A TRIP TO MT. SHASTA.
Report of a lecture delivered in the National Museum of Washington, D. C., by Prof. J. S. Diller, of the U. S. Geological Survey.
The Great Basin Country is bounded to the westward by the Cascade Range in Oregon and the Sierra Nevada Mountains in eastern California. The axes of these two mountain ranges make an angle of over 140° with each other, and at their point of intersection in northern California rises Mt. Shasta, one of the most conspicuous and imposing topographical features of the Pacific coast, above which it rises 14,440 feet. Early in the days of western exploration its summit was declared to be inaccessible, but whether this assertion was made to inspire greater respect for the abode of the Indian gods, or to excuse a disinclination to physical exertion, must ever remain a matter of conjecture. Certain it is that the ascent, frequently made within the last few years by ladies is not a remarkable feat of mountaineering. Under the direction of Captain Dutton of the Geological Survey, a detailed exploration of the mountain has been accomplished.
The belt of territory bordering upon the Pacific embraces two parallel mountain chains, the Sierra Nevada and Cascade Range on the east, and the illy-defined Coast Range on the west. Between these lies the valley region of the Willamette and Sacramento rivers, whose headwaters are among that complex group of mountains through which the Klamath River, in a deep cañon, finds its way to the sea.
Of all the volcanic regions of the world, the one to which Mt. Shasta belongs is the largest. It extends from Lassen’s Peak, in California, north through Oregon to Mt. Rainier in Washington Territory, and eastward far into Idaho, covering an area larger than that of France and Great Britain combined. Within this wide expanse are extensive plains, whose broad surfaces indicate that the basaltic lava beneath at the time of its eruption possessed such a high degree of fluidity that it spread out far and wide like the waters of a lake. Upon the western border the more viscous lavas built up the Cascade Range, whose mammoth arch is surmounted by numerous mighty volcanoes, among which Mt. Shasta is one of the most prominent.
Seen from all sides Mt. Shasta presents a remarkably regular outline, and its beautiful conoidal form has excited the admiration of many observers. Its slopes are exceptional for the high angle and graceful curves of their inclination. The upper 3,000 feet of the mountain, where cliffs are most abundant, dips away toward all points of the compass at an average angle of 37°. Further down the mountain the slope gradually decreases in inclination to 20°, then to 15°, 10°, and finally the long, gentle slope about the base of the mountain deviates but 5° from a horizontal plane. In all directions from the summit of Mt. Shasta its flanks increase in length as they decrease in angle of inclination, presenting a curved mountain side concave upwards, and has the greatest curvature near the top. Mr. Gilbert, in his excellent monograph of the Henry Mountains, shows that such a curve is the natural result of erosion. In the case of some volcanic mountains, however, an important coöperative cause may be found in the fact that at each successive eruption the lava decreased in quantity and became more viscous. The grandest approach to Mt. Shasta is from the north, in the broad valley of the same name, where it is presented to full view, and the deepest impression of its colossal dimensions is experienced. It stands at the head of Shasta valley, above which it rises 11,000 feet, with a volume of over 224 cubic miles, and presents, in strange contrast with the sterility of the valley, the luxuriant vegetation of the forest belt. The timbered slopes lie between the altitudes 4,000 and 7,000 feet above the sea, and belong to the most magnificent forest regions of the world. Above the forest belt the mountain rises more than a mile into the heights of eternal snow, and its brilliant white slopes present an imposing contrast to the deep green of the pines beneath. Viewed from the southeast, Mt. Shasta appears to be surmounted by a single peak, but seen from the north, the upper portion is found to be double. The smaller of the two cones, broad topped and crater shaped, has been designated Shastina, to distinguish it from the other acute cone, which rises 2,000 feet higher and forms the summit of Shasta proper.