172 H. A. Nicholson — On the Lake District. 



of the beds consisting of coarse felspathic aslies, tlie dip of whicli can 

 be satisfactorily made out to be S.S.E. at 40^^. The inclination, 

 therefore, of the Green Slates is in this locality considerably lower 

 than that of the Skiddaw Slates beneath them. 



(IV.) Skiddaio Slates between Bampton and SJiap. — Proceeding up 

 the river Lowther from Bampton to Shap three small areas of Skid- 

 daw Slate are crossed, one at Eossgill, a second at Keld Beck, and 

 the third in the course of Thornship Beck. In all these localities 

 the upper shaly beds of the Skiddaw Slates are brought to the sur- 

 face, and dip S.S.E. to S.E. at angles of from 45° to nearly 90°. In 

 each case they are surmounted by the fine-grained, greenish- gray 

 felspathic trap which forms the base of the Green Slate series, but 

 the dip of this could not be determined. 



Conclusion. — Having now surveyed all the localities in Cumber- 

 land and Westmoreland in which the Skiddaw Slates come into con- 

 tact with the Green Slates and Porphyries — with the single excep- 

 tion of the Black Comb area — the following conclusions appear to 

 be deducible as to the relations of the two formations : — 



1. Where the inclination of the Green Slate Series agrees in 

 direction with that of the Skiddaw Slates, the dip of the former is 

 almost invariably lower in amount ; the difference varying from a 

 few degrees to as much as half the dip of the inferior formation. 



2. The dip of the Skiddaw Slates, at the point where tbey are 

 overlaid by the base of the Green Slates, is occasionally directly 

 opposed in direction to the inclination of the latter. This is seen at 

 the head of Mosedale Beck under Wolf Crags, and also in the course 

 of EUengill, near Overwater. 



3. The strike of the Green Slates is sometimes at variance with 

 that of the Skiddaw Slates. This is seen to a slight extent in pro- 

 ceeding from Troutbeck to Keswick, and again from Borrowdale 

 in a S.W. direction towards the head of Buttermere ; since the fels- 

 pathic trap which forms the base of the Green Slate Series reposes 

 at first upon the upper, shaly beds of the Skiddaw Slates, but seems 

 gradually to become transgressive upon them, so as finally to rest 

 upon beds which, though high in the series, are not the highest. It 

 is also seen in Torpenhow Common, to the north of the foot of Bas- 

 senthwaite Lake. This phenomenon is, however, best exhibited on 

 the N.E. margin of the great area of the Skiddaw Slates, where the 

 two formations strike for a considerable distance nearly at right 

 angles one to another. 



4. As a consequence of the above, the base of the Green Slates 

 reposes at one time upon the higher, and at another upon the lower 

 beds of the Skiddaw Slates. This is seen near Melmerby, beneath the 

 Penine chain, but it is much more strikingly exhibited on the N. 

 and N.E. margin of the great area of the Skiddaw Slates. Thus at 

 both extremities of this boundary, the base of the Green Slates 

 reposes upon the soft black shales which form the summit of the 

 Skiddaw Slates, resting between these points upon all the inter- 

 mediate beds of the great anticlinal of the Skiddaw Slates, down to 

 their base. 



