484 
GEOLOGY OF CENTRAL WASHINGTON TERRITORY. 
granite, with white and flesh-colored feldspar. The bend of the Columbia at Fort Okinakane 
seems to be the northern limit of basalt to the east side of the river, as the Pisquouse is on the 
west. The prevailing rocks on the Okinakane as far up as its forks were syenite and gneiss; 
above that point, granite and gneiss, overlaid with coarse conglomerate containing granitic 
masses. The gneiss is much altered by contact with this, its stratification being obscure and 
often contorted. At the foot of the principal lake, porphyritic rocks replaced the gneiss. On the 
west branch of the Okinakane (the Mil-a-kite-kwu) the conglomerate formed the predominant 
rock. There was first noticed talcose slate in place, but much dislocated. Gold was found in 
both branches, in rather larger and sharper particles than below. The soil of the valley is sandy 
and in some places covered with alkaline efflorescence. We met with two or three small lakes, 
the waters of which were impregnated with the salt incrustations which had formed on their 
borders. 
The valley of the Okinakane presents a series of basins divided from one another by projecting 
points, which exhibit marks of disruption. The sides are terraced as on the other streams, 
some of the tables rising to the height of 1,600 feet above Vancouver, or about 900 above the 
river. The lower of the existing lakes were once all evidently connected with the Upper or 
Great lake, and have been separated by the alluvial deposits filling up the intermediate tracts, 
which now form reedy marshes. They all appeared to be shallow, except in channels in the 
centre. In returning to the forks, on the eastern side of the river, we passed through one of the 
coulees, terminated at either end by terraces, in which were several small lakes at the foot of 
the precipitous bluffs, in situations which suggested that their beds had been scooped out by 
eddies in the ancient stream. 
The width of the Cascade chain at the latitude of the forks of the Okinakane is probably seventy- 
five miles, and a large basin would seem to be enclosed between the ranges respectively bordering 
that river and Puget sound. The western range is broken and craggy, rising in points to the 
snow-line. Mount Baker was not visible from even the highest points that we passed over. 
Ascending the divide between the Okinakane and the waters of the small river emptying into 
the Columbia at Fort Colville, the terraces were found surrounding an upper basin at the summit. 
The height of this by an aneroid barometer was 2,647 feet over Fort Vancouver, and 1,500 feet 
above the lake. This divide was rolling, covered with bunch-grass and wooded with pine and 
larch, with a few cedars and firs intermixed. Birch and poplars were noticed in the valley. 
The paper birch does not appear to grow south of the 48th parallel. 
Here again the conglomerate overlaid syenite and gneiss; and following the stream, serpentine, 
granite, greenstone, gneiss, porphyritic serpentine, quartz rock, crystallized carbonate of' lime in 
large veins, and talcose slate, were found. Approaching the Columbia, gneiss and stratified 
quartz prevail. This last forms the canon at the mouth of tne stream, and a vein traversing the 
bed of the Columbia a little below it causes the cascade known as the Kettle falls. The soil in 
this valley is a light sandy loam, much better than that on the Okinakane. 
From Fort Colville the trail towards the Spokane river rose by another high terrace to a valley, 
through which a small stream flows into the Columbia at the falls. This valley is flat and 
marshy, and evidently has formed another lake or arm. The soil is clayey, and generally of 
good quality, with a subsoil of gravel and round stone. A small colony of Hudson’s Bay Com¬ 
pany’s servants whose terms have expired have here commenced farming. They state that 
the small grains and roots thrive well. The company formerly raised in this neighborhood suffi¬ 
cient wheat to supply all their northern posts with flour; but the climate is cold, and the winters 
set in early. On the 23d October the thermometer stood, at the camp of the expedition, 10° at 
sunrise, and on the 24th snow fell to the depth of six or eight inches. 
Quartzose rock, gneiss, granite, and talcose slate occur in the hills bordering the valley. A low 
divide separates it from the Chemakane, which runs into the Spokane. Approaching the latter 
river, basaltic dykes show themselves occasionally, the debris of which forms small pyramids. 
