Vol. 67.] IX THE OLD RED SAXDSTOXE OF nrOXMOTTHSniRE. 



4(51 



Pig. 1. — Map of the neighbourhood of the Great House, 

 Golden Hill (Monmouthshire). 



Feet ,100 200 



1 '■":_! L_ 



Contour-lines 



II. FlELD-CflARACTEES AXD E-ELATIOXS TO THE COXTACT-ROCKS. 



The rock in the recently opened quarry l is much weathered to a 

 buff or rusty colour for a depth of 6 to 10 feet, and along the joints ;. 

 but where unweathered it is dark grey, nearly black, compact 

 and glassy looking, and extremely hard and tough. It contains 

 remarkably big phenocrysts of augite and biotite, the former 

 measuring up to 5 or 6 inches in length ; and when much corroded, 

 as is often the case, they form spherical or ovoid masses, of a black 

 or dark greenish colour. The biotite-plates up to 2 inches across 

 lie on the face of the quarry, or project conspicuously from the rock. 



In the ground-mass, white, green, and pink patches, some small 

 and round, others large and irregular, are evidently filled with 

 secondary products. Here and there are patches of rounded or 

 oval shape, up to 8 or 9 inches across, quite different in appearance 



1 I was told by a man on the estate that it was opened about ten years ago. 



2k2 



