278 TRANSACTIONS OF THE 



over whose edges we have crossed, appears to increase 

 gradually, until at this point it approaches within a few 

 degrees of verticality. 



RICHMOND COAL FIELD. 



The section we have thus partially described is de- 

 signed to illustrate the prevailing geological features of 

 a small yet valuable subdivision of this state, and extends 

 north west from Richmond nearly parallel with the 

 James river, so as to cross the coal field about at right 

 angles in its centre, and at its widest diameter ; thus 

 exhibiting the trough or basin-form disposition of its in- 

 terior beds. 



By the diagram, which is sufUciently in detail for our 

 present purpose, it will be seen that the granite declines 

 at a great angle towards the west, on the eastern margin 

 of the coal region, sinking to an unknown depth below it, 

 and rising again at a gradually increasing angle, in an 

 opposite direction, towards the western margin. The 

 coal beds crop out immediately over this granite on both 

 sides, evidently conforming to the configuration of that 

 rock. 



The writer by no means announces as a newly disco- 

 vered fact that this coal deposit rests upon granite, with- 

 out any interposing rocks, except occasionally a few 

 inches of coal shale ; but he is desirous here to add his 

 testimony in corroboration of so interesting an occurrence. 

 It appears the more desirable that he should do so, since 

 an authority of deservedly high reputation in natural 

 science, who will be quoted in another part of this arti- 

 cle, has stated that he has found on examination, that the 

 coal basin of Richmond is '^actually underlaid with a 

 calcareous rock of a peculiar appearance.'' We place 

 before the society specimens of the granitic rock on which 

 this coal reposes, which specimens we detached from their 

 sites in the mines. 



