112 PROCEEDINGS OF SOCIETIES. 



again, and in a narrow band proceeds to a mile south of the parallel of 

 Ballintra, where it disappears; and from this to Ballyshannon, five or six 

 miles, the mica slate and limestone are in contact, without the usual in- 

 tervening Old Red, which is not at the surface at Ballyshannon, nor 

 round thence by Lough Erne to near Pettigo. At this place it again ap- 

 pears, and continues five miles farther north-east to Grouse Lodge. It 

 is there well developed. From this place it curves to the north towards 

 Killeter, and then eastward it extends, in a broad expanse, toMountjoy 

 Forest, north of Omagh. 



I have been thus particular in describing the appearance and the 

 absence of this band at intervals along the mica slate border, to show a 

 reason for what I believe, but cannot see, and that is, that the disap- 

 pearance of the Old Red at Ballyshannon does not arise from its being 

 absent from its position under the Carboniferous Limestone along the 

 shores of Donegal Bay, but from being buried in a fault along the junc- 

 tion of the mica slate and limestone. It is not going too far to assume 

 that it underlies the whole of the Carboniferous Limestone round the 

 bay. 



At par. 7 it is stated that the Calp and Shale division is best deve- 

 loped on the west coast of the counties of Leitrim and Sligo ; and more 

 in detail Mr. Griffith describes a section from Ballyshannon to Benbulben. 

 He says : — " In this line of section the strata dip to the southward, at 

 an angle of 2° to 5° from the horizon. The lower limestone of Bally- 

 shannon is succeeded by beds of black shale, containing balls of clay iron- 

 stone, interstratified with impure argillaceous limestone. These beds 

 continue as far as the parallel of Bundoran, where they are succeeded by 

 a series of alternations of gray, and occasionally reddish-gray, sandstone 

 and black shale, with argillaceous limestone. These beds are succeeded 

 by alternations of black shale with impure argillaceous limestone, or 

 calp, which form the precipitous cliffs of Dartry mountain, facing the 

 west, and which near the summit are capped by the upper or splintery 

 limestone." 



Putting this succession into something of a tabular form, it is — 



1 . Lower Limestone at Ballyshannon. 



2. Black shale, with impure argillaceous limestone. 



3. Gray and reddish-gray sandstone, with black shale. 



4. Black shale and impure limestone. 



5. Upper limestone. 



I object to this arrangement and succession for many reasons, which 

 I shall endeavour to explain. 



1 . I think the sandstone about Bundoran is the Old Red Sandstone, 

 and not calp sandstone, or any other imaginary band of rock. 



2. I think the description given of the shales in Bundoran Bay, at 

 the quotation No. 7 r is not correct, nor the succession stated in the same 

 paragraph. 



3. I think the great wedge-shaped mass of calp about Bundoran, 

 partly described and partly inferred, is a fiction. 



4. I think the appearance of Lower and Upper Limestone, described 



