288 DE. C. A. MATLEY ON THE [May IQ06, 



fine shales being cleaved but occasionally, and then imperfectly. 

 There is, moreover, very little good cleavage in any of the beds to the 

 north of the Conglomerate-Group 1 for some distance, and theu only 

 on a small scale. 



Correlating the Rush Conglomerate-Group on the evidence of the 

 fossils, Dr. Yaughan regards the lower beds (about 160 feet) as 

 probably belonging to the 'Main Syringotliyris-ZoweJ and places 

 the upper beds (about 340 feet, commencing with the thick con- 

 glomerate-bed [P10 7i]) in the 'Upper Syringotliyris- and Lower 

 Semimda-ZoTLQ.'' This determination of their horizon brings out 

 the interesting fact that these conglomerates are synchronous 

 with the Pendine Conglomerate 2 of South Wales, and approach the 

 horizon of the volcanic rocks of Weston-super-Mare. 3 It seems, 

 therefore, probable that the Mid-Avonian disturbance and elevation, 

 hitherto recognized only in the South-West of England and Wales, . 

 was not a local phenomenon, but was possibly part of a movement 

 extending over a wide area. 



Another remarkable conglomerate intercalated in Carboniferous 

 Limestones occurs on the coast at Point Lane, 2| miles north of Push, 

 between Loughshinny and Skerries, the contemporaneity of which 

 with the Push Conglomerates is discussed in the Geological Survey- 

 memoir (op. cit. p. 66). This question has yet to be investigated, 

 but it seems likely that the Point- Lane Conglomerate will prove to 

 be on a much higher horizon. 



(c) The Supra- Conglomerate Limestones. 



The upper boundary of the Conglomerate-Group has been taken 

 at a 5-foot conglomerate bed [Pll 7i], with a 14-inch pebbly band 

 on its upper surface. The succeeding beds are for the most part 

 thin, flaggy and shaly limestones, and dark calcareous flags with, 

 especially towards the top, occasional thicker beds of limestone, 

 sometimes 2 feet thick. They contain several pebbly horizons, and 

 there is a 2-foot pebbly limestone [P 12 d] near the top. The bed 

 [R 12 e] immediately overlying this contains plant-remains, but 

 these are in so poor a state of preservation that Mr. P. Kidston, 

 F.P.S., who kindly examined them, can only say of them that they 

 have 'a fern-like look.' 



These limestones, etc. have the high northerly dip (60° to 65°) of 

 the underlying group, and their outcrop terminates at the entrance 

 to Push Harbour. About 1 00 feet of beds are seen, 30 feet of which 

 are assigned to the Upper Syringothyris- and Lower Serninula -Zone. 

 No zonal fossils have been collected from the uppermost beds, which 

 probably belong to the same zone. 



1 It may be remarked, in passing, that this area appears to be the most 

 northerly spot in the British Isles in which cleavage occurs in beds of so late 

 a period as the Carboniferous. The occurrence of cleavage so far north may be 

 connected with the deflection of the general lines of Armoriean folding in the 

 South of Ireland by the great mass of the Wicklow Granite. 



2 'Summary of Progress of the Geological Survey for 1904' Mem. Geol. 

 Surv. 1905, p. 44. 



3 C. Lloyd Morgan & S. H. Eeynolds, Quart. Journ. Geol. Soc. vol. lx (1904) 

 p. 148. 



