302 GROVE KARL GILBERT— DAVIS [MEMO,RS [ ^ouxxt 



Peaks in the Cottonwood district is estimated to be at the very least 7,000 feet, and more 

 probably as much as 10,000 feet; and this requires a slip or slanting movement down the fault 

 surface of 17,900 feet and a heave or horizontal displacement of 14,800 feet. It is this enormous 

 movement of horizontal extension to which reference has been made in earlier pages. Had 

 similar extension been found to characterize other fault-block mountains, Gilbert would surely 

 have had some interesting generalizations to present as to the origin of such movements if his 

 report had been carried to completion. 



In conclusion the Wasatch is regarded as a great crustal block, with an average width of 

 8 or 9 miles. Its eastern margin is tentatively explained as due to the down-faulting of a narrow 

 slab or slabs, by which a series of "back valleys" was initiated, although the down-faulting 

 there was much less than on the west. Several transverse streams which cut canyons through 

 the ran^e from east to west are regarded as antecedent to the block faulting. As to the pre- 

 faulting form of the region: 



Before the range arose its site — or at least part of its site — was a land tract of low relief. This is shown by 

 remnants and other vestiges of a peneplane. ... At the north the peneplane was developed on Archean and 

 Paleozoic rocks, at the south on Carboniferous. . . . These imperfectly correlated data . . . serve to show that 

 the period of diastrophism to which its [the range's] growth belongs is distinct from the period of the great post- 

 Jurassic revolution, being separated from it by the period of quiet in which the peneplane was developed. 



Thus at the end Gilbert makes perfectly explicit statement of the long period of undis- 

 turbed erosion which Powell had, in some almost intuitive manner, detected nearly 40 years 

 earlier, and of which Gilbert himself had found evidence in the summer of 1901. His note- 

 books of that year, as already cited, make it clear that the same long period of erosion was 

 recorded in some of the isolated basin ranges which he then studied. 



How unavoidable is the regret that he was not spared with bodily health to carry through 

 to completion this superb product of his unimpaired men tab ty! 



FINAL ILLNESS AND DEATH 



The study of the basin ranges was still in progress when, in his seventy-fifth year, Gilbert 

 reached the decision to remove from Washington and make his home in California. On arriving 

 in San Francisco 15 years before, he had spent 30 hours without seeing a soul he knew; it was 

 then "a big, lonesome city." But as the years passed he formed many close friendships there 

 and in Berkeley across the bay, and at last came to wish that his remaining years might be 

 spent in that delightful region. With this object he began the journey westward in the spring 

 of 1918, but stopped at Jackson between Detroit and Chicago to see his sister, as he had done 

 so many times before on his travels across the country. While there his health failed so much 

 that he was removed from her house to a hospital which, curiously enough, had been built on 

 the ground where the sister's residence itself had stood for many years; and it was from the 

 hospital that, in the month before his death, he sent his last official letter, addressed to his then 

 successor in the position of chief geologist of the survey. After briefly mentioning the cause of 

 his detention at Jackson and the small likelihood of his being again as well as he had been, he 

 went on: 



Nevertheless I hope to be able to continue work on the report in hand — the Structure of the Basin Ranges — 

 and shall try to complete it. . . . Chapter I of my report, a historical introduction, is written. So is Chapter 

 II " Wasatch Range," which contains new material on the range and opens the discussion of the value of physio- 

 graphic evidence of block-faulting. In my judgment these chapters will be worth publishing, even if I fail to 

 complete the work. There is a chapter on the faults of the Klamath region, written with care, so as to make 

 full record of some observations while they were fresh. It has been my purpose to recast this after other chapters 

 have been written. . . . The chapter on hand is on the Fish Spring and House ranges and is intended as Chapter 

 III. It contains new material gathered in 1901. With a view to continuing the work whenever I have the 

 strength, I am sending west my assembled material, but as the journey will be at my own expense the draft 

 on Survey funds will be small. An outside estimate for the current fiscal year will be $150. 



The journey was not continued; the report was never finished. What strength remained 

 was given chiefly to setting affairs in order. On April 7, after much suffering the week before, 

 Gilbert wrote, in a greatly altered hand, to his elder son, Archibald, in San Francisco, asking 

 him to come to Jackson to take charge of certain business matters; he felt it was time to "cut 



