286 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
northward from the railroad toward the upper waters of Ham's Fork, 
the face of the country improves, and grass predominates. This continues 
northward nearly to the head of Ham's Fork, where timber usurps the 
soil. 
Turning now to the headwaters of the Snake River, the southern fork 
of the Columbia, we find ourselves in a different region. It is in large 
pari mountainous, and with the exception <>t'a few open valleys, most of 
which are small, it is very heavily timbered. Indeed, this region about 
the heads of the Snake, the Yellowstone, and Madison Rivers, embraced 
almost entirely in the Yellowstone Park, is the most densely timbered 
region in the West, with the exception of Washington Territory and the 
western part of Oregon. 
The Snake heads in a country of high mountains north of the Green 
River Basin, including the southern part of the Yellowstone Park. Its 
most northern branch, Lewis's Fork, Lakes its rise in Shoshone Lake, 
whence it flows southward. In a few miles it is joined by a large stream 
from the east. Both these streams flow through a heavily timbered 
country, where the grassy openings are of a very limited extent. 
Below their junction the river keeps its southerly course, through a 
narrow wooded valley, as far as Jackson's Hole, at the east base of the 
Teton Range. On either side, the mountains are heavily wooded up to 
the timber line, which in this region is at about 10,000 feet above the 
sea. 
Jackson's Hole is a large open valley 35 miles long by 10 miles in 
width, its length being in a north and south direction. Near its head, 
on the west side of the river, its surface is made up of low irregular 
hills of moraine deposits, which are very sparsely timbered, and other- 
wise covered with sage and grass, the former being the dominaut growth. 
On the east side of the river the open valley is several miles in breadth, 
and extends far up two large branches known respectively as Buffalo 
Fork and Gros Ventre Creek, which here enter the Snake from the east. 
In this part, the surface of the valley is but slightly broken and is well 
grassed, with a due mixture of sage. 
Farther down the valley on the west side of the river, that is, below 
the foot of Jackson's Lake, the surface is largely made up of bench land, 
producing a similar mixture of vegetation, while the river which here 
flows near the eastern side of the valley has a bottom land fully two 
miles in width, which supports a dense growth of large willows and 
cottonwoods. This broad timbered bottom land accompanies the river 
to the foot of the valley, while the river itself gradually moves diag- 
onally across the valley to its western side, leaving a broad grassy area 
on the east, below the Gros Ventre Buttes. 
Nearly all of this valley is burnable, the exception being the broad, 
timbered bottom land along the Snake. The soil throughout is gravelly, 
being coarsest in the northern part on and near the moraiual deposits 
mentioned above. 
