Reports of Explorations and Surveys to Ascertain the Most Practicable and Economical Route for a Railroad from the Mississipi River to the Pacific Ocean Volume 6 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1857 edition. Excerpt: ...greater local variation than the tem Note by Lieut. Abbol.----This subject is fully treated in Chapter I of the General Report. perature, being greatest toward the coast and northward, less on the southern than northern coast, and least in the interior. Geological structure.---The geology of that portion of California and Oregon under consideration has been given somewhat in detail in the accompanying geological report. It will, therefore, not be necessary to repeat what has already been said upon the subject. The general characteristics of the geology of this region may, however, be said to consist in the great prevalence of comparatively recent volcanic rocks, and of a soil derived from their decomposition, in all the mountain ranges. In the valleys, and on the flanks of the coast mountains, tertiary strata, generally of sandstones, constitute the sub-structure, and give character to the soil. As compared with the valley of the Mississippi, and the more northern of the eastern States, the Pacific coast is much more recent, the greater part of it having emerged from the ocean since the middle of the tertiary period. LOCAL BOTANY. COAST MOUNTAINS. Clz'mate.--The climate of the immediate shore of the Pacific is quite unlike that of the interior, a difference dependent upon its proximity to the evaporating surface of the ocean, the ocean currents, and the prevalent winds. It is much more uniform, cooler, and more moist. The uniformity of temperature which it exhibits is due, unquestionably, to the equalizing influence of the nearly constant temperature of the wide expanse of open sea which lies adjacent to it, and over which the winds blow inland, almost without intermission, throughout the year. These winds, which are loaded with moisture, ...