674 Grove Karl Gilbert. 



base could not be easily apprehended from the few lines 

 that Gilbert gave to it; indeed some of those geologists 

 who, a quarter of a century later, opposed Gilbert's view 

 do not seem even then to have appreciated this essential 

 element of his discussion. 



The regrettable brevity of the Basin-range chapter is 

 perhaps to be explained by the dissatisfaction of its 

 author with the military ordering of the Wheeler Survey. 

 The young geologist had been permitted by Newberry to 

 publish an abstract of his Maumee valley studies in the 

 American Journal of Science two years before it came 

 out in a volume of the Ohio Survey ; but on asking a sim- 

 ilar permission regarding some of his v/estern work it 

 was refused by General Humphreys, chief of engineers, 

 under whose direction Lieutenant "Wheeler's Survey was 

 conducted. Whether this was also the cause of Gilbert's 

 leaving the Wheeler and joining the Powell Survey does 

 not appear ; but on Nov. 27, 1874, after the transfer had 

 been made, he wrote from his home in Eochester to 

 Powell: — "I feel little ambition to write anything for 

 publication with the uncertainty that would hang about 

 the date of its appearance. ... I am getting a little 

 anxious to be at work — partly because it has come to be 

 more natural than play, and partly because I ought to be 

 earning something. So I am going to Washington in a 

 few days, with the intention — if you have not changed 

 your mind — to begin work with you at once." Thus he 

 entered upon a period of the most loyal and substantial 

 service under his new chief. 



In the course of his continued western field work, Gil- 

 bert spent a week in the summer of 1875 in the Henry 

 mountains of southern Utah, and found them so inter- 

 esting that, probably on his own request, he was sent 

 there for two months of 1876; as a result we have one 

 of the most notable of all his reports. Its greater part 

 treats the type of intrusive structures, previously recog- 

 nized in a general way by earlier geological visitors, to 

 which he gave the name of "laccolites." This text 

 clearly illustrated his power to deal convincingly, if he 

 took the time, with a new structural problem, involving 

 many local details. The report described an area of 

 about 1000 square miles of desert, mountainous country, 

 as surveyed on his two visits. Gilbert recognized that 

 the time was short for so great a task, for he wrote : — 

 "A few comprehensive views from mountain tops gave 



