THE FOUNDATIONS OF THE CONTINENTS 97 



which such veins occur in modern bituminous lime- 

 stones and shales. Such bituminous veins occur 

 in the Lower Carboniferous limestone and shale of 

 Dorchester and Hillsborough, New Brunswick, with 

 an arrangement very similar to that of the veins 

 of graphite ; and in the Quebec rocks of Point 

 Levi, veins attaining to a thickness of more than a 

 foot are filled with a coaly matter having a trans- 

 verse columnar structure, and regarded by Logan 

 and Hunt as an altered bitumen. These Palaeozoic 

 analogies would lead us to infer that the larger 

 part of the Laurentian graphite falls under the 

 second class of deposits above mentioned, and that, 

 if of vegetable origin, the organic matter must have 

 been thoroughly disintegrated and bituminized be- 

 fore it was changed into graphite. This would also 

 give a probability that the vegetation implied was 

 aquatic, or at least that it was accumulated under 

 water. 



" Dr. Hunt has, however, observed an indication 

 of terrestrial vegetation, or at least of subaerial decay, 

 in the great beds of Laurentian iron ore. These, 

 if formed in the same manner as more modern 

 deposits of this kind, would imply the reducing 

 and solvent action of substances produced in the 



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