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.
covered the ground for some hundred yards beyond it, and pumice was occasionally found along
the route. This is supposed to be the most recent lava ejected from St. Helens.
Leaving the Cathlapoot'l, we commenced the ascent of the Cascade range. The eastern side
of the valley rises in high tables, with level tops and steep banks, which are continued to the
summit. Unfortunately, we could obtain no view of the country, the smoke from the burning
timber, which had prevailed for some days, effectually obscuring the atmosphere. The rock in
place was a gray feldspathic trap, covered on the surface with a whitish coating. Large, loose
blocks of the same and of trachyte were scattered around. Basalt prevails upon the summit,
and forms turrets and pinnacles on some of the heights around St. Helens and Mount Adams.
Elsewhere the hills are covered with reddish scoria. One field of lava was passed, fractured in
the same manner as that on the Cathlapoot'l, but apparently of older date, and assuming columnar
forms, which was not the case with the latter.
The height of Chequoss where the party encamped from the 8th to the o10th of August was
4,053 feet. It is a circular basin, containing a small pond, one of a number lying at the head of
the White Salmon river, and presenting the appearance of an ancient crater. Notwithstanding
its elevation, this spot is tolerably.fertile; the basin, as well as the hills around it, being covered
with grass and producing strawberries in profusion, which were in season at the time of our visit.
The soil of the mountains is a yellowish loam, except where colored by the decomposition of
scoria. The character of the forest changes entirely with the summit of the Cascades. The
details of this change belong to another report, but it is proper to refer to it in connexion with the
geological face of the country. The arbor vitae does not cross the dividinlg ridge; the firs and
spruces are speedily lost, and succeeded at first by intermixed larches and pines, and lower
down by the pine alone. The larch seems to be confined altogether to the eastern side of the
mountains, and the long-leaved pines nearly so. The limit of the firs on the eastern slope would
seem to be not far from three thousand feet above the Columbia. The forest retains a considerable size to nearly four thousand feet.
During our stay at Chequoss the weather was only at intervals clear enough to afford a view
of the mountains; with the exception of the great snow-peaks, their aspect is that of a chaos of
hills, of very equal height, rising from an elevated plateau, but few points rising to a greater elevation than 5,000 feet, which is about that of the snow-line on Mount Adams. No ranges of any
great length were distinguishable; the sides of the hills were long, sweeping slopes, enclosing shallow valleys which exteniid to the very feet of Mounts St. Helens and Adams, and some of which
contain marshy prairies, the beds of ponds. The range in.this part appears to be about thirty
miles in width at the base and fifteen on the top, the steepest slope being to the west. From the
hills around Chequoss, the five snow-peaks-Mounts Hood, Jefferson, St. Helens, Adams, and
Rainier-were visible, Mounts Hood and Jefferson bearing southwesterly; Mount St. Helens
nearly northwest; Mount Rainier a little west of north, and Mount Adams north. The latter was
not more than fifteen or twenty miles distant. The height of Mount Rainier, as given by Captain Wilkes, is 12,330 feet, and that of St. Helens 9,550; from which last Mount Adams does
not apparently vary much. It is not a little singular that neither Lewis and Clark, nor Lieut.
Wilkes, distinguished Mount Adams as a separate peak from St. Helens; for, although they
resemble each other considerably ins general form, their positions andl range are very different..
Mount Adams alone is visible from the Dalles; but both of them, as well as Rainier, can be
seen from a slight elevation at the mouth of the Willamette. The sketches of Lieut. Duncan,
accompanying the reports, will better convey an idea of these mountains than a mere verbal
description. The angle of incidence of their sides was taken by a clinometer. The steepest
continuous face of St. Helens, disregarding precipices, was about 40~, and none of the others
exhibit a greater declivity. The crater of Mount Hood is on its south side; that of Mount St.
Helens on the noithwest, and of Mount Adams apparently on the east; that of Rainier seems to
have been at the summit. Smoke was distinctly seen issuing from St. Helens during our journey.
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