Reports of explorations and surveys, to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean: Vol. 1, Pt. 2

GEOLOGY OF CENTRAL WASHINGTON TERRITORY.
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
Columnbia 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 stripae on the surface. On the tops of these mountains, however, there are quite
extensive levels of prairie and open woods, 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. Oln 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 towards 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. Hiow 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
Fraser's river exhibits a considerable number of lakes, mostly of elongated form, such as they
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