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VOLCANIC ASHES, ETC., MERIONETHSHIRE. 



179 



grey felspathic matter irregularly cleaved, with included 

 concretionary felspathic spheroids. 



From the uppermost part of the Lingula flags or base of 

 the Llandeilo beds, underlying the thick ashy strata on the 

 north slope of Cader Idris. Principally formed of consoli- 

 dated felspathic dust and talcose mud, which have become 

 subsequently cleaved. 



4. — Calcareous, talcose, and felspathic slaty 



ashes. — Allt-Lwyd, 4J miles south of Barmouth, Merioneth- 

 shire. Map 59, N.E. Dark greenish-grey sediment, with 

 specks and films of black slate ; cleavage very imperfect. 



From near the top of a great series of thick beds of vol- 

 canic ashes which underlie the solid crystalline felspathic 

 trap of Cader Idris, Aran Mowddwy, Arenig, &c. It occurs 

 about the junction of the Llandeilo and Caradoc or Bala 

 beds. 



Upper 

 Gallery. 



jWall-case 4, 



5. 



(si 



cherti/ layers. — Mynydd Gader, Dolgelli, Merionethshire. 

 Map lix., N.E. Banded alternations of felspathic and 

 cherty matter ; the more purely felspathic layers thin and 

 deeply eroded. Original colour light greenish-grey. Co- 

 vered on the divisional planes with ferruginous stains. 



From the lower part of the above (No. 4). Principally 

 formed of consolidated felspathic ashy dust. 



6. — Compact, brecciated felspathic ashes, slightly 



talcose— Mynydd Gader, Dolgelli, Merionethshire. Map 



59, N.E. Light greenish grey felspathic substance, with 



included felspathic and grey cherty fragments. Weathers 



grey, and assumes a brecciated appearance on the weathered 

 surface. 



From the same strata as No. 5. 



7. — Brecciated felspar-ash, slightly talcose. — Mynydd 

 Gader, Dolgelli, Merionethshire. Map 59, N.E. Similar 



in composition and colour to No. 6, but of a finer structure. 



The brecciated structure is chiefly shown on weathered 

 surfaces. 



From the same strata as Nos. 5 and 6. 



