256 GEOLOGY OF THE HIGH PLATEAUS. 



end, where a number of basalt streams appear to have burst out of the 

 western wall near the summit and poured down upon the talus and 

 slopes below. They are of small extent and mass, and are noteworthy- 

 only as an instance of the peculiar positions from which basalt sometimes 

 breaks out. 



A few miles to the south of the southern cape of the plateau is another 

 small field of basaltic eruption. It is located in the bottom of a rather 

 broad valley or basin. A large cinder-cone is still standing singularly 

 perfect in symmetry and perfect also in its preservation. The cup at the 

 summit is not broken down, but still preserves a continuous rim. From 

 this cone streams of basalt flow southward, and entering a canon in the 

 Jurassic sandstone reach the front of the White Cliffs nearly 12 miles from 

 their source. The individual streams have spread out very thin, and are 

 in some places very slender, with every indication of extreme fluidity at 

 the time of their passage. In the canon the basalt is nearly all swept 

 away by erosion, only a few small patches (in situ) being left to indicate 

 its former existence. But beyond the canon larger remnants are seen, and 

 these evidently formed the terminations of the coulees. It is impossible to 

 affirm anything as to the age of this basalt, though I have little doubt that 

 all the damage it has suffered from weathering and erosion might surely 

 have been accomplished in the period of a thousand years and perhaps in 

 a shorter time. On the other hand, it may be several thousand years since 

 the vent became silent. Four miles to the west of this cone stand half a 

 dozen others, perched high upon cliffs or mesas, and sending their streams 

 into the upper canon of Kanab Creek. These appear to be older and more 

 weather-beaten, though evidently belonging to the most recent geological 

 history of the country. 



