STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 95 



him to suspect that the unconformity may indicate a time interval 

 and that possibly the Paonia and overlying rocks may not be older 

 than Laramie. The unconformity is distinct, for the Bowie de- 

 creases from 425 feet on Grand River to nothing in the Rollins 

 district ; and it seems to be suggested on Grand River by the irregular 

 contact between Paonia and Bowie at Palisades. It may be in- 

 judicious, it may savor of temerity for one who has not visited the 

 localities to controvert the opinion of one who has examined the 

 area in detail, especially when the latter is a model of accuracy in 

 observation and caution in conclusion, but the writer feels compelled 

 to believe another explanation not improbable. The vast area of 

 Cretaceous deposition was subsiding until certainly toward the close 

 of the Cretaceous as was the Appalachian Basin during Coal 

 Measures time : but there were local crumplings as there were in the 

 Appalachian. In the latter, these have left their records in deep 

 stream valleys, filled with later deposits. Similar conditions have 

 been observed in the British coal fields. It would be strange if evi- 

 dences of local elevations or depressions were wanting in the vast 

 subsiding Cretaceous region. The irregular contact on Grand River 

 seems to indicate change in direction of drainage on the broad plain. 

 A serious argument in favor of assigning Laramie age to the 

 Paonia and overlying deposits is the presence of a flora, which is 

 described as containing Montana Laramie and even Post-Laramie 

 forms, the Montana forms being few. The origin of a flora is a 

 perplexing problem, but there seems to be no reason to suppose that 

 it sprang into existence full- formed and without local forerunners, 

 probably at many places. But, be that as it may, the Bowie and the 

 Paonia appear to be continuous in the eastern part of the region 

 described by Lee and no plane of separation has been determined. 

 Farther north, just beyond the existing limits of the Uinta Basin, 

 the Lewis shale has been recognized. It seems not unreasonable to 

 suggest that in the southern part of this basin as in the southern part 

 of the San Juan Basin, fresh-water sandstones may hold the place 

 of the Lewis. The doubts must be dispelled by stratigraphy. The 

 " Fox Hills " and " Laramie " of the earlier students have been placed 

 in the Pierre, in spite of the remarkable resemblance to the later 



