1868.] 



HARKNESS AND NICHOLSON C0NI8T0N GROUP. 



297 



felspar which is so abundant in the granite of Wastdale Crag. At 

 Scale Head the Coniston limestone is in very close proximity to the 

 granite ; and its peculiar aspect doubtless results from the granitic 

 influence : the granite itself, near the point of junction with the 

 limestone, has also undergone considerable change, becoming fine- 

 grained and compact, and losing those large imbedded crystals of 

 felspar which arc such a characteristic feature in the Wastdale-Crag 

 granite. Some portions even approximate to a felstone in their 

 aspect and composition. 



Section from below the Coniston Limestone to the Coniston Grits, 



inclusive. 



% k . h . h g fe 



a. Coniston grits. 



b. Sheerbate flags. 



c. Cleaved flags. 



d. Grey grits. 



e. Graptolitiferous mudstones. k. Ash-beds. 

 /. Trinucleus-shales. i. Felstone. 



y. Coniston limestone. /c. Porphyry. 



The country westward from Scale Head, for some distance, is 

 moory, and the small brook-sections expose no Coniston limestone 

 until a small stream flowing into the valley of Long Sleddale, called 

 Arnco-side Beck, is reached *. 



Although we have no exposures of Coniston limestone between 

 Scale Head and this locality, the rocks that form the summits of the 

 hills a little to the north of the strike of the line of the Coniston 

 limestone are of a very interesting nature. 



These rocks underlie the Coniston limestone, and they occupy the 

 horizon of some of the ash-beds associated with the green slates and 

 porphyries ; but in their mineral aspect they differ very greatly from 

 the ordinary ash-beds, of which they are the representatives. They 

 are very compact, usually of a light flesh -colour, and are composed of 

 almost pure felspar. Their stratigraphical nature, however, is well 

 marked, and the original lines of lamination are generally beautifully 

 distinct. They form a considerable portion of the summit of Harrop 

 Pike, where they can be well seen ; and to the northward they pass 

 downwards into the ordinary green slates and porphyries. These 

 rocks can, however, be traced further westward, and are seen near 

 Little London, in the course of a small stream which here joins Arnco- 

 side Beck from the north-east. The latter locality affords some in- 

 sight into the origin of these compact stratified felspars. They are 

 here covered by a mass of felstone resembling the portions of Wast- 

 dale Crag, near where the granite comes in contact with the Conis- 

 ton limestone ; and the influence of this felstone seems to have so 

 far altered the felspathic ash-beds as to have converted them into a 

 perfectly compact flesh-coloured rock. The felstone can be seen both 

 on the east and west side of Long Sleddale. It is probably a 



* In Prof. Sedgwick's Memoir this stream is called Iron Crow GiU. 



t2 



