gassbtt.] GREEN RIVER BASIN. 691 



nels, and. islands. Two or three miles below the mouth of Horse 

 Creek the river turns again to the south and its velocity increases. 

 Throughout its course, as far as it has fallen under my observation in 

 the Basin, an eastern or western course is accompanied by a marked de- 

 crease in velocity. It is bordered on the left-hand side, as far down as 

 the mouth of Slate Creek, by a high bench 200 to 300 feet above the 

 liver, the normal level of the interior of the Basin. In most places the 

 edge of this bench is bluff, sometimes precipitous, but in certain places 

 presents easy slopes to the river. Throughout the greater part of the 

 distance its edge is two or three miles back from the river, but in places 

 the river flows close under its bluff wall. 



As we go south from Horse Creek, the country becomes more undu- 

 lating and hilly, with buttes, bluffs, &c, the remains, as above, of higher 

 formations. It becomes, also, more forbidding in aspect. Patches of 

 snow-white alkali diversify the yellow surface ; the sage becomes more 

 stunted, and cacti are seen more frequently. Marsh and White Clay 

 Creeks flow through this country. The former stream carries about 100 

 cubic feet of water, which, near its mouth, is decidedly alkaline. It col- 

 lects its tributaries behind the rim of the Basin, through which it forces 

 its way. The latter stream heads in the basin-rim. It is a small stream, 

 flowing in a deep arroyo cut in the stiff clay which here forms the soil. 

 The water is thick and white with alkali, and utterly unfit to drink. 



At the mouth of the New Fork the Green turns nearly west, flowing 

 in this course for about seven miles, then turns abruptly to the south 

 again. At this bend it receives the contributions of White Clay, Bit- 

 teiToot, and Piney Creek. The last two are good-sized streams of clear, 

 sweet water, each delivering about 100 cubic feet per second in July. 

 They come from the Wyoming Range, and, like Marsh and Horse Creeks, 

 collect their waters in the meridional valley back of the basin-rim. The 

 country between and about them is much more uniform than farther 

 north, and there is a decided decrease in the amount of alkali, accom- 

 panied by a change for the better in the character of the vegetation. 



Below the mouth of Horse Creek, the Green is in a bottom-land from 

 one to two miles in width, but narrowed in some places by the advance 

 of the bluffs. This bottom is limited on the west by low bluffs, perhaps 

 50 feet in average height. Opposite the mouth of New Fork these bluffs 

 increase in height until they rival those on the east side of the river, but 

 almost immediately break away and disappear, and at the bend where 

 the Bitterroot and Piney enter there are no bluffs whatever. The bot- 

 tom-lands of the river contain no timber except cottonwood, which form 

 an almost continuous belt of fine, large trees. 



Following the river down, we find it preserving an almost southerly 

 course, with broad bottoms containing magnilicient groves of cotton- 

 wood and richly carpeted with grass. Between the Piney and the La 

 Barge, a distance of 25 J miles, the only water entering the river is a wet- 

 weather stream, known as Feather Creek. The country west of the 

 river has become more broken. Great masses of plateau, with clean, 

 sharp-cut edges appear, and back of them a long mountain ridge, trend- 

 ing south, and known as La Barge Mountain, becomes a prominent ob- 

 ject in the landscape. It stands a few miles east of the Basin-rim and 

 rises to an equal height with it. In its northern end heads Feather 

 Creek, while jjast its southern end La Barge Creek flows, collecting the 

 drainage of that part of the mountain. 



La Barge and Fontenelle Creeks are considerable streams, the former 

 carrying about 75, the latter about 50, cubic feet per second. They head 

 in the Absaroka Ridges, which form the southern continuation of the 



