﻿Vol. 64.] CARBOlSriEEROITS EOCKS AT LOUGHSHINNT. 435 



or Silurian slates. The contributions of mud, at first almost 

 continuous, became more intermittent in Eush-Couglomerate and 

 Carlyan-Limestone times, although even then they were made in 

 considerable quantity. This mud seems to have been carried only 

 a short distance to the north, if the correlation of these deposits 

 with the Lane and Holmpatrick beds is correct, as very little 

 argillaceous material is found in these latter beds. 



The Lane and Rush Conglomerates must both have been formed 

 quite close to the shore : although the overlap on to the shore itself 

 is not exposed, except perhaps at Shenick's Island. While at Lane 

 strong currents prevailed continuously, as shown by the thick 

 continuous mass of very coarse conglomerate, there were at Rush 

 many and considerable fluctuations in the force of the marine 

 currents, indicated by the numerous intercalations of finer pebbly 

 and sandy layers and fine laminated shales among the coarser 

 conglomerate-beds. 



The Dihunophyllum-JAm.e&ionQs north of the Copper-Mine Fault 

 represent apparently a continuance of the clear-water conditions of 

 the Holmpatrick Limestone. The dolomitic character of the lowest 

 beds may be original, and indicate a shallow- water phase. The upper 

 beds are, for the most part, well-stratified clear-water limestones 

 on the south ; but, as already stated on p. 428, they pass laterally, 

 northwards, into irregular lenticular limestones with intercalated 

 bands of black shale and fine conglomerate. These facts suggest 

 strongly that the land lay in close proximity to the north or north- 

 east. The Popeshall Limestone, about one-third of a mile to the 

 west, and the Curkeen-Hill Limestone, about a mile to the west, 

 both of which, as shown by their fossils, are approximately of the 

 same horizon as the Dihunophyllum-lAv(iei9,t>OTiGS> of the coast, are 

 clear- water limestones without any shaly partings.^ Whether they 

 represent a deeper-water phase of the beds on the coast, or belong 

 to a slightly higher or slightly lower horizon than the latter, cannot 

 at present be stated. They may bridge over the gap between the 

 Holmpatrick and the Dihunopliyllum-lAme?,tonQs. 



The Gyathaxonia-Beds, Posidonomya-liimestones, and the Lough- 

 shinny Black Shales form a continuous sequence in which the 

 gradual cessation of normal Carboniferous-Limestone conditions 

 by the slow shallowing of the water and the increasing invasion of 

 muddy sediment is clearly indicated. Ripple-marks and, occasion- 

 ally, false bedding in the beds just below the shales, as well as the 

 numerous remains of land-plants found in these upper beds, together 

 with the almost complete disappearance of calcareous deposits in 

 the highest exposed part of the series, show that a new phase in the 

 history of Carboniferous physical conditions had at length set in. 



^ The section at Curkeen Hill shows about 120 feet of good continuouB 

 Hmestoue. [A short search in the disused hmestone-quarry at Popeshall re- 

 sulted in the discovery of the following species : — Productus aculeatiis, Mart. (?), 

 Schizophoria resupinata, Mart, (common), Spirifer striatus, mat., Martluia 

 glabra, Mart. (Dav.) (common), Atkyris cf. glahristria (Ourkeen-Hill form) 

 (abundant), Athyris cf. ex-pansa, Phill. (Dav.), Ptiguax actiminaia, Mart., and 

 Bhynchonella (1) reflexa, de Kon.— C. A. M., July 7th, 1908.] 



