466 MmiNG INDUSTRY. 



sequence of geological changes liere with the change of physical conditions 

 that closed the Cretaceous epoch and ushered in the Tertiary of Europe, 

 especially in France, seems to me scarcely to admit of any well-grounded 

 doubts. While I am, therefore, willing to admit that facts may yet be dis- 

 covered that will warrant the conclusion that some of these estuary beds, so 

 widely distributed here, should be included rather in the Cretaceous than in 

 the Tertiary, it seems to me that such evidence must either come from 

 included vertebrate remains, or from further discoveries respecting the strati- 

 graphical position of these beds with relation to other established horizons, 

 since all the moUuscan remains yet known from them (my own opinions are 

 entirely based on the latter) seem to point to a later origin. 

 Very respectfully, yours, 



F. B. MEEK. 



Having thus generally sketched the geological relations of the coal 

 series where within the limits of this exploration they have been developed, 

 it only remains to add some notes on the coal-mining district and upon the 

 chemical and calorific nature of the coal itself 



Although coal has been known in this region since the early explora- 

 tions of the Engineer Corps, it is only within six or eight years that mining 

 has actually been prosecuted, and had it not been for the sudden demand 

 for railroad fuel, the coal would have lain unutilized for an indefinite period. 

 Under the stimulus of the railroad completion a number of important mines 

 have been opened. 



The coal series occupies a very wide geographical extent, reaching from 

 New Mexico certainly as far north as Dakota, and in all probability stretching 

 northward into British America. Its western boundary is the Wahsatch 

 Range, from whose meridian it continues eastward as far as Central Colorado. 



To the Green River Basin only have the observations of this Explora- 

 tion been confined. So far no beds have been worked within this area 

 except in the neighborhood of the Union Pacific railroad. 



The valleys of the Weber, Bear, and Bitter Creek have been eroded 

 through the overlying Tertiaries and opened up the coal series, and it is in 

 their canons that the main mining localities are found. 



