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ALTERED SHALE AND CONGLOMERATE. 



103 



unlikely that igneous rocks exist at no great depth beneath 



the surface 



12. 



Q 



rock, lower Coal measure sandstone, 



Upper 

 Gaixeby. 



Wall-case 45. 



Salisbury Crags, Edinburgh. It is in contact with and 

 overlaid by an intrusive greenstone, No. 13. 



13. — Greenstone, composed of 



augite 



Salisbury Crags, overlying and altering No. 12. 



and felspar. 



14.— Q 



Wellingh 



4 miles 



No. 14 is 



This rock is part of a considerable tract of quartz rock, 

 altered by intrusions of igneous rocks, such as those of the 

 Wrekin, Wrockwardine, and of Charlton Hill, 

 from the immediate neighbourhood of No. 15. 



15 — Greenstone. Hornblende with a little felspar. 



16 — Altered Caradoc conglomerate, as above, from 

 the Wrekin, Shropshire. The centre of the Wrekin is 

 greenstone, and the rocks in its immediate neighbourhood 

 have been so much altered by heat, that, in some cases, the 

 base has been fused, and there is great difficulty in sepa- 

 rating the trap from the stratified rock. 



17.— Caradoc conglomerate, altered, Hope Bowdler 

 Hill, Church Stretton, Shropshire, containing small pebbles 

 of slate, quartz rock, felspar, &c, bedded in a crystalline 

 felspathic base, the result of alteration by No. 18. 



18 — Amygdaloid al greenstone, with nests of epi- 



dote. In contact icith 17. This greenstone is one of several 

 bosses of rocks intruded into the Caradoc sandstone, viz., 



Hill H 



Hill, Caer Caradoc, and 



In ron- 



the Lawley. 



19 — Wen 



tact with greenstone, Upper Heblands, Bishops Castle, 

 Shropshire. 



20.— Altered Cambrian conglomerate, Skerries, off 

 the north-west shore of Anglesea. Many of the rocks of An- 

 glesea are highly metamorphic j they are pierced by bosses 

 and numerous veins of granite. (See p. 115.) The Skerry 

 conglomerate is traversed by dykes, and contains pebbles of 



