298 GROVE KARL GILBERT— DAVIS [MBa0IBS [ ^^t 



cal review of theba sin-range problem and the account of the Wasatch Range to which refer- 

 ence has already been made, and was about to supplement them with the results of his field 

 studies of other ranges in 1901 and later; but his strength was then so far reduced that he 

 could spend only a small part of each day in writing. He fully recognized the uncertainty 

 that attended the completion of his plans and talked freely of the possibility that he might 

 not be able to carry them through. 



THE WASATCH RANGE 



Extracts have already been made in an earlier chapter from Gilbert's historical review 

 of the basin-range problem; it remains to present here some of the most significant passages 

 from his final account of the Wasatch Range. This occupies about 200 typewritten pages, 

 and it is as keenly critical and analytical and demonstrative as any essay he ever wrote. It is 

 a perfect example of scientific acumen and impartial equanimity; and it shows that his mental 

 capacity was unaffected by his loss of bodily strength. He not only patiently analyzed the 

 various interpretations that have been proposed for the observed facts, but he carefully criti- 

 cized the analyses by which the interpretations are reached. If there be a fault in the dis- 

 cussion, it is in the overelaborate demonstration that the Wasatch escarpment can not have 

 been produced by such agencies as ocean waves, glacial erosion, or wind action. Gilbert's 

 own opinion, quoted below, that this chapter is "worth publishing" is a most modest estimate 

 of its value. Had other ranges been afterwards treated with equal fullness, the resulting report 

 would have been without question Gilbert's greatest work. It is quite impossible, on reading 

 the Wasatch chapter, not again to feel deep regret that a great part of his time after liberation 

 from Washington in 1893 was not given to a comprehensive examination of the mountain ranges 

 of the Great Basin. He did not believe in the inclosure of scientific preserves, and he would 

 surely have welcomed cooperation of others in his studies; yet the origin of those mountain 

 ranges was peculiarly his problem. Moreover it was a greater problem than any other that 

 he undertook; the history of Lake Bonneville was a simple story in comparison; the evolution 

 of Niagara as a phase in the history of the Great Lakes was more complicated, but it did not 

 approach in complexity the origin of the basin ranges. And there is every reason for believing, 

 from the results that he had already reached, that if he had been able to examine a good number 

 of the basin ranges he would have been led to set forth a theory of mountain making involving 

 not simply vertical uplifts, as he had long before suggested, but strong crustal extension; and 

 that would have been even a greater novelty than his idea of fault-block ranges. 



The Wasatch Range, 130 miles in length, rises some 4,000 feet above the adjoining plains 

 and has a dozen peaks which rise from 1,500 to 4,000 feet higher still. It is composed of a 

 great variety of rocks, including formations from Archean to Jurassic in age. 



Following the Jurassic deposition was a diastrophic revolution. The formations were folded and faulted 

 on a grand scale and among the faults were extensive overthrusts. The intrusion of the granite bodies is assigned 

 to the same period. The mountains and valleys created by these dislocations were not coincident with the 

 present mountains and valleys. ... A profound syncline crosses the Wasatch ... at right angles. At the 

 south the axis of an important anticline enters the present range obliquely; and at the north the upbuilding 

 by overthrust is not expressed by the existing relief. 



The topography created by dislocation was so far reduced by erosion in Cretaceous time that a transgres- 

 sion by the sea spread sands of Dakota age over worn edges of Jurassic, Triassic, and Upper Carboniferous 

 strata. The evidence of that transgression has been found only on the eastern flank of the range. After the 

 retreat of the sea were other crustal changes, and then an important period of crustal quiet in which the general 

 movement of detritus was from west to east and a broad area at the east received terrestrial and lacustrine 

 deposits. These deposits, referred to the Eocene, 'rest, in the Wasatch district, on all formations of earlier 

 date, from Archean to Cretaceous. . . . The diastrophism to which the greater features of the present relief 

 are due is clearly post-Eocene, but the date of its beginning cannot be yet assigned. Its changes have continued 

 to the present time, but only a small fraction are post-Pliocene. 



One crustal change of the Tertiary system was of broad or epirogenic character and resulted in a general 

 reversal of the slopes controlling drainage. The field of Eocene deposition became an upland, and a western 

 district which had been a field of Eocene degradation became a lowland. ... A coordinate crustal change 

 was orogenic, the creation of mountain ridges and intermont troughs. The Wasatch range was separated from 

 the chain of broad valleys that follow its western base by a great fault. ... Up to the present time only physio- 



