Vol.51.] THE COHJmtr AEOHND FISHGUARD. 193 



of this Norwegian rock. It will be seen that they closely agree, 

 except in the percentage of lime. Some of Lossen's Harz kerato- 

 phyres approach it in composition, but are deficient in iron oxides. 



G. H. 



Si0 2 54-89 59-15 



A1 2 3 16-48 14-54 



$ e e § 3 } 10-05 12-31 



K,0 630 6-56 



Na 2 7-04 4-01 



MgO 0-74 1-97 



CaO 4-01 trace 



H„0 0-60 1-51 



100-11 10005 



G. Rhombenporphyr, Riis (Brogger). 



H. Gam Fawr, Strumble Head (Tadman). 



Age. — The age of the intrusive masses is not easy to decide. 

 Some were injected prior to the tilting, cleavage, and faulting of 

 the strata, and the fact that intrusive sheets are absent from 

 the Silurian area to the north-east, according to the Geological 

 Survey map, suggests that they are also pre-Silurian. But I am in- 

 clined to hold that the large Strumble Head masses were intruded 

 subsequent to the tilting and folding of the beds, and the injection 

 of the great northern mass, which apparently is composed of several 

 distinct intrusions, may have been spread over a considerable 

 period. 



VI. CORRELATION WITH OTHER AREAS. 



The adjoining St. David's area practically forms part of the same 

 province, and frequent comparative allusions have been made to it 

 in the course of this paper, so that it is unnecessary to repeat the 

 points of agreement or difference. Until further fossil zones are 

 discovered it would be injudicious to institute a close comparison 

 with more distant regions; 



A table of the succession of the beds (in descending order) in the 

 Fishguard-Newport area is given for the convenience of the reader. 



Llandovery (?). Dinas Head Beds. 



( Black shales and slates of Porth Melyn ^ 

 I and Pwll Deri, with the thin volcanic beds 

 of Poi-th Sychan and Porth Melyn 



( Slates be- 

 I tweentheUp- 

 I per Llandeilo 



Bala. J. Lower black shales, slates, and flaggy )■ = ■{ Series and the 



beds of Pwll Deri ; and the central volca- coast from 



I nic series of Strumble Head. j Coch y Ceiliog 



^ / \to Newport, 



f Graptolitic shales (Diplograptits englyphics, D.foliaceus, etc.) 

 of Newport, and Pont Iago, Strumble Head : 150 feet. 

 Upper ! Tough calcareous beds with Siphonotreta onicula: 



Llandeilo ' 10-20 ? ee t (only near Newport). 



Grey tuff-beds near Newport : 50 feet. 

 Felsites, breccias, and tuffs of Coch y Ceiliog to the River Cly 

 { dach, and of the eastern side of Strumble Head (Goodwick, etc.). 

 Middle f Slates and flags of Goodwick Bay, and of Clydach 



Llandeilo (?) \ Valley, etc. 



