PROCEEDINGS 



ov 



THE ROYAL IRISH ACADEMY 



PAPERS READ BEFORE THE ACADEMY 



I. 



THE PEOBLEM OF THE BRAY SERIES. 



By GRENVILLE A. J. COLE, F.R.S., M.R.I.A., 

 Director of the Geological Survey of Ireland. 



Read May 23. Publislied August 12, 1921. 



I. — The Relations of the Series to its Surroundings. 

 The folded and crushed slates and quartzites that are so well known in the 

 promontories of Bray and Howth, near Dublin, have not been traced down 

 to their foundations. They appear to be of estuarine origin, formed near a 

 shore where Oldhamia, the ally of Monocraterion,' and Eldonia,- which is 

 possibly a Holothurian, found nourishment on the mud-flats, and were 

 occasionally overwhelmed by incursions of quartz sand. The intense dis- 

 turbance of these strata, of very unequal " competence," was well indicated 

 by John Kelly' in 1853, who recognized that the quartzites showed traces 

 of stratification, but that they were not " in their original position with 

 regard to the adjacent rocks." He held that they had been " protruded 

 through enormous fissures made in the overlying graywacke by volcanic or 

 other expansive power from below." J. B. Jukes,^ wliile rejecting this 

 extreme view, pointed out that the beds of sand were probably very irregular 

 to begin with, and that they had been disturbed and "enormously contorted " 



' G. A. J. Cole, "On Oldhamia and Histioderma," Irish Naturalist, vol. x, p. 8.3 

 (1901) : G. F. Matthew, " Monocraterion and Oldhamia," ibid., p. 135. 



- W. J. Ryan and T. Hallissy, "Preliminary notice of some new fossils from Bray 

 Head," Proc. R. Irish Acad., vol. xxix b, p. 246 (1912). 



^ " On the Quartz Rocks of the northern part of the county of Wicklow," Jouni. 

 Geol. Soc. Dublin, vol. v, p. 237 (1853). 



* Annual Address, Journ. Geol. Soc. Dublin, vol. vi, p. 91 (1854). 



B.I. A. PROC, VOL. XXXVI, SECT. B, [B] 



i«H» 



