242 GROVE KARL GILBERT— DAVIS pfcMt "rl5£SE 



impatience from him; the records were lost and there was an end to the season's work. The few 

 intimate friends to whom he mentioned the calamity might have thought he was talking about the 

 misfortune of some other person, so calm was his mien under this cruel buffet of adverse fate. 

 Yet his uncomplaining reticence only exemplified the philosophy of life that he practiced more 

 than he preached. While he always did his best to prevent trouble that could be prevented, he 

 seemed to realize not only the uselessness but the harm of spending time and words in regretting 

 what was past and beyond remedy. He turned instead to something new that could be accom- 

 plished; his life was one of practical optimism. 



FIELD NOTEBOOKS OF 1901 



How deep must have been the disappointment over the loss of his maps, if it caused a man so 

 well balanced as Gilbert to leave unused all the laboriously recorded notes of his summer among 

 the basin ranges and turn away from the fine problem that they represented. Even without the 

 maps, he had the materials to make a noble essay, grounded on an abundance of critically deter- 

 mined facts, illustrated with detailed sections and excellent photographs, and set forth along 

 many converging lines of convincing logic in a manner that Gilbert knew so well how to employ. 

 And yet it all came to naught! 



The field route of 1901 led Gilbert and his topographer, Johnson, for a short distance south- 

 ward from Salt Lake City along the base of the Wasatch Mountains before they struck westward 

 across the desert to the basin ranges proper. Many items were noted on the way concerning such 

 physiographic matters as "mature topography," "graded plains," "cycles of erosion," and the 

 like. One of the first was a high valley in the Wasatch front, belonging to a topography estab- 

 lished "after some faulting but before the main faulting." The truncation of the valley ' was 

 begun by faulting and continued (perhaps) by the breaking away of the [fault] cliff sapped bj 

 continuance of faulting." A diagram here shows in section the loss of a large part of an up- 

 faulted mass, marked X, between the steep pitch of the fault plane and the gentler slope of the 

 actual profile; and the notes ask: 



What has become of the wedge X? The visible alluvial cones, etc., do not account for it, but it may be 

 buried under lake beds on the thrown block. 



A more general statement is then added : 



This high valley is one of a system, all reaching the cliff above PB [Provo Beach] and some above BB [Bonne- 

 ville Beach]. There is an upland topography, older than the cliff and truncated in the production of the cliff. 

 Still older is the topography of the high alluvial cones. Still younger is the shallow trenching of the cliff by the 

 drainage from the upland valleys. 



At a point farther along the Wasatch front the spur-end facets, slightly dissected, were 

 taken to represent the fault plane of mountain uplift, although they have the small dip of 30° 

 below the horizontal, or the large hade of 60° from the vertical. At another point parts of three 

 spurs were found to have fallen in a landslide, as if exemplifying the suggestion above quoted 

 that they had been sapped by a continuance of faulting. This raises a o^xestion which the notes 

 do not answer; namely, whether the spur-end facets are parts of a true fault plane which descends 

 uniformly far down into the earth's crust, or whether they are parts of a curved fracture surface 

 which, unlike a true fault plane, decreases its dip as it descends. Surely a surface which 

 hades 60° to the downthrow can hardly be the plane of a deep fault caused by vertical forces of 

 upheaval; but it might represent the lower part of a concave fracture surface, the upper part 

 of which, now lost by erosion, was steeper, following a principle "enounced" by McGee but 

 little attended to by his contemporaries. 4 If the better explanation be found in a curved 

 surface, then the highest portions of the uplifted mountain block must as a rule have been 

 rapidly eroded, by reason of the steepness of the fault scarp there; and erosion must now be 

 slower. 



1 W J McGee. On the origin and hade of normal faults. Amer. Journ. Sci., xivi, 1883, 294-298. 



