September 23, 1921] 



SCIENCE 



267 



visible and the answer is tliat niuc]i depends 

 iipon the climatic conditions of any selected 

 section. Where rainfall is abundant, vegeta- 

 tion vigorous and erosion elBcient, there is not 

 much to be seen after fifteen years ; but under 

 arid conditions the marks of the disturbance 

 of 1857 survive plainly. 



The essential fact is that the Eift is a 

 line, and features peculiar to it must fall into 

 line. The general position and course of this 

 Rift being known, the observer was constantly 

 noting valleys, lakes and ponds, ravines, washes 

 or scars on the surface, which lined up with 

 one another. From over Mussel Rock, where 

 the Rift cuts the shore, the range along the 

 Rift was plainly that of the axis of 

 San Andreas and Crystal Springs Lakes, and 

 was continued in the valley through Searles 

 Lake and beyond to Black Mountain. Stevens 

 Creek heads in that summit on the Rift, and 

 flows for six miles along it. Thus for a dis- 

 tance of 33 miles the earthquake line is marked 

 by major features of the topography, by val- 

 leys which are due to the cooperation of dis- 

 placement and erosion. Similar valleys might 

 be produced by erosion alone, and since the 

 rocks are hidden by water, soil and vegetation, 

 the aerial observer could not see the dis- 

 placement. In this section the observer could 

 infer, but could not demonstrate the existence 

 of the Rift. 



Continuing southeastward beyond Wright's 

 Station on the Santa Cruz branch of the 

 Southern Pacific the Rift traverses the west- 

 ern slope of the Santa Cruz Mountains near 

 the summit, and determines the course of nu- 

 merous small valleys which are the head-val- 

 leys of streams that flow south to Monterey 

 Bay, but which contrary to what would be ex- 

 pected, range themselves into line parallel 

 with the crest of the mountains. Along this 

 same line there are numerous landslide scars 

 and small ponds. ISTo one or small group of 

 these features would necessarily indicate the 

 existence of the Rift, but their alignment over 

 a distance of 25 miles would be strong pre- 

 sumptive evidence of it, and that alignment 

 can be seen from the airplane. The only other 

 way in which it can be demonstrated is by a 



study of an accurate topographic map, which 

 is in itself, as it were, an airplane view. Thus 

 for any section of an earthquake track which 

 might be indicated by features similar to those" 

 occurring on the western slopes of the Santa 

 Cruz Mountains observation by airplane 

 would constitute a valuable method of in- 

 vestigation. 



Passing to the middle section of the earth- 

 quake Rift where the aridity of the climate 

 prevents the growth of vegetation, and limits 

 the destructive work of erosion, the marks of 

 the earthquake became more distinct and more 

 continuous. Thus my notes read : " Mustang 

 Ridge and Peach Tree Valley, Rift shows in 

 serpentine slides in the ridge. Temblor 

 Range, the line of the Rift shows like a light 

 soil streak for miles ahead. Over Carrizo 

 Plains at Wolforts, Rift shows up in a line 

 of white washes easily lined up," and a little 

 further along : " Rift shows plainly like a 

 canal ditch." 



The ditch-like character of the Rift along 

 the northeast slope of Carrizo Plain has been 

 noted by Fairbanks and others. It is remark- 

 able, plainly visible from an altitude of 12,000 

 feet, like a large empty irrigation canal. I 

 could see it perhaps 10 miles ahead till it was 

 lost in the rosy dust haze. 



At this point the aviator passed me a note : 

 " Forty minutes more gas." I scaled off the 

 distance to Bakersfield, the only landing place. 

 It was 35 minutes away and we turned from 

 the Rift. 



Returning from Los Angeles on the 11th 

 we flew along the southeastern section of the 

 Rift from Tejon Pass up Cuddy Valley to San 

 Emidio Peak. In this stretch it is marked 

 by springs which give rise to alkali patches 

 or to green mallins, the marshes peculiar to 

 seepages in arid valleys. Its features are 

 easily traceable because of their linear con- 

 tinuity. 



Photographing from an airplane is less 

 satisfactory than observing. When the camera 

 is fixed on the plane, as it must be to secure 

 continuity of views, there is the trouble of 

 swinging already referred to. I myself lost 

 the sense of horizontal or vertical and was 



