176 THE CARBONIFEROUS SYSTEM. 



The bituminous limestone has scales of fishes, Spirorbis, and 

 Cythere. The coal has Cordaites and vascular bundles of ferns. 



(Red and gray sandstone and shale. One underclay, ft- in - 

 and erect Calamites at one level) . . . . 98 6 

 'Reddish shale. 

 Carbonaceous shale, 10 inches. 

 Coaly matter, ^ inch. 



i Hard underclay, Stigmarla, 2 feet. 

 Coal-group 4S 4 Coal!/ matter ^ ^ inch 



Underclay, Stigmaria, 7 feet. 



Coal, 3 inches . . . . . . . 10 2 



Arenaceous underclay, Stigmaria. 



In the roof of the lower coal is an erect tree. The coal has 



vascular bundles of ferns, remains of fern-leaves, and bast 



tissue. The underclay has many coaly films, apparently 



flattened bark of trees. 



Reddish and gray sandstone and shale . . .56 



Total thickness of Division 4, according to Logan's measurements 2539 1 



Division 5. 

 This consists of reddish shales and red and gray sandstones. It 

 contains no coal, and is poor in fossil", only a few drifted trunks 

 appearing in the section. It corresponds to the upper part of the 

 Millstone-grit series. Its thickness, according to the measurements 

 of Sir W. E. Logan, is 2082 feet. 



Division 6. 



This may be regarded as the middle of the Millstone-grit series. 

 It constitutes a sort of false coal formation, separated from the Middle 

 Coal Formation by the barren beds of Division 5. It contains nine 

 small or rudimentary coal-beds, which, however, are not well seen in 

 the section, and have afforded few facts of interest. It has many 

 thick and coarse sandstones and much red shale, with comparatively 

 few dark-coloured beds. Its total thickness is stated by Sir W. E. 

 Logan at 3240 feet. 



Though this group contains little coal, it is to be observed that it has 



many underclay s, indicating soils which supported forests of Sigillaria, 



and that erect Sigillarice occur very near the base of the division. 



The absence of important beds of coal is therefore due to the local 



physical conditions, and not to the want of the necessary vegetation. 



(Sandstones and shales with many drifted trunks of ft- >n- 

 Dadoxylon) ........ 539 7 



f Blackish gray shale. 

 Calcareous shale, 1 foot. 

 Black shale, 3 feet. 



Coaly shale, 2 inches 4 2 



Argillo-arenaceous underclay, Stigmaria. 



Coal-group 1 < 



