106 Proceedings of the Royal Irish Acadermj, 



largest tributary, the Slate Quarry stream. They also appear again 

 in the bed of one of the tributaries of Corrycroar river, in the extreme 

 south of the Pomeroy inlier, where they are directly overlain by the 

 conglomerates of the Old Eed Sandstone. The lowest beds of the 

 series include a few bands of smooth grey shales, not unlike the 

 fossiliferous Crocknagargan beds ; but the greater part of the Slate 

 Quarry beds consist of soft, easily bruised blue-grey micaceous 

 flagstones, with a texture rather like cardboard and splitting with 

 difficulty. Fossils, when found, are in general fairly well preserved, 

 and in low relief ; but they are not abundant. Some of the beds 

 contain a good deal of rather coarsely distributed pyrites, and, in the 

 early stages of weathering, become coated with a thick rust, but in 

 later stage are more or less completely bleached. This bleaching is 

 particularly prone to occur in places which have been long exposed to 

 chemical weathering — as, for example, near faults and in upstanding 

 cliffs. A curious lemon-yellow stain on the surfaces is also charac- 

 teristic of certain of the members of this series. Diplograptus 

 modestus is the commonest and most widely distributed fossil, but 

 Diplograptus vesiculosus is also found in certain of the finer-grained 

 beds, especially in the southern exposures, and with these are 

 associated the usual Climacograpti, CI. normalis^ and CI. medius, &c. ; 

 the whole assemblage is strongly reminiscent of the fauna described 

 by Herbert Lapworth from the Lower Dyffryn, or modestus-Flags of 

 "Wales. The Slate Quarry beds are always recognizable by the large 

 proportion of micaceous material they contain, and, like the members 

 of Desertcreat group, seem to have been formed by the denudation of 

 some ancient series of crystalline schists. Though not the hardest, 

 they seem to resist denudation more than any other member of the 

 Little Kiver group, and, where exposed, almost always confine the 

 streams to quite narrow gorges. 



The Edenvale Beds. 



The Edenvale beds follow directly upon the Slate Quarry beds, and 

 in their exposures along the Little Kiver, the Edenvale mill- sluice, and 

 the Slate Quarry stream, occur as narrow synclines folded in among 

 the broader anticlines. Their lowest bed is very characteristic ; it 

 shows a marked tendency to break into cuboidal blocks, and is a hard, 

 dark, fine-grained, and very calcareous rock, and, unlike even the highest 

 member of the Slate Quarry beds, contains but a very small proportion 

 of mica. Dimorphograptus is its characteristic Graptolite genus : we 



