ACADEMY OF SCIENCES] GILBERT'S WORK 287 



have been first detected by Powell, who is seldom thought of in that connection. It is to be 

 regretted that, during the discussion which brought out King's and Powell's suggestions, Gilbert 

 remained silent, apparently on principle; he certainly had abundant opportunity to contribute 

 to the discussion whde he was in Salt Lake City, before he was overwhelmed with work on his 

 return to Washington in 1881, but took no public part in it. And it is still more to be regretted 

 that, after his first idea was extended by these suggestions from his seniors as well as by new 

 observations and reflections of his own, and thus developed into a more completely reasoned 

 form, it was never published. 



The statement of his views which he made as censor of a paper submitted by another 

 author to the Geological Society of America, although now brought out in an earlier section of 

 this memoir, was not made public in his lifetime; and moreover it included no adequate mention 

 of a long period of erosion between two periods of deformation. When he was about ready to 

 break his long silence after a season of field work in the Great Basin in 1901, an unhappy acci- 

 dent discouraged him from reporting on the many excellent observations he had then recorded, 

 and the accident is thus responsible for a serious loss to American science. The new facts 

 that he discovered in support of Powell's erosional element of the basin-range theory remain 

 unpublished in his field notebooks, except in so far as brief extracts of them are here' presented 

 on an earlier page; the evidence that he detected in confirmation of the occurrence of master 

 faults along one or both margins of the ranges was presented orally at a meeting of the Geolog- 

 ical Society and survives only in the memory of those who were fortunate enough to hear him; 

 the newer inference of the oblique uplift of the ranges and the strong lateral extension of the 

 region at the time of the faulting, by which subsequent observations led him to replace the 

 earlier inference of vertical uplift with little compression, was published only as a brief assertion 

 13 years later in a paper on isostasy, where few have seen it. Even the essay on the basin 

 ranges that was left unfinished at the time of his death was not, except for the Wasatch Range, 

 as shown in the next chapter, carried far enough beyond a historical review to include an 

 account of his observations in the field seasons of 1901 and of after years on the elevated and 

 dissected peneplains which he recognized in the highlands of certain ranges, or an estimate of 

 the amount of lateral extension indicated by the moderate slope of the fault surfaces; much 

 less a discussion of the mechanism of such faulting. It is as if fate had been here working 

 against him. Would that his life had been spared long enough and with sufficient strength 

 to complete that essay; for his early statement of the basin-range problem, the only one that 

 he published, although it includes one of his most original ideas, is the least complete of all his 

 more important discussions. It is clear that he came to know vastly more about those ranges 

 than he ever put into print. 



THE POWELL SURVEY REPORTS 



With Gilbert's transfer to the Powell survey in 1874, two years of great opportunity were 

 opened to him for the serious investigation of large problems — the geology of the high plateaus 

 and of the Henry Mountains — but his work on the high plateaus, winch for some unexplained 

 reason was allowed to duplicate Dutton's study of the same province at the same time by the 

 same survey, was not published. On the other hand, his work on the Henry Mountains stands 

 out as one of the most notable successes of his career. The problem was novel and interesting; 

 the opportunity for studying it was planned to Gilbert's entire satisfaction; the solution reached 

 was unusually gratifying; the report upon it was prepared with eager promptness and soon 

 published in good form. A comparison of this most convincing discussion of the novel struc- 

 tures exhibited by laccolithic mountains, as prepared for the Powell survey, with the brief and 

 unsatisfactory account of the equally novel structures exhibited by the basin ranges, as submitted 

 in the earlier Wheeler reports, makes it clear that if favorable opportunity, such as was provided 

 for the examination of the Henry Mountains, had been likewise provided for that of a few selected 

 basin ranges, they also might have been treated with convincing clearness and completeness. 



As to the Henry Mountains volume itself, it is characteristically free from lithological 

 details and fully charged with critical description and reasoning about intrusive structures and 



