ff the North East of Ireland. 187 



Near the Giant's Causeway it is confined to the lower portion of 

 the cliffs, where beds of it in various states are seen, sometimes- 

 assuming the character of a decided red ochre, sometimes variegated 

 red and cream yellow, containing imbedded heterogenous portions, 

 wearing at a small distance the external appearance of agates, but 

 when examined found to be as tender as the softest steatite. Specific 

 gravity 1,92. 



Similar characters apply to the bole in other places. The lowest 

 bed of the trap formation where it comes in contact with the upper 

 surface of the chalk, and contains chalk flints imbedded in its mass, 

 is most generally a red ochrey bole. 



7. Wacke, 



This rock appears to be of extremely rare occurrence in the Ulster 

 trap series ; it is found however in Portnoffer near the Causeway, 

 underlying the upper stratum of columnar basalt, and alternating 

 with the wood coal described in article 9; the thickness of the 

 whole amounting to eight feet : it forms vesicular concretions of a 

 trapezoidal or rounded figure ; without coherence j texture dull and 

 earthy, with a few specks of mica ; the colour varies from yellowish 

 grey to brownish grey, apparently derived from iron ochre. The bed 

 or horizontal dyke of wacke traversing the chalk cliff at Murlough 

 bay has before been noticed. A seam of wacke, not more than 

 three or four inches thick, is interposed between the greenstone and 

 sandstone of Cross hill. 



2 A 2 



