OF THE ROCKS OF THE SOUTH OF IRELAND. 259 



conditions prevailed over the area of the South of Ireland during the 

 deposition of these beds, and that thus by their fossils and physical 

 relations they correspond with the deposits of those great inland 

 lakes vrhich modern geologists, such as Mr. Godwin- Austen and 

 Professor Ramsay, regard as the basins of deposit for the Old Eed 

 Sandstone *. 



This distinction between the lacustrine fauna of the Old Eed 

 Sandstone and the marine fauna of the succeeding beds has been 

 noticed by Prof. Haughton as well as Mr. Baily, and my late col- 

 leagues Messrs. Jukes and Salter. It seems to me that in this di- 

 stinction we have a well-defined ground of classification, which is 

 also concurrent with slight, but definite, distinctions in the litholo- 

 gical characters of the beds themselves over considerable areas. 



In accordance, therefore, with the above views supported by so 

 strong a body of evidence, I shall continue to regard the line of 

 division between the Old Eed Sandstone and the Carboniferous 

 series as traceable at the base of the Coomhola-grit series, or at 

 the top of the Kiltorcan beds with Anodonta and Palceopteris. From 

 these premises I now pass on to describe briefly the corresponding 

 series in North Devon, as generally recognized. 



Y. Descending Series, North Devon and W. SoMERsET.f 

 (Carboniferous and Upper Devonian.) 



Carboniferous Limestone. (Benn Quarry.) Dark earthy carbonaceous lime- 

 stone in regular beds {Posidonomya Becheri). 



Carboniferous- Slate Series. (Barnstaple beds.) Top beds, dark schists 

 (contorted) resting on light-grey slates, with calcareous nodules. 

 Cyathocrinus distans &c. seen at Barnstaple station. 



'^ Pilton beds" (Phillips). Slates of a purplish or greyish tint, Brachio- 

 pods, crinoidal stems, and a small Crustacean {Phacops latifrons) ; tliin 

 intermittent bands of limestone are common, and are highly fossili- 

 ferousj. 



^' Cuctdlcsa-zone" (Hall), also called "Marwood Beds", by Jukes and 

 Salter. Light grey and olive-green slates with bands of hard grit, and 

 calcareo-ferruginous beds with three species of Cueullcea. These beds are 

 shown in the railway-cutting north of Bravmton Church. 



Below the above are found (east of the village of Upcot) yellowish and 

 greenish flags and shales, passing downwards into purple sandy shales 

 and grits, sometimes of a pale green colour, similar in appearance to 

 the " Kiltorcan beds." 



*^ Pickwell-Bown Sanditone!^ Purple and red sandstones with thin shaly 

 bands in the upper part ; greyish grits, sometimes massive, with thin 

 shaly bands, in the lower ; no fossils ; the bands of shale, though x*e- 

 quiriug to be mentioned, are quite unimportant. 



* R. Godwin- Austen, Quart. Journ. Geol. Soc. vol. xii. p. 51 ; Prof. A. C. 

 Ramsay, ibid. vol. xxvii. p. 243 ; Prof. Geikie, Trans. Roy. Soc. Edinb. vol. xxviii. 

 part 1. 



^ t Descriptions of these beds will be found in the writings of several authors ; 

 bvit I give those written down by myself during my visit in the autumn of 

 1879, under the friendly guidance of Mr. Townshend Hall and Mr. Ussher. 



I Hall, Quart. Journ. Geol. Soc. vol. xxiii. 874. According to this author, 

 the Pilton beds form the uppermost inember of the Devonian series. This view 

 was also maintained by the late Mr. Salter, who, however, recognized the presence 

 of some forms found in the Lower Carboniferous series of the S. of Ireland 

 {ibid. vol. xix. p. 482). 



