NATIONAL PARK SERVICE Glimpses of our National Parks

XI
THE LASSEN VOLCANIC NATIONAL PARK

Special Characteristic: Volcano in semi-action

ONE of the greatest fields of former volcanic activity in the world lies in the northwestern corner of the United States; its lavas cover a quarter of a million square miles and include large areas of the States of Washington and Oregon and portions of California, Nevada, Idaho, Montana, and Wyoming. Most of this great region now, of course, blooms with forest and prairie. The origin of its soil foundations is apparent only to the eye of the geologist except where the ice-clad cones of monster volcanoes rise from the Cascade Range, where Lassen Peak still vomits smoke and steam, and where remnants of twisted lavas emerge, as on Mount Washburn, above the forests of Yellowstone.

To-day Lassen Peak only is aggressive, and for this reason Congress has set it apart as a national park. Here alone within the borders of the United States may be seen and studied the phenomena of volcanic activity.

Lassen Peak is in northern California at the southern end of the Cascade Range. It had been quiet for 200 years. Then, at the end of May, 1914, as if precursor of the cataclysm of war so soon to follow, an explosion from its summit ushered in a new period of eruption which, feeble as compared with those of its violent past, was magnificent as a spectacle and educationally typical of volcanism.

LASSEN VOLCANO IN ERUPTION Eruption of October 6, 1915, seen from Manzanita Lake, at a distance of 5 miles. A column of "smoke," composed of steam, black with volcanic dust, rose from the crater and at a height of about 3,000 feet above the crater spread to the mushroom form shown above about 30 minutes after the eruption began. Photo © by C. Mullen, who took three views of the eruption, at 10-minute intervals, to show its progress. The "lid" of new lava, formed about May 22, fills the old crater at the time this view was taken, but can not be clearly seen on account of new snow and cloud shadows.

From the first explosion to the end of January, 1916, Lassen remained in more or less constant eruption. Within that period occurred 220 explosions, between which the volcano emitted day and night enormous quantities of smoke and steam.

The greatest of the explosions occurred May 22, 1915, nearly a year after the eruptions began. It was ushered in by the rising of a mushroom-shaped cloud of smoke to a height of 4 miles. Another interesting phenomenon of this explosion was the superheated gas blast which rushed down Lost Creek and Hot Creek Valleys during its continuance. For 10 miles it withered or destroyed every living thing in its path. Large trees were uprooted. Forests were scorched to a cinder, spreading fires. Large snow fields were instantly turned to water and flooded the lower valleys in rushing tides. Fortunately summer visitors had been well warned.

Examination showed that this explosion had opened a new fissure extending 1,000 feet from the summit down the slope toward Chaos Crags, the old and the new craters, now joined in one of irregular shape, filled to the brim with lava, forming what geologists call a lid. After this great explosion activity declined rapidly.

The national park has great natural charm as well as scientific interest. The lava forms, ancient as well as modern, are fantastic and striking. Its fumaroles, its very hot springs, its lofty ragged peak and twisted crater, its extremely interesting Cinder Cone, its minor vents, all have also a strange, almost uncanny, beauty. And these volcanic exhibits are set in an area of forests and ice-cold lakes and rushing trout streams, which add the enchantment of vivid contrast.