THE FOUNDATIONS OF THE CONTINENTS 99 



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La Cloche mountains in Canada, the pores of 

 brachiopodous shells and the cells of corals have 

 been penetrated by black bituminous matter, form- 

 in i^ what may be regarded as natural injections, 

 sometimes of much beauty. In correspondence with 

 this, while in some Laurentian graphitic rocks, — as, 

 for instance, in the compact graphite of Clarendon, — 

 the carbon presents a curdled appearance due to 

 segregation, and precisely similar to that of the 

 bitumen in more modern bituminous rocks, I can 

 detect in the graphitic limestones occasional fibrous 

 structures which may be remains of plants, and in 

 some specimens vermicular lines, which I believe to 

 be tubes of Eozoon penetrated by matter once 

 bituminous, but now in the state of graphite. 



" When Paktozoic land-plants have been con- 

 verted into graphite, they sometimes perfectly retain 

 their structure. Mineral charcoal, with structure, 

 exists in the graphitic coal of Rhode Island. The 

 fronds of ferns, with their minutest veins perfect, 

 are preserved in the Devonian shales of St. John, 

 in the state of graphite ; and in the same formation 

 there are trunks of Conifers {Dadoxylon ouangon- 

 dianuni) in which the material of the cell-walls has 

 been converted into graphite, while their cavities 



