418 K. DOrCJLASS (JK()I>()(JV OK THE IIXTA FORMATION 



over been publislied n detailed ^eologieal section of any portion of it. 

 'J'lie present uovernineiil i4eolo<ifieal survey, wliich lias done some woik in 

 adjacent eoal-bearin^i'" and oil-bearinu- roiinat ions, has lefl some phases of 

 the geology of the Uinta in givatei- contusion than bel'oi'e. 



Mr. 0. A. Peterson was the first and almost the oidy geologist to give 

 us an outline of the subdivisions of the Uinta (Iroup and to furnish a 

 true basis for more detailed work. Prof. E. S. TJiggs has added very 

 valuable observations on the lithological characters and on the occurrence 

 of fossils in the lower portions of the deposits. 



Until the large amount of vertebrate material which has been collected 

 at various times by 0. A. Peterson and Earl Douglass, which is now being 

 prepared for study in the Carnegie Museum, has been studied in connec- 

 tion with sections and extensive field notes, only a provisional outline of 

 the geological conditions and their significance can be given ; but it is 

 hoped that this brief outline of section of the Uinta will sup])ly some 

 long desired and such needed light on this interesting group. 



Extent and Location of the Formation 



The lower portions of these deposits may be, and probably are, con- 

 temporaneous with i)ortions of deposits in the Bridger and Washakie 

 basins and with other deposits elsewhere. But these beds from the Cireen 

 River formation up to the superficial deposits, which in some places over- 

 lie them at the foot of the Uinta Mountains, will for the present be 

 treated under the old name "Uinta (iroup;" but it must be borne in mind 

 that it is probably only the u])per ]K)i-tion which belongs to the distinctive 

 "Uinta stage.'' 



The T'inta Tertiary de|)()sits ai'c in Uinta and Wasatch counties, Utah. 

 The extreme extent is something like 75 iniles east and west and 40 miles 

 north and south. They occui)y a large ])()rti()n of the Uinta liasin in the 

 southern base of the Uinta Mountains. 



"Divisions of tiii: Diiposrrs 



The deposits were diNidcd by Petei'son into A (lowiM'), B (middle). 

 and U (upper) Uinta. 



Uinta "A" occupies tlu' sonthei-n ])orti()n of the area. The lower por- 

 tion of "A," on White River at Wagonhound Uanyon, is about 585 feet in 

 thickness. \o deter»ninable mammalian remains have been found in it. 



