GEOLOGY OP CENTRAL WASHINGTON TERRITORY. 481 



Indians were in possession of one or two pieces of some size, which they said they had found in 

 the mountains, where there was more of it; but their statements are not to be relied on, and 

 it. was considered probable that they had brought them up from the settlements. They never 

 could produce others, or point out the locality of what they had. That gold will be found in 

 quantity, at least in this part of the range, is, however, questionable, as the-talcose rocks, if not 

 wanting, are very limited in extent. To the northward they are somewhat more abundant. 



The range already spoken of, which separates the Yakima from the Pisquouse and the 

 Columbia on the north and east, is little if at all inferior to the average height of the Cascades 

 themselves, the point at which the trail crossed them being 5,749 feet by barometrical measure 

 ment an elevation much greater than either pass of the Cascade mountains. It appears to be 

 formed entirely of basalt and volcanic conglomerate, the latter showing only on the northern 

 side of the Columbia. On the southern slope the basalt was but superficially covered with 

 earth, and the strata seemed to dip towards the southeast. The tops of the columns were much 

 broken up, the fragments strewing the hills, and, where denuded by the winter rains, exhibiting 

 long black strias on the surface. On the tops of these mountains, however, there are quite 

 extensive levels of prairie and open \voods, and the soil seems to be better than on the lower 

 ridges. The timber, at first yellow pine, changes towards the summit to a straggling mountain 

 species, intermixed with larch, spruce, and fir. Some of the larches were here as much as three 

 feet in diameter. 



The view from these mountains was magnificent. On reaching an open spot in our descent, 

 we saw the Columbia just beneath us flowing through a vast canon at its great bend ; to the east 

 stretched the central basaltic plateau, rising to wards the north into high and broken tables, beyond 

 which appeared the gap of the Okinakane ; while to the west and northwest the craggy sierra 

 of the Cascades reared itself above the lines of forest into the limits of perpetual snow. The 

 character of this range changes materially with its geological formation ; naked and precipitous 

 ridges, surmounted with sharp peaks, rising singly or in groups, some of which seem to be the 

 skeletons of mountains, distinguishing the granitic from the tamer features of the basaltic region. 

 The country on the Columbia from this point exhibits a corresponding change. On the left bank, 

 basalt continues to the Spokane river, being underlaid, according to Lieutenant Wilkes, by granite ; 

 and on the right bank it occurs interstratified with conglomerate at the foot of the mountain, but 

 ceases entirely a few miles above. How far down the river it continues we had no opportunity 

 of noticing, but presumed that it ceased at the Priest s rapids, as it is abrupt for some distance 

 above the mouth of the Yakima, where the banks, though high, consist of sand and boulders only. 



A little below the mouth of the Pisquouse the rock on the west bank changes to gneiss, which 

 near the river is broken up and scattered in enormous masses. Veins of quartz, covering each 

 other at different angles, intersect it, varying in thickness from a narrow line to several feet. It 

 is the prevailing rock on this bank as far as the mouth of the Enteatkwu, in one place resting 

 upon a gray porphyry. The strata were somewhat displaced, and occasionally had a slight dip 

 to the northward. The Pisquouse is a large and bold stream rising in the main divide of the 

 Cascades, and interlocking with one of those running into the Sound. It passes through a lake, 

 reported by the Indians to be larger than either of those on the Yakima. There appeared to be 

 no valley as far as could be seen, and but a small bottom at the mouth. Quartz boulders were 

 conspicuous in the stream. We noticed pipes brought by the Indians from higher up the river, 

 some of which were talcose slate, and others of stratite. Gold was found here also, but in finer 

 particles than that in the Columbia. Approaching the Enteatkwu, syenite replaces the gneiss. 

 Its precipitous bluffs were occasionally intersected with large dykes of reddish quartz, breaking 

 into angular fragments. The lacustrine terraces, which line the bluffs of the Columbia and its 

 tributaries from the Pisquouse northward, form one of the most remarkable features in the geology 

 of the country. A glance at the map of the region drained by the upper Columbia and by 

 Eraser s river exhibits a considerable number of lakes, mostly of elongated form, such as they 

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