NATIONAL ACADEMY BIOGRAPHICAL MEMOIRS VOL. VIII 



markable "Report on the geology of the eastern part of the 

 Uinta Mountains" (1876), published as the work of the second 

 division of the "U. S. Geological and Geographical Survey of 

 the Territories," of which he was then "geologist in charge." 

 His later western journeys, as well as those of the summers of 

 1872 and 1873, were chiefly occupied with ethnological studies, 

 of which brief accounts are given in Congressional and Smith- 

 sonian reports. Powell prepared no other important geologi- 

 cal volumes; the great impression that he made on American 

 geology must be credited apart from his later work as an 

 administrator to the two reports on the Colorado River and 

 the Uinta Mountains. The popular book on the "Canyons of 

 the Colorado" (Meadville, Pa., 1895) was prepared more than 

 twenty years after the event, and looks more like a publisher's 

 than an author's venture. Several chapters on the native 

 tribes were here included ; but the whole appears to have been 

 hastily put together, with too many pictures little related to the 

 text. 



REPORT ON THE COLORADO CANYON. 



Of the two reports the earlier one on the Colorado is the 

 more important; it is certainly one of the most famous books 

 of exploration published in this country. It is unusually well 

 illustrated, partly with wood cuts from photographs, partly 

 with schematic drawings by Holmes, in some of which a fore- 

 ground section showing geological structure and a perspective 

 view showing surface form were admirably combined in the 

 style of block diagrams. Powell himself seems to have had no 

 graphic skill, and perhaps for that reason permitted the publi- 

 cation of certain exaggerated pictures, such as that of Horse- 

 shoe Canyon (opposite p. 162), drawn by Moran in a mislead- 

 ingly realistic fashion ; and of a seriously incorrect picture 

 (opposite p. 212), probably drawn from verbal description, of 

 the double unconformity at the bottom of the Grand Canyon, 

 the interpretation of which has puzzled more than one reader, 

 all the more because the excellence of the other illustrations 

 gave reason for thinking that this one also must be trust- 

 worthy. The double unconformity is, however, correctly drawn 

 in a geological section of the Uinta Mountains report (p. 43). 



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