Page:The Pacific Monthly volumes 1-3.djvu/27

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PHYSICAL CHARACTERISTICS OF THE NORTHWEST.
7

these great peaks 1,000 feet or more, and in most instances all traces of a crater have been obliterated. Crater lake occupies a crater of what was probably a great lava vent in the earlier outflow. It is 6,000 feet above the sea level, and, being nearly 2,000 feet in depth, is the deepest body of fresh water in North America. On all these great peaks of the Cascade and Sierra Nevada range, of which the most southern is Lassen's butte, in Plumas county, California, solfataras, or hot springs, abound, an evidence that the subterranean fires are not yet extinct. Mount Vesuvius was not known to be a volcano until the year 79 A. D., when it broke forth in the momentous eruption that buried the cities of Herculaneum and Pompeii under a deluge of ashes and mud, and for nearly 2,000 years since has been periodically active.

There are traditions that Lassen's butte, Mounts Hood and St. Helens have given evidence of being still alive, but no great outburst of lava has probably taken place for a long period. Lassen's butte shows more signs of activity than any volcanic cone in the Sierra Nevada range, boiling springs, fumerells, geysers and mud volcanoes on a small scale being constantly active and energetic on the south side of that peak. On the peninsula of Alaska, however, and on several of the Aleutian islands, the volcano of Illiamnoe, the Redobt volcano and others are still alive and active. The great capes along the coast are generally of basaltic lavas, the result of the ancient flow; the sea, that great leveler, having eaten away the softer Tertiary deposits, leaving the harder material projecting far into the ocean.

Cape Lookout, for instance, projects two miles from the beach into deep water. It is a great basaltic dike, perpendicular along the south face, 430 feet high at the point, and nearly 1,000 feet high where the coast trail passes over.

When the Cascade range was elevated large bodies of the ocean were enclosed between that range and the Rocky mountains. The transverse fissure, now occupied by the Columbia river, was afterwards formed and served to drain the salt water from a vast portion of the interior, the sea retreating to a few of the saline lakes in Southeastern Oregon. During the cretaceous period, animal and plant life was abundant in the Northwest, as is shown by the great number of fossil remains in the valleys of the Des Chutes, Crooked and John Day rivers; also in Grand Ronde valley and Hangman's creek. Huge animals of the mastodon family wandered through the forests of the infant world, and along the grassy shores of the ancient lake grazed the gentle oreodon, unmolested by the twang of the bow-string or crack of the hunter's rifle; man had not yet appeared upon the earth.

In regard to the carboniferous measures, geologists are disposed generally to refer all the coal deposits to the Tertiary period, and class them as different forms and grades of lignite. Several deposits of coal in British America are asserted to be anthracite in character, but the anthracitic character of the deposits is claimed to be produced by heat due to local pressure only.

The coal deposits of the Northwest are found to the northward and within the Arctic circle. Coal is known to be due to the mineralized carbonaceous deposits of vegetable life; and, moreover, that life must have been very abundant and favored by the existence of a sub-tropical climate, as is shown by the fossil remains, animal and vegetable. But scientists are at a loss to account for the fact that such a climate and vegetation existed at that time in latitudes far beyond the present limits of trees, or indeed any other growth except mosses and lichens. If astronomy would admit that the poles oi the earth had changed during the life of the infant world, the problem would be solved. Many authorities claim that though the poles of the earth have during past ages pointed towards far different stars than they do now, the geographical poles have always maintained the present angle with the ecliptic or plane of the earth's path around the sun, thus making the seasons always the same as now. Others, however, admit that the axis of the earth may have changed 20, 30 or 40 deg. in inclination. The subject is too involved, except for a student of science, and need not be pursued further. No thorough geological examination of the country has yet been made, and until that