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 4Sth 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 loarn, 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. 



