46 ROUTE NEAR THE FORTY-SEVENTH AND FORTY-NINTH PARALLELS. 
east of the mountains. <A portion of the excavation on the first part of the Spokane Plain 
will be rock (basaltic trap.) Its eastern end rests upon the pine, cedar, and larch districts of 
the Columbia. 
Lumber can be brought down the Columbia to its western end, and also from the Yakima, 
100 miles above its mouth. Good granite is found on the Columbia, 140 miles above the 
mouth of the Yakima. 
Within our territory, nearly the whole space between the Columbia river (its general course 
being from north to south) and Puget sound, is occupied by the Cascade mountains, with their 
secondary chains, spurs, and high, broken table-lands. Through these mountain masses, 
between the parallels of 45° 30’ and 49° north latitude, there are but two passes reported 
practicable for a railroad—that of the Columbia river, and that in which the north or main 
fork of the Yakima (a tributary of the Columbia) heads. This latter pass has been heretofore 
erroneously called Snoqualme Pass. The Yakima Pass gives the most direct route to Puget 
sound, the distance by it being 150 or 160 miles shorter than by the Columbia River Pass. 
The approach to it is by the valley of the Yakima. From the crossing of the Columbia to the 
commencement of the pine timber, 96 miles, the valley is wide, open, and terraced; the 
ground is sand, gravel, or loose stones. For 21 miles further, an open pine wood extends, 
with a light soil, sometimes gravelly. The grades are from 8 to 12} feet per mile. No diffi- 
culties of construction whatever are met with. From this point there are two methods of pass- 
ing the dividing ridge—one by a tunnel 4,000 yards long, 3,000 feet above the sea; the second 
by a tunnel of 11,840 yards, 2,400 feet above the sea. For the short tunnel the ascent of 895 
feet is made in 184 miles, giving a grade, supposing it to be uniform, of 48.4 feet per mile, 
in fifty per cent. rock-cutting. The tunnel 4,000 yards long will pass through solid rock, 
(silicious conglomerate ;) thence to the falls of the Snoqualme, 45 miles from the tunnel, the 
road will be in side-cutting, (silicious conglomerate) with a grade of 59.8 feet per mile, suppos- 
ing it to be uniform. The distance to the falls of Snoqualme was travelled over and estimated 
to be greater by Mr. Tinkham, and the grade proportionately less. From the Snoqualme 
falls to Seattle, on Puget sound, it is about 30 miles; the first ten will require a grade of not 
more than 20 feet per mile, and the remaining 20 miles will pass over a level country. If the 
second tunnel be used, the 184 miles before reaching it will be with a grade of 15.2 feet per 
mile, with little side-cutting, through a thickly timbered country. The divide must be pierced 
by a tunnel 11,840 yards long, of a similar character to the short tunnel; the grade to the 
Snoqualme falls will then be 46.3 feet per mile, and the total length of the section 240 miles. 
But the grades in both cases will be necessarily broken, and higher than the estimate in 
many places. 
The elevations of the different points from the Columbia, to a point about three miles west 
of the summit, were taken with a barometer; the distances were estimated. 
In conclusion, Captain McClellan states: ‘“‘I am of the opinion that the Yakima Pass is 
barely practicable, and that only at a high cost of time, labor, and money.’’ The depth of snow 
upon the summit of this pass has been much discussed. Captain McClellan, who made the 
reconnaissance, says, that he and his party spared no pains in inquiring of the Indians during 
the summer, fall, and winter, as to the quantity and nature of the snow in the mountains during 
the winter. We examined (he says) the snow-marks on the trees, (similar, he informs me, to 
those made by standing water on trees,) in the passes, &c. All the information obtained was 
consistent; and the resulting conclusion, that in ordinary winters there could not be less than 
from 20 to 25 feet of snow in the passes. 
For the purpose of examining this point, Mr. Tinkham crossed the mountains from Wallah- 
Wallah to Seattle, by the Yakima Pass, during the month of January, passing the summit 
on the 21st of January. ‘For about six miles on the summit the snow was found to be six 
feet deep, with an occasional depth of seven, as also of four feet.’? ‘‘The whole breadth of 
snow, over twelve inches deep, was somewhat less than sixty miles in extent. Of this, about 
