Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/559

 9. Notes on certain of the Intrusive Igneous Rocks of the Lake- district, By Henry Alleyne Nicholson, M.D., D.Sc., 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 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.

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

a Skiddaw Slates.

b Metamorphosed Skiddaw Slates.

c Green Slates and Porphyries.

d (Intrusive igneous Rocks.

e Old Red Sandstone.

f Scar Limestone.

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