Febeuakt 7, 1908] 



SCIENCE 



219 



in the topography of the region, do not find a 

 place in this description. The account of the 

 Great Plains (pp. 212-215) leads the student 

 to believe that the surface is a gently undu- 

 lating peneplain surface with a little gravel 

 strewn over it near the base of the Eocky 

 Mountains ; and that the eastern slope of the 

 Rocky Mountains west of Colorado Springs is 

 formed by the up-folded layers which underlie 

 the plains. (" The steep slope of the eastern 

 face of the mountains marks the point where 

 the strata, which underneath the plains are 

 nearly flat, have been sharply folded " — p. 

 214.) 



The reviewer's experience as a teacher leads 

 him to conclude that students profit more from 

 a statement of both sides of a question con- 

 cerning the answer to which some doubt might 

 reasonably be entertained, than from a definite 

 settlement of the question according to the 

 author's best opinion. Some teachers would 

 prefer to omit the consideration of such ques- 

 tions altogether. Teachers having either con- 

 viction will doubt the wisdom of such state- 

 ments as that on page 256, where it is con- 

 fidently asserted regarding a low mountain 

 fold in Washington, that " the movement un- 

 doubtedly stopped long ago, and will never 

 result in a greater elevation." In a reference 

 to that problematic ring or crater known as 

 Ooon Butte, Arizona, we read : " This iron 

 [meteoric iron found about the crater] was 

 thought by those who found it to be fragments 

 of an enormous meteorite which had struck 

 the earth with such force as to bury itself 

 deeply where the crater stands. The iron, in- 

 deed, proved to have belonged to a meteorite 

 that by mere chance had fallen by the crater 

 and really had nothing to do with it " (p. 268). 

 The student would not realize, from this state- 

 ment, that the meteoric origin of the crater 

 is still maintained by competent geologists. 



The author's discussion of glacial erosion 

 includes the following statements : " It is even 

 thought by some that the rounded canyons in 

 glaciated areas, including the fiord canyons of 

 Norway and Alaska, are in their essential 

 features the work of glaciers; but there is 

 much more reason in the view that they were 

 maade by running water, and that their flooded 



mouths have resulted from a subsidence of the 

 land." " As a usual thing, the trunk stream 

 in a given basin will deepen its channel more 

 rapidly than its tributaries, so that the latter 

 will for a long time enter the main canyon or 

 valley by a rapid or waterfall. It is also true 

 that a large glacier will erode its bed more 

 than a small one, and this fact has given rise 

 to the view held by some geographers that 

 hanging valleys in glaciated regions are the 

 result of differential action of ice streams of 

 unequal size. From the fact that similar val- 

 leys exist in non-glaciated regions, however, it 

 seems more reasonable to believe that the 

 main features of hanging valleys result from 

 stream erosion previous to glaciation " (pp. 

 314-316). It is to be feared that the student 

 will here be misled as to the real reason why 

 some geographers believe hanging valleys and 

 fiords in glaciated regions are due to glacia- 

 tion; also that he will not appreciate the very 

 limited occurrence of hanging valleys in non- 

 glaciated regions, or the special conditions 

 under which they occur in such regions. He 

 will later have to learn that, except in certain 

 young valleys, tributaries as a usual thing 

 enter the main stream at accordant levels, as 

 announced by Playfair many years ago. It is 

 interesting to note that the example of a hang- 

 ing valley ascribed by the author to normal 

 stream action (p. 330), is that of Bridal Veil 

 Creek where it enters the Tosemite Valley; 

 an example taken from a glaciated region, and 

 believed by many to be due to glacial over- 

 deepening of the main valley. 



The antecedent origin of the course of the 

 Green Eiver through the Finta Mountains is 

 set forth without question (p. 362), notwith- 

 standing the doubt long entertained regarding 

 the correctness of that interpretation. The 

 popular misapplication of the term " tidal 

 wave " to a wave produced by an earthquake 

 shock is adopted on page 434, without any 

 explanation ; confusion is . made easy because 

 tides are treated in the same connection. The 

 relation of the two high tides is stated in the 

 following words : " It (the water) is heaped up 

 on the side nearest the moon, because there the 

 pull of the latter is strongest; while a cor- 

 responding rise in the water takes place upon 



