CHAPTER III. 



PHYSICAL FEATURES. 



The district is drained by the Green, Snake, and Bear Rivers and their 

 branches. The areas drained respectively by these three streams are 

 as follows : Green River, 5,223 square miles ; Bear River, 4,898 square 

 miles ; and the Snake, 2,879 square miles. 



The area is characterized by broad meridional valleys, separated by . 

 short, mainly simple mountain ranges. There is a very noticeable ab- 

 sence of timber; it is only on the slopes of the higher mountain ranges 

 that any is found, while not only the valleys but the hills and many of 

 the mountain ranges, especially in the western part, are treeless. The 

 Wyoming, Salt River, and Bear River Ranges comprise practically all 

 the timbered areas. There is abundant pasturage of the best quality, 

 not only in the valleys, but over the hills and the minor mountain 

 ranges. Except in the caseof the Green River Basin, where all the waters 

 cannot be used, the amount of arable land is measured by the quantity 

 of water available for irrigation. 



On Smoking Creek, a large western branch of Salt River, are exten- 

 sive deposits of salt, to which the river owes its names. 



DRAINAGE AREA OE GREEN RIVER. 



Green River, one of the forks of the Colorado of the West, rises in the 

 western slopes of the Wind River Mountains, near Union Pass, and pur- 

 sues a general southerly course to its junction with the Grand. It flows 

 from north to south, in general course, across the district under consid- 

 eration, in a broad valley known as the Green River Basin. Of that 

 portion of its drainage area with which we are here concerned, this basin 

 forms the larger part, though the tributaries of Green River extend some 

 distance into the mountains on either side. 



THE GREEN RIVER BASIN. 



Extending from latitude 43° southward to the TJinta Mountains, and 

 from the Wind River Range westward to the Wyoming Range, is a broad 

 valley, with a surface generally flat and unbroken, semi-desert in char- 

 acter, with a gravel or clay soil. Its length is about 140 miles,, its mean 

 breadth 75 miles, and its area about 10,000 square miles. 



On the northwest the Basin rises to a rim, beyond which the country 

 breaks off abruptly to a much lower level, forming the valley of Hoback's 

 River, a large branch of the Snake. North of this valley rises the mag- 

 nificent wall of the Gros Ventre Range, trending northwest and connect- 

 ing the Wind River and Wyoming Ranges. The Wind River Range, 

 trending north-northwest, limits the Basin on the east as far south as the 

 South Pass. Beyond this range to the southward the Basin has no well- 

 defined eastern limit, but merges gradually into the sterile plateaus which 

 form the Continental Divide. On the south, the transverse range of the 

 44 G s 689 



