CHARACTERISTICS OF THE MOUNTAIN AREA. 289 
riant that there is no doubt about the ease, but over most of the interior 
of this area the sage, though of enormous size, is not, probably, suffi- 
ciently abundant to sustain combustion without constant attendance. 
The Snake River, on emerging from its long canon, comes out on the 
eastern border of the Snake River Plains. Its course changes from 
west to south, and it flows thus across this basalt plain, keeping near its 
eastern margin. Near the southeastern corner of the plain the river 
turns west, and on that course skirts the southern border of this desert 
waste. 
Shortly after leaving the mountains, the Snake receives a large branch 
from the north, known as Henry's Fork. This stream flows south along 
the eastern margin of the lava-field. Through most of its course its 
valley is heavily timbered. At its head, however, which is in a small 
lake in a loop of the main watershed is a small valley containing a few 
square miles of burnable laud. 
On Cascade Creek, a large left-hand branch of Henry's Fork, is a 
small valley, containing 20 to 30 square miles. It is open, very marshy, 
and grassy. Farther south, extending from the base of the Teton Range 
westward nearly to Henry's Fork, is a fine large valley, watered by 
Pierre's River, and known as Pierre's Hole or the Teton Basin. This 
valley has an area of open country of about 150 square miles, well 
grassed, but, of course, containing a due proportion of sage. Quite a 
large area in the middle of the valley is swampy. 
With these exceptions, the country lying between Henry's Fork on 
the west and the Madison and the Snake Rivers on the east is very 
heavily timbered, with few openings of any magnitude whatever. In 
its northern part, it consists of a high basaltic plateau, cut by numerous 
canons, while towards the south the lofty and rugged range of theTe- 
tons separates the drainage system. 
Below Henry's Fork the Snake receives no tributaries from the north 
for hundreds of miles — indeed, until it has passed the Shake River Plains. 
Then it is joined by the Malade, the Bois<§, and Payette, which head in 
the Salmon River Mountains. Of this group of mountains little is known, 
as it has never been traversed by explorers, and it is but recently that 
mining discoveries have drawn settlement in that direction. These 
mountains seem to cousist of a succession of ranges, trending parallel 
to the Rocky Mountains, i. e., a few degrees west of north. The gen- 
eral fact that they are well clothed with timber, and that the forests de- 
scend well down into the_valleys between the ranges, and into the broken 
country west of them is well known. Of the details of the distribution 
of forests and grass land it is at present unsafe to speak. 
The southern section of the Rocky Mountain region is comprised in 
Southern Wyoming, Colorado, and New Mexico. It is characterized by 
the greatest elevation of the continental plateau, which rises as we pass 
southward from Southern Wyoming into Colorado, and near the center 
of the latter State attains a mean elevation of about 10,000 feet, and 
19 L 
