of the Cumbrian Mountains. 49 



In subsequent communications I hope to prove : Ist^ That the crystalline 

 unstratified masses form the true geological centres of the mountain groups ; 

 and that by their protrusion the schistose formations have been elevated into 

 the position they now occupy. 2ndly, That a true mineralogical axis may be 

 traced through the inferior divisions of the slate rocks on each side of which 

 the successive formations, as far as they are clearly developed, are arranged 

 symmetrically. 3rdly, That the beds of these formations, when we exclude 

 irregularities arising from local causes, have a nearly constant strike from 

 a few degrees north of magnetic east to a few degrees south of magnetic west. 

 And, lastly. That all these peculiarities of structure and position originated 

 in causes brought into action at a period anterior to the existence of the old 

 red sandstone. 



On these several subjects I wish, for the present, to avoid any further de- 

 tails : I may, however, be permitted so far to anticipate the materials of a 

 future communication as to describe the range of the remarkable calcareous 

 beds, interposed between the green quartzose roofing slate and the greywacke 

 slate. Such a description will place in a clear point of view the kind of evi- 

 dence by which we determine the strike of the slaty masses, and will at the 

 same time make us acquainted with a succession of dislocations which have 

 considerably modified the external forms of the Cumbrian mountains. It will 

 also form a natural introduction to the description of a second system of dis- 

 locations, by which, at a later geological epoch, these older mountain groups 

 were snapped off from the central carboniferous chain, and brought into their 

 present almost insulated position. 



§ 2. Range of a hand of Limestone and Calcareous Slate, between the 

 Quartzose Green Slate and the Greywacke Slate, ^c. Sfc* 



This band is full of organic remains, and is separated by masses of enor- 

 mous thickness from all other calcareous strata with which it could possibly 

 be confounded : moreover, it occupies, as before stated, a place intermediate 

 between two entirely distinct formations. Hence, although varying in thick- 

 ness from 30 or 40 to 200 or 300 feet, it can be easily followed ; and in the 

 places where its continuity has been broken by great internal movements, we 

 can generally, in imagination, reunite the disjointed portions, and calculate 

 the amount of their dislocation, without running the very common risk of mis- 

 taking one bed for another. 



The most western appearance of the limestone is at Beck, a farm in the 



* See Plate IV. 

 VOL. IV. — SECOND SERIES. H 



