of the North East of Ireland, 1 85 



of the regular articulations and neatness of form which distinguish 

 the basaltic pillars of the Causeway ; they form enormous prismatic- 

 masses, often quadrilateral, and these latter appear to be formed of a 

 congeries of smaller prisms, aggregated in a manner which brings to 

 the mind the clustered assemblage of shafts forming a Gothic 

 column ; the greatest length of these columns is not less than 250 

 feet ; the greenstone is highly crystallized, the concretions being dis- 

 tinct and large, and contains augite. 



Slievemish, a remarkable mountain, which lies like a colassal land- 

 mark in the middle of the county, is from its basis to its summit 

 composed entirely of greenstone, thus forming a mass of nine 

 hundred feet in thickness. 



Notwithstanding Slievemish has at a distance the appearance of a 

 cone, yet it is, like all the other mountains in Antrim, much mofe 

 extended in the direction from north to south than in a transverse 

 section : the ascent is steep and almost impracticable on the west 

 side, where we rise to the top by a succession of short terraces similar 

 to a flight of stairs. 



The greenstone is here remarkably beautiful, being of a tender 

 mountain green, interspersed with crystals of augite and granular 

 olivine ; the fracture is in flat or scaly concretions : it lies in distinct 

 tabular masses two or three inches thick, perpendicular to the 

 horizon, or sometimes with a slight dip to the westward. 



The mountain of Teabuliagh near Newton Glens, has a cap of 

 finely granular greenstone five hundred feet in thickness. 



The rock which overlies the chalk at Magheralin, may perhaps 

 with greater propriety be arranged as greenstone than basalt. 



Vol. III. 2 a 



