Millions of years ago, in the period which geologists call Tertiary, the pressure under that part of the crust of the earth which now is Washington, Oregon, and northern California, became too powerful for solid rock to withstand. Long lines of hills appeared parallel to the sea, and gradually rose hundreds, and perhaps thousands, of feet. These cracked, and from the long summit-fissures issued hot lava, which spread over enormous areas and, cooling, laid the foundations for the coming Cascade Mountains.
When the gaping fissures eased the pressure from beneath, they filled with ash and lava except at certain vent holes, around which grew the volcanoes which, when their usefulness as chimneys passed, became those cones of ice and snow which now are the glory of our northwest.
There may have been at one time many hundreds of these volcanoes, big and little. Most of them doubtless quickly perished under the growing slopes of their larger neighbors, and, as they became choked with ash, the lava which had been finding vent through them sought other doors of escape, and found them in the larger volcanoes. Thus, by natural selection, there survived at last that knightly company of monsters now uniformed in ice, which includes, from north to south, such celebrities as Mount Baker, Mount Rainier, Mount Adams, Mount St. Helens, Mount Hood, vanished Mount Mazama, Mount Shasta, and living Lassen Peak.
Whether or not several of these vast beacons lit Pacific's nights at one time can never be known with certainty, but probability makes the claim. Whether or not in their decline the canoes of prehistoric men found harbor by guidance of their pillars of fire by night, and their pillars of smoke by day is less probable but possible. One at least of the giant band, Lassen Peak, is semi-active to-day. At least two others, Mount Rainier and Mount Baker, offer evidences of internal heat beneath their mail of ice. And early settlers in the northwest report Indian traditions of the awful cataclysm in which Mount Rainier lost two thousand feet of cone.
Lassen Peak National Park
Lassen Peak, the last of the Cascades in active eruption, rises between the northern end of the Sierra Nevada Mountains, of which it is locally but wrongly considered a part, and the Klamath Mountains, a spur of the Cascades. Actually it is the southern terminus of the Cascades.
Though quiet for more than two hundred years, the region long has enjoyed scientific and popular interest because it possesses hot springs, mud volcanoes and other minor volcanic phenomena, and particularly because its cones, which are easily climbed and studied, have remained very nearly perfect. Besides Lassen Peak, whose altitude is 10,437 feet, there are others of large size and great interest close by. Prospect Peak attains the altitude of 9,200 feet; Harkness Peak 9,000 feet; and Cinder Cone, a specimen of unusual beauty, 6,907 feet.
Because it seemed desirable to conserve the best two of these examples of recent volcanism, President Taft in 1906 created the Lassen Peak and the Cinder Cone National Monuments. Doubtless there would have been no change in the status of these reservations had not Lassen Peak broken its long sleep in the spring of 1914 with a series of eruptions covering a period of nineteen months. This centred attention upon the region, and in August, 1916, Congress created the Lassen Volcanic National Park, a reservation of a hundred and twenty-four square miles, which included both national monuments, other notable cones of the neighborhood, and practically all the hot springs and other lesser phenomena. Four months after the creation of the national park Lassen Peak ceased activity with its two hundred and twelfth eruption. It is not expected to resume. For some years, however, scientists will continue to class it as semi-active.
These eruptions, none of which produced any considerable lava flow, are regarded as probably the dying gasps of the volcanic energy of the Cascades. They began in May, 1914, with sharp explosions of steam and smoke from the summit crater. The news aroused wide-spread interest throughout the United States; it was the first volcanic eruption within the national boundaries. During the following summer there were thirty-eight slight similar eruptions, some of which scattered ashes in the neighborhood. The spectacle was one of magnificence because of the heavy columns of smoke. Eruptions increased in frequency with winter, fifty-six occurring during the balance of the year.