140 /S. F. Emmons — Little Cottonwood Granite. 



fields and orchards of tlie Mormon farmers, we looked with 

 delight at the deep clefts of the many canyons that scored its 

 flanks, foreseeing that here at last might be found a key to the 

 problem that so long had troubled us, in the actual superposi- 

 tion of the complete Paleozoic series. 



As originally planned, the season of 1869 was intended to 

 complete the field work of the 40th Parallel Survey. There 

 remained of tlie Desert Region all the ranges from the Wasatch 

 westward to the western edge of the Great Desert, and east of 

 the "Wasatch the western end of the Uinta liange and a por- 

 tion of the Tertiary Basin of Green River were included 

 within our field of work, an extent of country 125 miles long 

 in an east and west direction and with a normal width of 102 

 miles north and south or 12,750 square miles. To cover this 

 area required the utmost diligence and careful allotment of the 

 time from May to November, in which alone field work was 

 possible at that latitude and elevation. Three weeks were all 

 that could be allotted for the topographic and geological recon- 

 naissance of the whole Wasatch range south of the latitude of 

 Salt Lake City, wliicli fell to the lot of my party. It can 

 readily be conceived that under such relations of time to area 

 many phenomena would necessarily be but imperfectly observed. 

 As regards the completeness of the geological column, 

 expectations were more than realized. It was found that not 

 only was the entire Paleozoic section completely developed but 

 representatives of two series of pre-Cambrian formations and 

 of a remarkably full suite of Mesozoic and Tertiary formations 

 were exposed in this range. In the field, therefore, attention 

 was mainly devoted to the working out of the columnar sec- 

 tion, and it was not until many years afterwards, when, by the 

 completion of the topographic maps, it was made possible to 

 represent their relations graphically, that the true import of 

 some of the great structural problems involved could be fully 

 appreciated. 



I have gone somewhat at length into these preliminary obser- 

 vations because the purpose of this paper being to acknowl- 

 edge that an important mistake was made in the course of the 

 work, it seems no more than justice to those that carried it on 

 — more particularly to our deceased 'chief, Clarence King, to 

 whose genius and energy was due the conception and carrying 

 out of this great work and who personally drew all its most 

 important conclusions — that geologists of the present day 

 should have a realizing sense of the conditions under which it 

 was carried on. During the nearly thirty years that have 

 elapsed since its conception, I have had opportunities of verify- 

 ing the work in many parts of the field in the light of the 

 more complete knowledge of later times, and it has always 



