G. H. Kinahan — Geology of Parts of Galway and Mayo, 45 7 



and the metamorphic rocks may be divided into three groups, all of 

 which graduate from one to another : — 

 III. Schist Series. 

 II. Gneiss Series. 

 I. Granite of metamorphic origin. 



The rocks in Group I. are perfectly crystalline, and usually have 

 lost all their sedimentary characteristics ; but between them and the 

 rocks in Group No, II. there is a regular gradation ; while Group II. 

 graduates into Group III., and the latter into unaltered rock.^ Besides 

 the granite of undoubted metamorphic origin, there are other granites, 

 evidently intrusive, with numerous Plutonic rocks. The granites 

 are of two ages, one being Pre- Llandovery but Post-Cambro-Silurian, 

 and the other Post-Llandoverij, and probably Pre-Wenlock, 



The Plutonic rocks can be divided into two groups — Felstones 

 or siliceous, and Whinstones or basic rocks. The felstones seem 

 to be of at least five different ages : First, Cambro-Silurian (?) 

 age. These are all more or less metamorphosed, some into 

 granitoid or even granitic rocks. Second, Pre-Llandovery age. These 

 are newer than the time of the metamorphism of the Cambro- 

 Silurian rocks, but older than all the Upper Silurian rocks. Third, 

 Llandovery age. These are principally represented by bedded or 

 interstratified basic felstones, that answer to the description of the 

 rocks called eurites by Daubuisson, associated with which are tuffs, 

 and in places limestones, the latter containing Upper Silurian fossils 

 (Llandovery). Fourth, Ijudlow? age. These occur bedded in the upper 

 portions of the Salrock series (Ludlow?), and are eurites similar to 

 the Llandovery eurites (No. III.). They were only found in one 

 place south of Leenaun, but in the Loughnafoey district similar rocks, 

 but intrusive, appear — coming up along the line of break by which, 

 the Salrock beds were let down against the Toormakeady con- 

 glomerates. And Fifth, Post- Silurian. These may be of any newer 

 age. All we can prove about them is, that they are of subsequent age 

 to the Salrock beds, the newest Upper Silurians in the country. 



The whinstones, somewhat similar to the felstones, are divisible 

 into ; First, Oambro-Silurian age. These are all more or less meta- 

 morphosed, and the major part occur as bedded rocks, i^econd, Pre- 

 Llandovery age. These are evidently newer than the time of the 

 metamorphism of the Cambro-Silurian rocks, but appear to be older 

 than all the Upper Silurian rocks. Third, Llandovery age. Bedded 

 dolerites in tbe Toormakeady conglomerates. Fourth, Post-Silurian 

 age. These rocks occur as dykes breaking up through the Salrock 

 beds, but none of them were found associated with the Carboniferous 

 rocks of the adjoining country. Fifth, Carboniferous age. These 

 consist of dolerites similar to those that in the adjoining country 

 occur associated with Carboniferous limestone. They are evidently 

 newer than all the other whinstones ; but they are very similar in 

 aspect to the dolerites in the Toormakeady conglomerates. 



' These gradations the author fully explained in a similar manner to that given in 

 liis book " Handy Book of Eock Names" (Hardwicke), to which the reader is referred. 



