Page:Popular Science Monthly Volume 86.djvu/306

vember is doubtless far from complete—the region extending from 15 to 20 miles around the mountain being almost if not entirely deserted by the last of October. The resort at Drakesbad at the southeastern base of the mountain closed for the season on September 21 and the headquarters of the forest service were removed to Red Bluff on October 12. The houses on the stock ranches in the vicinity are also deserted during the winter and the few wagon roads are blocked by deep snow until late in spring. Under the conditions indicated, the fact that October and November together are credited with but sixteen recorded eruptions furnishes no basis for any inference that volcanic activity on Lassen Peak is decreasing. At the date of reading proof the activity continues. A dispatch published in the San Francisco Chronicle, January 23, 1915, describes an eruption from a new crater on the east as equal to any which have gone before. The dispatch adds that no one has visited the volcano’s summit for over two months.

An interesting suggestion concerning the November record comes in a private letter from Mr. Rushing. The eruptions from the summit which were observed during November were all ranked as medium in severity. The suggestion is that this may be explained by the fact that a new vent has been opened at a much lower level. The eruption of November 18 as seen by two observers at stations situated north of west from Lassen came from a point on the north slope of the mountain about a mile from the top and presumably near timber line. A comparison of distant observations from the north and from the south may soon test the correctness of this supposition.

Some further idea of the magnitude of the eruptions of Lassen Peak may be gained from the record of distant observers. A letter from Professor Charles F. Shaw, who was at Amadee about 65 miles eastward from Lassen Peak on October 23, contains particularly interesting observations. The eruption began at 5:40 P.m. The mountain showed plainly over the tops of the nearer hills and the smoke of the eruption was clearly sihouetted against the western sky, extending directly upward from the peak.

The smoke rolled up until practically the entire height [12,000 ft.; see list of eruptions] was reached before any change in form occurred, when just below the top of the column there was a tendency to stratification and a layer extended out toward the south and toward the north. When this appeared, the smoke column began to lean toward the north and from our point of vision, apparently toward the northeast and with this inclination of the column, distortion took place, the upper part spreading out into streamers. As soon as the inclination of the smoke column became very plain, we could readily distinguish indications of falling material. The lower two thirds of the column seemed to be dropping some material that was falling in a slightly oblique line, the obliqueness pointing back toward the mountain peak. As the eruption continued and the smoke column blew out more toward the north, the streaked condition indicating falling material became more and more apparent, but as the light was failing it became rather hard to distinguish the exact outlines of the lower portion of the column.