192 



IGNEOUS ROCKS, 



Upper 

 Galleky. 



Wall-case 4. 



47 to 70, as a whole, are specimens of ashy beds which 

 were spread contemporaneously amid the Lower Silurian 



The slates interstrati. 



rocks of the Llandeilo flag series. 



fled with them contain the ordinary Llandeilo flag fossils 

 and some of the beds are also fossiliferous. They are 

 partly arranged so as to show the passage of fine felspathic 

 ashes into coarse breccias. 



Nos. 47 to 56, 62, 66, and 70 are all from a set of ashy 

 beds that lie low in the Llandeilo flags, between the Stiper 

 stones and the road from Rorrington to the turnpike road 

 half a mile east of Church Stoke. Maps 60, N.E. and 

 S.E. Nos. 57 to 61, 63 to 65, and 67 to 69, are from 



higher bands of ash in the same series, near Harrington 

 Dingle, Chirbury. These last, in their line of strike, pass 

 gradually from sandstones worked for building, into coarse 

 brecciated and conglomeratic volcanic ashes. The Har- 

 rington beds are the equivalents of the eastern igneous 

 ridge of the Breidden Hills. See sections above wo. 3, 42 



to 46, and No. 5, 57 to 71. 



71. — Porphyritic felspathic ash. — Moat by Nant 

 Cribba Hall, 2\ miles north-west of Chirbury, Montgomery- 

 shire. Hap lx., N.E. Greenish-grey rock. Dark green 

 felspathic base, containing light green and grey fragments 

 of felspar, porphyry, and crystals of felspar. 



This rock is very similar to, and may be the equivalent 

 of the volcanic beds of Harrington Dingle, but is not imme- 

 diately connected with them. It occurs in a small boss, 

 separated from the Chirbury rocks by an intervening tract 

 of Wenlock shale, which rests on the Llandeilo beds uncon- 

 formable and in Wales never contains volcanic ashes or 

 lava. 



Specimens of felspathic Sandstones and Ashes, from 

 the Llandeilo flags, Radnorshire, near Builtii. 

 Hap 56, S.W. and S.E., and Section no. a above. 



72. — Sandy felspathic rock. — Carneddau, Radnorshire ; 

 near Builtb, Breconshire. Map 56, S.W. Yellowish- 



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