LINE FROM BASE OF THE MOUNTAINS TO PUGET SOUND. 123 
ascent, there is a gain in the descent. The natural descent of the valley of Clark’s fork, as 
already stated, is about eleven feet per mile. In general the road need not much exceed this, 
as in all mountain valleys an undulating grade will be necessary. The passage from the valley 
of Clark’s fork to the Spokane river, and in like manner from the Spokane river to the summit 
of the Spokane plain, is made with a forty-feet grade. 
The bridge and culvert work will be very extensive, and greater in this section than in any 
other. With the possible necessity of crossing Blackfoot river several times, it includes the 
bridging of the many small mountain tributaries which make into that river, the crossing of 
the principal fork of Jocko river, all of them of small volume, but rapid and liable to freshets, and 
some of them to be crossed higher above their water-level ; twv, and perhaps four crossings 
of Clark’s fork, with a width of from one hundred to two hundred yards; the crossing of Pack 
river, a small stream, making into Pend d’Oreille lake, which will probably be with a long 
causeway, leaving sufficient water-way for the passage of the river, and the crossing of Spokane 
river. The latter river, where crossed by the train, has a width of one hundred and seventy yards. 
The bridge crossing will not be so long. 
The woods with which this region is covered are a species of yellow pine, of excellent quality 
for lumber; larch of large size; white cedar of large size; spruces and firs, with a mingling 
of the bitter cotton-wood in the river bottoms; scattering white birches, and other and smaller 
trees. For fuel and construction wood is abundant, convenient, and of good quality. I believe 
that the only coal observed was a single isolated specimen found by Mr. Tinkham, in the bed of a 
tributary of Clark’s fork, and out of place. 
Of building-stone the mountain regions contain vast quantities, which undoubtedly will be made 
accessible when the necessity for their use comes. Perhaps the most convenient and valuable 
which will be found, are a hard stratified limestone and granite. The first was noticed in the 
mountains northeast of Flathead lake, but it is probably to be obtained elsewhere, and more con- 
veniently ; and the second was observed at the head of Bitter Root river. While the most of the 
stones exposed in the progress of the excavations may prove unsuitable for building purposes, 
there is every probability that some of them will be found available for such uses. Good granite 
is also found on the Columbia. 
The limestone referred to is apparently a carbonate, and suitable for the manufacture of lime. 
Clear sand is frequently met with on the line. It was observed, in abundance, in the valley 
of Clark’s fork, and it is to be obtained from Pend d’Oreille lake, and elsewhere. 
Pure cool water is lavishly supplied by the mountain streams. 
The road-way, for nearly the whole of this section, will have to be cleared and grubbed. 
With the attainment of the summit of the Spokane plain, or, as I have termed it, the Great 
Plain of the Columbia, the timbered and wooded country ceases until the line enters the firs of 
the lower Columbia, two hundred and sixty-five miles farther on. For a while the pine region 
skirts the route on the east, but in a half day’s journey from the summit disappears from view 
altogether. 
The Great Plain of the Columbia, which for about one hundred miles the railroad traverses 
before striking the Columbia river, resembles a rough, rocky prairie. Descending towards the 
Columbia, and entering its valley above the mouth of Snake river, the Columbia has a width 
of from four hundred to four hundred and fifty yards; the banks are low, and the approaches per- 
fectly good. Near this point must deflect any route which, seeking a more direct passage to the 
sound than is afforded by the Columbia river, shall cross the Cascade range by one of the 
passes at the head of Yakima river. 
On the Columbia the line is for most of the way located on the bottom lands of the river, and 
will rarely be forced from them to the rocky bluffs bordering its intervale. To the Dalles the 
bottom lands of the river have a width of from one-quarter to three miles. Bluffs, with a nearly 
uniform height of one hundred and fifty feet, limit the bottom lands, and are the slopes abruptly 
