January 8, 1897.] 



SCIENCE. 



45 



work of the survey was carried eastward to 

 the Great Plains, taking in the great Eocene 

 beds of the Green Eiver basin; the Uinta 

 Range, unique on account of its east and 

 west trend and its anticlinal structure; the 

 Elkhead Mountains with their remarkable 

 development of rare varieties of igneous 

 rocks; the inclosed Mesozoic and Tertiary- 

 valleys of the North Park and the Laramie 

 Plains; the Medicine Bow Range, with its 

 series of Algonkian rocks, then classed as 

 Huronian; and finally the northern exten- 

 sion of the Front or Colorado Range, with 

 its granite core flanked by upturned Paleo- 

 zoic rocks, which had thinned from 30,000 

 feet in the Wasatch section to less than 

 2,000 feet, and were only visible at a few 

 points, being overlapped by Mesozoic or 

 Tertiary beds, as the case might be. 



The thorough study and discussion of the 

 material gathered during these years of 

 field exploration necessarily occupied much 

 time, but the then-existing conditions pro- 

 tracted the work much more than would be 

 the case at the present day. The topo- 

 graphical base of the five large atlas sheets 

 was not completed until 1874. In the 

 summer of that year a member of the Sur- 

 vey visited Europe and conferred with the 

 directors of the leading Geological Surveys 

 there on methods of treatment and of publi- 

 cation. 



Microscopical petrography was then an 

 unknown science in this country, and one 

 result of this visit was that Prof. Ferd. 

 Zirkel, of Leipzig, then the highest authority 

 in this branch of geology, was induced to 

 visit this country to examine the collections 

 of igneous and crystalline rocks and take 

 notes on their field habits. Chips for mak- 

 ing thin sections were taken back by him 

 on his return to Germany for systematic 

 microscopical study, and his report (Vol. 

 VI.) published in 1876 was the first work 

 of this kind on American rocks. 



The final determination of the fossils 



collected was confided to F. B. Meek, James 

 Hall and R. P. Whitfield, at that time the 

 only paleontologists competent to undertake 

 so important a work, but they could only 

 devote to this task moments of leisure from 

 other and to them more pressing work, 

 consequently it was nearly four years after 

 the completion of field work before the 

 geological material was finally ready for 

 publication. The volume on Descriptive 

 Geology by A. Hague and S. F. Emmons 

 with the final sheets of the geological atlas 

 went to press in 1876, and in the following 

 year was written Mr. King's masterly 

 summary of the whole work, designated 

 ' Systematic Geology,' which discussed not 

 only the general history and structure of 

 the Cordilleran system, but also such sub- 

 jects of general theoretical interest as the 

 ' Genesis of granite and crystalline schists,' 

 the ' fusion, genesis and classification of 

 volcanic rocks,' etc. 



The distinguishing character of this Sur- 

 vey, as compared with the other organiza- 

 tions, was that its work was founded on a 

 complete and comprehensive plan adopted 

 before taking the field, which in all its es- 

 sential features was systematically followed 

 out during the ten years of its existence. 



Hayden Survey. The names of Hayden 

 and Meek had long been identified with the 

 geology of the Missouri Valley and the 

 Great Plains, and when it was found in 

 1867 that of the appropriation for legisla- 

 tive expenses of the Territory of Nebraska 

 there remained an unexpected balance of 

 $5,000 it was very wisely given to Dr. 

 Haj'den to expend in geological researches 

 in that territory. From this modest be- 

 ginning grew, by a process of gradual evo- 

 lution, what became finally known as the 

 United States Geological and Geographical 

 Survey of the Territories, the catalogue of 

 whose reports constitutes a pamphlet of 

 fifty pages. F. B. Meek and Dr. C. A. 

 White assisted Dr. Hayden duiing the first 



