146 DESCRIPTIVE GEOLOGY. 



Feet. 

 G. Drab sandstonej with plants 8 



7. Dark clay .\ 4 



8. Coal 1 



9. Sandstone and interstratified shale, with plants 11 



10. Coal , 4 



11. Argillaceous sandstones 18 



12. Main coal 9 



13. Clay and sandy shales, with plants 20 



14. Coal 4 



102 



Below the lower coal, yellowish-gray sandstones occur, which were not 

 estimated. The third stratum of coal, number 12 in the section given 

 above, is the only coal that has been worked. In its physical appearance, 

 it resembles the other Cretaceous coals of Wyoming, and is regarded as one 

 of the best for railroad purposes. It is highly prized, although it carries 

 narrow seams of earthy impurities and slate bands. In the cracks and 

 fissures of the coal are thin layers, or films, of yellowish-gray carbonate of 

 lime. It crumbles readily on exposure to the air, and takes fire sponta- 

 neously on the dumps. When burned, it yields a large percentage of yel- 

 lowish-gray ash ; but the amount of water present appears to be lower than 

 most of the Wyoming coals From bed number 6, a fine-grained, calcareous 

 sandstone, large quantities of fossil leaves of dicotyledonous growth have 

 been collected, many of them well preserved ; also, from bed number 9, 

 below the first coal stratum, and from number 14, below the main working- 

 seam, other collections were made. 



Professor Lesquereux, who gathered a large suite of specimens from 

 these beds, has determined fifty-six distinct species, and has come to the 

 conclusion that the beds are, without doubt, of Miocene age. From this 

 collection, eighteen species are identical with the Miocene flora of Europe, and 

 thirteen with that of the Arctic regions. Among the species found here which 

 Professor Lesquereux regards as indicating a Miocene flora may be men- 

 tioned the following : Betula Stevensoni, Acer trilobatuni, Alnus Kiefersteini, 

 and JEquisetum Ilaydeni. Associated with these, however, in the same beds, 

 are other species, subtropical types, which Professor Lesquereux says are 



