766 INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



Osborn ^^^^ gives a columnar section of the Bridger formation, 1,875 feet, as 

 developed in the Bridger Basin, based on detailed stratigraphic and paleontologic 

 work by Matthews and Granger. Five divisions are distinguished according to 

 faunas. The Bridger is assigned to middle Eocene time and correlated with the 

 upper part of the Huerfano formation, the lower part of the later Eocene (Uinta- 

 therium zone) of the Washakie Basin, Wyoming, and the lower part, or Uintatherium 

 zone, of the later Eocene of the Uinta Basin of northern Utah ; also with the Clarno 

 formation of the John Day Basin, Oregon. 



K 12. WIND BIVER BASIN, WYOMING. 



E. G. Woodruff has contributed the following data on the Tertiary of the Wind 

 River Basin: 



The highest Tertiary beds recognized in the Wind River Basin are called by Osborn and 

 others the Wind River formation (Eocene), They consist of alternate beds of gray, drab, and 

 pink very sandy shale and a few sandstone members near the base. In several areas about the 

 edge of the basin a conglomerate member is the base of the formation. The Wind River is 

 notably unconformable above the Fort Union formation, and probably was deposited subse- 

 quently to the formation of the Wind River Basin. The material composing it is beheved to 

 have been derived from the surrounding mountains. The thickness of the formation is unde- 

 termined. The Fort Union formation (Eocene) peeps out from beneath the Wind River cover 

 in a few places around the edge of the Wind River Basin. It is beheved that all of the Fort 

 Union is not represented in any of these exposures. The formation where seen consists of a 

 series of sandy shales and both shaly and massive sandstones which are generally pale rusty 

 colored but' are locally gray. The underljdng formation is the Mesaverde (Upper Cretaceous). 



Osborn,*^^** who bases a section of the Wind River formation on work done by 

 Hayden and Loomis, assigns 1,200 to 1,400 feet to the formation, with red beds at 

 the base. The strata comprise the Lambdotherium and Bathyopsis zones (lower 

 to middle Eocene) and fall into two divisions which correspond to the upper part of 

 the Wasatch of the Bighorn Basin and the lower part of the Huerfano formation 

 of Colorado. (See J 13, pp. 758-759.) 



K 13. WYOMING AND COLORADO. 



The eastern border of the Washakie Basin has been mapped by Ball/^ who 

 determined the following section of the Tertiary on the southern line of Wyoming: 



The coal field drained by Little Snake River extends from the Sierra Madre westward to 

 and partly into the Red Desert, and from the summit of the Elkhead Mountains of Colorado 

 northward to the divide between the Pacific and Great Divide Basin drainages, a few miles 

 south of the Union Pacific Railroad. 



The area discussed in this paper is located near the middle of the southern boundary of 

 Wyoming. > 



The stratigraphic relations of the coal-bearing and associated formations, with t*heir general 

 character and approximate thicknesses, are shown in the following table [only the Tertiary part 

 of the table is quoted] : 



