492 Proceedings of the Royal Irish Academy. 



town and Ballaghaderreen. The rocks, to a certain extent, belong to 

 both types, as in the Fintona district, to the south-eastward of Six- 

 mile- Cross ; but at the same time, except that in a few green and cal- 

 careous beds, fossils of typical Silurian (marine) species have been 

 found, all would have been included in the '' Lower Old Eed Sand- 

 stone." These rocks give the following sequence : — 



Cashelduff and Ballaghaderreen Section. 



5. Eurites, tuffs, and limestones, over 200 feet. 



4. Purplish, red and greenish conglomeritic sand- 

 stones and sandy shales, about 5000 feet. 



3. Green conglomeritic sandstones and shales, with 

 a few thin impure limestones, and some subor- 

 dinate red shales, about . 4000 feet. 



2. Red and purplish conglomerates, sandstone, and 



sandy shales, about , 1500 feet. 



10,700 feet. 

 Unconformahility. 



1. Metamorphosed Cambro-Silurians or Cambrians. 



The rocks in group 2 are exposed in a continuous section in the 

 stream between Cashelduff and Cranmore, there being an uncon- 

 formahility between them and the underlying metamorphic rocks ; 

 they may possibly be a little thicker than represented, as a fault, 

 with a downthrow to the southward, crosses the section, and may 

 conceal some of the beds. The rocks in group 3 are not as well ex- 

 posed, while the thicknesses of groups 4 and 5 had to be estimated. 

 A little above the base of group 3, in the Cashelduff stream, are two 

 fossiliferous bastard limestones ; the fossils being principally of "Upper 

 Llandovery types, although a few are of Caradoc-Bala species (see 

 Mr. Baily's list). To the west is Griffith's fossil locality, in the 

 boundary of Glenmullynamaher and Uggool, where the fossils are 

 principally of "Wenlock types, although in beds below and above 

 (Cloonnamna) this bastard limestone, they are of Upper Llandovery 

 species ; showing here also, as elsewhere in Ireland, the mixing to- 

 gether of species which in Wales are characterisic of distinct groups 

 of rock. 



The rocks in groups 2 and 4 are so nearly allied that they would 

 not have been separated but for the intervening fossiliferous strata, 

 furthermore, the intervening rocks (group 3) are not so very unlike 

 "Lower Old Eed Sandstone," except as to colour, and the few calca- 

 reous and shale inliers ; they being principally pebbly sandstones, 

 with the inlying patches of shales so characteristic of the rocks of the 

 Topped Mountain, Co. Fermanagh ; they ought not, therefore, to be 

 considered a separate gioup, but only a subordinate portion of a group. 



