64 CAMBRIAN. 



Palastcrina Ramseyensis, was obtained from these beds in Ramsey- 

 Island. 



]Mr. Belt has remarked that in the Tremadoc rocks we appear to 

 have the return of a fauna driven from our area at the close of the 

 Lower Cambrian period.^ 



Near Tremadoc and Moel-y-gest, the beds are fossiliferous ; but 

 where exposed in the cliffs of Ogof-ddu, near Criccieth, the strata 

 appear to be barren. 



Dr. Hicks has made two divisions in the Tremadoc slates near 

 St. Davids — the lower beds consisting of grey flaggy sandstones, 

 about 200 feet in thickness. The upper division consists of iron- 

 stained flags and dark earthy slates, about 800 feet in thickness. 

 The beds occur at Ramsey Island and St. Davids. These two 

 divisions form the Lower Tremadoc group of Salter and Belt. 



Slates have been worked in places. Beds of pisolitic ironstone 

 occur in the Tremadoc Beds at Bettws-garmon. 



LINGULA FLAG SERIES AND TREMADOC SLATE SERIES. 



MALVERN AREA. 



The following succession of beds may be traced near White- 

 leaved Oak, south of Malvern : — 



Tremadoc Slate Series. •;. Dictyonema Shales ) at 1 ci 1 



1^ i\i 1 m 1 ci 1 • Malvern Shales. 



T • 1 171 c • (2. Malvern Black Shales... I 



Lingula FlaCT Series ... i , tt n 1 10 \ , 



^ '^ (I. HoUybush Sandstone. 



Hollybush Sandstone. 



This bed, so named by John Phillips, consists of greenish-grey 

 or brown sandstone, with quartz-conglomerate at the base, resting 

 unconformably upon the gneiss of Malvern, and attaining a thick- 

 ness of from 200 to 600 feet (see Fig. 4, p. 31). It yields Annelides 

 Scolecodenna {Trachyderma) antiquissima, and Dr. H. B. Holl found 

 the Brachiopoda Lingula and Ktiforgina {Obolella) cingulata? 



The Hollybush Sandstone may be studied on Raggedstone Hill, 

 overlooking the Hollybush valley, Malvern. Dr. Hicks places it 

 on the horizon of the Ffestiniog beds. 



Malvern Shales. 



Above the Hollybush Sandstone comes the 'Black Shale' of 

 Malvern. This deposit consists of thinly laminated black carbon- 

 aceous and pale greenish shale, from 500 to 1000 feet in thickness, 



' G. Mag. 1868, p. 8. ' Q. J. xxi. 89. 



