Meeting of the British Association — Exeter, 1869. 451 



In the county of Cork, gritty bands make their appearance in the 

 Carboniferous slates. In the eastern portion of the area, where the 

 grits first occur, they are thin and very irregular. They become 

 very thick in the western portion of the county ; and in Coomhola 

 glen they have their greatest development, being at least 3,000 feet 

 in thickness. These gritty beds have been termed " Coomhola 

 grits." They contain some peculiar fossils, and they have others in 

 common with the Carboniferous slates. They are interstratified with 

 slate bands ; and, although most extensively developed near the base 

 of the Carboniferous slates, they are merely local members of this 

 series, emanating from conditions somewhat different from those 

 whence the great mass of the Carboniferous slates originated. 



Having described generally the arrangement of the rocks of the 

 south of Ireland which represent the Pilton beds, and also the 

 deposits which support them, we have now to refer to North Devon. 

 On the north side of Baggy Point, and eastward thereof, there are 

 hard purple sandstones, possessing many of the features of the 

 sandstones of the South of Ireland, which immediately amderlie the 

 " yellow sandstones ;" and upon those in North Devon are light- 

 coloured beds, which represent the Irish Yellow Sandstones. In the 

 neighbourhood of Marwood, reposing on the equivalent of the 

 Yellow Sandstones, are greenish-grey grits, affording a group of 

 fossils intimately allied to those contained in the Coomhola grits ; 

 and among these are plant-remains identical with such as occur near 

 the base of the Carboniferous slates. These have been obtained by 

 the Eev. Mr, Mules. 



Their mineral nature and fossil remains place the Marwood 

 sandstones and the Coomhola grits on the same horizon. The fossil 

 plants which occur near the base of the Carboniferous slate and in 

 the Marwood sandstones, are specifically identical with such as are 

 found at the base of the Carboniferous formation in the north of 

 England. Here Mlicites linearis and Sagenaria VeWieimiana occur, 

 and these are the forms which the base of the Carboniferous slates 

 afford. The Pilton rocks succeed the Marwood sandstones, and 

 these Pilton rocks, in their mineral nature, are intimately allied to 

 the Carboniferous slates. The strata which make up the Pilton 

 group consist of shales and slates, generally of a dark colour, with 

 associated sandstones and gritty beds, and occasional thin bands of 

 limestone full of corals. The fossils of the Pilton rocks are very 

 closely connected with those of the Carboniferous slates. Forms, 

 however, occur in the Pilton beds which have not yet been recog- 

 nised in their Irish representatives. There are species of Phacops, 

 Strophalosia productoides, etc., etc. But such fossils as are most 

 abundant in the Pilton rocks are those which are most common in 

 the Carboniferous slates. 



There is an idea prevalent among many English geologists, that 

 the Coomhola grits are a series of rocks distinct from and lying 

 beneath the Carboniferous strata ; and this idea has, I believe, given 

 rise to erroneous impressions concerning this series. I have pointed 

 out that this is not the conclusion of the officers of the Irish G-eo- 



