THE OLDER ROCKS AT ST. DAVIDS. I25 



beautiful gabbro ; in Ramsay Island in beds of the same age is 

 seen a dark grounded quartz-porphyryj quite a different type 

 to anything piercing the older rocks. 



To conclude — we may sum up the results of Dr. Hicks' 

 researches in which we have, I think it will be confessed, a remarkable 

 advance in knowledge, and a vista opened up to us in the rocks of 

 St. David's, of age behind age most pleasing to the imagination of 

 the geologist. Formerly the state of things was roughly supposed 

 to be a Syenite ridge piercing Cambrian rocks, flanked on each 

 side for miles, by these altered Cambrian rocks. Now we are led 

 to see in the so-called Syenite a metamorphic series, flanked by 

 rocks composed largely of eruptive rocks detritus, long subsequent 

 to it in age, as the Pebidian is again unconformable, prior to, and 

 utterly distinct from any Cambrian rock. 



