Haigh — Carboniferous Volcanoes of Philipstown, King's Co. 33 



The basalt from many of the outcrops shows the glomero-porphyritic structure, 

 and where an appreciable quantity of felspar is present, it occurs generally 

 with irregular boundaries, notched by the intrusion of idiomorphic crystals of 

 augite and magnetite. This is, perhaps, the most noticeable feature to be 

 observed in this series of rocks. The intrusive sill in the Clonearl quarry 

 is the most basic rock occurring in the district, and is a true limburgite. 



At Castle Barnagh a small intrusive knoll occurs which is composed of a 

 rock best described as a mica-augite-lamprophyre. 



The ash is of a very uniform nature throughout the district. It is composed 

 of angular, sub-angular, and rounded fragments of a pale, greenish grey basic 

 pumice, the vesicles of which are filled with calcite. The ash encloses 

 rounded fragments of chert and limestone, the whole being held together 

 by a cement of calcite. 



B.I.A. PEOC, VOL. XXXII., SECT, B. [F] 



