ON THE OLDER ROCKS OF ANGLESEY. 419 



209. Junction near Bwlch, Llanddona — Fine mica schist. 



210. Llanflewin — Fine-grained rock with few fragments, and confused orienta- 



tion. 



211. Mynydd Mechell — Fine mica schist with quincuncial orientation. 



212. Mynydd Mechell — Fine quincuncial orientation, parallel to bedding. 



213. Llanrhwydrus to Camlyn — Fine-grained chloritic rock with fragments. 



214. Port Unal, Camlyn — Quartz elements with sericitic boundaries, zircon. 



215. Intrusive, Port Unal — Fine mosaic limestone with quartzose cracks. 



216. West of Cemmaes — Fine and coarse mixed; tension areas. 



217. Llanbadrig — Oolitic limestone (fig. 19). 



218. Llanlliana — Fine mosaic limestone. 



219. West of Llanfechell — Fine-grained chloritic rock with fragments. 



220. Bodewryd Turret — Fine abundant mica quincuncially orientated. 



221. Llechog Ucha, west of Amlwch — Mylonised fine-grained rock witli tension 



areas. 



222. Pengorphwyfsa, east of Amlwch — Fine-grained rock with fragments; tension 



areas. 



223. Llaneilian, east of Amlwch — Plagioclase well preserved. 



224. Point JSlianus, east of Amlwch — Plagioclase well preserved. 



225. Dyke, east of Mynydd Mechell — Macrofelsite with epidote nests (fig. 20). 



226. Dyke, east of Mynydd Mechell — Spherulitic microgranite. 



227. Spheroidal boss, west of Almwch — Spicular macrofelsite with idiomorphic 



epidote. 



228. Hafod Onen, south of Amlwch — Pseudo-spherulitic granophyr (fig. 21). 



229. Almwch to Parys Mountain — Diabase with epidote and leucoxene. 



230. Boss at Tygorphwyfsa — Microgranite. 



231. Quartz mass, west of Bull Bay — Quartz elements with sericitic boundaries. 



232. Quartz knob, south-west of Parys Mountain — Pure quartz of polygonal 



structure (fig. 18). 



233. North side of Forth Lygan — T3'pical granite. 



234. Porth Lygan district — Granular sericitic felsite. 



235. Porth Lygan — Non-quartzose, slightly foliated micaceous tuS. 



236. Porth Lygan — Mylonised micaceous tuff. 



237. Opposite island, Forth Lygan — Quartzo-felspathic micaceous tuff. 



238. Abertywedog — Garnet, quartz, and diallage (?). 



239. Abertywedog— Micaceous tufl: with altered garnets. 



240. Abertywedog — Quartzose non-micaceous tuff. 



241. Trwyn, near Abertywedog — Decomposed plagioclase, two pyroxenes and 



sphene. (Paraboloid.) 



242. Llanwenllwyfo, south end — Quartzose micaceous tuff. 



243. Rhos Manarch, inland— Dolerite. 



244. Pen-yr-Allt, west of Forth Lygan — Granite with altered garnets. 



245. Ty Newydd, north of Nebo — Gneiss with brown mica. 



246. Penrhynglas, Llanwenllwyfo — Micaceous tuff with garnet groundmass. 

 24.7. Nebo, south of Road — Felspathic micaceous tuff. 



248. In micaceous rock, Nebo — Calcite, plagioclase, and sphene. 



249. Outer ridge, east of Parys Mountain — Mica-diorite with apatite, &c. 



250. East of Parys Mountain — Grey gneiss. 



251. East of Parys Jlountain — Brown-mica-diorite with sphene, apatite, (fee. 



252. East of Parys Mountain — Plagioclastic rock with mica in cracks. 



List of Figures. 



1. No. 151. Showing speckled felspar in fragments (1, 2, 3, 4). 



2. „ 81. Sutural junctions of elements. 



3. „ 5. Lamination and foliation coincident. 



4. „ 32. Fine-grained mosaic rock with tension areas. 



5. „ 75. Quincuncial orientation. 



6. „ 150. Linear orientation. 



7. „ 155. Elemental orientation. 



8. „ 69. Laminar orientation. 



9. „ 66. False orientation by a series of cracks, producing fracture cleavage. 

 10. „ 20. Foliation oblique to bedding, and to cracks in a fine-grained rock. 



E B 2 



