i 



332 THE CARBONIFEROUS SYSTEM. 



Ft. in. 



Brought forward, 2 9^ 



4. Coal, fine, cubical, and laminated ; much mineral 

 charcoal . . . . . . .32 



5. Carbonaceous shale and ironstone, with layer of coarse 

 coal ("holing stone") ; remains of large fishes and 

 coprolites. This bed varies much in thickness 4^ 



6. Coa^, laminated and cubical, coarser towards bottom 9 3 



7. Ironstone and carbonaceous shale, with coaly layers 

 and trunks of Lepidodendron, Ulodendron, Sigil- 

 laria, Stigmaria, etc., all prostrate . . .08 



8. Coal, laminated as in No. 6, a line of ironstone balls 

 in bottom . . . . . . .12 



9. Coal, laminated and cubical, a few small ironstone 

 balls ; many vascular bundles of ferns iu this and 



-{ ■ *f^? underlying coal ...... 



10. Ironstone and pyrites . . . . 



11. Coal, laminated and cubical, as above . 



12. Coal, coarse, layers of bituminous shale and pyrites 



13. Coal, laminated, with a fossil trunk in pyrites 



14. Coal, laminated and cubical, with layers of shale, 



passing downward into black slicken-sided under- 

 clay with coaly bands ..... 



15. Underclay (to bottom of specimen) 



Thickness perpendicular to horizon . 



Vertical thickness . . . . . . 38 6 



From this seam at least 24 feet in vertical thickness of good coal 

 can be extracted. A cubic foot of Pictou coal weighs about 82 lbs., 

 rather less than 28 feet being equal to a ton of coal ; hence a square 

 mile of this seam would yield in round numbers 23,000,000 tons of 

 coal — an enormous quantity as compared with the present annual pro- 

 duce, but less than two-thirds of the annual consumption of Great 

 Britain. The other seams in the Albion measures may be safely 

 estimated at half the value of the main seam. 



The Albion coal has a laminated texture, and much mineral charcoal 

 on its surfaces, and is a highly bituminous caking coal. Its specific 

 gravity, according to the trials of Professor W. R. Johnston,* is 1-318 

 to 1*325. The result of twelve trials made by the writer of samples 

 from different parts of the mine was, that the specific gravity varies 



* Report to the United States Government on American Coals. 



