314 



University of California. 



[Vol. 2. 



Ash Beds. — At many localities, particularly in the northern 

 part of the John Day basin, an ash bed of comparatively recent 

 origin is seen in the flood plain deposits or on the alluvial slopes 

 near the streams. In the upper end of Haystack Valley a stratum 

 about i y z feet thick is exposed at several places in the river 

 bank. It is here covered by 6-10 feet of alluvium with angular 

 pebbles. On Rudio Creek there are fine exposures of an ash bed 

 along the bank of the stream. The bed is here much thicker than 

 at Haystack. Similar deposits were seen as far east as the writer 

 has explored. 



Though deposits somewhat similar to those described might 

 be formed by material washed down from fossil beds or other 

 deposits of volcanic materials, the origin of these beds can not be 

 ascribed to such a cause. Where they have been carefully 

 examined the ash is perfectly pure and is sharply separated from 

 the deposits above and below. It has apparently not been worked 

 over appreciably and was probably deposited rapidly, otherwise it 

 would be mingled with other detrital material. Its deposition is 

 evidently to be correlated with some catastrophic volcanic outburst 

 occurring in comparatively recent times. Possibly it has been de- 

 rived from the volcanoes of the Cascade Range. 



University of California, 



April, igoi. 



