THE GREEN RIVER COAL BASIN. 455 



tems: first, those old Cordillera beds which have been folded up into the 

 prominent ranges of the Wahsatch and the Uintah; secondly, the coal-bearing 

 group of Cretaceous and Tertiary rocks, which lie in broad, gentle folds; and 

 thirdly, that series of Green River Tertiaiies, as we propose to call them, 

 which, over the greater part of the basin, are still in an undisturbed position, 

 but which, in the neighborhood of the Wahsatch and Uintah, are slightly 

 tilted and thrown into a state of gentle curvature. 



Two points in the geology of this region are of the utmost importance : 

 First, the identity of those conglomerate and arenaceous beds, which, along 

 the eastern flank of the Wahsatch, overlie the Cretaceous folds with those 

 honzontal deposits with which the whole plain of the Green River Basin is 

 at present covered ; secondly, the entire nonconfonnity between this series 

 and the underlying, folded, coal-bearing series. Whatever may be the rela- 

 tions of these beds in other places, it is absolutely certain that within the 

 region lying between the Green River and the Wahsatch, and bounded on 

 the south by the Uintah Range, there is no single instance of conformity 

 between the coal beds and the horizontal fresh-water strata above them. 

 The disturbances of the latter series are confined to within 15 miles of the 

 Wahsatch itself, and where they and the coal series are uplifted together the 

 discrepancy of the angle has a minimum of 11° and a maximum of 45°. 

 Actual tracing of the continuity of strata has proven that the uppermost beds 

 of this region stretch uninterruptedly from the Wahsatch to the east side of 

 the Green River; as they lie further and further from the Wahsatch and 

 Uintah, which are in reahty the sources of supply of their material, they 

 become finer and finer, the deposits of gravel and conglomerate die out, and 

 the series is composed of an uninterrupted group of sand, marl, clay, and silt 

 beds. The fresh-water origin of these strata is clearly seen from the fossil 

 life they inclose. Mollusks, testudinata, and mammalian remains indicate 

 clearly that they belong to the great fresh- water Miocene series, of which the 

 White River is the type. It is only, therefore, where these superimposed 

 Miocene beds have been eroded that the coal series is discovered. It first 

 makes its appearance in East Canon Creek, a tributary of the Weber, which 

 flows from south to north, joining the stream in Morgan Valley. Here, rising 



