Tol. 55.] SERPENTI^sE AND ASSOCIATED KOCKS IN ANGLESEY. 283 



lim or crust recalling a bubble (doubtless owing to the weathering- 

 out of a carbonate). All the rock is much jointed and ' crackled,' 

 but parts of it are more squeezed, and jjrojecting knobs (often 

 spherulitic) seem to represent harder ' eyes ' in the crushed ma^s. 



(6) North of Graig-fawr. — It is diflficult to describe the relations 

 of the spherulitic parts of this rock, since they are recognizable 

 only here and there in hand-specimens. Much of the rock in the 

 quarry is dark and compact ; the more clearly spherulitic parts 

 resemble somewhat the glassy-locking serpentine of a, but appa- 

 rently a carbonate is more generally disseminated and gives a whitish 

 tint to the small spherules. 



(c) East of Penrhyn-Fadog, at the northern point of the small 

 inlet. — A few square feet of rock, scattered on the beach over about 

 15 yards, exhibit spherules which vary in size, being about that of a 

 small pea in one boss and much less in another. In weathering, the 

 dark green rock becomes a pale greyish-green, the spherules being 

 lighter in colour and projecting on exposed surfaces. The whole 

 mass, including the non-spherulitic parts, is usually permeated by 

 a carbonate. The rock is closely associated with a much crushed 

 variety containing diallage ; and the low clifi's, where they ])roject to 

 the east, include a gabbro, a serpentine, and apparently ' schists,' all 

 crashed. 



(d) Immediately east of the lihoscolyn road, one field-length south 

 of the ' School.' — The richly spherulitic part of this mass measures 

 roughly about 10 feet each way ; the remaining portion (sometimes 

 of compact rock) shows little else than slickensided joint-surfaces. 

 Another boss in the field contains a few spherules. The sjDherulitic 

 rock is dark, sometimes reddish-purple, including spherules (roughly 

 ^ to I inch in diameter) varying from greyish to pale green. These 

 are sometimes isolated but often in strings, almost axiolitic, and 

 sometimes are massed into a small patch. The ground is crossed 

 in various directions by numerous very thin chrysotile-veins, which 

 traverse or surround the spherules, llather irregular joints also 

 occur, sometimes filled by serpentine, occasionally | inch thif^k. 

 An old surface sometimes darkens, showing greater contrast with 

 the pale spherules, but a faint purplish tinge may be acquired by 

 further weathering. The pale spherules are clustered closely in 

 patches, some of which form band^ or narrow tracts around non- 

 spherulitic islets, suggesting a brecciation, which however may 

 perhaps be due to flow. (See fig. 1.) 



(e) East of PwU-pillo. — On a grassy knoll in a field near the 

 farm, spherules (mostly of the size of hemp-seed, sometimes that of 

 millet-seed) are to be seen on a partly moss-covered stone (about 

 5 feet across). Spherules of uniform size have a tendenc}" to occur 

 in groups, but the different sizes are often mixed. They form bands 

 or vein-like parts (perhaps 1| inch wide) which themselves are a 

 little depressed below the weathered surface of the intervening rock. 

 This rock when fresh is dark green, compact, w^ith an almost 

 flinty fracture, but parts of the pale brown weathered face suggest 

 spherules clotti'd together. (See fig. 2.) 



(/) Xorth-west of Cerig-moelion Quarry (about one field away). — 



