561 Proceedings of the Royal Irish Academy. 



&c., he assigns to the "Calp" or middle limestone a thickness of 1400 to 

 1000 feet, and says of it : — " The ' Calp' consists of black limestones, 

 sometimes very earthy, interstratified with black shales, so that they 

 become in some places moi-e important than the limestones. The 

 limestones of this group are -usually unfit for burning into lime. Chert 

 beds and nodules are very abundant in the ' Calp.' " 



In the second edition of this work (Jukes' and Geikie's "Manual of 

 Geology," 1872), it is stated, at p. 589 : — "The Carboniferous lime- 

 stone of the south of Ireland is perhaps one of the largest aggregates 

 of beds of limestone to be seen anywhere in the world. In some 

 places it contains beds of black shale, and becomes earthy in its middle 

 portion, and sometimes the whole of it, except the lower part, puts on 

 this shaly and earthy character. This middle earthy and shaly 

 part has been called ' Calp ' from a local term signifying ' hiack shale.' 

 Black chert is often developed in the limestone, rows of nodxiles and 

 seams of it appearing in great abundance, sometimes in one part and 

 sometimes in another." 



It is stated at p. 595 : — " The great Carboniferous limestone 

 series of Ireland contains evidence that here and there, at various 

 intervals during its formation, minor volcanic vents were active in 

 different parts of the sea bottom. In the county Limerick masses of 

 trap 1200 to 1300 feet thick, with well marked ashy interlacings lie 

 amongst the limestones." 



In the Explanation to Sheets 102 and 112 of the Geological Survey 

 (1878), p. 7, it is stated : — " Hitherto these black shales and the beds 

 between them and those assigned to the lower limestone have been 

 mapped and spoken of as ' Calp ' both by Sir Richard Griffith and in the 

 Index Map of the county of Dublin published by the Geological Survey 

 in 1851. ' Calp ' seems to be a local provincial term for ' black earthy 

 stone ' or shale, and in that lithological sense it is perfectly applicable 

 to all these upper beds, so much so, that it is impossible to separate 

 the dark earthy limestones which overlie the lower limestone into 

 two groups of beds, differing either in lithological or palseontological 

 characters." 



Page 25. In all the Dublin district, however, the beds are sup- 

 posed to belong to the upper dark " Calp " division of the limestone 

 series, including some more purely calcareous and fossiliferous beds 

 stretching cast and west near Crumlin. 



It will thus be seen that the term " Calp " originally applied by 

 Earwan to a rock which he classed with the traps, has subsequently 

 been applied to the black shales which so largely constitute the middle 



