184 



IGXEGUS ROCKS, NORTH WALES. 



Upper 

 Galleey 



Wall-case 4. 



with talcose slate, showing ripple marks. It belongs to th P 



same set of rocks as No. 24. 

 26. 



Calcareous felspathic and talcose ash, i mDeP 

 feetljPORPHYRiTic._South.east end of Cwm Orthin Lake 



Ffestiniog, Merionethsh 



grey-. 



if 



with 



white crystals 



Map 75, N.E. 



fragments of ft 



Blackish. 



and 



scales and short layers of black slate interspersed ; rudely 

 laminated. Crossed by section above, No. *, near No. 26 . 



REDS. 



Snowdon Series and their Equivalents. 

 27. — Felspathic sandy and slaty calcareous 



Snowdon, Caernarvonshire. Map 75, N.E. Somewhat 

 ashy. Alternations of blue slaty, and brownisWrey 

 sandy beds, the latter full of small cavities on the weathered 

 surfaces. The cavities probably formed by the decomposi- 

 tion of lime, originally derived from fossils. 



28.— Sandy volcanic asil— -North side of Crib Goch, 

 Snowdon, Caernarvonshire. Map 75, N.E. Alternations 

 of grey and bluish-grey sandy calcareous sediment, the 

 latter somewhat coarser in texture than the former,' and 

 weathering brownish ; shows a coarse slaty cleavage. From 

 the same beds as 27. 



29.— Sandy calcareous ash.— Crib Goch, Snowdon, 



Finely-bedded bluish- 



Caernarvonshire. 



Map 



N 



grey sandy calcareous sediment ; weathers in bands un- 

 equally. Contains small interspersed crystals of iron pyrites. 

 Freshly broken surfaces show a slaty lamination. Weathers 

 very irregularly. 



°0. 



Calcareous asil— Nor 



Snowdon, Caernarvonshire. 



Map 75, N 



Dark, 



blackish-grey, very calcareous rock. Weathers black, with 

 an irregular honeycomb surface, caused by decomposition 

 of the contained lime. Slightly laminated in structure, very 

 hard, and brittle. 



31. SCORIACEOUS FELSPATHIC AND CALCAREOUS ASH. 



Crib Goch, Snowdon, Llanberis, Caernarvonshire. Map 









P 





Y s 



,< 





y> 





fe 





mil' 



small 



'Jill 



ip, 



D 



.'• 





-Fel 



kn 



: 



*fc 



i: 





.v 



1 I 



5S 







■i 



* 



