AMERICAN GEOLOGY SURVEYS UNDER POWELL. (V23 



resist the tendency of the walls to How together. This consideration 

 led him to the conclusion that — 



just as for each rock there is a crushing weight, so there is for each rock a certain 

 depth at which it can not be fissured. 



Applying this principle to faults and fissure veins he concluded that — 



if the fault extend to a # r eat depth it will finally reach a region where the hardest 

 n tcks which it separates are coerced by so great a pressure that they can not h< »ld them- 

 selves asunder, but are forced together before the fissure can be tilled by mineral 

 deposits. Thus, there ia a definable inferior limit to the region of vein formation. 



This the present writer believes to be the first time the doctrine of 

 rock no wage was put forth in America and by an American. 



The matters of instability of drainage lines, planation, and formation 

 of river terraces were discussed, and it was shown that Hitchcock's idea 

 of the formation of river terraces by successive periodsof sedimentation 

 (p. -±6*2) was erroneous, such in fact being but the recorded stages of 

 progressive erosion. In this work Gilbert used the terms conseguent, 

 (int< cedt nt, and supt rimposed as introduced by Powell, and showed that 

 the drainage of the Henry Mountains, while as a whole consequent, 

 was not so in all of its details. 



The igneous rocks of the mountains were studied microscopically by 

 Capt. C. E. Dutton, who classed them as trachytes. 



Powell was born of English parentage in Mount Morris, New York, 

 March 24, 1834, and died September 23, 1902. From childhood he 

 manifested a deep interest in all natural phenomena and early gave 

 evidence of that bold and self-reliant spirit which 

 sketch of Poweii. in later years found vent in his hazardous explora- 



tion of the Grand Canyon of the Colorado. Vigor- 

 ous, impetuous, and sometimes intolerant of the opinions of others, 

 he made warm friends and strong enemies. Rising from obscurity, 

 without university training, indeed almost wholly self-taught, to 

 become a bold and aggressive thinker, and finally the head of the l T . S. 

 Geological Survey in 1881, it is little to be wondered at that he became 

 for many a target for sneers as well as an object of envy. But how- 

 ever much men may differ as to the value of his individual work in 

 the geological as well as ethnological field, no one will for a moment 

 question that it was through his efforts that others were given the 

 opportunity to carve out their own immortality. Upon his success as 

 an administrator his fame may safely rest. 



After his retirement from the Survey in 1894 Powell limited him- 

 self mainly to abstruse psychological problems and the directorship 

 of the Bureau of American Ethnology, which, it should be said, he 

 had been largeby instrumental in founding in 1880. 



Powell served with gallantry during the civil war, rising to the 

 rank of major of artillery. He lost his right arm at the battle of 

 Pittsburg Landing. 



