June 17, 1910] 



SCIENCE 



923 



answer to this question is decidedly in the 

 affirmative, and I propose to illustrate at 

 once the need and the value of some sort 

 of systematic method by the rather in- 

 vidious device of giving an example of 

 unsystematic description, taken 'from the 

 first geographical journal on which my 

 hand happened to fall after the intention 

 to cite such an example was formed. The 

 following abstract, therefore, presents all 

 the statements concerning the structure 

 and form of a certain mountain range, in 

 the order in which they are presented in 

 the essay referred to ; but distances, direc- 

 tions and other details are changed so that 

 the source of the abstract can hardly be 

 identified, and a considerable ampunt of 

 general description that is aside from my 

 purpose is omitted. 



The mountain mass, entirely isolated and having 

 a very remarkable geological oonstitution, is a 

 high range, which rises abruptly at its northern 

 end in the form of a great escarpment, surmount- 

 ing the plain by some 3,000 or 4,000 feet; the 

 range continues in an almost direct course to the ' 

 south for about 40 miles. The summit is of very 

 diflScult access, the rocky wall being nearly ver- 

 tical and mostly bare for the uppermost 1,500 

 feet. There is said to be no deep pass through 

 the range. At an elevation of 2,000 or 3,000 feet 

 there are grassy benches. On all sides the crests 

 are very steep, with altitudes of from 4,500 to 

 6,000 feet; the culminating point rising to 6,300 

 feet. The crest is not continuous. Erosion has 

 dissected the top of the mountain into a multitude 

 of knobs and small plateaus. The entire range is 

 formed of sandstones, inclined in general at an 

 angle of 45°, and trending like the range from 

 north to south. The sandstones rest on granite, 

 which reaches an altitude of 1,900 feet at the 

 village of Blank; while near River So-and-so the 

 sandstones are seen at an altitude of 1,200 feet. 

 On certain lower terraces, horizontal sandstones 

 are deposited. The range has the appearance of 

 constituting the eastern limb of an anticline, but 

 it is difficult to explain in what way erosion has 

 removed the sandstones of the western limb from 

 the plain, since tliey form a heavy body in the 

 range. Deep V-shaped valleys, parallel to one 

 another, veritable torrent beds, are seen in large 



number on the eastern flank. After reaching the 

 foot of the range, at an altitude of 1,000 feet, the 

 torrents become quiet streams. 



Part of this description is rather baf- 

 fling. For example, what is the general 

 form of the top of the mountain, in which 

 erosion has produced a multitude of knobs 

 and small plateaus 1 On reaching this 

 statement, after having previously read 

 that the summit is of difficult access, the 

 upper rocky walls being nearly vertical 

 and the crest very steep on all sides, one 

 might make the provisional inference that 

 the mass was of horizontal structure, like 

 a lava-capped mesa; but this inference is 

 not consistent with the earlier statement 

 regarding the well-defined north-south 

 trend of the range, and it is explicitly con- 

 tradicted by reading, a little farther on, 

 that the mountain is formed of inclined 

 sandstones. One must feel rather vexed 

 not to be told at once in which direction 

 the sandstones dip ; for until such informa- 

 tion is given, the reader has to keep two 

 pictures floating in his mind; one of an 

 ea.st-dipping monoclinal range, the other 

 of a west-dipping monoclinal range. But 

 he may throw away the second picture 

 after reading a little farther and coming 

 to the comparison of the range with the 

 eastern limb of an anticline, of which the 

 western limb is lost. This is the only indi- 

 cation given by the observer that the dip 

 of the sandstones is to the east. The ab- 

 sence of the western limb of the postulated 

 anticline tempts the reader to suppose that 

 the range, instead of being part of an anti- 

 cline, is really an east-tilted and dissected 

 fault-block; even though the observer, 

 after he has himself discredited the 

 suggestion of anticlinal structure, says 

 nothing about this manifest possibility. 

 Theoretical discussion is therefore as frag- 

 mentary as the record of observation. In 

 fine, the more carefully one reads the 



