Lower Palceozoic Rocks of the Soutli-East of Ireland. 589 



PART 11. 



MiNEBALOGICAL RELATIONS OF THE IgNEOUS RoCKS OF THE SoUTH-EAST OF 



Ireland. 



Page. 



I. Granitic Axis of the Disthict, 589 



1. General Description of the Granite, 590 



2. Quartz, 590 



3. Orthoclase, 5gO 



4. Felspar of Paste, 592 



5. White Mica, 593 



6. Black Mica 596 



7. Granite Rock, 598 



II. OuTLTiKG Granitic Tracts, 607 



1. General Description, 607 



2. Chemical Composition of the Outlying Granitic Tracts 608 



3. Origin o{ the Outlying Granitic Tracts, 610 



III. Felstones and Associated Traps, 613 



1. General Description, 613 



2. Granitic and Trappean Patches; Bearings, ... . 614 



8. Felstones of the south-east of Ireland, 615 



4. Greenstones associated with the Felstones of the south-east of Ireland, .... 619 



The igneous rocks requiring description and illustration in the district we 

 have under consideration are divisible into three groups : viz. — 1st. The 

 granitic axis, described as (F) in the preceding part ; 2nd. The granitic rocks 

 of Carnsore and the Saltees (G) ; and 3rd. The igneous rocks, granitic or 

 otherwise, contained in the Cambro-Silurian region described as (D). 



I. Granitic Axis of the District. 



The granitic area is fully described at p. 583, et seq., and will be best 

 understood by a reference to the map. In addition to the area coloured on 

 the map, it is probable that this granitic axis extends in a north-easterly direc- 

 tion under the sea, by Rockabill, off the north coast of the county of Dublin ; 

 and perhaps even extends as far as the granitic district of Creetown in Scotland, 



VOL. XXIII. 4 H 



