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ON THE CONSTITUTION OF THE CALP SHALE OE THE 

 NEIGHBOURHOOD OF DUBLIN. Bx PROFESSOR J. P. 

 O'REILLY, C.E., Royal College of Science, Dublin. 



(Plate XL) 



[Eead April 12, 1897.] 



The beds of the Carboniferous formation which, show themselves in 

 the many quarries which have from time to time been opened up and 

 worked in the vicinity of Dublin, are marked by the Geological 

 Survey as belonging to the middle or ' ' Calp Limestone ' ' series. This term 

 or designation is found for the first time in Kirwan's "Mineralogy," 

 2nd edition, vol. i. (1794), wherein at p. 233, under the heading of 

 " Basalts" he mentions " Calp " or hlach quarry stone of Dublin : and 

 having given some of the characteristics such as the density = 2-646 to 

 2-7, and its fusibility at 130° of the pyrometer of Wedgewood, he 

 states that: — "It seems to be the calcareous trap of Lasius Hartz, 

 170; at least this agrees with its colour, sp. gr., and in containing 

 calcareous matter." The next mention that is found of the term is in 

 " Griffith's Report on the Leinster Coal Fields." In the Introduction 

 (p. iv), he says: — " Slate clay, either black, grey, or reddish grey, is 

 another supposed indication of Coal and is certainly common in all 

 coal countries, but not peculiar to them. This rock is frequently 

 found alternating with Limestone and particularly with that species 

 called 'Calp'' which occurs in the neighbourhood of Dublin." 



He also adds at p. viii of Introduction : — " Slate clay is some- 

 times so compact that it resembles jasper. In the Kilkenny coal dis- 

 trict, instances frequently occur of its passing, by insensible gradations, 

 from soft clay s^te into a siliceous slate rock resembling Lydian 

 stone. This gradation is frequently visible in this district, near the 

 junction of the limestone with the rocks of the Coal formation." 



In Jukes' " Manual of Geology," 1857, p. 446, when describing the 

 Carboniferous formation in " Clare, Limerick, Tipperary, Kilkenny," 



E.T.A. PEOC. SEE. III. VOL. IV. 2 E 



