1862.] HARKNESS SKIDDAW SLATE SERIES. 125 



On the north side of the granite of Brandy-gill, in the conrse of 

 the stream, hard, grey, crystalline rocks devoid of bedding occur ; and 

 rocks of this character are seen likewise in the courses of Thief-gill, 

 which flows from the north side of the western spur of Carrock-fell 

 into Brandy-gill. Although devoid of bedding, these rocks often 

 show traces of lamination, and they appear to be the representatives 

 here of those gneissic rocks which are so well developed on the 

 south side of the plutonic area. What they pass into northwards is 

 not seen, the flat summits of the Caldbeck-fells being extremely 

 peaty. 



The interval between the north end of Carrock-fell and the south 

 side of High Pike, the adjoining mountain, does not exhibit the rocks 

 in situ, so that the relation between the plutonic masses of Carrock- 

 fell and the igneous rocks of the Caldbeck range is not apparent. 

 The brook- courses in the interval also afford no Skiddaw slate, and 

 there is strong reason for concluding that no sedimentary rocks in- 

 tervene between these plutonic and igneous masses. 



High Pike itself is composed, for the most part, of claystone-por- 

 phyry, which is well seen in the course of the Pottsgill-beck, a 

 stream flowing from the north side of this mountain by Caldbeck 

 into the Caldew. This clay stone-porphyry has a greyish-drab colour, 

 and contains yellow crystals of felspar, which are generally partially 

 decomposed. The stream which flows to the west of Pottsgill passes 

 over rocks which have a similar nature. 



In the upper portion of Roughten-gill, a stream which rises among 

 the flat summits of Caldbeck-fells and flows northwards through 

 these mountains, there is a more varied series of igneous rocks. On 

 the moors at the head of this stream claystone- porphyry, similar to 

 that just alluded to, occurs ; on passing down the stream, a mass of 

 compact felspar makes its appearance ; and this is succeeded by a 

 considerable development of a rock composed of orthoclase and la- 

 bradorite, like that forming the south side of Carrock-fell, and in 

 which the lead-veins at Roughten-gill principally occur. 



One of the best exposures of the porphyritic rocks of Caldbeck- 

 fells is seen in the course of a stream called Charlton-wath, flowing 

 between Brae-fell and Langlands-fell. The upper portion of this 

 stream is over claystone-porphyry, being an extension westwards 

 of that at the head of Roughten-gill. Lower down the stream, and 

 near the junction of a rivulet flowing from the south-west, a grey 

 trap makes its appearance. For some distance below this junction 

 no rock is seen ; but after the barren interval is passed over, we come 

 upon a fine-grained, greenish-grey, felspathic rock, beyond which is 

 a small development of claystone-porphyry. Still lower down the 

 stream we meet with a rock having a singular aspect. This rock is 

 much broken up in structure, has a mottled appearance, and seems to 

 be composed of white and green felspars. It is usually partially 

 decomposed, and its mottled character is well seen on its weathered 



of phosphate of lead. There occur also arsenio-phosphates, sulphates, cupreous 

 sulphates, and cupreous sulphato-carbonate of lead ; and along with these are 

 seen radiated malachite, brochantite, and other minerals. 



