MONIAN SYSTEM OF BOCKS. 



493 



farmyard are seen masses of pelite, flaky and somewhat micaceous. 

 This micaceous character increases towards one side of the yard, 

 and here there is an intrusion of the granite into it (see fig. 10). 



Fig. 10.^ Plan of the Farmyard of Maen Gwyn. 



1. Granite. 



2. Micaceous Pelite. 



The granite occurs in one boss in a gradually narrowing vein, with 

 a quite irregular course, and branching out it dies away in quartzose 

 strings in the midst of the pelite which overlies and underlies it. 

 Separate from this is another patch of granite surrounded by the 

 pelite and crossing its structural lines. This expands from a narrow 

 neck into a larger mass, and here entirely surrounds a kind of 

 inlier of the pelite, or, as one might more correctly call it here, the 

 micaceous schist. The two rocks at the contact are so distinct that 

 both may be recognized in any small hand-specimen. Is there any 

 escape from this ? 



There is a second such inlier on the Survey map, near Llecheyn- 

 farwy ; but at the spot indicated I could find no rock which ought 

 to have been thus coloured, and certainly no granite junction. A long 

 tongue is also indicated as running up N.E. from near Gwyndy. 

 This 1 have verified, but could seldom find the actual junction ; only 

 in one knob, south-west of the farm of Y-foel, did the surface of the 

 rock show a vein of granite running into the pelite. On the road 

 from Gwyndy southwards the relations of the granite to its neighbour 

 are not very clear, and resemble rather those to the south of the 



