208 



INTRUSIVE IGNEOUS ROCKS. 



162.— Greenstone.— South-west of Bwlch-Llyn-Fawr, 



Map 56, S.E. 



Dark 



Upper 

 Gallery. t , n 



TO T" near -Llandcgley, Radnorshire. 



Wall-case 4. v i i • i , , , , «. --> ~«uv 



felackish-grey rock, hornblende and felspar mixed, not dis- 

 tinctly crystalline except near the outer surface, where the 

 felspar crystals become apparent from decomposition. 



From a line of greenstone 2\ miles in length intruded 

 between the beds of slate. See horizontal sections, sheet 



No 



163. 



Greenstone. 



Carneddau, Radnorshire, near 



Builth, Breconshire. Compact dark green rock, with a few 

 small crystals of felspar ; amygdaloidal structure, with 

 large calc spar nodules. 



From the same mass as No. 

 1 64. — Greenstone. — Gaer 



north-east of Builth, Breconshire. 

 blendic rock, with a little felspar. 



Einon, Carneddau, 11 mile 



Compact black horn- 



From a boss, like an old volcanic neck, piercing Llandeilo 

 flags, and felspathic volcanic ashes. 



Intrusive Igneous Series St. David's, Pembrokesl 



nre. 



165. 



Felspathic trap. 



Between Trewellell and 



Caerforiog, 3 miles north-east of St. David's. 



Map 40. 



Bluish-green compact felspathic rock, with dark green 

 Stripes and small crystals of iron pyrites diffused through it. 

 From a great mass of syenitic and felspathic rock 7 miles 



in length, intruded among and very much 



altering the 



Cambrian slates, grits, and conglomerates, among which it 

 lies. It extends from Forth Lisky, on the coast. 2 miles 

 south-Avest of St. David's, to Carn-ymyl, north-east of 



Llanhowel. 



166. 



CUAYSTONE PORniYRY. 



Porth-bynawyd, south 



coast, at the north-east angle of St. Bride's Bay, St. David's. 

 Map 40. Yellowish-white felspathic rock, with black par- 

 ticles of hornblende and white felspar crystals. Emits a 

 strongly argillaceous odour. 



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