DIFFERENT SUCCESSION OF COALS. 73 



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LIGNITIC COAL. 



An examination of the section will reveal the fact that lignitic coal is 

 found abundant from the base of the Cretaceous through the recognized 

 groups of that division, and in three of the groups of the Tertiary, giving 

 a horizon of 11,500 feet. I know of no lignite bearing group in the Pla- 

 teau Province which may be said to be richer in this product than others, 

 and it would have led to confusion to characterize any group as the "Lig- 

 nite beds." 



While lignitic coal is found in great abundance through a long succes- 

 sion of formations or groups, it is rarely or never the case that any partic- 

 ular bed is persistent over a great area. In the Point of Rocks Group I 

 have at one place found eleven beds, varying from ten inches to four feet in 

 thickness, and three miles away where the exposure was complete so that 

 no mistake could be made except by careless observation I have found 

 each one of these beds represented by carbonaceous shales ; and facts simi- 

 lar to this have been noted in all the other groups. It is frequently the 

 ca.so that, in studying the same group at two places separated by a few 

 miles, a veiy different succession of coals will be observed. It seems that 

 they were formed in small, irregular basins, from time to time, beginning 

 with the Lower Cretaceous and ending high up in the Cenozoic. 



Dr. C. A. White has prepared a catalogue of the species which, so far, 

 have been collected in the Plateau Province, by myself and those assisting 

 me in the work, and tabulated them in groups agreeing with the above 

 scheme. He has also appended to each an additional list of fossils collected 

 by others. The general correlation of the section to established successions 

 elsewhere must at present rest on the evidence furnished by this catalogue. 



