these remarkable facts are ex- 

 pressed in a section from N. to S. in Ribblesdale, which may be compax-ed 

 with Diagrams No. ■!■, 5, 6. 



As already observed, the rocks which form the needles and sharp crests on 

 the flanks of Mont Blanc, appeared to Studer and other geologists to be com- 

 posed of laminge which, viewed on a great scale, dip inward on each side of 

 the great chain, so as to produce in the section a fan-shnped structure; and 

 this has the more caught attention because the lowest in the scale of lamina- 

 tion contain organic remains and appear to be covered by crystalline schists, 

 : — the gneissic and granitic series of Mont Blanc. It appears to Mr. Sharpe 

 that these fan-shaped laniinaa are due to cleavage; that an anticlinal axis of 

 foliation shows itself between two lines of vertical foliation in Mont Blanc, 

 and runs through the whole chain ; and tliat there is really no superposition 

 of gneiss above fossiliferous strata. He traces across the region of the Swiss 

 Alps, nine of these parallel axes and ten vertical bands of cleavage and folia- 

 tion. The following is Mr. Sharpe's section* of the granitic or gneissic 

 mass (protogine) of Mont Blanc, and the strata adjoining which appear to 

 dip into or under the gneissic rocks. 



Wltn. 





c ^ 



The Section No. 19 exhibits the same systems of cleavage and foliation, 

 the same axes, and the same verticals; the strata on the flanks of the Mont 

 Blanc are seen reposing against the gneiss, not dipping into or under it. The 

 gneiss is not supposed to be stratified, but foliated; the foliation being in 

 planes parallel to, and even continuous with, those of cleavage. 



Fig. 19. From the Col de Balme to the Col Ferret. 



Aiguille Mnnt 



de Tour. Doleiit. 



Prof. Forbes and Prof. Rogers do not admit the statements and conclu- 

 sions of Mr. Sharpe in regard to the Mont Blanc range. They are indeed 

 much different from the usual ideas of geologists, and well deserve a careful 

 revision and verification before being implicitly adopted in the theory of 

 * Geol. Proceedings, Nov. 1854. 



