86 



THE GEOLOGIST. 



tains, is about 5 miles from N.W. to S.E., with an average width of 

 about 1 mile at Kilronan mountain, which forms the eastern termina- 

 tion of that long narrow coal-measure basin. The Altagowlan basin, 

 on the opposite side of the Arigna valley, may be about 3 miles, from 

 N.W. to S.E., with a width of three-quarters of a mile. In these 

 areas there are but three beds of workable coal, the thickest of 

 which is not over 2 feet 6 inches, and one of the beds has its roof and 

 floor of hard sandstone. See "upper coal seam of Creughnaslieve." 



The following is Sir E. Griffith's section of the Kilronan Mount 

 coal-measures, taken from his ' Mining Report on the Connaught 

 Coal-fields,' and its general accuracy is undoubted : — 



Strata. 



Feet. 



Surface 



18 



30 to 50 



Sandstone flags. 



17 



30 to 60 



Blackish-grey sandstones and gritty slate. 



16 



100 to 200 



Slate clay, in beds of variable thickness and hardness, and con- 

 taining innumerable beds of clay iroustone. 



15 



Coal. 



Third or upper seam, 8 to 9 inches thick (?). 



14 



24 to 45 



White sandstone. 



13 



10 to 15 



Grey soft slate clay. Coal roof. 



12 



Coal. 



Second coal, 2 ft. 6 in. to 3 ft. 4 in. (Over-estimated.) 



11 



12 to 15 



Sandstone. 



10 



6 to 15 



Black slate clay. 



9 



4 to 20 



Greyish-white sandstone. 



8 



Coal. 



Third or "Crow" coal, intermingled with claylaminse, 1 to 3 

 feet. (Over-estimated.) 



7 



1 to 3 



Fire clay. Coal seat. (Over-estimated.) 



6 



1 to 3 



Sandstone, with plant impressions. (Often much thicker.) 



5 



6 to 10 



Grey (and very hard) sandstone. 



4 



9 to 20 



Black slate clay (shale). 



3 



30 to 60 



Greyish-white sandstone, known as the first or bottom sand- 

 stone.* 



2 



300to600 



Black slate clay, with grey flags, and innumerable ironstone 

 nodular layers and beds, varying from half an inch to 2 feet 

 in thickness. f 



1 





Carboniferous limestone, unknown. Page 20 of Report. 



As my examination of these coals was confined to the Arigna dis- 

 fcrict, and had distinct reference to those places where coal is now 

 being raised, 1 shall limit my remarks to the facts which came 

 under my own observation, as by so doing I shall afford some aid to 

 t'ui mo explorers in this most interesting and important field of 

 research, and 1 cannot prejudice the question as to the advisability 

 of these beds being worked as a profitable mining speculation. 



* Upwards of .050 feci thick at Altagowlan, and close on 200 feet on the south-east 

 (lank of Kilronan. 

 t Upwards of 800 feet at Altagowlan mountain. 



