1869.] NICHOLSON IGNEOUS EOCKS OF THE LAKE-DISTRICT. 



435 



9. Notes on certain of the Intrusive Igneous Rocks of the Lake- 

 district, By Henry Alletne Nicholson, M.D., I). So., M.A., 

 F.G.S. 



The rocks which I purpose noticing in the following communication 

 are certain igneous rocks, of an intrusive character, and holding an 

 almost identical position in the stratified series of the Lake-district 

 of Cumberland and Westmoreland. The rocks in question are the 

 syenite of the Yale of St. John, the syenitic porphyry of Ennerdale 

 and Buttermere, and the felstone porphyry of Carrock Eell, aU. of 

 which come into contact, on the one hand, with the Skiddaw Slates, 

 and on the other with the series of the green slates and porphyries. 



Fig. 1. — Sketch Map of the North-western portion of the 

 Lake District. 



Cb Skiddaw Slates. 



3 Metamorphosed 



o \ Skiddaw Slates. 





^ (Intrusive ig- 

 1 neous Rocks. 



S Green Slates and 



\ Porphyries. 





jOld Red 

 ^ 1 Sandstone 1 



/• j SearLime- 

 ■^ 1 stone. 



I. The Syenite of the Vale of St. John. 



The area occupied by the main exposure of this rock is situated 

 on both sides of the mouth of the Yale of St. John, distant about 

 three miles to the east of Keswick, and occupying a space of nearly 

 two miles from east to west by nearly a mile from north to south. 

 On the east side of the valley it forms a cluster of minor elevations, 

 of which the highest is known as Knotts. On this side of the valley 



