post- Cretaceous Motmtain-making along its course. 187 



similar import as to flexures and as to the time of the disturb- 

 ance. 



Thus the great bend of the protaxis is passed by the Paleo- 

 zoic and Cretaceous formations without essential change of 

 characteristics either in kinds of rocks, or in their disturbed 

 condition, or in time of disturbance.* It is of especial interest 

 therefore to compare these regions with the mountain region 

 farther south, that of the Wasatch and Uinta, very fully de- 

 scribed, and mapped in colors, in the reports of the 40th 

 Parallel. f In order that the facts and conclusions stated by 

 Mr. King in his " Systematic Geology " may be the better 

 understood, a copy of the map, but without the colors, is here 

 given reduced from the large map of the Atlas (21x27 in.). 

 But I would advise all readers to refer to the original map, if 

 possible, as it is the grandest exhibition of facts pertaining to 

 an individual case of mountain-making in all geological litera- 

 ture. 



The following facts are from Mr. King's description of the 

 region. 



1. Rocks. — The series of rocks above the Archaean involved 

 in the post- Cretaceous upturning included 13,000 feet of Cam- 

 brian (consisting of quartzyte 12,000 feet, with shales and 

 siliceous schists and containing fossils above the quartzyte ; 

 1000 feet of Silurian (the Ute limestone) ; 2400 feet of Devo- 

 nian (including 1000 to 1500 feet of Ogden quartzyte, and the 

 lower 1600 feet of the 7000 of Wasatch limestone) ; Carbonif- 

 erous series (comprising (1) the remaining 5400 feet of the 

 Wasatch limestone, (2) 5000 to 6000 feet of Weber quartzyte 

 or Middle Carboniferous, (3) 2000 feet of Upper Coal-measure 

 limestone, and (4) 650 feet of Permian) ; making in all about 

 30,000 feet of conformable Paleozoic beds. Above this series 

 follow conformably, 1000 to 1200 feet of Triassic beds, 1600 to 

 1800 of Jurassic, and just eastward, in the Green River basins, 

 the Cretaceous series 11,000 to 13,000 feet thick comprising (1) 

 the Dakota beds 500 feet, (2) the Colorado beds 1000 feet (in- 

 cluding Fort Benton, Niobrara and Fort Pierre groups of 

 Meek and Hayden), (3) the Fox Hill beds 3000 to 4000 feet, 

 and (4) the Laramie beds 5000 feet. 



Explanations of the map. — A portion of Great Salt Lake lies 

 on the western border of the map and Utah Lake on the southern, 

 within a valley of Quaternary deposits (lettered Q), which has 



* The only prominent difference in the rooks is the absence or non-repognition 

 in the British America sections of the Triassic and Jurassic. 



f Geological Exploration of the 40th Parallel, under Clarence King: vol. i, 

 Systematic Geology by Clarence King, 804 pp. 4to, 1878, with many maps and 

 plates ; vol. ii, Descriptive Geology, by Arnold Hague and S. F. Emmons, 890 

 pp., 4to, 1877, with 26 maps and many plates. 



