Vol. 56.] INLIER AT OLD RADNOR. 513 



the breccia may be described as 'nascent,' the rock being traversed 

 by numerous planes of division, the fragments remaining never- 

 theless in contact, save for the film of infiltrated matter. The 

 crushing forces have evidently acted with varying degrees of in- 

 tensity ; but they have nowhere been severe. They have sufficed 

 to obliterate the bedding of the grit, although they have not 

 produced mylonite, nor have they even flattened out fragments into 

 lenticles. 



The following descriptions of thin sections throw light on the 

 constitution of the grit and its degree of alteration. For purposes of 

 comparison, I have included slides from the derived fragments in the 

 Woolhope Limestone : — 



[553] l Old Eadnor Hill, northern end. 



A grit, composed of angular bits of quartz, some of it showing mosaic 

 structure ; and angular bits of felspar (both orthoclase and plagioclase), some 

 of which is partly decomposed into microliths of mica. In less proportion are 

 angular fragments of felsite and andesite. Some scattered particles of epidote 

 and a little mica are also present. 



[554] In Woolhope Conglomerate, Yat Hill. For comparison. 



A very similar grit, though with less quartz. Felsite and mica more abundant, 

 but less epidote, 



[555] Old Eadnor Hill, southern end. Selected as micaceous. 



Angular quartz, felspar, and felsite as before, the felspar being less abundant 

 than the quartz. Mica, both white and brown, rather conspicuous, much of it 

 roughly orientated in one direction, but some not. It is cut normal to the 

 cleavage, and shows the regular outlines of unbroken mica, except where it is 

 moulded on fragments of quartz and felspar. It would appear to be authi- 

 genous, and is associated with cracks in the rock in such a way as to suggest 

 that it is the result of infiltration. It also occurs in cracks in individual 

 fragments of quartz. Judging from this slide, the rock has been but slightly 

 compressed, the mica being the only mineral that shows any approach to 

 parallelism. 



[557] Old Eadnor Hill, southern summit. 



Angular bits of quartz and quartz-mosaic predominating; felspar incon- 

 spicuous, some of it partly decomposed; very little felsite or mica; a fair 

 proportion of opacite, apparently resulting from the decomposition of a basic 

 mineral. The slide is traversed by several cracks, on the walls of which is 

 deposited a greenish mineral, and the middle of the cracks is often filled in with 

 opaque matter. 



[556] Woolhope Conglomerate, Yat Hill. Derived. 



Quartz as in No. 555 ; felsoar in subordinate proportion ; felsite fairly 

 abundant ; a little mica and mica-schist ; a few fragments of a fine-grained grit 

 composed mainly of angular quartz ; opacite as in No. 557. 



[558] Same locality. 



A grit similar to No. 557, but it contains a little chlorite and the opacite is 

 less abundant. The rock is somewhat crushed, and the cracks are filled with 



calcite. 



1 The numbers in square brackets are those of the slides in my own 

 collection. 



