ACADEMY OF SCIENCES] BASIN RANGES 237 



existing ranges as Tertiary, and which, following Powell and Dutton, introduces a long period 

 of erosion, almost reaching planation, in the intermediate periods whereby the earlier-formed 

 mountains were essentially destroyed before the later-formed mountains were uplifted; but he 

 designated this composite theory as a "compromise" (219), as if it represented a partial and 

 unwilling concession of opinions by opposed partisans, whereas it really represented a well- 

 advised acceptance, by open-minded truth seekers, of the vital elements found in two contra- 

 dictory theories, and an ingenious reduction of the contradictions by the addition of an equally 

 vital element of a third theory. Indeed the third element — the wearing down of the earlier 

 before the upheaval of the later mountains — does not seem to have engaged the dissenter's 

 attention to any great degree, for without especially inquiring into the characteristics that 

 should be presented by fault-block mountains of a second generation, after the almost complete 

 obliteration of their folded and faulted predecessors, he adopted the view that the existing 

 mountains "as we see them, are the net result of compound erosion since Jurassic times, operating 

 on rocks upheaved by compound earth movements which have been probably also continuous 

 during the same period" (265). 



Furthermore, on passing from general considerations to details, the dissenter did not 

 analyze the specific consequences that must follow from the action of subaerial erosion on folded 

 structures; for he concluded that long-continued erosion, unaided by recent faulting, could leave 

 a whole anticline in one part of a range while consuming the greater share of it in another part 

 (238). Indeed, he appears not to have regarded the frequently occurring discordance between 

 the strike of the range structures and the trend of the range form — especially the trend of the 

 base line along the steeper side — as either important or significant, for he compared the basin 

 ranges with the ridges of the folded Appalachians, in which the accordance of rock strike and 

 ridge trend is always a leading characteristic. He even asserted that if "the Appalachians, 

 which likewise [i. e., like the basin ranges] consist of parallel ridges eroded along lines of folding, 

 should become arid . . . there would develop in course of time exactly what exists in the Basin 

 region ... a series of parallel, synclinal and anticlinal ridges" (255). This clearly overlooks 

 the repeated occurrence of more or less resistant strata which stand obliquely or even trans- 

 versely within the basin ranges, and which are truncated along the range margins; for such dis- 

 cordance between structure and form is unknown in the Appalachians, except where it is caused 

 by faults. 



Finally, in common with others who rejected Gilbert's theory, the dissenter failed to dis- 

 criminate sufficiently between scarps of different kinds and faults of different ages; for he argued 

 that as "many of the most pronounced scarps are along no fault lines" — that is, are due to 

 differences of structure — and "while many heavy faults have absolutely no direct effect on the 

 topography" — that is, are so old that their original inequality has been obliterated — therefore 

 the theory that the more abrupt sides of the basin ranges are fault scarps, more or less dissected 

 and battered during and since their production, must be untenable. In this connection he 

 stated that " actually ascertained heavy faults along the main fronts of the ranges are exceedingly 

 rare" (259); and he evidently meant by "actually ascertained faults," those that are demon- 

 strated by the occurrence of corresponding strata in discontinuous attitudes on the two sides of 

 an invisible fracture, this demonstration being of course based on the universally accepted 

 geological principle that the corresponding strata were continuous when originally formed. He 

 stated also that "the mountains fronts are, in general, not marked by great faults" (265), thus 

 rejecting or ignoring GUbert's demonstration of faults based on the universally acceptable but 

 more novel and therefore less widely accepted physiographic principle that if the strata of a 

 mountain front in a continental interior are truncated by the mountain base line, their absence 

 beyond the base line, not being explainable by erosion, must be explained by displacement. 



But it was by no means only because of the dissenter's manner of approach to the basin- 

 range problem that he rejected Gilbert's interpretation of it. An equally potent cause for 

 dissent lay in Gilbert's failure to set forth his original views and the reasons for them in sufficient 

 detail when they were first announced; and in his failure to make public announcement of 



