42 Mr. Weaver on the Geological Relations of the South of Ireland. 



chiefly composed of flat tabular masses of trap conglomerate (enveloping, as 

 usual, fragments of limestone), and generally of a greenish colour, from the 

 intimate diff'usion of green earth in its composition. To the east of this, and 

 about one mile from Cahirnarry trap hill, is the limestone hill of Carrig Par- 

 sons, which I have already mentioned. 



There are few parts of the trap district in which the red felspar porphyry, is 

 better developed than in a hill called Knock Derg, situated to the south of 

 Lough Gur. 



The basis is ehiefly a finely granular or compact felspar, containing crystals of glassy felspar ; the 

 whole being, where the rock is fresh or not weathered, of a deep flesh colour or reddish brown, 

 or of a brownish red cast. When much disintegrated, the stone, at the first glance, looks like a 

 dirty or brick-red sandstone. The porphyry, however, is not uniformly red or brown, being in some 

 places striped or mottled with disseminated portions of green earth. The mass of the rock is 

 formed occasionally of spheroidal or ovoidal concretions, which separate by atmospheric influences 

 into concentric layers. Toward the northern foot of the hill green-coloured trap conglomerate 

 also occurs. 



It is much to be wished that some one, possessed of the necessary leisure and 

 gifted with sufficient devotion, would construct an exact topographical map of 

 the Limerick district occupied by trap and porphyry, showing in all cases, by 

 the aid of sections, the precise relations of these rocks to the limestone with 

 which they are there associated. 



(57.) Large tracts of the limestone field may be traversed without encoun- 

 tering more than a few, thinly scattered, organic remains. It is from local de- 

 posits met with incidentally, that they are chiefly to be procured. One of the 

 most productive is in the valley of the Maine, in the Ardconnaught quarries, 

 and adjacent to Castlemaine mine. The following is a list of those I procured 

 in that quarter ; and the fossilist will readily notice that while most of the or- 

 ganic remains enumerated, are of common occurrence in the carboniferous 

 limestone of other countries, several are also found in transition tracts, some 

 of which have hitherto been considered as distinctive of the transition period : 

 to these I have prefixed the mark, § . 



But to such as have hitherto been noticed only in the Cork transition lime- 

 stone, and not in other transition tracts, I have affixed the mark (c.) The 

 signs t+ have the same import as was explained in §§, 13 and 33. 



Crustacea : 

 §Calymene concinna, (Dalman, Tab. I. fig. 5.) '.besides fragments of one or two indeterminate 

 species of Trilobite. 



> Om Palaeaderna eller de sii kallade Trilobiterna af J. W. Dalman. Ur K. Vet. Acad. Hand- 

 lingar, 182C. Stockholm, 1827. 



