18 NORTH AMERICAN FAUNA [No. 55 



chutes and John Day Valleys, with an enormous extent of rich 

 land, is being rapidly brought under irrigation. The Snake River 

 Valley, including in Oregon the Malheur and Owyhee River drain- 

 age valleys, still largely undeveloped, has a great agricultural future. 

 The northern part of Malheur Lake Valley, including the inland 

 drainage of the Silvies River and Silver Creek, with rich soil and 

 good water has grown into a prosperous agricultural section. In 

 many other valleys small streams and large springs provide water 

 for ranch purposes and livestock centers, while others are used largely 

 by game. These conditions obtain in the valleys of Warner, Goose, 

 Abert, and Summer Lakes, with their limited water supply, and in 

 many smaller isolated valleys over eastern Oregon. 



The Klamath Valley section with ample water for its rich-soiled 

 valleys is just awakening from the lethargy of the old days of 

 scattered grazing to its possibilities in terms of industries and inten- 

 sive agriculture. 



Practically all of these valley and basin areas of eastern Oregon 

 lie within the limits of Upper Sonoran Zone, with mild climate and 

 open winters. There is, however, one great disadvantage that cannot 

 be ignored without serious danger of losses and failure. The exces- 

 sively dry climate of this part of the State during the summer causes 

 occasional frosts at intervals during the growing season, and the 

 irregular frosty nights often destroy flowers, young fruit, or the 

 leaves of tender crops that would otherwise prove profitable. The 

 climate is mild, the growing season is long, and the summer days are 

 hot, but superdried air loses its heat so quickly that a sharp frost at 

 night may follow a hot day in summer. As is well known, it is the 

 moisture in the air that retains and equalizes the heat from the sun's 

 rays, for excessively dry air has little power of retaining heat. 



This frost danger has greatly restricted the agricultural value of 

 much of the arid interior of the country, especially that lying at eleva- 

 tions above 4,000 feet, and while many hardy and frost-resistant 

 crops and vegetables can be raised with partial success, the section is 

 generally devoted to stock raising, or has been until much of it, over- 

 stocked and overgrazed, no longer produces a food supply to make 

 this industry profitable. 



Originally this arid interior when fully stocked with native game 

 and teeming with wildlife was the hunting ground of numerous bands 

 of Indians, who made little impression upon the game until horses 

 and firearms were introduced among them. 



Now the game is scarce and scattered and some of the original 

 species are gone past recall, but great areas in eastern Oregon are 

 still better adapted to game production than any other industry and 

 could with practical advantage be utilized for such purposes. 



Owing to their low altitude and greater moisture, the immediate 

 valleys of the Columbia and Snake Rivers are comparatively free 

 from the danger of serious frosts. The higher and drier basins, even 

 with the same fauna and flora, must be carefully watched and studied. 



In the Rogue and Umpqua River Valleys west of the Cascades, 

 where the proximity to the Pacific Ocean affords a greater moisture 

 content to the summer atmosphere, the danger from frost is not notice- 

 able. Here fruits and tender crops of the Sonoran Zone are produced 

 in their perfection. 



