128 PBOCEEMNGS OF SOCIETIES. 



black spots; on a gray ground with largo black or white spots, 

 those spots sometimes hard at the edges, and sometimes softened. In 

 grain it is very compact, with a conchoidal fracture. It is arenaceous, 

 siliceous, argillaceous, splintery, crystalline. There are three or four 

 varieties of grain and colour in one quarry at Merlin Park, near Galway. 



I was at intervals, for many years, employed by Mr. Griffith at the 

 " Geological Map." The Calp was always a special object of inquiry. 

 About the middle of the limestone close search was made for a little 

 black shale, or a few layers of flint, or a few beds of black or dull 

 earthy limestone, which ought, according to the fixed notion, to be 

 found thereabouts. Any little change of lithological character from the 

 usual light gray type was welcome, and made a foundation for the band 

 of Calp. In this way all the narrow bands were determined upon. 



I shall consider one or two of those bands as examples : — say, first, that 

 at the thin end of the great calp wedge already mentioned, a mile south 

 of Drumahaire, in Leitrim. It proceeds from this place and passes im- 

 mediately to the south of Markree Observatory ; then gets very narrow 

 at Killoran church, and continues on to the west of Tobercurry ; from 

 this place it turns eastward, by Carrowilkin, to Gorteen, and ends in a 

 pretty broad expanse about Battlefield, to the west of Keshcorran 

 mountain. I believe that in this whole dark-coloured band there is 

 nothing but solid beds of limestone, and they are visible in it where the 

 rock is not covered with drift, which is generally the case. Advantage 

 appears to have been taken of the low situation and the covering of drift 

 to introduce the Calp band along here, to give colour to the theory. The 

 sandstone, which is so thick at Bundoran, is wholly absent, and the re- 

 presentation of the whole band here, fifty miles in length, as it appears 

 on the " Map," is I believe a geological romance. 



There is a band of Calp shown surrounding Slievecorran, to the 

 east of Castlebar, which has a ramification to the east of Hollymount, 

 and thence towards Mountbellew Bridge. This is another case founded 

 upon change of lithological character in the limestone. But I need 

 not further particularize those bands. If the Calp be not at Bundoran, 

 as I said before, it is not anywhere, and all those small bands shown 

 upon the "Map" must be swept away. 



I have stated that there is a great variation in the lithological cha- 

 racter of different parts of the Carboniferous Limestone. In the north 

 of Ireland, about Cookstown and Stewartstown, and in the country on 

 to Clogher, it is, perhaps, not more than from 100 to 200 feet thick. At 

 Blackhead, in the county of Clare, immediately south of Galway Bay, 

 there is a well developed and undisturbed section. Here there is about 

 1200 feet in thickness of it over water, and some more, buried in Galway 

 Bay, not visible. 



The general colour of the mass of the limestone is gray ; towards 

 the base it is dark-coloured ; towards the top it is of a light-smoke gray. 

 It may be of interest to notice some of the variations of character, and 

 in doing so I shall take them in geographical order, beginning at Dublin, 

 and proceed thence to the north, west, and south. 



