450 THE IGNEOUS ROCKS OF THE SOUTH OF THE ISLE OP MAN. 



mass of igneous rock, which I provisionally term augite-picrite-por- 

 I)hyrite. The same rock is said by Gumming to occur at Cronk 

 *Urley (Urleigh) and Port St. Mary, and Gumming considers it to be 

 of post-Garboniferous age. 



Numerous dykes of ophitic olivine-dolerite with a prevalent north- 

 westerly strike occur between Eay-ny-Garrickey and Gastletown 

 Bay, at Langness, &c. They are of post-Lower Garboniferous, and 

 possibly of early Tertiary age. Among the " Supplementary 

 Observations" a diorite at Langness, a granite at Oatland, near 

 Port Soderick, and a basic igneous rock at llockmount are described. 

 A duplicate series of sections of the rocks described will be depo- 

 sited in the Owens-Gollege Museum. 



In concluding this paper I wish to express my thanks to Prof. W. 

 33oyd Dawkins, F.R.S., who has accorded me the free use of his maps 

 and notes in connexion with his survey of the Isle of Man on the 

 six-inch scale, to which the present paper forms a contribution. 



Plate XIY. 



Geological Map of the South of the Isle of Man and sections through 

 Scarlet Point, Isle of Man. 



Discussion. 



Prof. BoTD Dawkins said that the paper was a first instalment 

 of the results of the geological mapping on the six-inch scale of the 

 Isle of Man which he had been carrying on for several years, and 

 in which he had been assisted by the Author. The igneous rocks of 

 the island presented points of considerable difficulty. The Author 

 had, in his opinion, made a valuable addition to our knowledge. 



Mr. RuTLEr inquired what was the relation of the picrites to the 

 other members of the volcanic series, and commented on the very 

 careful manner in which the Author had described the rocks. 



The AuTHOE, in reply to Mr. Rutley's query, explained that the 

 igneous rocks at Scarlet Point belong to two distinct periods, the 

 augite-porphyrites being of Lower-Garboniferous age, while the 

 olivine-dolerite dykes are certainly post-Lower Carboniferous, and 

 perhaps of early Tertiary age. 



