THE BOTANY OF THE EOUTE. 
15 
Dalles, on November 17, we found the mountains to rise very rapidly in height and become 
suddenly densely wooded; the trees observed being usually of the species prevailing on the 
western slopes of the range. 
This great mountain gap, unequalled in depth and extent by any on the continent, presents 
in some parts the perpendicular walls of the canon, in others the gradual slopes of a narrow 
valley. 
Even from the Dalles we could perceive a thick fog hanging in the gap, but -were quite 
unprepared to find a heavy rain, which we entered long before reaching the Cascades, and 
which continued unceasing during the whole day and night following, when we reached 
Vancouver. Even after entering this rain we could see the bright unclouded sky of the plains 
eastward, but I thought the moist and milder air more agreeable than the cold dry climate we 
had just left. The change in the appearance of the country in the distance of a few miles was 
almost as great as I have since observed between New York and the isthmus of Panama in 
January, as we left the ground at the Dalles covered with snow, and entered a region of 
perpetual spring, with gigantic evergreen forests, tropical looking shrubs, and large ferns, 
where several spring flowers were still blooming. Even the perpendicular rocks supported a 
green covering of mosses, &c., over which cascades, unbroken for a thousand feet, fell from 
the mountains directly into the river. 
This change in the character of the scenery, so strongly observable in passing from the 
central plains to the western region, prevails over the whole of the latter,' though less marked 
in portions of a drier climate. The " Cascades " are noted for rain, Avhich prevails there at all 
seasons, being caused by the precipitation among the surrounding cold mountain summits. This 
moisture assimilates the vegetation of the gap to that immediately on the coast, and the shores 
of the Columbia everywhere below show less of the regional peculiarities than are observed a 
little distance from them. 
These, though not sufficiently extensive and Avell marked to constitute regions, are yet 
divisions important enough for separate descriptions. As a whole, the region has a surface 
mountainous and hilly, interspersed with fine valleys lying between the level of the sea and an 
elevation of about 2,000 feet at the summits of the Coast range, and perhaps somewhat more on 
the w^estern slopes of the Cascade mountains. 
PRAIRIES OF THE WESTERN REGION. 
The first division which I shall describe is that of the prairies, which naturally follow after 
the central plains, of which they may be considered branches, closely similar in vegetation, 
and, to some extent, in animal products. They form, too, the division most important to the 
settler, who, in the western section, finds the absence of trees as desirable as is their presence in 
the open country of the interior. The prairies generally occupy the lowest lands only, and are 
divisible into several kinds, differing in soil, vegetation, elevation, and in the causes which 
produced them. To commence with the lowest, we find about the mouths of rivers running 
into the ocean extensive tracts of "tide-lands," resembling the salt meadows of the eastern 
coast, but much superior in soil and products. They are overflowed by the tide only at its 
highest periods about two or three times annually, and this may be easily and entirely pre- 
vented by embankments. At all other times they may be traversed without difficulty, and are 
so dry as to produce excellent vegetables of many kinds. Potatoes and almost all garden vege- 
tables succeed abmirably with a little care, and even good crops of wheat have been raised on 
