280 3Ir. Fareifs Statement of Geological Fads 



vol. XXXV. p, 370, Mr. D. p. 53, and App. p. 36 : Dr. R. 

 seems, however, only to mention the Ammonites: and. 

 Dr. D. says, pref. p. xv. " At Portrush, the Chert, Pelro- 

 silex, or Si/icious Basalt, abounding with impressions of 

 the Cornua Ammonis (many of which are perilous, and 

 emulate the splendour of gold) rises to puzzle the Geo- 

 log'st." 



Of the Whyvn Dijkes or Veins of Basalt which intersect 

 and branch off in iiorthern and eastern directions from this 

 great Basaltic Area, I must at present say nothing, but refer 

 to Dr R.'s valuable paper on this subject in your 35th 

 volume, p. 364. 



It will be necessary here, to say something more parti- 

 cularly as to the limits of the Basaltic strata, and their po- 

 sition, preparatory to assigning the Coal-series a place 7ipon 

 them, both to show the grounds of my proceeding therein, 

 arid to furnish what clues I am able to future observers, 

 who may, and I hope ere long will undertake, the decision 

 of the important questions stated in page 267* From So- 

 lomon's Porch NW of Coleraine in Derry to Ballycastle 

 in Antrim, the N end of the Basaltic Trough occupies the 

 cliffs of the Ocean ; from Ballycastle* to the heights above 

 Newtownglens, its NE irregular corner, crosses the moun- 

 tains: from the last mentioned place round the coast of 

 the Ocean, the Lough, and the banks of the River Lagan, at 

 a somewhat greater distance than that of the Limestone 

 edge, the eastern Basaltic edge is to be traced, till it crosses 

 the Lagan near Moira (Mr. D. p. 3p), but turns then 

 again suddenly to the E (as the Limestone also did, I ex- 

 pect) and proceeds in Down Count-', " considerably to the 

 Eastwaid of Lisburn," Mr. D. p. 38, Note: this deep in- 

 dent into the edge of Limestone and Basalt strata being 

 occasioned by the excavation of the Lagan valley, just as 

 they are indented on the west side in Derry by the Mayola 

 excavation (which Dr, R. has so well described, vol. xxxiii. 

 p. 202), except that here Red Marl is exposed by the exca- 

 vation, and there Schistus which has occupied its place, in 

 *'a little system." From Dr. Hamilton's Map, referred toby 

 Mr. D. in a note, p. 38, leaving the basaltic bounds against 

 Down County undefined, and from the obscurity of the 

 descriptions that I have read of the same, in Down and 

 Armagh and Tyrone : I am led to suppose, that consider- 

 able accumulations of alluvia are there lodged and conceal 



* The detached Basaltic ClifFof Fairhead NE of Ballycastle will be men- 

 tioned fuitheron, as a severtd and sunk corner of the Basalt with Coal- 

 measures on it. 



most 



