376 Scientific Proceedings, Royal Dublin Society. 



IV. Burren type. The limestone of this class was so called by 

 Foot on account of its being best developed in the barony of 

 Burren, Co. Clare. These rocks, when typical, are in shades of 

 grey and blue, being crystalline, but compact and free-working ; 

 while many beds are suitable for all kinds of cut-stone work. All 

 the chief Irish quarries of the present day are situated in the 

 limestone of this type, and in ancient times all fine workman- 

 ship, with rare exceptions, such as the work at Askeaton, was 

 executed in stone of this class. It might naturally be expected 

 that the principal black marbles should be found in the Calp : 

 this, however, seems not to be the case, as some of the world- 

 famed Irish black marbles are from subordinate beds in the lime- 

 stone of the " Burren type." This, to us, appears to have led to 

 a misconception, as some of the tracts classed on the geological 

 maps as "Calp" are so called solely from their having in them 

 beds of black marble, while, correctly speaking, they should be 

 mapped as "Burren limestone." 



It is necessary to explain that the above classification is solely 

 a lithological one, the rocks being arranged according to their 

 general characters, and not to their geological position. The ordi- 

 nary geological classification has been found, even by those who 

 still use it, to be unstable, as the rock-characters, at first adopted 

 as conclusive of age, being now found to vary according to the 

 circumstances under which the rocks accumulated ; purer lime- 

 stones accumulating in deep water, while littoral and shallow water 

 depositions had peculiar and special characteristics. The rocks of 

 class I. were evidently littoral accumulations ; those of class II. » 

 the growth of coral reefs or such like ; those of class III., accumu- 

 lations in greater or lesser expanses of shallow, still water, into 

 which fine silt or mud was drifting ; while the nature of the 

 accumulations of the rocks of the Burren type is hard to deter- 

 mine, as at the present day there do not appear to be any records 

 of exactly similar depositions. 



We have adopted as much as possible the recognised names — a 

 plan which may be, in part, unsuitable to pure geology ; but, at 

 the same time, as the geologists of the present day, in respect to 

 Europe in general, and also more or less elsewhere, are colouring 

 their maps, rather in accordance with lithology than geology, it 

 seems allowable for us to adopt the names that are best known and 



