~I 
Or 
THE DEPOSITS OF METALLIC 
AND OTHER MINERALS SURROUNDING THE 
SKIDDAW GRANITE. 
By JOHN POSTLETHWAITE, F.G.S. 
(Read at the Ambleside Annual Meeting. ) 
A TREATISE on the mineral deposits which surround the Skiddaw 
Granite, must necessarily deal with the whole of the area embraced 
in the Skiddaw group of mountains, comprising a surface of about 
eighty square miles, mostly mountain and moorland. The 
- dominant rock of this area is Skiddaw Slate, but there is a broad 
belt of volcanic rock, of the Eycott Hill series, extending along 
_ the northern side of the area; also several intrusive masses and 
: dykes of felsite, diorite, gabbro, and picrite, in addition to the 
' granite, which occupies the central portion of the area. Very 
‘little of the granite is visible on the surface, a small patch being 
exposed in Syning Gill, between Skiddaw and Blencathra, a larger 
Mass at the upper end of the Caldew valley, and a third a little 
lower down the course of the river. The largest exposure measures 
about a mile in length and half a mile in width, and the three no 
doubt form portions of one mass which extends over a large area 
at a moderate depth beneath the surface; its presence being 
in dicated by the changes produced in the surrounding and over- 
lying Skiddaw Slate. These changes have been described in detail 
elsewhere, therefore, it will be sufficient to state here that there are 
traces of metamorphism, in a higher or less degree, extending over 
