142 — NARRATIVE OF 1853. 
miles in width, and are bordered with terraces, which decrease in productiveness with their 
elevation above the water, becoming more gravelly, and, finally, like the intermediate ridges, 
almost destitute of vegetation. f 
The average width of the main stream is five or six miles, becoming, at ninety miles up, 
reduced to one or two miles, and the extent of cultivable land is proportionately greater than 
on its branches. 
The ridges between the different branches of the Yakima, and separating it from the Columbia 
north and south, are chiefly composed of basaltic rock, generally columnar, and more or 
less covered with gravelly and sandy detritus. On many parts of the highest ridges the basalt 
has been entirely denuded, leaving nothing but angular fragments of rock, and supporting no 
vegetation of any value. Wherever covered with earthy materials there is a good growth of 
grass, and probably the allied cereal grains might be produced, particularly the winter kind. 
Towards the base of the mountains the valleys, both of the main Yakima and of its branches, 
improve much in appearance and agricultural capacity. Yellow pine appears, and gradually 
increases in amount on the banks of the streams, and about ninety miles from its mouth begins 
to appear on the mountain slopes, marking with rather a sudden and sharp line the border of 
the unwooded plains. 
Going southward from the Yakima to the Dalles in September, Lieutenant Mowry followed a 
trail leading through the outskirts of the pine forest and over the ridge south of the Yakima, 
where it is about fifteen hundred feet high. He met with three extensive and rich prairies, 
and several smaller ones, and many parts of the ridges were covered with good bunch grass. 
The poorest part of the whole is the descent of the high slope to the Columbia, opposite the 
Dalles, which is forty miles directly south of the most southerly branch of the Yakima. 
On September 20th the march towards the north was resumed, and though the hills north of 
the Yakima valley had not appeared very high from a distance, the trail led over a portion of 
them higher even than the passes of the Cascade range. Here the mountains towards the 
north and west were to be seen for a great distance, nothing, apparently, but mountain piled 
upon mountain, rugged and impassable, and a large portion of their summits covered with 
perpetual snow. à; 
Descending from this to the Columbia river, the mouth of the Pisquouse, the route led along 
its rugged western bank for four days, when, reaching Fort Okinakane, an old and ruinous estab- 
lishment of the Hudson Bay Company, (see sketch,) where Mr. Lafleur, the person in charge, 
informed him of a foot-trail leading from the headwaters of Methow river to Puget Sound. 
From September 28 to October 4 was spent in exploring this route, the whole party going as 
far up the river as practicable with animals, and Captain McClellan making a further survey - 
foot, until the roughness of the trail and the barometer assured him of its unfitness for a rail- 
road. The following is the description of the country traversed between the Yakima and Fort 
Okinakane: the range separating the Yakima from the Pisquouse, or Wenatshapam, rises to 
5,149 feet above the sea, and along its summit the mountain forests extend further to the east 
than they do southward, ending a few miles east of where the trail crossed it. 
The greater amount of vegetable matter, and the increased moisture of these elevated tracts, 
are causes of a superior soil in this forest. 
From the summit of this ridge a view was obtained of the northwestern part of the Great 
Plain. It is thus described by Captain McClellan: ‘That portion of the Cascade ich 
which crosses the Columbia sinks into an elevated plateau, which extends as far as the limit of 
