Kinahan — On Irish Marbles and Limestones. 375 



except some near Belfast, which were formerly exported to Scot- 

 land for the manufacture of sulphate of magnesia. 



In Ireland, the great development of limestone was in the 

 Carboniferous Period. These rocks occupy nearly the whole of 

 the central plain, with ramifications from it, and in some places 

 they exist in tracts that are more or less isolated and of variable 

 extent. In these the characters of the rocks differ greatly, some 

 being nearly pure limestone, while others are argillaceous or arena- 

 ceous, often to such an extent as to almost lack the calcareous 

 constituent. 



For convenience of description, the Irish Carboniferous Lime- 

 stones may be subdivided as follows : — 



I. The earthy crystalline, or Loiver- Bedded Limestone. These 

 rocks are more or less common at the margins of the tracts of the 

 different types of limestone ; they are bedded, and in general have 

 shales or clayey partings between the beds, and are often capable 

 of being raised in large masses, but rarely are they eminently 

 suited for cut- stone purposes. As large blocks, they are valuable 

 in the building of piers, foundations, or other massive works. 



II. Amorphous or Fenestella Limestone. The latter name has 

 been suggested by Wynne, as the mass of the rock in general is 

 made up of this Corralline. The rock originally seems to have 

 been coral reefs, any bedded portions in it being for the most 

 part above or below, or as isolated subordinate parts in the mass. 

 This rock, in general, is not suited for cut- stone purposes, although 

 some of the included portions, when manufactured, afford beautiful 

 marbles. At the present time, except some few beds, none of the 

 rocks of this type seem to be in much favour with the marble- 

 workers ; yet from them our ancestors were able to produce exqui- 

 site specimens of art. The work cut from stones of this class in 

 the Greraldine banqueting hall atAskeaton, Co. Limerick, and that, 

 in the chaste and beautiful pillars of the cloisters in the adjoining 

 abbey, cannot be surpassed. 



III. Calp, or earthy compact limestone. These rocks are, in 

 general, not good for cut-stone purposes ; but they can usually be 

 raised in large blocks, for which reason they are valuable for 

 massive works. Some beds, however, are very compact, homo- 

 geneous, and capable of taking a fine polish, and, under such 

 circumstances, have produced first-class marbles. 



