BOTANY OF THE ROUTE. 19 



Dulles, 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 tho 

 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, 

 Avhere several spring flowers were still blooming. Even the perpendicular rocks supported a 

 green covering of mosses, &amp;lt;fcc., over which cascades, unbroken for a thousand feet, fell from 

 the mountains directly into the river. 



This change in the character of tho 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&quot; are noted for rain, which 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 well 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 western 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 &quot;tide-lands,&quot; 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 admirably with a little care, and even good crops of wheat have been raised on 



