GEOLOGY OF BUTE. 



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limestone. Over it is a bed of black bituminous shale, b, 

 containing veins of coal about a quarter of an inch thick ; 

 and upon these rests a bed of concretipnary limestone, c, the 

 base or paste being a dark-coloured limestone, and the 

 concretions rounded lumps of the same rock, often of con- 

 siderable size. The upper part of the cliff is occupied 

 by trap in various prismatic forms. The base of the con- 

 cretionary limestone is so much altered by the contact of 

 the trap, that the two rocks can only be distinguished 

 by the action of a strong acid. A like change is produced 

 upon the imbedded lumps in the upper part of the bed. The 

 limestone, shale, and coal seams extend under high-water 



Fig. 38. 



a, Limestone; 6, shale with thin coal seams; c, b'mestone breccia; d, 



trap. 



mark, and when the tide is very low considerable pieces 

 of coal are often dug out from beneath the sand and mud 

 covering the tide-way. Several sinkings have been made 

 here for the purpose of discovering workable coal seams, 

 but without success. The Eev. A. M'Bride, of Port Banna- 

 tyne, informs me that stigmaria and other fossils of the coal 

 formation have been found by him in the sandstone here, 

 thus bringing it into close analogy with the Corrie beds. 



