HISTORICAL REVIEW OF THE LARAMIE PROBLEM. 



55 



UINTA AND GREEN RIVER BASINS. 



The Uinta and Green River basins are broad 

 structural basins or depressions of rock strata 

 in northwestern Colorado, southern Wyoming, 

 and the adjacent part of Utah. The Uinta 

 Basin, which lies south of the Uinta Mountains, 

 extends on the east to • the foothills of the 

 Rpcky Mountains and on the west to the 

 Wasatch Mountains in Utah and is terminated 

 on the south by the La Sal Mountains and the 

 San Rafael Swell. It is separated from the 

 Green River Basin by the anticlinal axis of the 

 Uinta Mountains, which reaches eastward 

 through Axial Basin, Colo., to the White River 

 Plateau and the western spurs of the Rocky 

 Mountains. 



The Green River Basin was defined by 

 Emmons 93 as follows : 



The Green River Basin proper is a rudely triangular 

 area embraced between the systems of elevation of the 

 Rocky Mountains on the east and the Wasatch Range on 

 the west and extending from the sources of the Green 

 River, in the Wind River Mountains, on the north, to the 

 base of the Uinta Range, on the south. * * * From 

 the western flanks of the Park Range to the outlying 

 ridges of the Wasatch, a distance of about 150 miles, [it] 

 extends a practically desert region. 



The area as thus denned may be considered 

 as the broader conception of the Green River 

 Basin. It is capable of division into a number 

 of more or less well-defined subordinate basins, 

 such as the Red Desert Basin, the Great Divide 

 Basin, and the Green River Basin proper. 



H. S. Gale 94 in writing of these basins said: 



These two basins outline the dominant geologic struc- 

 ture of nearly the whole of northwestern Colorado. They 

 are in the form of broad synclinal folds or troughs, nar- 

 rowing to an apex toward the southeast. Within this 

 State their longer axes are approximately parallel, ex- 

 tending from southeast to northwest.. The coal-bearing 

 ro<;ks outcrop in practically continuous rims around the 

 borders of the basins where they have not been buried by 

 later formations, and the strata dip toward the interior of 

 the basins. 



These basins have been the scene of pro- 

 longed geologic research, especially in view of 

 the bearing they have or have been supposed 

 to have on the problems under consideration. 

 The several fields will be taken up in sequence, 

 so far as possible. 



m Emmons, S. F., U. S. Geol. Expl. 40th Far. Rept., vol. 2, p. 191, 1877. 

 »' U. S. Geol. Survey Bull 316, p. 270, 1907. 



UTNTA BASIN. 

 BOOK CLIFFS FIELD, UTAH AND COLORADO. 



The Book Cliffs coal field forms a part of the 

 southern rim of the Uinta Basin and extends 

 from the vicinity of Mount Hilgard, in central 

 Utah, northward to Castlegate and thence 

 southward to Colorado (formerly Grand) River, 

 in Colorado, beyond which it forms the south- 

 ern face of Grand Mesa. The geology of the 

 Book Cliffs was first studied by A. C. Peale, 95 of 

 the Hayden Survey, who in 1876 examined 

 the eastern part of the field. In his report the 

 rocks now referred to the Mesaverde were 

 separated into "Fox Hills" and "Laramie," 

 though it was recognized that there is no 

 lithologic break between the twO, and this 

 nomenclature was an attempt to conform to 

 the subdivisions used in other fields. 



The western part of the field was embraced in a 

 map of the Uinta Basin by George H. Eldridge 96 

 published in 1901 in his report on asphalt and 

 bituminous-rock deposits. On this map, 

 which is of small scale, the Book Cliffs are 

 simply denominated Cretaceous, but in the 

 description of the formations in the Uinta 

 Basin 97 the uppermost member of the Creta- 

 ceous, which contains the workable coals of 

 the region, is referred to the Laramie. 



The above-mentioned reports have, until 

 recently, been practically the only source of 

 information concerning the geology of this 

 region, though several short papers dealing 

 with the coal deposits were published by Hills, 

 Storrs, Lakes, and others. 



In 1905 Joseph A. Taff 98 made a careful 

 study of the western part of the Book Cliffs 

 field from the vicinity of Sunnyside to Castle- 

 gate, Utah, and its southern continuation 

 along the escarpment of the Wasatch Plateau. 

 In his report comparatively small space was 

 devoted to the geology, which he summed up 

 as follows : 



The rocks are naturally arranged in thick groups of 

 strata. In each group either sandstone or shale greatly 



's Geological report on the Grand River district: U. S. Geol. and Geog. 

 Survey Terr. Tenth Ann. Rept., for 1876, pp. 170-185, 1878. 



»8 The asphalt and bituminous-rock deposits of the United States: 

 U. S. Geol. Survey Twenty second Ann. Rept., pt. 1, p. 332, 1901. 



»' Idem, p. 334. 



" Book Cliffs coal field, Utah, west of Green River: U.S. Geol. Survey 

 Bull. 285, p. 289, 1908. 



