210 



INTRUSIVE IGNEOUS ROCKS. 



] 



UprER are all of the same character, and very much decomposed on 



, Gallery. 11 e 



the surface. 



Waii.case4. i73._Greenstone.— Solva, St. David's. Light green 



matrix, with white felspar crystals and small dark horn- 

 blende crystals ; felspar predominates. 



Similar to and belonging to the same set of rocks as 

 No. 171. Intruded in lines. 



174. — Greenstone. — West side of Porth Lisky, St. 

 David's. Compact dark green rock, composed of felspar 

 and hornblende, rendered porphyritic by small black horn- 

 blende crystals diffused through the mass. 



175. — Greenstone. — Pen Berry, 3 miles north north-east 

 of St. David's. Bluish-grey crystalline rock ; white fel- 

 ipar, and small dark hornblende crystals in about equal 



quantities. 



This begins a series of greenstone rocks, which occur in 

 small bosses, and run in lines intruded between the beds 



between St. 

 guard. 



Head 



the country round Fish- 



1 76. — Greenstone. 



Mel 



near 



St. David's Head. Dull bluish mass, fine grained horn- 

 blende and felspar, with large crystals of greenish felspar 

 and strings of felspar. Weathers to a reddish brown. 



177. — Greenstone. — West end of Cam Llidi, St. David's. 

 Light green felspathic base, with very small black horn- 

 blende crystals. Weathers much whiter than 176. 



178. — Greenstone. — Cam Llwyd, 2 miles north of St. 

 David's. Finely crystalline white and dark greenish felspar 

 w r ith much hornblende in small black crystals. 



179 to 183.— Greenstones of St. David's Head. Fel- 



spar 



and hornblende, showing the differences in size of 



the crystals of felspar and hornblende from the same 

 mass of rock. Felspar, grey and white ; hornblende in 

 cleaved plates and prismatic crystals. 



In rocks largely crystalline it is presumed that generally 

 they cooled more slowly than those more finely crys- 

 tallized. 



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