Vol. 55.] BEDDED EOCKS OF COTJNTY WATEEFOED. 721 



II. Desceiptiox of the Exposuees. 

 (a) Raheen and Newtown Head. 



It is along this strip of coast just north of Newtown Head, near 

 the mouth of the River Suir, that is seen the most distinct and 

 extensive section of the contemporaneous igneous rocks regularly 

 interstratified with the fossiliferous beds (fig. 1, p. 722). The 

 succession is traceable in a comparatively undisturbed series of 

 beds for a distance of nearly a mile along the shore. The exposure 

 begins on the foreshore a few hundred yards north of Raheen Bridge, 

 below the old Geneva Barracks. The cliffs themselves are here 

 composed of Boulder Clay, but on the beach, and particularly at 

 low water, are found reefs of rocks consisting of olive-coloured or 

 greyish mudstones, mostly without good cleavage, and either 

 breaking with a subconchoidal fracture or splintering into angular 

 fragments. Sandy seams from ^ to 6 inches thick are occasion- 

 ally interstratified with the mudstones, and the lower beds contain 

 black carbonaceous patches. The total thickness of these mudstones 

 is unknown, but they are exposed for fully 300 yards along the coast. 

 Their general dip is towards the line of cliffs, at angles of from 45 "^ 

 to 60° north-west. jSTumerous small faults traverse them, and 

 their strike is in places distorted for a short distance. An interesting 

 example of a small volcanic neck occurs in them about 150 yards 

 north of Raheen stream. 



Dipping below these mudstones a short distance north of tliis 

 stream are found hard, compact, black slaty mudstones breaking 

 up into irregular cubical fragments or splintering with a subcon- 

 choidal fracture. These beds, which are traversed by several small 

 faults, do not measure more than 12 feet in thickness, and beneath 

 them come greenish-grey, thin-bedded, ashy sandstones, with black 

 shaly fragments, exposed on the reefs opposite Raheen stream. The 

 individual beds are from 6 to 12 inches thick, and the thickness 

 of the whole series amounts to about 30 feet with a north- 

 westerly dip of 45° to 55°. The next bed in descending order 

 is a tough grey felsite [6 w] ^ about 6 feet thick, scarcely separable 

 from an underlying peculiar perlitic felsite into which it imper- 

 ceptibly passes. This perlitic felsite [7 w], which is fully described 

 on p. 763, shows its structure very distinctly on the white weathered 

 surface and forms a conspicuous rib of rock on the beach, about 

 35 feet thick, with a dip of 45° north-westward. Beneath it is a 

 bed of coarse volcanic breccia, 10 feet thick, composed of subangular 

 and rounded fragments of felsites and slates. Then comes a series 

 of thin-bedded fissile greenish ashes with a thickness of 70 to 

 80 feet, and resting on dark greenish and black sandy mudstones 

 with a slight unconformity, for the line of junction is somewhat 

 irregular, and the lowest layers of the ashes contain rounded masses 

 and pebbles of the mudstones pointing apparently to contem- 

 poraneous erosion. The mudstones are about 40 feet thick, and 



^ The numbers in brackets refer to slides in my collection. 



