118 REPORT 1861. 



The metamorphic rocks iu the vicinity of Bootle, under Black Comb, have been 

 noticed by Sedgwick, and also by Phillips, as offering many remarkable phenomena ; 

 and as the granite was not considered by either of these observers as a metamoi-jjhic 

 rock, I have been induced to pay another short visit to the locality in order to 

 examine especially the evidence for or against that supposition. 



The first point which I examined was the appearance of granitic rock in the 

 com-se of a branch of the stream which runs through Bootle from Black Comb, and 

 called Hole GUI. This rock fii-st appears in a quan-y near the enti-ance of the ravine 

 through which the stream descends Black Comb. It is seen in three places — two on 

 the southern side and one on the northern side, and all near the bottom of the 

 ravine and within a distance of 300 or 400 yards. This rock (specimens Nos. 1 & 2), 

 though of a felspathic and gi-anitic character, is far from being a perfectly fomied 

 granite, and appeared to me to be quite analogous to the transition beds so constantly 

 observed in the slaty rocks when the metamorphic change is just commencing. 

 Moreover, in the spot where this rock appears on the northern side of the ravine, 

 it is seen distinctly dipping conformably imder the soft clay-slate, at an angle of 

 about 25° or 30° to N.W. 



I am of course familiar with the syenitic dykes which so frequently occur in this 

 district, and have followed several of them for miles ; but I could see no appearance of 

 vertical or unconformable position in these gi-anitic rocks in Hole GiU to indicate 

 that they were dykes or elvans. They had rather the appearance of beds of the clay- 

 slate in which the metamoi-phic action was commencing ; and they appear at the 

 very base of Black Comb, and nearly on a level with the adjacent metamorphic rocks 

 of the greenstone slate formation. 



The next appearance of metamorphic action is at a distance of about half a mile 

 northward from the ravine just mentioned, in a range of slate rock which in the 

 distance of 300 or 400 yards is gradually and completely changed fi-om a perfectly 

 fissile and imaltered slate at the southern end to a compact massive greenstone and 

 orphyry at the other or northern end (Nos. 3-8 specimens), where it is intersected 

 y another branch of the Bootle sti-eam. It would be impossible to find a more 

 perfect example than this ridge of rock affords of gradual metamoi-phic change along 

 "the line of strike. Between this second branch of the stream and a third branch, 

 about half a mile fm'ther north, there is a broken hUloclcy lidge of metamorphic slate 

 changed into hard greenstone and poi-phjiy, and the beds much tossed about and 

 dislocated (specimens 9-11). 



The third branch of the stream intersects the border of the granitic range of 

 rocks, which from this point extend continuously to the Esk and up Eskdale. 



when first seen in situ the granite is very soft, incoherent, and disintegrating so 

 as to be little more than granitic sand, and yet in the faces of the escai-pment 

 formed by the stream in this soft mass all the marks of sti-atification and jointing 

 of the original slate rocks, of which it appears to have been formed, are distinctly 

 visible. This granite is hornblendic, and shows the nodular and concretionai'y 

 structure. A little further north, in a plateau or moderately elevated ridge, the 

 granitic rock appears in a hard and solid state ; the fomis of the blocks, however, 

 when in mass in situ, still preserving the angular and prismatic foims of the adja- 

 cent greenstone and porphyry beds, and with the same dislocated and broken ap- 

 pearance. 



I could not anywhere see any distinct jimction of the granite with the greenstone 

 and porphjTv rocks ; nor did I obsen^e veins or dykes proceeding fi'om the granite, 

 though possibly a longer search might have been more successful. 



The general result of the series of phenomena appeared to me to be the indication 

 of a gradually increasing intensity of metamorohic action in proceeding north or 

 north-westward in the direction of the general dip of the strata. The granitic 

 rocks appeared in the position in which the lower beds of the greenstone slate 

 would natui-ally be found, and there was no distiu-bance of a nature that would 

 indicate the intrusion of the granite amongst beds previously formed. 



It Is quite true that there is dislocation and tractm-e of the beds, both of the 

 granitic and porphyritic rocks. But a dislocation exactly similar occurs in the 

 same beds of gi-eenstone slate on the other or eastern flank of Black Comb, where 

 there is no granite. In both cases this dislocation of the beds seems to be produced 



I 



