Lassen is the southernmost fire mountain of that numerous group of volcanoes that have so greatly changed the surface of the Northwest. Among its conspicuous volcanic companions are Crater Lake, formerly Mount Mazama, Mount Hood, Mount St. Helens, Mount Baker, and Mount Rainier. Until Lassen Peak burst forth in 1914 it had slumbered for centuries, and was commonly considered extinct. It has probably been intermittently active for ages. Many geologists think that this activity has extended through not less than two million years. Just how long it may show its red tongue and its black clouds of breath is uncertain; and just how violent and how voluminous its eruptions may become are matters of conjecture.
All about Lassen Peak are striking exhibits of vulcanism—fields of lava, quantities of obsidian or natural glass, sulphur springs, hot springs, volcanic sand and volcanic bombs, and recent volcanic topography, including Snag Lake.
Copyright, 1914, by B. F. Loomis
Two of the imposing cañons here are Los Molinos and Warner Cañon. These and other changes in the sides of Lassen Peak illustrate the old, ever-interesting, and eternal story of erosion. Both these cañons are wild places which have cut and eroded deeply into the ancient lavas of Mount Lassen. Frost and water have reshaped the work of fire. The mountain's sides show that it withstood the latest visits of the Ice King. What appear to be the distinct records of glacial erosion mark many spaces of its slopes.
The eruption of May 19, 1915, produced many changes. A volume of super-heated gases burst out beneath the deeply snow-covered northeast slope. The snow was instantly changed into water and steam. The mighty downrush and onrush of water wrecked the channel of Lost Creek for several miles. Meadows were piled with boulders, rock fragments, and finer débris. Trees were uprooted or broken off, carried downward, and left in piles of fierce confusion.
The hot gases played havoc with the forests. A stretch from a quarter of a mile to nearly a mile wide and about ten miles long was killed by the heat of the sweeping hurricane. Thousands of trees were instantly killed and their green changed to brown. Others were charred. Forest fires were started in a number of places.
The spectacular ruins which this left behind—the trees, wreckage, slides, the changes made by ashes—may now be viewed with ease and safety. It is probable that for years to come this volcanic wreckage will be seen by thousands of visitors annually.
Fiery Lassen Peak is snow-crowned. One may ride to its summit on horseback. From the top one has magnificent views of the mountains to the north, the distant Coast Range, and the mountains eastward by the Great Basin. On the whole, the surrounding mountain distances are hardly excelled for grandeur in the entire country.
Cinder Cone is about ten miles to the northeast of Lassen Peak. It has an altitude of only 6907 feet. It appears to have been built up chiefly during the last two hundred years and for the most part by two eruptions. One of these occurred nearly two hundred years ago. It originated Stump Lake and ejected and spread materials over considerable territory. The more recent eruption appears to have taken place less than a century ago. In the summer of 1890 I found in the crater a lodge-pole pine that was about eighty years of age.