248 GROVE KARL GILBERT— DAVIS 



Basin for their area of overflow. The worn-down pore-faulting surfaces m these ranges may, 

 like cans of baking powder taken from the open market for analysis, be regarded as sample 

 areas preserved for inspection by chance — the chance of their having received a lava cover — • 

 from among many other worn-down Great Basin areas ; and therefore the rock mass of the other 

 ranges, even though they, having no basalt covers, are to-day so much dissected as not clearly 

 to reveal their worn-down surface, have presumably experienced the same long period of down 

 wearing by subaerial erosion after their ancient period of folding, and the same kind of later 

 deformation by faulting as those in the Humboldt region. But as this argument from analogy 

 even though supported by later studies of certain ranges that are not lava covered, may not 

 appeal to all readers, it is still desirable, as was suggested in an earlier chapter, to examine the 

 Mimbres and other ranges in southwestern New Mexico and southeastern Arizona, which 

 Gilbert described in his Wheeler report as consisting of deformed Paleozoic rocks buried under 

 lava sheets, in order to learn how far they confirm the evidence of the Humboldt Ranges. 



The presentation of Louderback's paper at the St. Louis meeting called forth little discus- 

 sion, because its arguments were conclusive. However, Emmons, who had long previously 

 been associated with King on the Fortieth Parallel survey and who happened to be present, 

 remarked that the conclusions reached seemed to him to support King's views as to the origin 

 of the basin ranges by post-Jurassic deformation, because the post-Jurassic deformation was 

 so clearly proved; but this was objected to by another member, who pointed out that the basin 

 ranges are existing topographic features which Louderback had shown to be of very modern 

 origin by upfaulting, while the mountains which King had inferred to result from post-Jurassic 

 folding were of so ancient origin that they had been obliterated by erosion before the existing 

 ranges were upheaved. When the objector afterwards asked Gilbert why he had not corrected 

 Emmons's misconception, he replied with a laugh: "I didn't want to be too hard on him." 

 It was as if he felt satisfied to leave the correction to the gradual processes of time. 



