ON THE ORIGIN OF COAL. 187 



Chester, proved in sinking Mr. Woolley's shaft. 

 It commences a little under the Gannister 

 Coal, and terminates with a portion of the 

 upper Flag Rock, and is interesting from the 

 circumstance of the roof of the upper seam 

 of Coal containing an abundance of Goniatites, 

 Pecten, Posidonia, and other marine shells. The 

 vertical black line indicates by its varying thick- 

 ness the degree of rapidity of the subsidence of the 

 bottom of the sea, at the particular period when 

 the part of the deposit at which it is opposite 

 was forming, as well as the strength of the cur- 

 rent produced by such alteration in level. 



The Sandstones, Rock Binds, Shales, Metals 

 and Binds, and Floors, indicate diminishing rates 

 of subsidence, and the breaks in the line are 

 periods of absolute rest, during which the vege- 

 table matter, now forming Coal, grew. 



The diagram, plate III, fig. 2, shows a section 

 of the St. George's Colliery, near Manchester, 

 the property of Edmund Buckley, Esq., M.P. 

 It commences with the upper portion of the 

 middle Coal-field, and terminates upwards with 

 the lower and richest part of the upper division. 

 This section is remarkable for the number of 



