The Shoshone Island. 81 



its later stages, that of vast showers of vol- 

 canic ashes, alternating with the denser flows 

 of lava. An example of this form of volcanic 

 agency is given from a modern instance of its 

 results. If it lacks in magnitude it will make 

 up in clearness of detail. The one offered is 

 from notes of a journey across the Cascades 

 along the line of the Middle fork of the Wil- 

 lamette river. 



At eight or ten miles from the summit, 

 going eastward, the whole surface soil seems 

 changed by a covering of yellowish dust grow- 

 ing thicker as one approaches the summit. 

 On the eastern descent the depth of this sur- 

 face addition is greatly increased and its true 

 character is plainly seen to be volcanic ashes. 

 While carefully exploring for evidence of its 

 thickness at its deepest, I became satisfied 

 that it could hardly be less than twenty-five 

 or thirty feet. It was distributed evenly as 

 a fresh snow in still weather. Where it was 

 at its greatest depth the whole country was 

 covered with a growth of forest trees and 

 all of the trees were growing naturally from 



