ROUTE NEAR THE FORTY-SEVENTH AND FORTY-NINTH PARALLELS. 45 
Lake Pend d’Oreille, and on the western side of the lake to its lower extremity. The river 
and lake are subject to freshets fifteen feet in height. 
The summit separating Clark’s fork and Spokane river is about 800 feet above the level at 
which these two rivers are crossed. The transit could be made, Lieutenant Donelson reports, 
with gradients not exceeding twenty-five feet per mile, though Governor Stevens says forty feet. 
The mountain region ends near the crossing of Spokane river. Mr. Lander, in continuation, 
after reporting upon the Bitter Root, says: ‘‘ From the junction of the Bitter Root with 
Clark’s fork to the crossing of Clark’s fork, below Lake Pend d’Oreille, the line assumes a 
more favorable character; and, although still severe, may be readily adjusted to reasonable 
rate of curvature and grade. The crossing of the summit section, between Lake Pend d’ Oreille 
and the valley of the Spokane, is very favorable, and can be made upon gradients of forty 
feet per mile. All great difficulties of location upon the route cease at the valley of the Spo- 
kane.’’ 
Regarding the subject of construction west of the Rocky mountain summit, the line passes, 
in nearly its whole extent, through forests which could furnish an abundance of pine and cedar 
of fine quality, and of fir and larch. The rafting of lumber cannot be carried on above Horse 
Plain, though it is probable that logs can be run in the freshets from the heads of the tribu- 
taries of Clark’s fork. Lieutenant Donelson saw no good stone for building over this space. 
A locality on the Blackfoot, not far from Hell-Gate, another at Big Rock, (on Clark’s fork,) 
and the mountains on the right of Clark’s fork, for some distance below Thompson’s prairie, 
would furnish stone in great abundance, which would answer for ordinary purposes. Mr. 
Tinkham states that not far from the Hudson Bay Company’s post, among the Flatheads, good 
limestone for building could be obtained. Good granite is found on the Columbia, 140 miles 
above the mouth of the Yakima. Dr. Evans, geologist, informs me that stone will be found 
throughout this section at distances sufficiently near to obviate excessive cost. Sand can be 
obtained from Clark’s fork, Pend d’Oreille lake, and elsewhere. The earth excavation and em- 
bankment throughout this section (from the east base of the Rocky mountains to the Spokane 
river) will be large in amount, and expensive. In all the mountain valleys the deep side-hill 
cuttings will frequently expose rock, and the bulk of the rock excavation in the entire railroad 
route will be in this section. 
It is evident that throughout this section, from the entrance of the Rocky Mountain Pass to 
the crossing of the Spokane, a distance of 365 miles, the difficulties of construction will be 
very great; and that even if the two extremities rested upon thickly inhabited districts, 
the cost would be excessive. 
Upon the passes of the Rocky mountains, Governor Stevens says: 
<<Tt is not doubted there are other passes in this portion of the Rocky mountain range, 
even better than those explored; they are indicated by the general depression of the mount- 
ain range, with the greater frequency of the streams stretching out to meet each other from 
the opposite slopes of the mountains ; and I consider it important that, in future operations, a 
whole season should be devoted to their thorough examination, and that instrumental sur- 
veys should be made of the pass found to be the most practicable.’’ 
The region between the Coeur d’Alene mountains and the Cascade range, a space of 200 
miles, is called the Great Plain of Columbia, or the Spokane Plain. It is a table-land, whose 
central and western portions are of trap formation, and are described on the map as sandy, 
rocky, and sterile. Its summit, some 800 feet above the level of the crossing of the Spokane, 
could probably be attained with gradients of 35 feet, the descent to the crossing of the Colum- 
bia river (near the junction of the Snake river) with grades of 30 feet, and from thence to 
Wallah-Wallah, 10 miles further, with grades of 20 feet. From the crossing of the Spokane 
to the crossing of the Columbia it is about 140 miles, 110 of which are over the treeless plain 
of the Columbia. The river is here from 400 to 450 yards wide, with good approaches. The 
earth excavation and embankment will not probably exceed the heaviest work of the prairies 
