216 TOPOGRAPHICAL REPORT ON WESTERN DIVISION. 



of it have a light gravelly soil ; good grass grows upon it. The old Presbyterian mission was 

 situated at the lower end of this valley. The valley varies from one to two miles in width, and 

 is skirted by low ranges of hills well covered with pine. From the mission the trail runs over a 

 low hilly country, covered with open pine woods, to the Spokane river, leaving the Chemakane on 

 the right. The descent to and ascent from the Spokane river is abrupt and rocky. There is a 

 tolerably good diagonal ford at this point bottom gravelly and somewhat stony. This river is 

 about seventy-five feel wide and three deep, current rapid. A very precipitous, high, rocky bluff 

 is on the left bank, half a mile below the ford. All the country between the Slawntehus and 

 Chemakane, westward towards the Columbia river, is more or less mountainous or broken by 

 irregular ranges. These mountains are higher towards the north, and break up and fall off 



O O -* i 



towards the south into low ranges and undulating plains in the great Spokane plateau. The trail 

 bears to the southwest from the Spokane river across this plateau crossing the Saptin or Lewis 

 fork of the Columbia at the mouth of the Peluse. This distance is seventy-six miles. There 

 is no timber on this plain, except a few narrow strips of pine wood, which stretch out to the west 

 ward from the Cceur d Alene mountains on the east. These strips proceed to the westward no 

 farther than the trail, and are confined to the country twenty-two miles from the Spokane river. 

 A little willow and cotton-wood are also found on the immediate banks of the streams, but in 

 small patches. A district of country about twenty-four miles wide commences twelve miles 

 south of the Spokane river, and runs east and west nearly, which is the highest portion of the 

 Spokane plateau. This district is basaltic and broken, and is covered with innumerable small 

 lakes scattered over its surface. These lakes appear to occupy the craters of extinct volcanoes, 

 and are fissures formed by the bursting of lava bubbles on cooling. The water in them is fresh, 

 and supplies the Peluse and its branches. These lakes are of all sizes; Silkatkwu is the largest 

 in the vicinity of the trail. It is five miles long, and varies from one-half to a mile in width. It is 

 drained by the Stkahp, a branch of the Peluse. The main Peluse also rises in this region of 

 lakes, to the east of the trail. I have no actual observations of the extent of this lake country 

 to the east and west, but presume that to the westward, particularly, it must run for many miles; 

 at least, up to what is known as the &quot;Grande Coulee,&quot; and, perhaps, over to even the great 

 western bend of the Columbia itself. The Spokane plateau embraces all the country included 

 within the limits of the Cceur d Alene mountains, the Saptin, Columbia, and Spokane rivers. 

 It has an undulating stratum of basalt, which is covered with deposits of earth, sand, and 

 gravel. The basalt occasionally crops out, particularly on the lake region and along the streams; 

 and large irregular masses, pillars, and architectural shapes are scattered over this region. The 

 country in such places is rough and broken, and covered with large and small fragments of sharp 

 fractured lava. The earth, sand, and gravel form rounded undulating chains, or isolated 

 hills or buttes, covered with wild sage and grass, the grass being found on the least sandy 

 portions. The plateau generally is high and rolling, and destitute of timber. The soil 

 is light and unfit for cultivation. Small tracts of arable land are found near the larger 

 lakes and the heads of the streams, but they do not exceed one or two acres in extent. 

 The Cherahna runs in a basaltic dalle or trough for most of its length ; the last part of it, before 

 its junction with the Peluse, being in a canon of columnar basalt. The Peluse, from the point 

 at which we crossed it, runs in a similar deep canon. The walls of the trough of the Cherahna 

 are not more than twenty feet high. A few stunted willow bushes grow in these canons on the 

 immediate banks of the streams. The basaltic walls and hills along the Peluse increase in 

 altitude towards the Saptin. The Saptin, at the crossing, is about one hundred and fifty yards 

 wide, very deep, rough and rapid. This river, at this point, has no valley, high hills running on 

 either side of it. The Peluse is first crossed quarter of a mile below the mouth of the Cherahna? 

 and the trail then passes over the hills, leaving the river some distance on the right, and comes 

 down to it again three and a half miles from its mouth. Between the trail and the river, on 

 the right, the country is much broken and very rough, with a good deal of lava on the surface. 



