122 LINE FROM BASE OF THE MOUNTAINS TO PUGET SOUND. 
valley. At several points on the route the rocky hill-sides crowd upon the river, and all deep 
cutting will probably expose the rock, apparently mostly species of limestone or trap; but the 
valley is wider than the valley of Blackfoot river, or of Bitter Root river soon after its junction 
with the latter stream, and has a general width of two or three miles. The descent of the vailey 
has an average rate of eleven feet per mile. 
The greatest gradients of the railroad would not exceed fifteen or twenty feet per mile. After 
passing from the valley of the Jocko to that of the Flathead, it would follow the hills on the left of 
that stream toa point some miles above its junction with the Bitter Root; then crossing the 
former, it would follow the right bank of Clark’s fork as far as Big Rock. The course then 
may either be on the right bank the whole distance to the lower extremity of Pend d’Oreille 
lake, or it may cross to the left bank at Big Rock, and recross to the right bank at the Cabinet 
mountain; or, continuing on the right bank to the Cabinet, some twenty miles above Lake 
Pend d’Oreille, where the river is compressed between walls of solid rock about one hundred feet 
high, and where the river could readily be spanned by a single arch, it could then cross the river 
and continue down on its left bank. Afier reaching the Pend d’Oreille lake it could readily skirt 
the eastern and southern shore, until it reached a southern prolongation of the lake, which 
extends about twenty-five miles in the direction of the Coeur d’Alene mission, and from that 
fact is called the Coeur d’Alene bay. From the upper end of this bay to the Coeur d’Alene 
lake there is said to be a very gentle rise, and a divide so low that it might readily be passed 
over by a traveller without notice. From the Coeur d’Alene lake to the valley of the Spokane 
there is a good natural, almost level grade. 
The Cabinet mountain might require tunnelling for three hundred yards, fifty per cent. rock, 
basalt trap; though, by a careful adjustment of the line of approach, tunnelling may be dispensed 
with without involving a grade greater than forty feet. Both Clark’s fork and the Pend 
d’Oreille lake are subject to freshets, fifteen feet being about the difference of level between high 
and low water marks, which would make it necessary that the road should keep the sides of 
the hill, or that high embankments should be used. 
The summit separating Clark’s fork and Spokane river, and the summit of the Great 
Spokane plain, are both about eight hundred feet above the level at which these two rivers are 
crossed. The opportunities afforded for side-hill location prevent the use of objectionable 
grades. 
The mountain region ends near the crossing of Spokane river. 
The earth excavation and embankment will, throughout this section, be large in amount, and 
expensive. The very best quality of material for a durable road-bed is met with all along the 
line. The hill-sides discover the disintegrated fragments of the different rocks, and the bottom 
lands of the rivers afford abundance of gravel for a road passing through them. With the general 
character of the excavation, and with the opportunities afforded for good ballasting, the road-bed 
of this section may be of a superior quality. 
In all the mountain valleys, the deep side-hill cuttings will frequently expose the rock, and the 
bulk of the rock excavation in the entire railroad route will be in this section. ‘The tunnel at the 
Rocky mountain divide will probably be through solid rock, and it is possible that one or two 
small tunnels may be required at other points. 
The approaches to the tunnel at the Rocky mountain divide can be made with a grade ot 
forty feet per mile, and an undulating grade of forty to fifiy feet will be required throughout 
Blackfoot River valley. The ascent from Blackfoot river to the summit divide, between the 
Bitter Root and Jocko. rivers, can be made with a fifty-feet grade, and with great care in the 
location the descent westward can be made with a sixty-feet grade. This declivity of sixty feet 
per mile is the highest required in all this section, and in a mountain country cannot be considered 
a high grade. On this inclination a train can descend with safety without the application of 
its brake, and without the use of its motive power ; so that while there is a loss of power in the 
