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NORTH WALES. 



203 



137. — Greenstone. — Half a mile south-west of Clynog 



Fawr, Caernarvonshire. Map 75, N.W. Dark, greenish- 

 grey felspar base, with a few white felspar and large platy 

 black hornblende crystals. 



Small boss of intrusive rock on the coast. 



138. — Greenstone. — Gymblet Rock or Carreg-y-rhim- 

 bill, Pwllheli, Caernarvonshire. Map. 75, S.W. Blackish- 

 green finely granular rock, composed of dark green horn- 

 blende and some white felspar crystals. 



139. — Felspar porphyry. 



Mawr. 14 mile south- 



east of Clynog Fawr, Caernarvonshire. A kind of greenstone 

 porphyry, composed of black hornblende base, with simple 

 and geniculated felspar crystals scattered through it. 



This rock is continuous with No. 129, and is a remark- 

 able example of the change in general character and com- 

 position which the same mass of rock exhibits. 



140. — Greenstone. — Tan-y-Graig, l^mile north north- 

 east of Pwllheli, Caernarvonshire. Porphyry. Imperfect 

 crystals of light green felspar in a black hornblendic base* 



From a mass, 4^ miles in length, intruded among the 

 Caradoc or Bala beds, between Pwllheli and Plas du, 



141. — Porphyritic greenstone. — Cam Fadryn, 6 miles 

 west of Pwllhelli, Caernarvonshire. Dark green granular 

 hornblendic base, containing crystals of felspar. 



From a continuation of the same mass as Nos. 127, 130, 

 and 131. These rocks show the variations of character in 

 the same mass in different localities. 



142. — Greenstone. 



Llanfaglan, about 1^ 



mile south- 



west of Caernarvon. Map 78, S.W. Large platy crys- 

 tals of black hornblende, with pink, green, and grey 



felspar ; the latter mineral in less quantity than the 

 former. 



From a mass about a mile in length intruded among the 

 Lingula flags. 



143— Greenstone. — Pen-ar-fynydd, 3 miles east of 

 Aberdaron, Caernarvonshire. Map 76, S. Large black 



Upper 

 Gallery. 



Wall-case 4. 



