Notes on certain of the Intrusive Igneous Rocks of the Lake-district

Abstract

T he 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 Vale of St. John, the syenitic porphyry of Ennerdale and Buttermere, and the felstone porphyry of Carrock Fell, all 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. 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 Vale 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 the syenite, in its main mass, nowhere comes into contact with the green slates and porphyries, but is everywhere surrounded by the upper beds of the Skiddaw Slates, which are often more or less indurated and penetrated by numerous small veins of quartz near the line of junction. It is well exhibited in a quarry about a quarter of a mile to the S.E. of Threlkeld Station, where it is so regularly