518 E. BLACKWELDEK — GEOLOGY OF WASATCH MOUNTAIKS, UTAH 



fully realize that they have only scratched the surface in a highly fertile 

 field of geologic study. 



The Wasatch Mountains, as defined by the U. S. Geographic Board, 

 comprises two distinct parallel ranges which are separated by depressions 

 4 to 10 miles wide. The eastern range is often called the Bear Eiver 

 range or plateau. For the western portion, which flanks the Salt Lake 

 plain, there seems to be no specific name. As it is the more conspicuous 

 of the two ranges, it is here called the "Wasatch range proper." The 

 field of study on which this paper is based includes that part of the west- 

 ern range which lies north of Weber Eiver (near Ogden) as well as adja- 

 cent parts of the Bear Eiver plateau. 



Stratigraphy 

 earlier investigations 



The general features of the geology of the Wasatch region have long 

 been known from the reports of the King^ and Hayden^ surveys. No 

 comprehensive general studies have been made since that time, but several 

 geologists have investigated special problems, and thereby contributed 

 important results. Walcott* has studied the Cambrian formations in 

 both the main Wasatch and the Bear Eiver ranges, and Has divided them 

 into many formations on the basis of abundant fossils. Weeks,^ in addi- 

 tion to his work in company with Walcott, has inspected the Paleozoic 

 rocks at various points in both ranges, and has made the only previous 

 reconnaissance of the Carboniferous phosphate deposits. Unfortunately 

 most of his results are still unpublished. The work of Boutwell,^ in the 

 Park City district, southeast of Salt Lake City, is important for the light 

 it sheds on the stratigraphy of the Carboniferous and early Mesozoic 

 formations. To him is due also a sounder interpretation of the complex 

 structure of the central part of the Wasatch range. The existence in the 

 Bear Eiver range of Silurian and Devonian limestones identifiable by 



2U. S. Geological Exploration of the 40th Farallel, vols, i, 1877, ii, 1877, iii,.1878; 

 and S. F. Emmons : Amer. Joiir. Sci., 4th ser., vol. xvi, 1903, pp. 139-147. 



^ U. S. Geographical and Geological Survey of the Territories : Idaho and Wyoming. 

 Fifth Ann. Rep., 1872, Sixth Ann. Rep., 1873, and 11th Ann. Rep., 1877. 



* C. D. Walcott : Cambrian faunas of North America. U. S. Geological Survey, Bulle- 

 tin 30, 1886, pp. 38-39. 



Cambrian sections of the Cordilleran area. Smithsonian Miscellaneous Collections, 

 vol. liii, 1908, pp. 167-230. 



5 F. B. Weeks : Contributions to economic geology, 1906. U. S. Geological Survey, 

 Bulletin 315, pp. 449-462. Also unpublished data. 



8 J. M. Boutwell : Stratigraphy and structure of the Park City mining district, Utah. 

 Journal of Geology, vol. xv, 1907, pp. 434-458. 



