GEOLOGICAL SOCIETY OF DUBLIN. 143 



the Yellow Sandstone resting conformably on the Old Bed Sandstone, the 

 Carboniferous Slate, or Lower Limestone shale, the Lower Limestone, the 

 Calp, and the Upper Limestone, the last being again succeeded by the 

 Millstone Grit, which in this locality contains thin beds of anthracite ; 

 and I may mention, that in this section the Calp series consists, as usual, 

 of alternations of blackish-gray, impure siliceo-argillaceous limestone, and 

 dark gray shale, the thickness being about 800 feet. 



For the Sections referred to in this Paper vide Plate VII. 



NOTES ON THE CALP OF KILKENNY AND LIMEBJCK. BY J. BEETE JUKES, 

 M. A., F. K. S. 



My friend, Mr. Kelly, having in his paper lately read before this 

 Society thrown some doubts on the existence of the group of rocks 

 known as the Calp, which occupies a conspicuous place in Mr. Griffith's 

 Map, and is shown as a distinct division on the lately published Maps 

 of the Geological Survey, — I feel compelled to offer a few observations 

 respecting it. I do this the more readily as Mr. Kelly endeavoured to 

 prove that what was called Calp was in reality Coal-measures, — an 

 assertion which would have such mischievous practical consequences 

 that it is necessary its error should be immediately pointed out. 



The lower part of the great Carboniferous formation has several dif- 

 ferent types in different parts of the British Islands. In Ireland these 

 different types are three, that, namely, of the south, that of the north, 

 and that of the centre. In the extreme south, namely, in Waterford, 

 Cork, and Kerry, the Carboniferous Limestone forms one group, having 

 underneath it a set of rocks which have two very different types in two 

 different districts, and over it a set of dark shales and olive- coloured 

 sandstones, containing some thin beds of coal, and therefore called Coal- 

 measures. In coming towards the north, namely, into Limerick on the 

 one side, and Kilkenny on the other, it becomes possible to subdivide 

 this single group of Carboniferous Limestone into three sub-groups, lower, 

 middle, and upper, — the middle receiving the provincial term of Calp. 



The sole invariable distinction on which this subdivision rests is one 

 of colour, — the Calp in the districts above named being invariably dark- 

 coloured, generally nearly or quite black ; while the upper and lower 

 limestones are commonly gray, sometimes dark gray, sometimes nearly 

 white. This Calp, then, is a mere local subdivision depending on litho- 

 logical distinctions, and is not to be looked at as a geological formation, 

 the equivalents of which are to be sought in other localities, or to be 

 determined by separate suites of fossils. Its dark colour seems to be 

 the result chiefly of earthy, more or less carbonaceous, matter being 

 mingled with the limestone, sometimes in such proportion as to prepon- 

 derate over the calcareous matter, so much that the stone would be no 

 longer fit for burning into lime; sometimes to such an extent as to 

 become mere shale, and beds of dark shale are generally found in greater 

 or less thickness alternating with the limestones throughout the Calp 

 districts of Kilkenny and Limerick. 



