A GEOLOGICAL ROMANCE. 



227 



Fig. 5. — Eipple Marks in the Vol- 

 canic Dust. Reduced to 3^ diam- 

 eter. 



layers from above downward, for it is evident that as the direction 

 of the wind changed, the ripples were also turned. The deciphering 

 of this record must be made backward. The bottom layers were 

 deposited first, and the excavation must 

 begin on top. Otherwise the record is 

 as perfect as if it had been taken down 

 by an instrument when the shower oc- 

 curred. It may be only local in its sig- 

 nificance, for it shows the direction of 

 the wind at this particular place alone. 

 The wind may have been somewhat de- 

 flected from the general direction by 

 local topographic peculiarities, though 

 these appear to have been of small im- 

 portance. In any case, the old legend 

 is quite interesting to read, being, I be- 

 lieve, the only geological record ever found of the passing of a 

 cyclone over the United States. 



In the lowermost foot of the deposit no ripple marks can be seen. 

 But there appear some marks of sedges and other vegetation, and 

 these are inclined to the west, as if the plants had been bent by an 

 east wind. Just above the height to which the imprints of the vegeta- 

 tion extend, ripple marks begin to appear, running on a northeast- 

 southwest course. They were made by a southeast wind, for their 

 northwest slopes are the steeper. A little above this height some 

 peculiar small elevations appear on one of the bedding planes, and 

 slightly raised ridges run for a short distance to the northeast from 



9m/ 



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WE. 



LIBRAR 



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Fig. 6. — Peculiar Elevations caused by a Current from the Southwest to the 

 Northeast. Reduced to }4 diameter. 



each elevation, vanishing in the same direction (Fig. 6). A south- 

 westerly current was unmistakably obstructed by the little elevations, 

 and left the small trails of dust in their lee. Six inches higher up 

 the wind comes more from the south, and for the next foot the ripples 

 continue to gradually turn still more in the same direction so as to at 

 last record a due south wind. At this point it suddenly changed and 



