proceedings: geological society 255 



that these primitive mammals are not confined to the Fort Union 

 but are present also in the Wasatch beds. 



The fresh-water formations above the marine Fox Hills appear, 

 therefore, to belong to three formations: The Lance at the base, bear- 

 ing Triceratops; the Fort Union in the middle, bearing abundant leaves; 

 and the Wasatch at the top, containing remains of Coryphodon. The 

 Kingsbury conglomerate in the vicinity of Buffalo is probably basal 

 Wasatch, and the great erosional unconformity on which it rests repre- 

 sents the one which is present at many localities between the Fort 

 Union and Wasatch formations. 



C. J. Hares: Stratigraphic relations of some.' of the Cretaceous and 

 Tertiary formations of the Hanna and Powder River basins with those 

 of the Wind River Basin. 



Mountains did not exist or were very small between Hanna, Wind 

 River, Big Horn, and Powder River basins until the lower group of the 

 Upper Laramie of Hanna Basin, the Great Pine Ridge beds of Powder 

 River Basin, and the beds mapped as Fort Union in Wind River Basin 

 were deposited. Only in the Bighorn Basin has an unconformity been 

 demonstrated below a formation correlated. with these beds. The posi- 

 tion of the so-called Fort Union beds, only 250 feet above the Lewis 

 Shale at Alkali Butte, is now believed to be due to extraordinary 

 thinning of the Lance formation. These widely separated so-called 

 Fort Union beds contain the same cherty conglomerate, but contain, 

 so far as satisfactorily shown, no pebbles of Upper Cretaceous age, ex- 

 cept possibly west of Rawlins and at Alkali Butte. Should the pebbles 

 at these localities prove to be Mowry shale, then it is still necessary to 

 prove that the containing beds are pre-Wind River in age. These 

 formations contain no dinosaur bones, but many Fort Union leaves. 

 Succeeding their deposition orogenic movements were pronounced be- 

 tween the present intermontane basins; in the Granite Mountains 

 relative uplift amounting to nearly 20,000 feet took place, but in the 

 middle of the basins the algebraic sum of the movements was nearly 

 zero. 



Succeeding these greatly deformed so-called Fort Union beds occurs 

 the only profound, angular, and overlapping unconformity in the 

 Cretaceous-Eocene series of Wj^oming. This occurs at the base of the 

 Wind River formation and is believed to be obvious at all places except 

 in the middle of the basins of deposition. The Wind River formation 

 rests on upturned Cambrian to Fort Union strata, and the relief of 

 this old surface even in short distances is certainly 1000 feet and 

 may have amounted to 5000 feet. The Wind River formation con- 

 tains fragments of all underlying formations including Madison lime- 

 stone pebbles with Niobrara fossils and ferruginous material contain- 

 ing Fort Union leaves, all derived from the adjacent mountains. Strata 

 below the unconformity contain no recognizable local material. Thin 

 sections of Mesaverde, Lower Laramie, lower group of the Upper 

 Laramie, Lance, and so-called Fort Union show no marked differences. 

 The Wind River formation contains much arkosic material and granite 



