GEOLOGICAL SOCIETY OF DUBLIN. 101 



when he examines a district, to give to the Society the result of his own 

 experience, no matter with whom he may differ or agree. 



This calp is a new subject in Geology. It was not known in any 

 other part of Europe, until it got " a local habitation and a name" from 

 Dr. Griffith in Ireland. Yet, it has not been questioned by any geologist, 

 but accepted at his word, apparently because he was the most eminent 

 teacher of the science in the country, at a time when it was in its in- 

 fancy. The opinion regarding it was formed almost in the first days of 

 geological knowledge, about the years 1810 to 1813, and before organic 

 remains had been applied to the identification of strata, and, therefore, 

 cannot be supposed to be above suspicion. It appears to me to be a very 

 important subject, as it involves the great question — whether above 1 700 

 square miles of country, coloured on the Geological Map as calp, be not 

 the rocks of the Coal formation, as I believe them to be, and may not 

 have, in some places, a sufficient accumulation of the strata to contain 

 coal ? At all events, inquiry regarding it will be useful to the science 

 we have joined together to cultivate, either in getting altered what may 

 be erroneous, or in establishing the views already entertained. 



Mr. Kirwan, a man of some repute in science in Dublin about the 

 year 1 800, was the first who gave any account of a black argillaceous lime- 

 stone, got at Donnybrook, Rathgar, and other places in the vicinity of 

 Dublin, to which he gave the name of Calp. His, however, was a mi- 

 neralogical notice, and bore no reference to any geological group. 



Dr. Griffith adopted the name, and gave the rock an important po- 

 sition in Geology, by making it a subdivision of the Carboniferous for- 

 mation. He divided the mountain limestone into three parts — the lower 

 limestone, the calp, and the upper limestone. The localities where these 

 subdivisions occur are shown on the several successive issues of his Geo- 

 logical Map, and its position in the Carboniferous formation may be seen 

 in the explanatory section at the bottom of the Map. 



In the Report of the Railway Commissioners for Ireland, 1838, there 

 are several Appendices. The first of these is an " Outline of the Geo- 

 logy of Ireland," written by Dr. Griffith, who was one of the Commis- 

 sioners. In this document we have his matured views of the calp de- 

 scribed ; but, as it is not in the hands of many, and may not ever be re- 

 printed, I shall make a few quotations, to show on what data those views 

 are founded. As I shall have occasion to reply to some of the paragraphs 

 of the " Outline" which I will quote, I think it well to number the ex- 

 tracts as I proceed, for sake of reference. At page 8, and a few of the 

 succeeding pages of this Outline, is given his subdivision of the Carbo- 

 niferous formation, in substance as follows : — 



1. " Of the Secondary Rocks. — We next proceed to the consideration 

 of the great interior valley, which is entirely composed of secondary 

 rocks, consisting of the Old Red Sandstone, Carboniferous Limestone, and 

 Coal, and its accompanying strata." 



2. " As far as our present knowledge extends, the following, in an 

 ascending series, appears to be the order of succession of the different 

 groups or assemblages of rocks belonging to each period of deposition: — 



