lieved to have once been a thousand feet loftier than any of these, collapsed during its final convulsion, and Crater Lake, Oregon, now remains in its stead, a body of water two thousand feet deep and six miles in diameter. These have all been considered "extinct" volcanoes. Now with the Lassen eruption, there seems to be no reason why Shasta, or Hood, or Mount Rainier, the last overlooking the cities of Seattle and Tacoma, may not at any time explode. It is true that in the case of Lassen Peak, old Vulcan has never been considered as really dead, since there have been solfataras, hot springs, and geysers on its slope, but such evidence of internal fires is equally true of the other mountains. Mount Rainier, for example, has several steam. caves which, as it happens, have saved

the lives of members of more than one party who, having been caught in terrific blizzards near the summit, crept into these caves, where, though they were nearly steamed alive, still they were saved from the storm and intense cold until the blizzard had subsided.

Twenty-six years ago J. S. Diller, a member of the United States Geological Survey, made a detailed geologic study and map of Lassen Peak and the surrounding country, and wrote a highly entertaining account describing what

was, until the present eruption of Lassen Peak, the most recent volcanic activity in the United States. He described a volcanic outburst from a crater on the lower slopes of Lassen Peak as having occurred about fifty years previous or just about at the period that the United States came into possession of this region through the cession of California by Mexico. At this time the region was totally uninhabited, except by Indians; but the evidence to the geologist of a very recent eruption was indisput

able.

Terrific as the present eruption of Lassen may seem to eye witnesses, it must be like the breaking of a tiny blood vessel compared with the titanic arterial mechanism which pulsed and throbbed and burst forth a thousand times through this entire area during the ages past. There have been twenty-two geologic formations, or different deposits of rock, one on top of the other, the last nine being erupted in a molten condition, forming an average thickness of fully

two thousand feet of lava, spread over a wider area than Great Britain and France combined.

And even preceding this era of turmoil and the rise of Lassen Peak and other huge volcanic cones looming above the present rocky chaos of the Cascade Plateau, the region was subject to many vicissitudes. At one time, so many million years ago that no geologist will venture an estimate, the entire area was the ocean bottom. Then the whole of California was pushed upward from the sea and became dry land; later, during what is known as the cretaceous period, the land subsided and the sea again swept over and covered a large part of the area that had lately been raised above the ocean level. The Pacific at this time occupied nearly the whole of the Lassen Peak district and spread far into Oregon. Still later, Northern California and Oregon were again elevated above the waters, although an arm of the sea separated the Sierra Nevada backbone from the Lassen Peak region.

After this uplifting, the land of Northern California was for long ages subject to continuous erosion

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storm and stream action until it was reduced to almost a plain and the streams were unable to remove the insoluble material resulting from the disintegration of the rocks. As a result the land became coated with a blanket of such material containing quartz, gold, silver, and other minerals, when there was another uplift of the whole region. and the increased velocity of the streams carried the lighter soil material into the Sacramento Valley, while the coarse and heavy material, including the gold and silver, accumulated in the old channels. These have furnished the principal placer mines of the present day that have given up their many millions of precious metal. The gold-bearing gravels of these western mountains have yielded in a little over fifty years over three hundred million dollars.

Some of the gravels which were once at sea level are now on the summits of

COPYRIGHT, 1914, P. J. THOMPSON, SUSANVILLE, CAL

the Sierra Nevada seven thousand feet above the sea. They contain fossil leaves of maple, fig, walnut, magnolia, and other trees common at low altitudes, but none of the pines which are now growing on the mountains. The fossils, petrified remains of land and marine animals, both salt and fresh water, and land forms of animals and plants, are the keys which enable the geologist to trace back into the dim shadowy past of the earth's history and tell of the rise and fall of continents.

occurred. Volcanic activity has never, however, been extinct in the Lassen Peak district as is shown by the continuous presence of numerous solfataras and hot springs which are in evidence about the mountain.

The last violent volcanic eruption, prior to the present one, in the Lassen Peak district, occurred at the cinder cone of the mountain about two hundred years ago. Some of the trees killed at the time were still standing when examined by Geologist Diller. The lava, although very thick and viscous, spread more than a mile from the vent and formed a huge dam, several hundred feet high, creating Snag Lake, which still contains stumps of some of the trees submerged at the time of the formation of the lake. About one hundred and fifty years later, or some time in the first half of the last century, another outbreak of the cinder cone

As distinguished from the past and present white-hot activity of Lassen Peak, enormous glaciers, at intermediate periods, stretched in all directions from the mountain, great ice rivers flowed slowly down the canyons which had been cut through the earlier lavas.

Mr. Diller calls attention to the marked similarity between the Lassen Peak cinder cone and the cinder cone of Mount Vesuvius, and while Lassen Peak has been generally referred to along. with other volcanoes of the Northwest as "extinct", mention is made of the fact that previous to the year 78 A. D., Vesuvius was not recognized by the Greeks and Romans as an active volcano. In that year the first great historic eruption occurred, accompanied by torrents of rain