January 8, 1897.] 



SCIENCE. 



41 



nent men ia the East were temporarily at- 

 tached to the various parties. W. H. Jack- 

 son, the eminent photographer, was also a 

 member of the Survey. 



Dr. Hayden's plan was to make the Sur- 

 vey as widely popular as possible, and one 

 method of accomplishing this result was to 

 publish a volume every year, abounding in 

 excellent illustrations from the pen of 

 Holmes, which were gratuitiously distribu- 

 ted in very large numbers. One consequence 

 of this method was that the geologists did 

 not have time to thoroughly digest their 

 material, or correlate and compare it one 

 with another. It is much to be regretted 

 that in consequence no summary like the 

 ' Systematic Geology ' of King has ever 

 been written of the Hayden work. The 

 beautifully colored maps in the atlas of 

 Colorado, which were compiled and drawn 

 by Holmes, answer in one sense as such a 

 summary, for they indicate graphically 

 many general conclusions that are not to be 

 found in the annual reports. The latter, 

 on the other hand, often have a different 

 system of geographical nomenclature from 

 that given on the map, which renders them 

 sometimes almost unintelligible. 



The Colorado areal work joined that of 

 the 40th parallel on the south. In the years 

 1877 and 1878 the areal work was trans- 

 ferred to "Wyoming and carried northward 

 from the northern limit of the 40th parellel 

 maps northward to the Yellowstone Park. 

 On this work St. John served one season in 

 the Wind River country and in 1878 Holmes 

 and Peale made an extensive study of the 

 phenomena of the Yellowstone Park. Even 

 photography has not accomplished, in all 

 the time that has elapsed since, any im- 

 provement on the admirable illustrations 

 drawn by Holmes of the geological wonders 

 of this region. 



Poivell Survey. In the summer of 1869 

 Maj. J. W. Powell made, under the auspices 

 of the Smithsonian, his famous boat explo- 



ration of the mysterious depths of the can- 

 yons of the Colorado River, starting from 

 Green River City, on the Union Pacific 

 Railroad, in May, and emerging from the 

 mouth of the dark canyon nearly 900 miles 

 below, three months later, a journey that 

 is unequalled for its courage and daring in 

 the annals of geographical exploration. 



Already in the two preceding summers 

 he had visited the valleys of many of the 

 streams tributary to the Green River, and 

 during 1870 and 1871 his explorations of 

 the canyons were continued, still under the 

 same auspices. With the narrative report 

 of these explorations, published in 1875, ap- 

 peared an admirable discussion of erosion 

 and land sculpture in its relation to geologi- 

 cal structure, defining for the first time 

 base-levels of erosion. This, with the similar 

 discussions of Gilbert, based on his studies 

 of the Colorado Plateau region in 1871-2, 

 have formed the starting point of modern 

 physical geography. 



In no part of the world can there be 

 found so admirable a region to study the 

 elementary processes of stratigraphical ge- 

 ology as in that traversed by Powell's ex- 

 ploration. It is, so to speak, nature's text 

 book of geology, whose pages lie open to 

 the inspection of any one who possesses the 

 physical courage and endurance to reach 

 the depths of its canyons. Hence, Powell's 

 geographical exploration was at the same 

 time a valuable contribution to geology, in 

 that it opened the road to so important a 

 field that had hitherto been supposed to be 

 inaccessible except to the birds of the air. 



The Powell organization soon became a 

 geological exploration, receiving its appro- 

 priations directly from Congress, and as- 

 suming the title of Second Division of the 

 United States Geological and Geographical 

 Survey of the Territories. It did not at- 

 tempt to make an areal survey of this in- 

 teresting region, but devoted itself to mono- 

 graphic studies of some of the most novel 



