GEOLOGICAL SOCIETY OF PENNSYLVANIA. 



293 



there repose in basins of granite and gneiss. The fossil 

 plant of the Richmond coal measures, bears some resem- 

 blance to one of the calamites of this French coal region. 

 But even there it remains undetermined, I believe, as to 

 what geological period or formation the conglomerate 

 rocks contained within these primitive basins can be re- 

 ferred ; and as many similar species of fossil vegetables 

 exist alike in the grauwacke series and in the newer 

 carboniferous groupe, it does not appear that the rela- 

 tive ages of the beds containing them, can be determined 

 with that precision we are frequently enabled to do, by 

 means of animal organic remains. 



For instance, in the five varieties of our Richmond 

 coal plant, Calamites Suckowii, M. A. Brongniart de- 

 scribes : 



The first as existing in the Newcastle bituminous coal 

 of England ; at Doutweiler near Saarbruck ; in the coal 

 mines near Liege, and near Valenciennes. 



The second in the mines of Litry, department of the 

 Calvados. 



The third in the anthracite coal of Wilkesbarre, in 

 Pennsylvania. 



The fourth in the bituminous coal shale of Richmond, 

 Virginia. 



The fifth in the coal pits near Valenciennes. 



Varieties of the same species are here shown to exist, 

 in the secondary bituminous coals of England, Germany 

 and France ; in the anthracite or transition coal of Penn- 

 sylvania; and in the Virginia coal resting upon granite : 

 deposits formed at distant and remote epochs. 



Among the desiderata demanding the attention of geo- 

 logists, a strict examination into the component materials 

 of the transition and secondary conglomerates has been 

 urged. A familiar acquaintance with the nature of these 

 conglomerates, particularly in the secondary coal fields 

 of America, confirms the opinion, previously suggested, 



