u 



TALCOSE ROCKS. 



Ill 



i 



*t. 



\ 



ki 



^ 



til. 



;■• 



8 



* 



t 





rSB 



- 



1 



• 





J 



1 / 



; ; 





80. 



shire. 



Talcose felspathic rock, between Tan-y- Grisiau Uppbb 

 m Orthin, 3 miles N.N.W. of Ffestiniog, Merioneth- Gaiieet - 



Wall-case 45 



This rock passes in places into ordinary felspathic ash. 

 (See 23 to 26, Case 4, and section wo. a, near Moelwyn, 24 

 & 25.) It, however, also passes into snakes tone, for the rochs 

 of the district are partly metamorphic, the metamorphism 



Case 



of the Fft 



81. 



Padarn 



Llanberis, Caernarvonshire, 78 S.E. Close to a great mass 



>f 



• 82 — Talcose schist, Porth 



brokeshire. Map 4. Cambriai 



(See No. 167, Case 4.) 



124 and 186, Case 



Case 4.) 



(S 



David's, Pern 

 nass of syenite 



83. — Felspathic conglomerate, decomposing, altered 



Porth 



84. — Porphyritic conglomerate, undecomposed. From 

 same locality as 82 and 83. 



This rock has undergone the same kind of alteration as 

 Nos. 16, 20, 32, and 49. The alteration of the rocks at Porth 

 Liskyis similar to that illustrated by specimens 185 to 192, 



Case 



Case 4, Nos 



Passage of shales, slates, grits, Src., into talc schist, mica 



schist, gneiss, fyc. 



85 — Argillaceous slate, Devonian, containing corals, 

 St. Austell, Cornwall. Sheet 31. 



86 — Argillaceous slate, killas, Devonian, Great 



Anchor, Perranzabuloe, Cornwall. Map 29. 

 _ 87.— Argillaceous slate, killas, Devonian, Wheal 



Bedding faintly 



D 



Map 



traversed by cleavage nearly at right angles. 



88. 



Pay 



T yfi 



Map 30. 



