VOLCANIC NATIONAL PARK UNITED STATES Historic Events Lassen DEPARTMENT OF THE OPENING AND CLOSING INTERIOR DATES DEPEND UPON Harold L. Ickes, Secretary 1820 Arguello exploring party first to Volcanic record and name Lassen Peak WEATHER CONDITIONS (St. Joseph's Mountain). NATIONAL PARK CALIFORNIA 1 19 4 1850-51 Last lava flow from Cinder Cone. NATIONAL PARK SERVICE EARLY FALL SKIING ON SHORE OF Newton B. Drury, Director LAKE HELEN 1864 Helen Brodt, first white woman to climb Lassen Peak, made ascent with Major Reading. Lake Helen named CO^TE^TS for her. Lassen Peak from ASSEN VOLCANIC NA­ GEOLOGIC HISTORY TIONAL PARK, in northeast­ Manzanita Lake . Cover The Cascade Range, which is vol­ ern California, was created by (Eastman Photo) 1906 May 6. Lassen Peak and Cinder Cone L canic in origin, is not ancient, measured act of Congress approved August 9, Geologic History 3 National Monuments established. in geologic time. Its beginning dates 1916, to preserve Lassen Peak and the back to the Pliocene period, about a Lassen Peak and Vicinity . 3 park area of 163.32 square miles con­ million years before the great ice age Chaos Crags and Chaos taining spectacular volcanic exhibits or glacial epoch. The present range 1914 May 30. First known eruption of which surrounds it. This impressive rests upon a great platform of lava Jumbles 6 Lassen Peak since coming of white peak, from which the park derives its flows, which issued from many vents man. Ancestral Mount Tehama . 6 name, stands near the southern end of and fissures. These lavas accumulated, Cinder Cone Area ... 7 the Cascade Mountains and is the only flow upon flow, to depths of several recently active volcano in the United thousand feet over wide areas in Wash­ View from Lassen Peak . 8 States proper. Its last eruptions, ington, Oregon, southern Idaho, and 1915 May 19 and 22. Major eruptions of occurring between 1914 and 1921, Wildlife 8 Lassen Peak devastated large forest northern California. Later this plat­ Fishing 10 aroused popular and scientific interest form was bent, or arched, slightly up­ in the area. ward along the line of the Cascades. Camping 10 Lassen Peak was named for Peter No more widespread floods of lava Educational Activities ... 10 Lassen, an early pioneer in northern came forth, but numerous localized 1916 Lassen Volcanic National Park cre­ Administration 11 California. He was born near Copen­ eruptions produced the magnificent ated by act of Congress. series of peaks which are now snow­ How to Reach the Park . .11 hagen, Denmark, in 1800, and came to the United States when he was capped and for which the Cascades are Accommodations and Services. 13 thirty. After he became acquainted famous. with northern California, he piloted What to Do and See .... 15 1921 Lassen Peak ceased to erupt and sub­ LASSEN PEAK AND VICINITY.—The Other Sections of Park . .15 sided into a state of quiescence. emigrants from Humboldt, Nev., into western part of the park includes a the Sacramento Valley, using Lassen profusion of volcanic peaks of the Peak as a landmark. "dome" type, of which Lassen Peak 2 jZassen Volcanic iSational "Park * California £assen Volcanic T^ational Tark * Qali]ornia 3 itself is the outstanding example. about the rising dome while the moun­ Others include White Mountain, Chaos tain was still growing and formed Crags, Eagle Peak, and Bumpas Moun­ great rock slides on its slopes, much tain, all closely related in origin. as they appear today. This rock mantle The great cone of Lassen Peak, ris­ (talus) in places reaches almost to the ing 10,453 feet above sea level, on the summit and caps the bulging dome in north slope of an ancestral mountain, the form of a cone. is almost completely wrapped in a Compared with the slow upbuilding smooth-sloping mantle of rock frag­ of the more common type of volcano, ments, broken from its own cliffs. Las­ the rate of growth of an upswelling sen differs from the "strato-volcanoes," dome is phenomenally rapid, as wit­ the most common type, which are built nessed by the history of Santa Maria, in Guatemala, and Mont Pelee, in the up of alternate beds of lava and frag- Island of Martinique. By comparison mental material, sloping away steeply with the growth of these two domes from a central crater. The mountain it has been estimated that the steep as it stands today has passed through cone of Lassen Peak may have been two stages of growth. The earlier Las­ thrust up in a comparatively short time. sen was a broad, gently sloping vol­ Grant Photo cano of the "shield" type, built of layer Most dome volcanoes have no crater WEIRD CINDER DEPOSITS NEAR BUTTE LAKE ARE COLORED IN SOFT SHADES upon layer of lava. at the top, but at Lassen Peak gases OF RED, BROWN, AND YELLOW It rose by a succession of lava flows escaping from lavas deep below main­ to an elevation above 8,500 feet, with tain open conduits through the softer, On May 30, 1914, a series of erup­ and lesser mud flow moved down the a base 5 miles across from north to central part of the cone. The violence tions began which lasted until February same slope, and minor flows took place south and 7 miles from east to west. of their discharge at times shoots forth 1921, the most recent volcanic activity on the north and west flanks of the In the second stage the steep Lassen lava in dustlike form, producing the in United States proper. Unfortunately, volcano. At the same time a terrific cone was built on this broad, substan­ so-called volcanic "ash" of the tuff beds during this period no scientific observ­ hot blast, heavily charged with dust tial platform. This, the more conspicu­ and "mud" flows. Such activity opens er was present in the region to record and rock fragments, was discharged ous portion, represents a still rarer a funnel-shaped or cuplike crater at and report the detailed account of down the northeast flank of the peak. "dome" type of volcano, formed by the top. Before the eruptions of 1914- events. So violent was this outburst that trees stiff, viscous lava which was pushed up 21 the crater of Lassen Peak was an Violent eruptions occurred in May on the slopes of Raker Peak, more than through the vent, like thick paste oval bowl approximately 1,000 feet 1915. On May 19 the first glowing 3 miles away, were felled uniformly in squeezed from a tube. Piling up in across and 360 feet deep. lava made its appearance, rising in the the direction of the on-rushing blast. and around the old crater, this stiff Following the rise of the Lassen new crater and spilling through the At the same time a vertical column of lava rose in a bulging domelike form Dome, there was a long period of western notch in the crater rim in the smoke and ash rose more than 5 miles high above it. quiescence. Nevertheless, prior to the form of a tongue which reached down above Lassen crater. Movements due to the rise of lava activity of 1914-21 one or more "mud" the slope 1,000 feet. During the night into the upswelling mass, the pressure flows had swept down the northeastern The energy of the volcano was large­ of May 19 the snow was melted on the of steam and gases imprisoned within slope, probably within the past 500 ly spent by the end of the 1915 erup­ northeastern slope, causing destructive it, and the chill of the outer portions years, as judged from the state of tion. With only occasional outbursts of flows of mud which swept 20-ton on exposure to the air caused a con­ preservation of logs that were buried steam and ash, the activity subsided boulders 5 to 6 miles into the valleys tinuous breaking away of huge blocks in the mud and recently have been during the next 2 years. A series of of Hat Creek and Lost Creek. and slabs of rock accompanied by many uncovered along the course of Lost violent explosions occurred in May and smaller fragments. These accumulated Creek. Three days later, on May 22, another June 1917, following the melting of 4 JCassen Volcanic Rational Tark • California JZassen Volcanic ISfational Tark * California 5 considerable quantities of snow. The of the rising masses, and the domes activity of 1916 and 1917 produced were thrust up through their own ac­ little effect besides modifying the form cumulating debris. of the crater by opening new vents The north dome had risen 1,800 feet within it. Most of the crater is now above the surrounding country when filled by the rough, blocky lava which explosions at the base of the rising rose into it in May 1915; but at the mass blasted away the support from northwest a yawning chasm through the north face and hurled vast quanti­ the crater wall was opened by later ex­ ties of broken and falling lava out plosive eruptions. In view of the vol­ upon the cinder-covered region below. canic history of the region, renewed This rock blast was shot forward with activity at Lassen is not probable for such momentum that its front advanced many years, although there is no reason 400 feet up the opposite slope of Table to suppose that the volcano is yet ex­ Mountain, 2 miles distant from the tinct. craters at the north foot of the Crags, and stopped there with an abrupt front. CHAOS CRAGS AND CHAOS JUMBLES.